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Riechelmann C, Habashy MM, Rene ER, Moussa MS, Hosney H. Assessment of hybrid fixed and moving bed biofilm applications for wastewater treatment capacity increase - In situ tests in El-Gouna WWTP, Egypt. Chemosphere 2024; 355:139783. [PMID: 37574084 DOI: 10.1016/j.chemosphere.2023.139783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 07/11/2023] [Accepted: 08/08/2023] [Indexed: 08/15/2023]
Abstract
This paper provides a procedure for comparing the performance of different biofilm carrier medias and their surrounding suspended biomass through oxygen uptake rate (OUR) tests. For in situ (oxygen uptake rate (OUR) measurements, three identical lab scale biofilm reactors were set up at the El Gouna wastewater treatment plant (WWTP). In this setup, two options of media for moving-bed biofilm reactors (MBBR) and one media for fixed-bed biofilm reactors (FBBR) were compared. The WWTP also used the same carrier in a real scale hybrid application to analyze how the interactions between the carrier type and the suspended biomass influences the overall performance. The in situ OUR approach is recommended to measure the contribution of the biofilm fixed biomass under site specific conditions. Specifically, settleability and diffusion limitations are the two opposite poles that cannot be predicted adequately for mild climate conditions based on the literature. A biofilm carrier application can add but actually can also reduce the capacity in a hybrid activated sludge system: The added MBBR-media was able to grind down the sludge flocs forming a poorly settleable suspended biomass. The added FBBR-media can lead to extracellular polymeric substances (EPS) rich biofilms that contribute very little as substrate and oxygen are unavailable for the microorganisms present in the biofilm. In this application of the comparison procedure, Kaldnes K1 like MBBR media was compared with a recycling MBBR carrier option (poly propylene bottle caps) and Jäger Envirotech "BioCurlz™" FBBR media. The study showed higher average rates for the MBBR but decreased settleability. The FBBR showed higher peak rates when flushed to break up the biofilm and well settleable sludge. The determination of OUR per g of volatile solids (SOUR) showed comparable results for all the carriers and in warm conditions, only the capacity to accommodate biomass determines the contribution of the carrier.
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Affiliation(s)
- Carsten Riechelmann
- Department of Urban Water Management, Faculty of Civil Engineering, Technische Universität Berlin, Germany
| | - Mahmoud M Habashy
- Department of Water Supply, Sanitation, and Environmental Engineering, IHE Delft Institute for Water Education, Westvest 7, 2611 AX, Delft, the Netherlands
| | - Eldon R Rene
- Department of Water Supply, Sanitation, and Environmental Engineering, IHE Delft Institute for Water Education, Westvest 7, 2611 AX, Delft, the Netherlands
| | - Moustafa S Moussa
- Director of Sustainable Development Center, Zewail City of Science and Technology, Giza, Egypt; Faculty of Engineering Mataria, Helwan University, Cairo, Egypt
| | - Hadeel Hosney
- Department of Water Supply, Sanitation, and Environmental Engineering, IHE Delft Institute for Water Education, Westvest 7, 2611 AX, Delft, the Netherlands.
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Gao X, Liu Y, Tang C, Lu M, Zou J, Li Z. Evaluating river health through respirogram metrics: Insights from the Weihe River basin, China. Sci Total Environ 2024; 919:170805. [PMID: 38342463 DOI: 10.1016/j.scitotenv.2024.170805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 01/18/2024] [Accepted: 02/06/2024] [Indexed: 02/13/2024]
Abstract
Human activities pose a significant threat to rivers, requiring robust assessment methods for effective river management. This study focuses on the Weihe River Basin in Shaanxi province and introduces the respirogram as an innovative assessment technique. The respirogram allows the simultaneous assessment of river health from two important aspects: pollution levels and microbial status. Specifically, the in-situ respiration ratio (Rs/t) serves as an indicator of pollution, with higher Rs/t values correlating with increased pollution levels. Conversely, the recovery index (RI) measures microbial vitality, with values below 0.15 indicating greater microbial activity and recovery potential. Using predefined thresholds of Rs/t = 0.3 and RI = 0.15, water bodies were categorized into four types. For example, rivers with Rs/t > 0.3 and RI > 0.15 were identified as receiving sewage, characterized by high pollution and low microbial vitality. Similarly, different assessment criteria delineated urban rivers, natural rivers, and wastewater treatment plants. Based on these classifications, targeted engineering measures were proposed to enhance the self-purification capabilities of rivers of different statuses.
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Affiliation(s)
- Xingdong Gao
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Yanxia Liu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Congcong Tang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Meng Lu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Jiageng Zou
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Zhihua Li
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
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Lu M, Zhao F, Qin F, Zhang F, Feng Q, Guo R. Novel flocking materials as biocarriers in moving bed biofilm reactor for improving simultaneous nitrification and denitrification performance. Bioresour Technol 2024; 396:130430. [PMID: 38342280 DOI: 10.1016/j.biortech.2024.130430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 02/05/2024] [Accepted: 02/06/2024] [Indexed: 02/13/2024]
Abstract
Biocarrier is the key factor for the stable operation of moving bed biofilm reactor (MBBR). To achieve efficient simultaneous nitrification and denitrification (SND), this study provided novel flocking materials as biocarriers. The biofilm formation experiment showed that longer flocking carrier was more conducive to biomass accumulation, resulting in greater oxygen uptake rate. The continuous operation results showed that the total nitrogen removal and SND performance of the MBBR with the addition of 5.0 mm flocking carriers reached 52.0 % and 70.5 %, respectively, which were 29.1 % and 33.3 % greater than those of the control. Compared with those in suspended sludge, the extracellular polymeric substances and protein components in the biocarrier were more abundant. Furthermore, the relative abundance of genera related to denitrification and the nitrogen metabolic sequence improved with the addition of the novel flocking biocarriers. This study demonstrated the effectiveness of novel flocking fillers in improving the performance of MBBR.
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Affiliation(s)
- Mingyi Lu
- Shandong Engineering Research Center for Biogas, Qingdao New Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China
| | - Feng Zhao
- Shandong Engineering Research Center for Biogas, Qingdao New Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China
| | - Fan Qin
- Shandong Engineering Research Center for Biogas, Qingdao New Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China
| | - Fengyuan Zhang
- Shandong Engineering Research Center for Biogas, Qingdao New Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Quan Feng
- Shandong Engineering Research Center for Biogas, Qingdao New Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China.
| | - Rongbo Guo
- Shandong Engineering Research Center for Biogas, Qingdao New Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China
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Ao Z, Li H, Chen J, Yuan J, Xia Z, Zhang J, Chen H, Wang H, Liu G, Qi L. A new approach to optimizing aeration using XGB-Bi-LSTM via the online monitoring of oxygen transfer efficiency and oxygen uptake rate. Environ Res 2023; 238:117142. [PMID: 37739155 DOI: 10.1016/j.envres.2023.117142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 09/04/2023] [Accepted: 09/13/2023] [Indexed: 09/24/2023]
Abstract
In wastewater treatment plants (WWTPs), aeration is vital for microbial oxygen needs. To achieve carbon neutrality, optimizing aeration for energy and emissions reduction is imperative. Machine learning (ML) is used in wastewater treatment to reveal complex rules in large data sets has become a trend. In this vein, the present paper proposes an aeration optimization approach based on the extreme gradient boosting-bidirectional long short-term memory (XGB-Bi-LSTM) model via the online monitoring of oxygen transfer efficiency (OTE) and oxygen uptake rate (OUR), thus allowing WWTPs to conserve energy and reduce indirect carbon emissions. The approach uses gain algorithm of XGB to calculate the importance of features and identify important parameters, and then uses Bi-LSTM to predict the target with important parameters as features. Operational data from a WWTP in Suzhou, China, is employed to train and test the approach, the performance of which is compared with ML models suitable for regression prediction tasks (XGB, random forest, light gradient boosting machine, gradient boosting and LSTM). Experimental results show the approach requires only a small number of input parameters to achieve good performance and outperforms other machine-learning models. When OTE and dissolved oxygen (DO) are used as features to predict the alpha factor (αF; since diffusers were used, multiply by the pollution factor F), the R-squared (R2) is 0.9977, the root mean square error (RMSE) is 0.0043, the mean absolute percentage error (MAPE) is 0.0069 and the median absolute error (MedAE) is 0.0032. When the predicted αF and the OUR are used as features to predict the air flow rate of an aeration unit, the R2 is 0.9901, the RMSE is 3.6150, the MAPE is 0.0209 and the MedAE is 1.5472. Using our optimized aeration approach, the energy consumption can be reduced by 23%.
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Affiliation(s)
- Ziding Ao
- Research Center for Low Carbon Technology of Water Environment, School of Environment and Natural Resource, Renmin University of China, Beijing, 100872, China
| | - Hao Li
- School of Environment and Natural Resource, Renmin University of China, Beijing, 100872, China
| | - Jiabo Chen
- Research Center for Low Carbon Technology of Water Environment, School of Environment and Natural Resource, Renmin University of China, Beijing, 100872, China
| | - Junli Yuan
- China Forestry Digital Co., Ltd, Beijing, 100036, China
| | - Zhiheng Xia
- Research Center for Low Carbon Technology of Water Environment, School of Environment and Natural Resource, Renmin University of China, Beijing, 100872, China
| | - Jinsen Zhang
- Research Center for Low Carbon Technology of Water Environment, School of Environment and Natural Resource, Renmin University of China, Beijing, 100872, China
| | - Huiling Chen
- Research Center for Low Carbon Technology of Water Environment, School of Environment and Natural Resource, Renmin University of China, Beijing, 100872, China
| | - Hongchen Wang
- Research Center for Low Carbon Technology of Water Environment, School of Environment and Natural Resource, Renmin University of China, Beijing, 100872, China
| | - Guohua Liu
- Research Center for Low Carbon Technology of Water Environment, School of Environment and Natural Resource, Renmin University of China, Beijing, 100872, China
| | - Lu Qi
- Research Center for Low Carbon Technology of Water Environment, School of Environment and Natural Resource, Renmin University of China, Beijing, 100872, China.
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5
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Hang Z, Tong P, Zhao P, He Z, Shao L, Jia Y, Wang XC, Li Z. Hierarchical stringent response behaviors of activated sludge system to stressed conditions. Sci Total Environ 2023; 870:161832. [PMID: 36716870 DOI: 10.1016/j.scitotenv.2023.161832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/18/2023] [Accepted: 01/21/2023] [Indexed: 06/18/2023]
Abstract
The stringent response of activated sludge systems to either stressed or harmful environments is important for the stable operation of activated sludge, which is examined by taking copper ion (Cu2+) as a stress model in this study. When weak stress was employed (Cu2+ ≤ 2.5 mg/L), the N-acyl-homoserine lactones (AHLs) of C6-, C8-, and C10-HSL increased by 30 %, 13 %, and 127 %, respectively, while the redox sensor green (RSG) intensity decreased by 28 %. Encountering the increased stress (2.5 mg/L < Cu2+ ≤ 5 mg/L), bacteria concentration in the supernatant increased by 87 %. However, the respiration rates of autotrophic and heterotrophic bacteria (SOURa and SOURh) and adenosine triphosphate decreased by 52 %, 18 %, and 27 %, respectively, and the flocs disintegrated with a diameter decreasing from 57 to 51 μm. When the stress became more serious (Cu2+ > 5 mg/L), the respiration rates continued to decline, but the quasi-endogenous respiration ratio (Rq/t) increased from 31 % to 47 %. Negligible changes occurred in the endogenous respiration rate (SOURe), adenosine diphosphate, and adenosine monophosphate. Based on these results, a hierarchical stringent response model of the activated sludge system to stressed conditions was proposed, and these responses were evaluated by respirogram. The initial response to weak stress was related to the most sensitive signals of quorum sensing and RSG intensity, well described by the quasi-endogenous respiration rate. The adaptive response to increased stress was the proactive migrations of low- and high-nucleic-acid bacteria to the supernatant, causing the looseness and even disintegration of sludge flocs, well described by SOURa, SOURh, and Rq/t. The lethal response to lethal stress was related to endogenous metabolic processes, well described by SOURe. This work provides new insights into understanding the stringent response of activated sludge systems to some stressed conditions. It helps to regulate the stability of activated sludge systems with respirogram technology.
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Affiliation(s)
- Zhenyu Hang
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Peipei Tong
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Pian Zhao
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Zhangwei He
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Linjun Shao
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Yanru Jia
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Xiaochang C Wang
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Zhihua Li
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology in Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
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6
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Li Z, Zhang Y, Hang Z, Lu M, Wang H, Gao X, Zhang R. A novel approach to estimate and control denitrification performance in activated sludge systems with respirogram technology. J Environ Sci (China) 2022; 121:112-121. [PMID: 35654502 DOI: 10.1016/j.jes.2021.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 09/07/2021] [Accepted: 09/07/2021] [Indexed: 06/15/2023]
Abstract
Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the evaluation of the performance of denitrification. The size distribution of flocs measured at different denitrification moments demonstrated a clear expansion of flocs triggered by denitrification, during which higher specific endogenous and quasi-endogenous respiration rates (SOURe and SOURq) were also observed. Furthermore, SOURq increases exponentially with the specific denitrification rate (SDNR), suggesting that there should be a maximum SDNR in conventional activated sludge systems. Based on these findings, an index Rq/t, defined as the ratio of quasi-endogenous (OURq) to maximum respiration rate (OURt), is proposed to estimate the denitrification capacity that higher Rq/t indicates higher denitrification potential, which can be readily obtained without complex measurement or analysis, and it offers a novel and promising respirogram-based approach for denitrification estimation and control by taking measures to extend anoxic time to maintain its value at a high level within a certain range.
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Affiliation(s)
- Zhihua Li
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
| | - Yali Zhang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Zhenyu Hang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Meng Lu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Haiguang Wang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Xingdong Gao
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Ruina Zhang
- Shanghai Environmental & Sanitary Engineering Design Institute Co. Ltd., Shanghai 200232, China
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Trout M, Harcum SW, Groff RE. Sensitive real-time on-line estimator for oxygen transfer rates in fermenters. J Biotechnol 2022; 358:92-101. [PMID: 36116734 DOI: 10.1016/j.jbiotec.2022.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 09/12/2022] [Indexed: 11/16/2022]
Abstract
Recombinant Escherichia coli grown in large-scale fermenters are used extensively to produce plasmids and biopharmaceuticals. One method commonly used to control culture growth is predefined glucose feeding, often an exponential feeding profile. Predefined feeding profiles cannot adjust automatically to metabolic state changes, such as the metabolic burden associated with recombinant protein expression or high-cell density associated stresses. As the culture oxygen consumption rates indicates a culture's metabolic state, there exist several methods to estimate the oxygen uptake rate (OUR). These common OUR methods have limited application since these approaches either disrupt the oxygen supply, rely on empirical relationships, or are unable to account for latency and filtering effects. In this study, an oxygen transfer rate (OTR) estimator was developed to aid OUR prediction. This non-disruptive OTR estimator uses the dissolved oxygen and the off-gas oxygen concentration, in parallel. This new OTR estimator captures small variations in OTR due to physical and chemical manipulations of the fermenter, such as in stir speed variation, glucose feeding rate change, and recombinant protein expression. Due its sensitivity, this non-disruptive real-time OTR estimator could be integrated with feed control algorithms to maintain the metabolic state of a culture to a desired setpoint.
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Affiliation(s)
- Marshall Trout
- Department of Electrical and Computer Engineering, Clemson University, Clemson, SC 29634, United States
| | - Sarah W Harcum
- Department of Bioengineering, Clemson University, Clemson, SC 29634, United States.
| | - Richard E Groff
- Department of Electrical and Computer Engineering, Clemson University, Clemson, SC 29634, United States
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Takács E, Wang J, Chu L, Tóth T, Kovács K, Bezsenyi A, Szabó L, Homlok R, Wojnárovits L. Elimination of oxacillin, its toxicity and antibacterial activity by using ionizing radiation. Chemosphere 2022; 286:131467. [PMID: 34346325 DOI: 10.1016/j.chemosphere.2021.131467] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 07/04/2021] [Accepted: 07/06/2021] [Indexed: 06/13/2023]
Abstract
The chemical changes caused by electron beam and γ irradiations and the biochemical characteristics of degradation products of a frequently used antibiotic oxacillin were investigated and compared with those of cloxacillin by applying pulse radiolysis, chemical and biochemical oxygen demand, total organic carbon content, oxygen uptake rate, toxicity and antibacterial activity measurements. Oxacillin was found to be non-toxic, but poorly biodegradable by the mixed microbial population of the activated sludge of a wastewater treatment plant. Therefore, it can significantly contribute to the spread of β-lactam antibiotic resistant bacteria. However, the products formed by γ-irradiation were more easily biodegradable as they were utilized as nutrient source by the microbes of the activated sludge and the products did not show antibacterial activity. During irradiation treatment of aerated aqueous solutions mainly hydroxyl radicals induce the elimination of antimicrobial activity by making alterations at the bicyclic β-lactam part of these antibiotics. Since the β-lactam part is the same in oxacillin and cloxacillin, the biochemical characteristics of products of the two antibiotics are similar. The attack of hydrated electron takes place on the carbonyl groups. When the irradiation is made under anoxic conditions these reactions may also contribute considerably to alterations at the β-lactam part and thereby to the loss of antibacterial activity.
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Affiliation(s)
- Erzsébet Takács
- Radiation Chemistry Department, Institute for Energy Security and Environmental Safety, Centre for Energy Research, H-1121, Konkoly-Thege Miklós út 29-33, Budapest, Hungary.
| | - Jianlong Wang
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084, PR China
| | - Libing Chu
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084, PR China
| | - Tünde Tóth
- Radiation Chemistry Department, Institute for Energy Security and Environmental Safety, Centre for Energy Research, H-1121, Konkoly-Thege Miklós út 29-33, Budapest, Hungary; Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, H-1111, Szent Gellért Tér 4, Budapest, Hungary
| | - Krisztina Kovács
- Radiation Chemistry Department, Institute for Energy Security and Environmental Safety, Centre for Energy Research, H-1121, Konkoly-Thege Miklós út 29-33, Budapest, Hungary
| | - Anikó Bezsenyi
- Budapest Sewage Works Pte Ltd, H-1087, Asztalos Sándor út 4, Budapest, Hungary; Óbuda University, H-1034, Bécsi út 96b, Budapest, Hungary
| | - László Szabó
- Radiation Chemistry Department, Institute for Energy Security and Environmental Safety, Centre for Energy Research, H-1121, Konkoly-Thege Miklós út 29-33, Budapest, Hungary
| | - Renáta Homlok
- Radiation Chemistry Department, Institute for Energy Security and Environmental Safety, Centre for Energy Research, H-1121, Konkoly-Thege Miklós út 29-33, Budapest, Hungary
| | - László Wojnárovits
- Radiation Chemistry Department, Institute for Energy Security and Environmental Safety, Centre for Energy Research, H-1121, Konkoly-Thege Miklós út 29-33, Budapest, Hungary
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Survyla A, Levisauskas D, Urniezius R, Simutis R. An oxygen-uptake-rate-based estimator of the specific growth rate in Escherichia coli BL21 strains cultivation processes. Comput Struct Biotechnol J 2021; 19:5856-5863. [PMID: 34765100 PMCID: PMC8564730 DOI: 10.1016/j.csbj.2021.10.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 10/05/2021] [Accepted: 10/09/2021] [Indexed: 11/24/2022] Open
Abstract
The cell cultivation process in a bioreactor is a high-value manufacturing process that requires excessive monitoring and control compatibility. The specific cell growth rate is a crucial parameter that describes the online quality of the cultivation process. Most methods and algorithms developed for online estimations of the specific growth rate controls in batch and fed-batch microbial cultivation processes rely on biomass growth models. In this paper, we present a soft sensor – a specific growth rate estimator that does not require a particular bioprocess model. The approach for online estimation of the specific growth rate is based on an online measurement of the oxygen uptake rate. The feasibility of the estimator developed in this study was determined in two ways. First, we used numerical simulations on a virtual platform, where the cell culture processes were theoretically modeled. Next, we performed experimental validation based on laboratory-scale (7, 12, 15 L) bioreactor experiments with three different Escherichia coli BL21 cell strains.
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Affiliation(s)
- Arnas Survyla
- Department of Automation, Kaunas University of Technology, Studentu 48, LT-51367 Kaunas, Lithuania
| | - Donatas Levisauskas
- Department of Automation, Kaunas University of Technology, Studentu 48, LT-51367 Kaunas, Lithuania
| | - Renaldas Urniezius
- Department of Automation, Kaunas University of Technology, Studentu 48, LT-51367 Kaunas, Lithuania
| | - Rimvydas Simutis
- Department of Automation, Kaunas University of Technology, Studentu 48, LT-51367 Kaunas, Lithuania
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Cervantes-Avilés P, Caretta CA, Brito EMS, Bertin P, Cuevas-Rodríguez G, Duran R. Changes in bacterial diversity of activated sludge exposed to titanium dioxide nanoparticles. Biodegradation 2021; 32:313-326. [PMID: 33811584 DOI: 10.1007/s10532-021-09939-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 03/24/2021] [Indexed: 11/29/2022]
Abstract
The rapid growth of the use of nanomaterials in different modern industrial branches makes the study of the impact of nanoparticles on the human health and environment an urgent matter. For instance, it has been reported that titanium dioxide nanoparticles (TiO2 NPs) can be found in wastewater treatment plants. Previous studies have found contrasting effects of these nanoparticles over the activated sludge process, including negative effects on the oxygen uptake. The non-utilization of oxygen reflects that aerobic bacteria were inhibited or decayed. The aim of this work was to study how TiO2 NPs affect the bacterial diversity and metabolic processes on an activated sludge. First, respirometry assays of 8 h were carried out at different concentrations of TiO2 NPs (0.5-2.0 mg/mL) to measure the oxygen uptake by the activated sludge. The bacterial diversity of these assays was determined by sequencing the amplified V3-V4 region of the 16S rRNA gene using Illumina MiSeq. According to the respirometry assays, the aerobic processes were inhibited in a range from 18.5 ± 4.8% to 37.5 ± 2.0% for concentrations of 0.5-2.0 mg/mL TiO2 NPs. The oxygen uptake rate was affected mainly after 4.5 h for concentrations higher than 1.0 mg/mL of these nanoparticles. Results indicated that, in the presence of TiO2 NPs, the bacterial community of activated sludge was altered mainly in the genera related to nitrogen removal (nitrogen assimilation, nitrification and denitrification). The metabolic pathways prediction suggested that genes related to biofilm formation were more sensitive than genes directly related to nitrification-denitrification and N-assimilation processes. These results indicated that TiO2 NPs might modify the bacteria diversity in the activated sludge according to their concentration and time of exposition, which in turn impact in the performance of the wastewater treatment processes.
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Affiliation(s)
- Pabel Cervantes-Avilés
- Departamento de Ingeniería Civil and Ambiental, DI-CGT, Universidad de Guanajuato, Av. Juárez 77, Col. Centro, 36000, Guanajuato, Gto, Mexico.,Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Reserva Territorial Atlixcayotl, vía Atlixcayotl 5718, 72453, Puebla, Pue, Mexico
| | - César Augusto Caretta
- Departamento de Astronomía, DCNE-CGT, Universidad de Guanajuato, Callejón de Jalisco S/N, Col. Valenciana, 36023, Guanajuato, Gto, Mexico
| | - Elcia Margareth Souza Brito
- Departamento de Ingeniería Civil and Ambiental, DI-CGT, Universidad de Guanajuato, Av. Juárez 77, Col. Centro, 36000, Guanajuato, Gto, Mexico.
| | - Pierre Bertin
- Institut de Biologie Intégrative de la Cellule, Université Paris Sud, Batiment 400, 91400, Orsay, France
| | - Germán Cuevas-Rodríguez
- Departamento de Ingeniería Civil and Ambiental, DI-CGT, Universidad de Guanajuato, Av. Juárez 77, Col. Centro, 36000, Guanajuato, Gto, Mexico
| | - Robert Duran
- Equipe Environment et Microbiologie, MELODY Group, IPREM UMR CNRS 5254, Université de pau et des pays de l'Adour, BP 1155, 64013, Pau Cedex, France
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Martínez-Monge I, Roman R, Comas P, Fontova A, Lecina M, Casablancas A, Cairó JJ. New developments in online OUR monitoring and its application to animal cell cultures. Appl Microbiol Biotechnol 2019; 103:6903-17. [PMID: 31309268 DOI: 10.1007/s00253-019-09989-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 06/17/2019] [Accepted: 06/17/2019] [Indexed: 10/26/2022]
Abstract
The increasing demand for biopharmaceuticals produced in mammalian cells has driven the industry to enhance the productivity of bioprocesses through intensification of culture process. Fed-batch and perfusion culturing strategies are considered the most attractive choices, but the application of these processes requires the availability of reliable online measuring systems for the estimation of cell density and metabolic activity. This manuscript reviews the methods (and the devices used) for monitoring of the oxygen consumption, also known as oxygen uptake rate (OUR), since it is a straightforward parameter to estimate viable cell density and the physiological state of cells. Furthermore, as oxygen plays an important role in the cell metabolism, OUR has also been very useful to estimate nutrient consumption, especially the carbon (glucose and glutamine) and nitrogen (glutamine) sources. Three different methods for the measurement of OUR have been developed up to date, being the dynamic method the golden standard, even though DO and pH perturbations generated in the culture during each measurement. For this, many efforts have been focused in developing non-invasive methods, such as global mass balance or stationary liquid mass balance. The low oxygen consumption rates by the cells and the high accuracy required for oxygen concentration measurement in the gas streams (inlet and outlet) have limited the applicability of the global mass balance methodology in mammalian cell cultures. In contrast, stationary liquid mass balance has successfully been implemented showing very similar OUR profiles compared with those obtained with the dynamic method. The huge amount of studies published in the last years evidence that OUR have become a reliable alternative for the monitoring and control of high cell density culturing strategies with very high productivities.
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Jiang Y, van der Welle JE, Rubingh O, van Eikenhorst G, Bakker WAM, Thomassen YE. Kinetic model for adherent Vero cell growth and poliovirus production in batch bioreactors. Process Biochem 2019; 81:156-164. [PMID: 31217725 PMCID: PMC6559155 DOI: 10.1016/j.procbio.2019.03.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mathematical model for Vero cell growth in batch bioreactors. Mathematical model for poliovirus proliferation on Vero cells. Oxygen uptake rate as process analytical technology for simple process monitoring.
The production of poliovirus vaccines in adherent Vero cells in batch bioreactors usually consists of a two-step upstream process: (1) Vero cell cultivation on microcarriers and (2) poliovirus proliferation. In this study we developed a mathematical model to describe this two-step process. We introduced the calculation of the oxygen uptake rate (OUR) and a correction of measurement for the sampling effect in order to ensure the high quality data sets. Besides the data of the OUR, we selected glucose concentration, Vero cell concentration and the virus titer for daily in process control to evaluate the progress of the process. With the selected data sets, the described model can accurately describe poliovirus production by Vero cells. Several other regular in process control samples (e.g. lactate concentration, ammonia concentration, and amino acids concentration) were excluded from the model, simplifying the process control analysis and minimizing labor.
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Affiliation(s)
- Yang Jiang
- Intravacc, Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
| | | | - Olaf Rubingh
- Intravacc, Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
| | | | - Wilfried A M Bakker
- Intravacc, Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
| | - Yvonne E Thomassen
- Intravacc, Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
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Galvão A, Pisoeiro J, Pinheiro H. Storage mechanisms in constructed wetlands: Should we modify heterotrophic bacteria modelling? Sci Total Environ 2019; 658:830-835. [PMID: 30583178 DOI: 10.1016/j.scitotenv.2018.12.120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 11/28/2018] [Accepted: 12/08/2018] [Indexed: 06/09/2023]
Abstract
This study investigated the occurrence of storage mechanisms in biofilm from constructed wetlands (CWs) through respirometric studies and calculated the corresponding heterotrophic growth yields. Respirometric tests were performed in biofilm extracted from horizontal sub-surface flow CWs batch loaded with three different COD mass loads: 7.0., 15.6 and 35.2 g COD/(m2∙day). The bed removal efficiency remained above 96% for all mass loads and COD mass removal rates increased from 6.8 g COD/(m2∙day) for the lowest load to 34.5 g COD/(m2∙day) for the highest load. The percentage of tests with storage evidence decreased from 85% to 10% with increasing mass loads and the responses of the microbial community to the acetate pulse showed an adaptation to the feast-famine conditions, through storage mechanisms, for lower loads, and a metabolic shift to the use of COD for growth for higher loads. Heterotrophic biomass yield values varied from 0.54-0.56 g COD/g COD for low mass loads to 0.69-0.71 for higher mass loads, indicating that greater substrate availably triggers growth and reduces the occurrence of storage. Storage yield values supported this trend varying between 0.89 and 0.94 with increasing mass loads. Given the significant storage evidence obtained in the present study, it is suggested that a modified modelling architecture, which includes storage mechanisms, should be considered in future simulations of CW systems.
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Affiliation(s)
- Ana Galvão
- CERIS, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
| | - Joana Pisoeiro
- CERIS, Instituto Superior Técnico, Universidade de Lisboa. Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
| | - Helena Pinheiro
- iBB-Institute for Bioengineering and Biosciences, DBE, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
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Kaeseberg T, Schubert S, Oertel R, Zhang J, Berendonk TU, Krebs P. Hot spots of antibiotic tolerant and resistant bacterial subpopulations in natural freshwater biofilm communities due to inevitable urban drainage system overflows. Environ Pollut 2018; 242:164-170. [PMID: 29980034 DOI: 10.1016/j.envpol.2018.06.081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 06/22/2018] [Accepted: 06/24/2018] [Indexed: 05/12/2023]
Abstract
Antibiotic resistant bacteria are a threat to human life. Recently, sewers have been identified as potential reservoirs. The intermittent injection of sewage into adjacent surface waters is inevitable, due to capacity limitations of the urban drainage system. Information regarding the effect to natural freshwater biofilms (NFB) due to the intermittent contaminations are scarce. Therefore, a fundamental screening is necessary. In April, we placed NFB-attachment constructions in a brook upstream and downstream from urban drainage overflow constructions. In meanwhile two sampling campaigns were conducted. The sewage and the brook water were collected to gather information about antibiotic background exposure of ciprofloxacin (CIP), clarithromycin (CLA) and doxycycline (DOX). Six months later we experimentally determined the oxygen uptake rate (OUR) of the NFB-communities after a 24 h lasting exposure with additionally dosed antibiotics. Concentrations of 0.1, 1.0 and 10.0 mg L-1 were selected. CIP, CLA and DOX were individually dosed, and also in mixtures. The mean antibiotic background concentration in sewage was in a range of 575.5-1289.1 ng L-1, which mainly exceeded the concentrations published in literature. The determined mean concentration in the brook was in a range of 4.6-539.0 ng L-1. The first significant inhibition of the OUR with individually dosed antibiotics started mainly at a concentration of 1.0 mg L-1. Antibiotics in a mixture with concentrations of 0.1 and 1.0 mg L-1 were as effective as single dosed antibiotics with a concentration of 10.0 mg L-1. The increased antibiotic tolerance and resistance of NFB-communities downstream of the combined sewer overflow (CSO) structure was a consequence of a severe impact due to urban drainage overflows. Hence, NFB-communities downstream of CSO-constructions are hot spots of antibiotic tolerant and resistant subpopulations and access restrictions should be announced, if an infection risk is present.
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Affiliation(s)
- Thomas Kaeseberg
- Institute of Urban Water Management, Technische Universität Dresden, 01062 Dresden, Germany.
| | - Sara Schubert
- Institute of Hydrobiology, Technische Universität Dresden, 01062 Dresden, Germany; Institute of Clinical Pharmacology, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01062 Dresden, Germany
| | - Reinhard Oertel
- Institute of Clinical Pharmacology, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01062 Dresden, Germany
| | - Jin Zhang
- Institute of Groundwater and Earth Sciences, Jinan University, 510632 Guangzhou, China.
| | - Thomas U Berendonk
- Institute of Hydrobiology, Technische Universität Dresden, 01062 Dresden, Germany
| | - Peter Krebs
- Institute of Urban Water Management, Technische Universität Dresden, 01062 Dresden, Germany
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15
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Li ZH, Zhu YM, Yang CJ, Zhang TY, Yu HQ. A simple respirogram-based approach for the management of effluent from an activated sludge system. Bioresour Technol 2018; 261:412-419. [PMID: 29698890 DOI: 10.1016/j.biortech.2018.03.134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 03/29/2018] [Accepted: 03/30/2018] [Indexed: 06/08/2023]
Abstract
Managing wastewater treatment plant (WWTP) based on respirometric analysis is a new and promising field. In this study, a multi-dimensional respirogram space was constructed, and an important index Res/t (ratio of in-situ respiration rate to maximum respiration rate) was derived as an alarm signal for the effluent quality control. A smaller Res/t value suggests better effluent. The critical R'es/t value used for determining whether the effluent meets the regulation depends on operational conditions, which were characterized by temperature and biomass ratio of heterotrophs to autotrophs. With given operational conditions, the critical R'es/t value can be calculated from the respirogram space and effluent conditions required by the discharge regulation, with no requirement for calibration of parameters or any additional measurements. Since it is simple, easy to use, and can be readily implemented online, this approach holds a great promise for applications.
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Affiliation(s)
- Zhi-Hua Li
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
| | - Yuan-Mo Zhu
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Cheng-Jian Yang
- School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Tian-Yu Zhang
- Department of Mathematical Sciences, Montana State University, Bozeman, MT 59717-2400, USA
| | - Han-Qing Yu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei 230026, China
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16
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Kaeseberg T, Schubert S, Oertel R, Zhang J, Berendonk TU, Krebs P. Hot spots of antibiotic tolerant and resistant bacterial subpopulations in natural freshwater biofilm communities due to inevitable urban drainage system overflows. Environ Pollut 2018. [PMID: 29980034 DOI: 10.1016/j.envpol.2018.06.081.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Antibiotic resistant bacteria are a threat to human life. Recently, sewers have been identified as potential reservoirs. The intermittent injection of sewage into adjacent surface waters is inevitable, due to capacity limitations of the urban drainage system. Information regarding the effect to natural freshwater biofilms (NFB) due to the intermittent contaminations are scarce. Therefore, a fundamental screening is necessary. In April, we placed NFB-attachment constructions in a brook upstream and downstream from urban drainage overflow constructions. In meanwhile two sampling campaigns were conducted. The sewage and the brook water were collected to gather information about antibiotic background exposure of ciprofloxacin (CIP), clarithromycin (CLA) and doxycycline (DOX). Six months later we experimentally determined the oxygen uptake rate (OUR) of the NFB-communities after a 24 h lasting exposure with additionally dosed antibiotics. Concentrations of 0.1, 1.0 and 10.0 mg L-1 were selected. CIP, CLA and DOX were individually dosed, and also in mixtures. The mean antibiotic background concentration in sewage was in a range of 575.5-1289.1 ng L-1, which mainly exceeded the concentrations published in literature. The determined mean concentration in the brook was in a range of 4.6-539.0 ng L-1. The first significant inhibition of the OUR with individually dosed antibiotics started mainly at a concentration of 1.0 mg L-1. Antibiotics in a mixture with concentrations of 0.1 and 1.0 mg L-1 were as effective as single dosed antibiotics with a concentration of 10.0 mg L-1. The increased antibiotic tolerance and resistance of NFB-communities downstream of the combined sewer overflow (CSO) structure was a consequence of a severe impact due to urban drainage overflows. Hence, NFB-communities downstream of CSO-constructions are hot spots of antibiotic tolerant and resistant subpopulations and access restrictions should be announced, if an infection risk is present.
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Affiliation(s)
- Thomas Kaeseberg
- Institute of Urban Water Management, Technische Universität Dresden, 01062 Dresden, Germany.
| | - Sara Schubert
- Institute of Hydrobiology, Technische Universität Dresden, 01062 Dresden, Germany; Institute of Clinical Pharmacology, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01062 Dresden, Germany
| | - Reinhard Oertel
- Institute of Clinical Pharmacology, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01062 Dresden, Germany
| | - Jin Zhang
- Institute of Groundwater and Earth Sciences, Jinan University, 510632 Guangzhou, China.
| | - Thomas U Berendonk
- Institute of Hydrobiology, Technische Universität Dresden, 01062 Dresden, Germany
| | - Peter Krebs
- Institute of Urban Water Management, Technische Universität Dresden, 01062 Dresden, Germany
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17
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Maqbool T, Cho J, Hur J. Changes in spectroscopic signatures in soluble microbial products of activated sludge under different osmotic stress conditions. Bioresour Technol 2018; 255:29-38. [PMID: 29414170 DOI: 10.1016/j.biortech.2018.01.113] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 01/19/2018] [Accepted: 01/22/2018] [Indexed: 06/08/2023]
Abstract
Spectroscopic techniques were used to examine the subtle changes in soluble microbial products (SMP) of batch activated sludge bioreactors working at different salinities (i.e., 0%, 1%, 3%, and 5% NaCl). The changes in different fluorescent constituent were tracked by excitation-emission matrix combined with parallel factor analysis (EEM-PARAFAC), and the sequential production was further identified by two-dimensional correlation spectroscopy (2D-COS). Greater enrichment of tryptophan-like component and large-sized biopolymer were found in SMP for higher saline bioreactors, suggesting the SMP sources from bound extracellular polymeric substances and excreted intercellular constituents. 2D-COS revealed the opposite sequences of the fluorescence changes in SMP between the low and the high saline bioreactors, following the order of "tyrosine-like > tryptophan-like > humic-like fluorescence" for the latter. This study clarified the dominant mechanisms involved in SMP formation during elevating salinity, which were well supported by the changes in SMP spectroscopic features, microbial activity, and organic degradation rates.
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Affiliation(s)
- Tahir Maqbool
- Department of Environment and Energy, Sejong University, Seoul 05006, South Korea
| | - Jinwoo Cho
- Department of Environment and Energy, Sejong University, Seoul 05006, South Korea
| | - Jin Hur
- Department of Environment and Energy, Sejong University, Seoul 05006, South Korea.
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Li ZH, Zhu YM, Zhang J, Yang CJ, Zhang TY, Yu HQ. Evaluation of robustness of activated sludge using calcium-induced enhancement of respiration. Bioresour Technol 2018; 253:55-63. [PMID: 29328935 DOI: 10.1016/j.biortech.2018.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 12/28/2017] [Accepted: 01/03/2018] [Indexed: 06/07/2023]
Abstract
Robustness of an activated sludge system, describing uncertainty and operational risk, was evaluated using the absence or presence of calcium-induced enhancement of respiration (CaER) effect. Generally, the fast-growing system was susceptible to external environmental variations, of which the sludge exhibited significant CaER effect under normal operational conditions, while the slow growing system showed less significant CaER effect. However, sludge in both systems exhibited CaER effect under stressed conditions of decreasing temperature or ammonia shocking. Therefore, the absence of CaER effect indicates a more robust system, while the presence of CaER effect indicates a susceptible system. Additionally, a method to identify safe and dangerous shocking was established by a hybrid usage of absence or presence of CaER effect and recovery index (RI) curve type. The evaluation of robustness could help determining when adjustment should be really taken to cope with the uncertainty, and thus holds a high promise for field application.
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Affiliation(s)
- Zhi-Hua Li
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
| | - Yuan-Mo Zhu
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Jing Zhang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Cheng-Jian Yang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Tian-Yu Zhang
- Department of Mathematical Sciences, Montana State University, Bozeman, MT 59717-2400, USA
| | - Han-Qing Yu
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei 230026, China
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Inglezakis VJ, Malamis S, Omirkhan A, Nauruzbayeva J, Makhtayeva Z, Seidakhmetov T, Kudarova A. Investigating the inhibitory effect of cyanide, phenol and 4-nitrophenol on the activated sludge process employed for the treatment of petroleum wastewater. J Environ Manage 2017; 203:825-830. [PMID: 27681869 DOI: 10.1016/j.jenvman.2016.08.066] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 08/24/2016] [Accepted: 08/25/2016] [Indexed: 05/07/2023]
Abstract
In this work, the inhibitory effect of cyanide, phenol and 4-nitrophenol on the activated sludge process was investigated. The inhibition of the aerobic oxidation of organic matter, nitrification and denitrification were examined in batch reactors by measuring the specific oxygen uptake rate (sOUR), the specific ammonium uptake rate (sAUR) and the specific nitrogen uptake rate (sNUR) respectively. The tested cyanide, phenol and 4-nitrophenol concentrations were 0.2-1.7 mg/L, 4.8-73.1 mg/L and 8.2-73.0 mg/L respectively. Cyanide was highly toxic as it significantly (>50%) inhibited the activity of autotrophic biomass, heterotrophic biomass under aerobic conditions and denitrifiers even at relatively low concentrations (1.0-1.7 mgCN-/L). The determination of the half maximum inhibitory concentration (IC50) confirmed this, since for cyanide IC50 values were very low for the examined bioprocesses (<1.5 mg/L). On the other hand, the IC50 values for phenol and 4-nitrophenol were much higher (>25 mg/L) for the tested bioprocesses since appreciable concentrations were required to accomplish significant inhibition. The autotrophic bacteria were more sensitive to phenol than the aerobic heterotrophs. The denitrifiers were found to be very resistant to phenol.
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Affiliation(s)
- V J Inglezakis
- School of Engineering, Chemical Engineering Department, Environmental Science & Technology Group (ESTg), Nazarbayev University, 53, Kabanbay Batyr Ave., Astana 010000, Kazakhstan
| | - S Malamis
- Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, 5 Iroon Polytechniou St., Zographou Campus, 15780 Athens, Greece.
| | - A Omirkhan
- School of Engineering, Chemical Engineering Department, Environmental Science & Technology Group (ESTg), Nazarbayev University, 53, Kabanbay Batyr Ave., Astana 010000, Kazakhstan
| | - J Nauruzbayeva
- School of Engineering, Chemical Engineering Department, Environmental Science & Technology Group (ESTg), Nazarbayev University, 53, Kabanbay Batyr Ave., Astana 010000, Kazakhstan
| | - Z Makhtayeva
- School of Engineering, Chemical Engineering Department, Environmental Science & Technology Group (ESTg), Nazarbayev University, 53, Kabanbay Batyr Ave., Astana 010000, Kazakhstan
| | - T Seidakhmetov
- School of Engineering, Chemical Engineering Department, Environmental Science & Technology Group (ESTg), Nazarbayev University, 53, Kabanbay Batyr Ave., Astana 010000, Kazakhstan
| | - A Kudarova
- School of Engineering, Chemical Engineering Department, Environmental Science & Technology Group (ESTg), Nazarbayev University, 53, Kabanbay Batyr Ave., Astana 010000, Kazakhstan
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Maqbool T, Cho J, Hur J. Spectroscopic descriptors for dynamic changes of soluble microbial products from activated sludge at different biomass growth phases under prolonged starvation. Water Res 2017; 123:751-760. [PMID: 28732328 DOI: 10.1016/j.watres.2017.07.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/10/2017] [Accepted: 07/15/2017] [Indexed: 06/07/2023]
Abstract
In this study, the spectroscopic indices of soluble microbial products (SMP) were explored using absorption and fluorescence spectroscopy to identify different distinctive biomass growth phases (i.e., exponential phase, pseudo-endogenous phase, and endogenous phase) and to describe the microbial activity of activated sludge in a batch type bioreactor under prolonged starvation. The optical descriptors, including UV absorption at 254 nm (UVA254), spectral slope, absorbance slope index (ASI), biological index (BIX), humification index (HIX), and the ratio of tryptophan-like to humic-like components (C1/C2), were examined to describe the dynamic changes in SMP. These indices were mostly associated with dissolved organic carbon (DOC) of SMPs and specific oxygen uptake rate (SOUR). Among those, ASI was the most strongly correlated with the SOUR data for the pseudo-endogenous and the endogenous periods. Although the three microbial phases were well discriminated using the spectral slope, BIX, and the C1/C2 ratio, the C1/C2 ratio can be suggested as the most preferable indicator as it can also trace the changes of the relative abundance of proteins to humic-like substances in SMPs. The suggested spectroscopic descriptors were reasonably explained by the general trends of decreased large-sized biopolymer fractions (e.g., proteins) and increased humic substrates (HS) with starvation time, which were detected by size exclusion chromatography. This study provides a novel insight into the strong potential of using optical descriptors to easily probe microbial status in biological treatment systems.
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Affiliation(s)
- Tahir Maqbool
- Department of Environment and Energy, Sejong University, Seoul, 05006, South Korea
| | - Jinwoo Cho
- Department of Environment and Energy, Sejong University, Seoul, 05006, South Korea
| | - Jin Hur
- Department of Environment and Energy, Sejong University, Seoul, 05006, South Korea.
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Mejias L, Komilis D, Gea T, Sánchez A. The effect of airflow rates and aeration mode on the respiration activity of four organic wastes: Implications on the composting process. Waste Manag 2017; 65:22-28. [PMID: 28396169 DOI: 10.1016/j.wasman.2017.04.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 03/02/2017] [Accepted: 04/03/2017] [Indexed: 05/23/2023]
Abstract
The aim of this study was to assess the effect of the airflow and of the aeration mode on the composting process of non-urban organic wastes that are found in large quantities worldwide, namely: (i) a fresh, non-digested, sewage sludge (FSS), (ii) an anaerobically digested sewage sludge (ADSS), (iii) cow manure (CM) and (iv) pig sludge (PS). This assessment was done using respirometric indices. Two aeration modes were tested, namely: (a) a constant air flowrate set at three different initial fixed airflow rates, and (b) an oxygen uptake rate (OUR)-controlled airflow rate. The four wastes displayed the same behaviour namely a limited biological activity at low aeration, while, beyond a threshold value, the increase of the airflow did not significantly increase the dynamic respiration indices (DRI1 max, DRI24 max and AT4). The threshold airflow rate varied among wastes and ranged from 42NL air kg-1DMh-1 for CM and from 67 to 77NL air kg-1DMh-1 for FSS, ADSS and PS. Comparing the two aeration modes tested (constant air flow, OUR controlled air flow), no statistically significant differences were calculated between the respiration activity indices obtained at those two aeration modes. The results can be considered representative for urban and non-urban organic wastes and establish a general procedure to measure the respiration activity without limitations by airflow. This will permit other researchers to provide consistent results during the measurement of the respiration activity. Results indicate that high airflows are not required to establish the maximum respiration activity. This can result in energy savings and the prevention of off-gas treatment problems due to the excessive aeration rate in full scale composting plants.
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Affiliation(s)
- Laura Mejias
- Composting Research Group (GICOM), Dept. of Chemical Biological and Environmental Engineering, Universitat Autònoma de Barcelona, 08193-Bellaterra, Barcelona, Spain
| | - Dimitrios Komilis
- Composting Research Group (GICOM), Dept. of Chemical Biological and Environmental Engineering, Universitat Autònoma de Barcelona, 08193-Bellaterra, Barcelona, Spain; Department of Environmental Engineering, Democritus University of Thrace, Xanthi, Greece.
| | - Teresa Gea
- Composting Research Group (GICOM), Dept. of Chemical Biological and Environmental Engineering, Universitat Autònoma de Barcelona, 08193-Bellaterra, Barcelona, Spain
| | - Antoni Sánchez
- Composting Research Group (GICOM), Dept. of Chemical Biological and Environmental Engineering, Universitat Autònoma de Barcelona, 08193-Bellaterra, Barcelona, Spain
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Nur Asshifa MN, Zambry NS, Salwa MS, Yahya AR. The influence of agitation on oil substrate dispersion and oxygen transfer in Pseudomonas aeruginosa USM-AR2 fermentation producing rhamnolipid in a stirred tank bioreactor. 3 Biotech 2017; 7:189. [PMID: 28664380 DOI: 10.1007/s13205-017-0828-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 04/18/2017] [Indexed: 10/19/2022] Open
Abstract
Water-immiscible substrate, diesel, was supplied as the main substrate in the fermentation of Pseudomonas aeruginosa USM-AR2 producing rhamnolipid biosurfactant, in a stirred tank bioreactor. In addition to the typical gas-aqueous system, this system includes gas-hydrocarbon-aqueous phases and the presence of surfactant (rhamnolipid) in the fermentation broth. The effect of diesel dispersion on volumetric oxygen transfer coefficient, k L a, and thus oxygen transfer, was evaluated at different agitations of 400, 500 and 600 rpm. The oxygen transfer in this oil-water-surfactant system was shown to be affected by different oil dispersion at those agitation rates. The highest diesel dispersion was obtained at 500 rpm or impeller tip speed of 1.31 m/s, compared to 400 and 600 rpm, which led to the highest k L a, growth and rhamnolipid production by P. aeruginosa USM-AR2. This showed the highest substrate mixing and homogenization at this agitation speed that led to the efficient substrate utilization by the cells. The oxygen uptake rate of P. aeruginosa USM-AR2 was 5.55 mmol/L/h, which showed that even the lowest k L a (48.21 h-1) and hence OTR (57.71 mmol/L/h) obtained at 400 rpm was sufficient to fulfill the oxygen demand of the cells. The effect of rhamnolipid concentration on k L a showed that k L a increased as rhamnolipid concentration increased to 0.6 g/L before reaching a plateau. This trend was similar for all agitation rates of 400, 500 and 600 rpm, which might be due to the increase in the resistance to oxygen transfer (k L decrease) and the increase in the specific interfacial area (a).
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Fan H, Qi L, Liu G, Zhang Y, Fan Q, Wang H. Aeration optimization through operation at low dissolved oxygen concentrations: Evaluation of oxygen mass transfer dynamics in different activated sludge systems. J Environ Sci (China) 2017; 55:224-235. [PMID: 28477817 DOI: 10.1016/j.jes.2016.08.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 07/31/2016] [Accepted: 08/19/2016] [Indexed: 06/07/2023]
Abstract
In wastewater treatment plants (WWTPs) using the activated sludge process, two methods are widely used to improve aeration efficiency - use of high-efficiency aeration devices and optimizing the aeration control strategy. Aeration efficiency is closely linked to sludge characteristics (such as concentrations of mixed liquor suspended solids (MLSS) and microbial communities) and operating conditions (such as air flow rate and operational dissolved oxygen (DO) concentrations). Moreover, operational DO is closely linked to effluent quality. This study, which is in reference to WWTP discharge class A Chinese standard effluent criteria, determined the growth kinetics parameters of nitrifiers at different DO levels in small-scale tests. Results showed that the activated sludge system could meet effluent criteria when DO was as low as 0.3mg/L, and that nitrifier communities cultivated under low DO conditions had higher oxygen affinity than those cultivated under high DO conditions, as indicated by the oxygen half-saturation constant and nitrification ability. Based on nitrifier growth kinetics and on the oxygen mass transfer dynamic model (determined using different air flow rate (Q'air) and mixed liquor volatile suspended solids (MLVSS) values), theoretical analysis indicated limited potential for energy saving by improving aeration diffuser performance when the activated sludge system had low oxygen consumption; however, operating at low DO and low MLVSS could significantly reduce energy consumption. Finally, a control strategy coupling sludge retention time and MLVSS to minimize the DO level was discussed, which is critical to appropriate setting of the oxygen point and to the operation of low DO treatment technology.
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Affiliation(s)
- Haitao Fan
- Research Center for Low Carbon Technology of Water Environment, Renmin University of China, Beijing 100872, China
| | - Lu Qi
- Research Center for Low Carbon Technology of Water Environment, Renmin University of China, Beijing 100872, China.
| | - Guoqiang Liu
- School of Environment, Jinan University, Guangzhou 510632, China
| | - Yuankai Zhang
- Research Center for Low Carbon Technology of Water Environment, Renmin University of China, Beijing 100872, China
| | - Qiang Fan
- Research Center for Low Carbon Technology of Water Environment, Renmin University of China, Beijing 100872, China
| | - Hongchen Wang
- Research Center for Low Carbon Technology of Water Environment, Renmin University of China, Beijing 100872, China.
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Viaene J, Nelissen V, Reubens B, Willekens K, Driehuis F, De Neve S, Vandecasteele B. Improving the product stability and fertilizer value of cattle slurry solid fraction through co-composting or co-ensiling. Waste Manag 2017; 61:494-505. [PMID: 28057418 DOI: 10.1016/j.wasman.2016.12.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 12/18/2016] [Accepted: 12/21/2016] [Indexed: 06/06/2023]
Abstract
Separating dairy cattle slurry in a liquid and solid fraction (SF) is gaining more interest, since it enables a more targeted use of both fractions. However, the valorization of the SF is limited on P-rich soils, due to its high P content, and the export or use as bedding material requires sanitation. Therefore, we investigated the influence of composting or ensiling the SF, whether or not mixed with bulking agents, on the product quality in terms of fertilizer value, sanitation and stability. Ensiling can be considered as a controlled storage method for conserving C and nutrients. Soil amendment with co-ensiled SF resulted in a higher N mineralization and crop growth compared to amendment of co-composted SF. Co-composting SF with structure-rich feedstock materials optimized the composting process and sanitation when compared with composting pure SF and did not increase the risk for extreme-heat-resistant spores of thermophilic aerobic spore-forming bacteria (X-TAS). Further, the composts contained more P per unit of fresh weight than the silages, beneficial for the export of the composted SF. The oxygen uptake rate was found to be less powerful to determine the stability of fresh, composted and ensiled SF.
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Affiliation(s)
- Jarinda Viaene
- Institute for Agricultural and Fisheries Research, Plant Sciences Unit, Crop Husbandry and Environment, Burg. Van Gansberghelaan 109, 9820 Merelbeke, Belgium; Department of Soil Management, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
| | - Victoria Nelissen
- Institute for Agricultural and Fisheries Research, Plant Sciences Unit, Crop Husbandry and Environment, Burg. Van Gansberghelaan 109, 9820 Merelbeke, Belgium.
| | - Bert Reubens
- Institute for Agricultural and Fisheries Research, Plant Sciences Unit, Crop Husbandry and Environment, Burg. Van Gansberghelaan 109, 9820 Merelbeke, Belgium.
| | - Koen Willekens
- Institute for Agricultural and Fisheries Research, Plant Sciences Unit, Crop Husbandry and Environment, Burg. Van Gansberghelaan 109, 9820 Merelbeke, Belgium.
| | - Frank Driehuis
- NIZO Food Research BV, Kernhemseweg 2, 6718 ZB Ede, The Netherlands.
| | - Stefaan De Neve
- Department of Soil Management, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
| | - Bart Vandecasteele
- Institute for Agricultural and Fisheries Research, Plant Sciences Unit, Crop Husbandry and Environment, Burg. Van Gansberghelaan 109, 9820 Merelbeke, Belgium.
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Schwerna P, Hübner H, Buchholz R. Quantification of oxygen production and respiration rates in mixotrophic cultivation of microalgae in nonstirred photobioreactors. Eng Life Sci 2016; 17:140-144. [PMID: 32624761 DOI: 10.1002/elsc.201600004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 06/28/2016] [Accepted: 07/11/2016] [Indexed: 11/05/2022] Open
Abstract
Online monitoring and controlling of different cellular parameters are key issues in aerobic bioprocesses. Since mixotrophic cultivation, in which we observe a mixture of cellular respiration and oxygen production has gained more popularity, there is a need for an on-process quantification of these parameters. The presented and adapted double gassing-out method applied to a mixotrophic cultivation of Galdieria sulphuraria, will be a tool for monitoring and further optimization of algal fermentation in nonstirred photobioreactors (PBR). We measured the highest net specific oxygen production rate (opr net) as 5.73 · 10-3 molO2 g-1 h-1 at the lowest oxygen uptake rate (OUR) of 1.00 · 10-4 molO2 L-1 h-1. Due to higher cell densities, we also demonstrated the increasing shading effect by a decrease of opr net, reaching the lowest value of 1.25 10-5 molO2 g-1 h-1. Nevertheless, with this on process measurement, we can predict the relation between the zone in which oxygen is net produced to the area where cell respiration dominates in a PBR, which has a major impact to optimize cell growth along with the formation of different products of interest such as pigments.
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Affiliation(s)
- Philipp Schwerna
- Institute of Bioprocess Engineering Friedrich-Alexander-Universität Erlangen-Nürnberg Erlangen Germany
| | - Holger Hübner
- Institute of Bioprocess Engineering Friedrich-Alexander-Universität Erlangen-Nürnberg Erlangen Germany
| | - Rainer Buchholz
- Institute of Bioprocess Engineering Friedrich-Alexander-Universität Erlangen-Nürnberg Erlangen Germany
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26
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Guo DS, Ji XJ, Ren LJ, Li GL, Yin FW, Huang H. Development of a real-time bioprocess monitoring method for docosahexaenoic acid production by Schizochytrium sp. Bioresour Technol 2016; 216:422-7. [PMID: 27262097 DOI: 10.1016/j.biortech.2016.05.044] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/13/2016] [Accepted: 05/15/2016] [Indexed: 05/21/2023]
Abstract
Oxygen uptake rate (OUR) and respiratory quotient (RQ) are key respiratory parameters for docosahexaenoic acid (DHA) production by Schizochytrium sp. HX-308 under dissolved oxygen limited conditions. To investigate the relationship of OUR and RQ with culture status, three independent cultures with different aeration rates were performed in a 50L bioreactor. OUR was found to be positively correlated with the aeration rate, which reflected the oxygen supply level in each culture. The highest biomass, reaching 124.5g/L, was achieved under the highest OUR. DHA content was found to be highly correlated with the RQ value, and the highest DHA content (44.85% in total fatty acids, w/w) was achieved in the highest RQ level, which implies that the polyketide synthase pathway was more active. OUR and RQ, which reflect the physiological state of microorganisms, are suggested as synergistic real-time bioprocess monitoring parameters for DHA fermentation.
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Affiliation(s)
- Dong-Sheng Guo
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China
| | - Xiao-Jun Ji
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), No. 5 Xinmofan Road, Nanjing 210009, People's Republic of China
| | - Lu-Jing Ren
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), No. 5 Xinmofan Road, Nanjing 210009, People's Republic of China
| | - Gan-Lu Li
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China
| | - Feng-Wei Yin
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China
| | - He Huang
- School of Pharmaceutical Sciences, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China; State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5 Xinmofan Road, Nanjing 210009, People's Republic of China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), No. 5 Xinmofan Road, Nanjing 210009, People's Republic of China.
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27
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Zhang J, Dong Q, Liu Y, Zhou X, Shi H. Response to shock load of engineered nanoparticles in an activated sludge treatment system: Insight into microbial community succession. Chemosphere 2016; 144:1837-1844. [PMID: 26539708 DOI: 10.1016/j.chemosphere.2015.10.084] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 10/17/2015] [Accepted: 10/21/2015] [Indexed: 06/05/2023]
Abstract
The environmental impacts of the use of engineered nanoparticles (NPs) remain unclear and have attracted increasing concern worldwide. Considering that NPs eventually end up in wastewater treatment systems, the potential impact of ZnO and TiO2 NPs on the activated sludge was investigated using laboratory-scale sequencing batch reactors (SBRs). Short-term (24 h) exposure to 1, 10 and 100 mg/L shock loads of NPs reduced the oxygen uptake rate of the activated sludge by 3.55%-12.51% compared with the controls. In our experiment, the toxicities of TiO2 NPs were higher than those of ZnO NPs as reflected in the inhibition of oxygen utilization in the activated sludge. However, both the short-term (24 h) and long-term (21 days) exposure to ZnO and TiO2 NPs did not adversely affect the pollutant removal of the SBRs. Furthermore, the polymerase chain reaction-denaturing gel gradient electrophoresis revealed that the microbial community did not significantly vary after the short-term exposure (24 h) to 1, 10 and 100 mg/L shock loads of NPs; however, the cluster analysis in our experiment revealed that the slight difference caused by the NPs largely depended on exposure time rather than on NP type and NP concentration. The long-term exposure (13 days) to 10 mg/L shock load of ZnO or TiO2 NPs caused no substantial microbial community shifts in the activated sludge. The microbial diversity also showed no significant change when exposed to NPs as revealed by the Shannon-Wiener index.
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Affiliation(s)
- Jing Zhang
- State Key Laboratory of Simulation and Regulation of River Basin Water Cycle, China Institute of Water Resources and Hydropower Research, A-1 Fuxing Road Haidian District, Beijing 100038, China
| | - Qian Dong
- State Key Joint Laboratory of ESPC, School of Environment, Tsinghua University, Beijing 10084, China
| | - Yanchen Liu
- State Key Joint Laboratory of ESPC, School of Environment, Tsinghua University, Beijing 10084, China
| | - Xiaohong Zhou
- State Key Joint Laboratory of ESPC, School of Environment, Tsinghua University, Beijing 10084, China.
| | - Hanchang Shi
- State Key Joint Laboratory of ESPC, School of Environment, Tsinghua University, Beijing 10084, China
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28
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Almeira N, Komilis D, Barrena R, Gea T, Sánchez A. The importance of aeration mode and flowrate in the determination of the biological activity and stability of organic wastes by respiration indices. Bioresour Technol 2015; 196:256-262. [PMID: 26253909 DOI: 10.1016/j.biortech.2015.07.102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 07/24/2015] [Accepted: 07/27/2015] [Indexed: 06/04/2023]
Abstract
The aim of this study was to assess the effect of different air flowrates and different aeration modes on the respiration activity of three organic substrates of different stability degree: (i) a constant flowrate and (ii) a continuously adjusted air flowrate that optimized the oxygen uptake rate (OUR). Above 20L air kg(-1)DMh(-1), at the constant flow regime, the resulting dynamic respiration index at 24h (DRI24) and the cumulative respiration at four days (AT4) were statistically similar. At the OUR based aeration regime, the DRI24 and AT4 were statistically similar at all initial flowrates tested. Above a minimum threshold, cumulative air flow of around 3000Lairkg(-1) DM during a 5day period, the respiration activity was similar, particularly for the two less active substrates. This study highlights the importance of selecting the aeration to obtain reliable measures of biological activity and stability in organic wastes.
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Affiliation(s)
- Natividad Almeira
- Composting Research Group (GICOM), Dept. of Chemical Engineering, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Dimitrios Komilis
- Composting Research Group (GICOM), Dept. of Chemical Engineering, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Raquel Barrena
- Composting Research Group (GICOM), Dept. of Chemical Engineering, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Teresa Gea
- Composting Research Group (GICOM), Dept. of Chemical Engineering, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Antoni Sánchez
- Composting Research Group (GICOM), Dept. of Chemical Engineering, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
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29
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Pfister C, Forstmeier C, Biedermann J, Schermuly J, Demmel F, Wolf P, Kaspers B, Brischwein M. Estimation of dynamic metabolic activity in micro-tissue cultures from sensor recordings with an FEM model. Med Biol Eng Comput 2015; 54:763-72. [PMID: 26296800 DOI: 10.1007/s11517-015-1367-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 08/07/2015] [Indexed: 10/23/2022]
Abstract
We estimated the dynamic cell metabolic activity and the distribution of the pH value and oxygen concentration in tissue samples cultured in vitro by using real-time sensor records and a numerical simulation of the underlying reaction-diffusion processes. As an experimental tissue model, we used chicken spleen slices. A finite element method model representing the biochemical processes and including the relevant sensor data was set up. By fitting the calculated results to the measured data, we derived the spatiotemporal values of the pH value, the oxygen concentration and the absolute metabolic activity (extracellular acidification and oxygen uptake rate) of the samples. Notably, the location of the samples in relation to the sensors has a great influence on the detectable metabolic rates. The long-term vitality of the tissue samples strongly depends on their size. We further discuss the benefits and limitations of the model.
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Affiliation(s)
- Cornelia Pfister
- Heinz Nixdorf-Lehrstuhl für Medizinische Elektronik, Technische Universität München, Theresienstr. 90/N3, 80333, Munich, Germany. .,HP Medizintechnik GmbH, Bruckmannring 19, 85764, Oberschleißheim, Germany.
| | - Christian Forstmeier
- Heinz Nixdorf-Lehrstuhl für Medizinische Elektronik, Technische Universität München, Theresienstr. 90/N3, 80333, Munich, Germany
| | - Johannes Biedermann
- Heinz Nixdorf-Lehrstuhl für Medizinische Elektronik, Technische Universität München, Theresienstr. 90/N3, 80333, Munich, Germany
| | - Julia Schermuly
- Institut für Tierphysiologie, Veterinärstr. 13, 80539, Munich, Germany
| | - Franz Demmel
- Heinz Nixdorf-Lehrstuhl für Medizinische Elektronik, Technische Universität München, Theresienstr. 90/N3, 80333, Munich, Germany.,HP Medizintechnik GmbH, Bruckmannring 19, 85764, Oberschleißheim, Germany
| | - Peter Wolf
- HP Medizintechnik GmbH, Bruckmannring 19, 85764, Oberschleißheim, Germany
| | - Bernd Kaspers
- Institut für Tierphysiologie, Veterinärstr. 13, 80539, Munich, Germany
| | - Martin Brischwein
- Heinz Nixdorf-Lehrstuhl für Medizinische Elektronik, Technische Universität München, Theresienstr. 90/N3, 80333, Munich, Germany
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30
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Biros Y, Çokgör EU, Yağcı N, Pala-Ozkok I, Çakar ZP, Sözen S, Orhon D. Effect of acetate to biomass ratio on simultaneous polyhydroxybutyrate generation and direct microbial growth in fast growing microbial culture. Bioresour Technol 2014; 171:314-322. [PMID: 25218203 DOI: 10.1016/j.biortech.2014.08.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 07/25/2014] [Accepted: 08/04/2014] [Indexed: 06/03/2023]
Abstract
The study investigated the effect of variations in the acetate to biomass ratio on substrate storage potential, and the kinetics of substrate utilization. A series of batch experiments were conducted with biomass taken from the fill and draw reactor operated at a sludge age of 2 d. One of the batch reactors duplicated the substrate loading in the main reactor. The others were started with different initial acetate to biomass ratios both in lower and higher ranges. Increasing available acetate did not totally divert excess substrate to storage; the microbial culture adjusted the kinetics of the metabolic reactions to a higher growth rate so that more substrate could be utilized for direct growth at high acetate levels. Conversely, storage rate was increased, utilizing a higher substrate fraction for polyhydroxybutyrate generation when acetate concentration was lowered. The physiological and molecular bases of storage at low substrate levels were discussed.
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Affiliation(s)
- Yester Biros
- Faculty of Civil Engineering, Environmental Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
| | - Emine Ubay Çokgör
- Faculty of Civil Engineering, Environmental Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
| | - Nevin Yağcı
- Faculty of Civil Engineering, Environmental Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
| | - Ilke Pala-Ozkok
- Faculty of Civil Engineering, Environmental Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
| | - Zeynep Petek Çakar
- Faculty of Science and Letters, Molecular Biology and Genetics Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey; Dr. Orhan Öcalgiray Molecular Biology, Biotechnology and Genetics Research Center (ITU-MOBGAM), Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
| | - Seval Sözen
- Faculty of Civil Engineering, Environmental Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey.
| | - Derin Orhon
- Faculty of Civil Engineering, Environmental Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey; The Science Academy, 34353 Beşiktaş, Istanbul, Turkey
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31
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Sibag M, Choi BG, Suh C, Lee KH, Lee JW, Maeng SK, Cho J. Inhibition of total oxygen uptake by silica nanoparticles in activated sludge. J Hazard Mater 2014; 283:841-846. [PMID: 25464327 DOI: 10.1016/j.jhazmat.2014.10.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/24/2014] [Accepted: 10/22/2014] [Indexed: 06/04/2023]
Abstract
Nanoparticle toxicity to biological activities in activated sludge is largely unknown. Among the widely used nanoparticles, silica nanoparticles (SNP) have a limited number of studies associated with inhibition to the activated sludge process (ASP). We demonstrated SNP inhibition of activated sludge respiration through oxygen uptake rate (OUR) measurement. Based on the percentage inhibition of total oxygen consumption (IT), we observed that smaller SNPs (12 nm, IT=33 ± 3%; 151 nm, IT=23 ± 2%) were stronger inhibitors than larger SNPs (442 and 683 nm, IT=5 ± 1%). Transmission electron micrographs showed that some of the SNPs were adsorbed on and/or apparently embedded somewhere in the microbial cell membrane. Whether SNPs are directly associated with the inhibition of total oxygen uptake warrants further studies. However, it is clear that SNPs statistically significantly altered the composition of microbial membrane lipids, which was more clearly described by principal component analysis and weighted Euclidian distance (PCA-ED) of the fatty acid methyl ester (FAME) data. This study suggests that SNPs potentially affect the biological activity in activated sludge through the inhibition of total oxygen uptake.
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Affiliation(s)
- Mark Sibag
- Department of Environment and Energy, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, Republic of Korea
| | - Byeong-Gyu Choi
- School of Civil, Environmental & Architectural Engineering, Korea University, 145, Anam-ro, Sungbuk-ku, Seoul 136-701, Republic of Korea
| | - Changwon Suh
- Energy Lab, Environment Group, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803, Republic of Korea
| | - Kwan Hyung Lee
- Department of Environmental Engineering & Program in Environmental Technology and Policy, Korea University, Sejong 339-700, Republic of Korea
| | - Jae Woo Lee
- Department of Environmental Engineering & Program in Environmental Technology and Policy, Korea University, Sejong 339-700, Republic of Korea
| | - Sung Kyu Maeng
- Department of Civil and Environmental Engineering, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, Republic of Korea
| | - Jinwoo Cho
- Department of Environment and Energy, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, Republic of Korea.
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Ciggin AS, Orhon D. Effect of storage on the respirometric relationship between substrate utilization and microbial growth. Bioresour Technol 2014; 167:331-335. [PMID: 24997376 DOI: 10.1016/j.biortech.2014.06.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 06/09/2014] [Accepted: 06/11/2014] [Indexed: 06/03/2023]
Abstract
The paper evaluated the impact of substrate storage on the respirometric assessment of process stoichiometry based on oxygen uptake rate (OUR) measurements. Two parallel sequencing batch reactors were operated with pulse feeding of synthetic substrate mixture at a sludge age of 8 days and 2 days. During the cycle experiments with acetate, 40-45% of acetate was converted to polyhydroxybutyrate, which was partly consumed during each cycle. Respirometric analysis also yielded OUR profiles for the corresponding cyclic operation. A mass balance expression was derived based on oxygen utilization. Oxygen demands calculated on the basis of partial PHB utilization closely matched the experimental values retrieved from OUR profiles within limits of analytical precision. The relative contribution of storage mechanism represented more than 50% of overall oxygen demand. Substrate storage, when totally disregarded or not properly evaluated, was observed to involve an error of around 10% on overall the oxygen demand.
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Affiliation(s)
- A S Ciggin
- Department of Environmental Engineering, Akdeniz University, Antalya, Turkey.
| | - D Orhon
- Environmental Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey; ENVIS Energy and Environmental Systems R&D Ltd, ITU Arı Teknokent, Arı 1 Building No. 16, Maslak 34469, Istanbul, Turkey.
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Puyuelo B, Gea T, Sánchez A. GHG emissions during the high-rate production of compost using standard and advanced aeration strategies. Chemosphere 2014; 109:64-70. [PMID: 24873708 DOI: 10.1016/j.chemosphere.2014.02.060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Revised: 02/11/2014] [Accepted: 02/12/2014] [Indexed: 06/03/2023]
Abstract
In this study, we have evaluated different strategies for the optimization of the aeration during the active thermophilic stage of the composting process of source-selected Organic Fraction of Municipal Solid Waste (or biowaste) using reactors at bench scale (50L). These strategies include: typical cyclic aeration, oxygen feedback controller and a new self-developed controller based on the on-line maximization of the oxygen uptake rate (OUR) during the process. Results highlight differences found in the emission of most representative greenhouse gases (GHG) emitted from composting (methane and nitrous oxide) as well as in gases typically related to composting odor problems (ammonia as typical example). Specifically, the cyclic controller presents emissions that can double that of OUR controller, whereas oxygen feedback controller shows a better performance with respect to the cyclic controller. A new parameter, the respiration index efficiency, is presented to quantitatively evaluate the GHG emissions and, in consequence, the main negative environmental impact of the composting process. Other aspects such as the stability of the compost produced and the consumption of resources are also evaluated for each controller.
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Affiliation(s)
- B Puyuelo
- Composting Research Group, Department of Chemical Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08913-Bellaterra, Cerdanyola del Vallès, Barcelona, Spain
| | - T Gea
- Composting Research Group, Department of Chemical Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08913-Bellaterra, Cerdanyola del Vallès, Barcelona, Spain
| | - A Sánchez
- Composting Research Group, Department of Chemical Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08913-Bellaterra, Cerdanyola del Vallès, Barcelona, Spain.
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Zhang L, Liao Q, Gu X, He W, Zhang Z, Fan C. Oxygen and phosphorus dynamics in freshwater sediment after the deposition of flocculated cyanobacteria and the role of tubificid worms. J Hazard Mater 2014; 266:1-9. [PMID: 24374559 DOI: 10.1016/j.jhazmat.2013.12.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 11/23/2013] [Accepted: 12/08/2013] [Indexed: 06/03/2023]
Abstract
Flocculation is a promising method for controlling harmful algal blooms; however, little is known about the effects of algae deposition by flocculation on benthic oxygen (O2) and nutrient dynamics. In this study, we aimed to investigate the influence of cyanobacteria flocculation deposition on benthic O2 and phosphorus (P) dynamics and the role of tubificid worms in the process. Chitosan and sediment particles were used to flocculate and deposit cyanobacteria cells onto lake sediment. The impulse deposition of algal flocculation degraded the deposited algal cells, which decreased the O2 penetration depth in sediment and increased the O2 uptake rate. Algae deposition also increased the soluble reactive P (SRP) in pore water and loosely adsorbed P in sediment, and changed SRP flux. Tubificid worms transported algal cells deeper into the sediment, mitigated their degradation, and altered the O2 penetration depth, but not the O2 uptake rate. Tubificid worms enhanced the increase in pore-water SRP and loosely adsorbed P in sediment. Therefore, the deposition of algal flocculation modifies the benthic O2 and P dynamics, and tubificid worms can mitigate or enhance some of these processes.
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Affiliation(s)
- Lei Zhang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China.
| | - Qianjiahua Liao
- Department of Environmental Science, China Pharmaceutical University, Nanjing 211198, PR China
| | - Xiaozhi Gu
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China
| | - Wei He
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China
| | - Zhe Zhang
- Department of Environmental Science, China Pharmaceutical University, Nanjing 211198, PR China
| | - Chengxin Fan
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China
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Makhaniok A, Haranava Y, Goranov V, Panseri S, Semerikhina S, Russo A, Marcacci M, Dediu V. In silico prediction of the cell proliferation in porous scaffold using model of effective pore. Biosystems 2013; 114:227-37. [PMID: 24141144 DOI: 10.1016/j.biosystems.2013.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 08/01/2013] [Accepted: 10/03/2013] [Indexed: 10/26/2022]
Abstract
The mathematical prediction of cell proliferation in porous scaffold still remains a challenge. The analysis of existing models and experimental data confirms a need for a new solution, which takes into account cells" development on the scaffold pore walls as well as some additional parameters such as the pore size, cell density in cellular layers, the thickness of the growing cell layer and others. The simulations, presented below, are based on three main approaches. The first approach takes into account multilayer cell growth on the pore walls of the scaffold. The second approach is a simulation of cell proliferation in a discrete process as a continuous one. The third one is the representation of scaffold structure as a system of cylindrical channels. Oxygen (nutrient) mass transfer is realized inside these channels. The model, described below, proposes the new solution to time dependent description of cell proliferation in porous scaffold and optimized trophical conditions for tissue development.
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Affiliation(s)
- A Makhaniok
- BioDevice Systems, Praha 10, Vršovice, Bulharská 996/20, Czech Republic.
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