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Sharma H, Nirmalkar N, Zhang W. Nanobubbles produced by nanopores to probe gas-liquid mass transfer characteristics. J Colloid Interface Sci 2024; 665:274-285. [PMID: 38531273 DOI: 10.1016/j.jcis.2024.03.080] [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: 12/12/2023] [Revised: 02/27/2024] [Accepted: 03/11/2024] [Indexed: 03/28/2024]
Abstract
HYPOTHESIS This study tested the hypothesis of how the nanopore size of membranes and how the surface charge of nanobubbles responds to its pinch-off from the nanopore. This study also tested the hypothesis that nanobubbles that remain in solution after production may increase the dissolved oxygen content in water. EXPERIMENTS The effect of membrane pore size, hydrodynamic conditions (gas and liquid flow rates), and physicochemical parameters (pH and temperature) on volumetric mass transfer coefficient (kLa) for oxygen nanobubbles formed by the nanopore diffusion technique was investigated. This study experimentally determined the kLa by carefully removing the dissolved oxygen by nitrogen purging from nanobubble suspension to examine the sole contribution of nanobubble dissolution in water to the reaeration. RESULTS Scaling estimates indicate that the nanobubble pinch-off radius and nanopore radius have a power-law correlation and that nanobubble size declines with the nanopore size. This is in line with our experimental results. The surface charge of nanobubbles delays its pinch-off at the gas-liquid interface. Nanobubbles offered 3-4 times higher kLa than microbubbles. Standard oxygen transfer efficiency in water was found to be 78%, significantly higher than that in microbubbles. However, dissolving stable nanobubbles in water does not considerably increase dissolved oxygen levels.
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Affiliation(s)
- Harsh Sharma
- Department of Chemical Engineering, Indian Institute of Technology Ropar, Rupnagar-140001, India
| | - Neelkanth Nirmalkar
- Department of Chemical Engineering, Indian Institute of Technology Ropar, Rupnagar-140001, India.
| | - Wen Zhang
- John A. Reif, Jr. Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA
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2
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Abdelfattah A, Eltawab R, Iqbal Hossain M, Zhou X, Cheng L. Membrane aerated biofilm reactor system driven by pure oxygen for wastewater treatment. Bioresour Technol 2024; 393:130130. [PMID: 38040304 DOI: 10.1016/j.biortech.2023.130130] [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: 10/02/2023] [Revised: 11/19/2023] [Accepted: 11/28/2023] [Indexed: 12/03/2023]
Abstract
Pure oxygen is proposed for wastewater treatment due to its advantages over conventional air aeration. This study investigates a Pure Oxygen-based Membrane Aerated Biofilm Reactor (PO-MABR) for the first time under various operating conditions. The PO-MABR employs a gas-permeable membrane for direct diffusion of low-pressurized pure oxygen to the biofilm, ensuring exceptional carbon and nitrogen removal. The effectiveness of PO-MABR was investigated by varying operational conditions, including temperature, carbon-to-nitrogen ratio, gas pressure, and flow rate. Results indicate superior performance, with a 97% chemical oxygen demand removal and 19% higher total nitrogen removal than Air-Ventilated MABR (A-MABR) due to thicker biofilm and unique microbial structures in PO-MABR. Also, PO-MABR demonstrated resilience to low temperatures and effectively treated both high and low-strength wastewater. The findings emphasize the efficiency of PO-MABR in wastewater treatment, advocating for its adoption due to superior carbon and nitrogen removal across diverse operational conditions.
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Affiliation(s)
- Abdallah Abdelfattah
- School of Agricultural Engineering, Jiangsu University, Zhenjiang 212013, China; Department of Public Works Engineering, Faculty of Engineering, Tanta University, Tanta 31511, Egypt.
| | - Reham Eltawab
- Institute of Environmental Health and Ecological Safety, School of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Md Iqbal Hossain
- School of Engineering and Information Technology, Murdoch University, Australia; Commonwealth Scientific and Industrial Research Organisation (CSIRO) Environment, 147 Underwood Avenue, Floreat, WA 6014, Australia
| | - Xiangtong Zhou
- Institute of Environmental Health and Ecological Safety, School of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Liang Cheng
- Institute of Environmental Health and Ecological Safety, School of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China; Institute of Materials Engineering, Nanjing University, Nantong 226000, China.
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3
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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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4
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Elad T, Hally MP, Domingo-Félez C, Knoop O, Drewes JE, Valverde-Pérez B, Smets BF. Exploring the effects of intermittent aeration on the performance of nitrifying membrane-aerated biofilm reactors. Sci Total Environ 2023:164329. [PMID: 37236447 DOI: 10.1016/j.scitotenv.2023.164329] [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] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/03/2023] [Accepted: 05/17/2023] [Indexed: 05/28/2023]
Abstract
Membrane-aerated biofilm reactors (MABRs) are an emerging technology for nutrient removal; however, a trade-off remains between their removal rate and oxygen transfer efficiency. This study compares nitrifying flow-through MABRs operated under continuous and intermittent aeration modes at mainstream wastewater ammonia levels. The intermittently-aerated MABRs maintained maximal nitrification rates, including under conditions allowing the oxygen partial pressure on the gas side of the membrane to considerably drop during the no-aeration period. Nitrous oxide emissions of all reactors were comparable and amounted to approximately 20 % of the converted ammonia. Intermittent aeration increased the transformation rate constant of atenolol, yet did not affect the removal of sulfamethoxazole. Seven additional trace organic chemicals were not biodegraded by any of the reactors. The ammonia-oxidizing bacteria in the intermittently-aerated MABRs were dominated by Nitrosospira, previously shown to be abundant at low oxygen concentrations and provide reactor stability under changing conditions. Our findings indicate that intermittently-aerated flow-through MABRs can achieve high nitrification rates and oxygen transfer efficiencies, highlighting the possible implications of air supply discontinuity on nitrous oxide emissions and trace organic chemical biotransformation.
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Affiliation(s)
- Tal Elad
- Department of Environmental and Resource Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark.
| | - Maria Philipsen Hally
- Department of Environmental and Resource Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark
| | - Carlos Domingo-Félez
- Department of Environmental and Resource Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark
| | - Oliver Knoop
- Chair of Urban Water Systems Engineering, Technical University of Munich, 85748 Garching, Germany
| | - Jörg E Drewes
- Chair of Urban Water Systems Engineering, Technical University of Munich, 85748 Garching, Germany
| | - Borja Valverde-Pérez
- Department of Environmental and Resource Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark
| | - Barth F Smets
- Department of Environmental and Resource Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark
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Campbell K, Wang J, Daigger GT. Filamentous organisms degrade oxygen transfer efficiency by increasing mixed liquor apparent viscosity: Mechanistic understanding and experimental verification. Water Res 2020; 173:115570. [PMID: 32062221 DOI: 10.1016/j.watres.2020.115570] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [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: 08/31/2019] [Revised: 01/25/2020] [Accepted: 01/29/2020] [Indexed: 06/10/2023]
Abstract
Recent findings have demonstrated that activated sludge morphology significantly impacts oxygen transfer efficiency (OTE) in the activated sludge process. In this study, we developed a mechanistic understanding of this impact. Mixed liquor samples collected from a domestic wastewater treatment plant (WWTP) were blended with a bulking activated sludge from a bench scale reactor (BSR) cultured on synthetic wastewater to manipulate various morphological parameters such as the settled sludge volume (SV), the sludge volume index (SVI), and the specific filament length (SFL). The filaments that were present in the blended sludges consisted largely of Type 0041 and Type 021N, which are commonly found in WWTPs that treat domestic wastewater. Variations in sludge morphology, as quantified by settled sludge volume after 30 min (SV30), SVI, and SFL, systematically affected the mixed liquor apparent viscosity (μapp), which consequently impacted OTE. An increase in the SFL from 9.61 × 106 μm g-1 to 6.88 × 107 μm g-1 resulted in a 41.4% increase in apparent viscosity and a 24.6% decrease in volumetric mass transfer coefficient (KLa). A new parameter, named the ultimate settleability (SVULT), was developed by curve fitting the SV versus time data and found to relate with μapp through an expanded form of the Einstein Equation for the viscosity. Therefore, SVULT is a corollary for the particle volume fraction that incorporates effects of both the sludge morphology and mass concentration on μapp. Theoretical derivation revealed that an increase in SVULT resulted in an increase in μapp, which reduced oxygen transfer by increasing the air bubble size and reducing refreshment of the liquid at the gas-liquid interface. The KLa was found to be inversely proportional to μapp0.75 through fitting the experimental data with the theoretical model. Using a variance-based global sensitivity analysis, three operating parameters that have the most impact on oxygen transfer were identified: the power input per unit volume, the superficial gas flowrate, and the μapp.
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Affiliation(s)
- Ken Campbell
- Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, MO, USA
| | - Jianmin Wang
- Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, MO, USA.
| | - Glen T Daigger
- Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, MI, USA
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Xiao W, Xu G. Mass transfer of nanobubble aeration and its effect on biofilm growth: Microbial activity and structural properties. Sci Total Environ 2020; 703:134976. [PMID: 31757539 DOI: 10.1016/j.scitotenv.2019.134976] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [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: 07/04/2019] [Revised: 10/11/2019] [Accepted: 10/12/2019] [Indexed: 06/10/2023]
Abstract
It is necessary to improve the performance and reduce the aeration cost is of wastewater treatment by aerobic biofilm systems. Nanobubble aeration is supposed to be a promising method to achieve these goals. Compared with coarse bubbles, dissolved oxygen profiling showed that the nanobubbles provided more oxygen to biofilms, offering superior oxygen supply capacity and 1.5 times higher oxygen transfer efficiency. Nanobubble aeration accelerated the growth of the biofilm and achieved better removal efficiencies of chemical oxygen demand and ammonia, with as maximum as six times higher dehydrogenase activity, and more extracellular polymeric substance content than when using the traditional aeration mode. This is attributed to the enhancement of metabolism and the proliferation of microorganisms. Confocal laser-scanning microscopy imaging confirmed that nanobubble aeration affected the components of biofilm by shifting the microbial community and changing its metabolic pathways of biofilms, such as carbohydrate synthesis. Nanobubble aeration resulted in an energy saving of approximately 80%. The assessment of nanobubble aerated biofilm growth suggests that this technique can offer a rapid-initiation, high efficiency, and low-cost strategy for aerobic biofilm systems in wastewater treatment.
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Affiliation(s)
- Wanting Xiao
- National Engineering Laboratory for Sustainable Sludge Management & Resourcelization Technology, Harbin Institute of Technology, Harbin 150090, China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Guoren Xu
- National Engineering Laboratory for Sustainable Sludge Management & Resourcelization Technology, Harbin Institute of Technology, Harbin 150090, China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
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7
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Duan Y, Liu Y, Zhang M, Li Y, Zhu W, Hao M, Ma S. Start-up and operational performance of the partial nitrification process in a sequencing batch reactor (SBR) coupled with a micro-aeration system. Bioresour Technol 2020; 296:122311. [PMID: 31678708 DOI: 10.1016/j.biortech.2019.122311] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [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: 07/13/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 06/10/2023]
Abstract
Partial nitrification (PN) of ammonia to nitrite is investigated in a lab-scale sequencing batch reactor (SBR) coupled with both a microporous aeration system and a mechanical agitation system at a moderate temperature of (27 ± 1 °C). The SBR has a high actual oxygen transfer efficiency (AOTE) of 2.0% and dynamical efficiency (DE) of 20.0%. Alkalinity consumption declined with the decreasing ratios of HCO3- to NH4+-N in the influent from 2.57, 1.96, 1.91 to 1.66, while the pH of the effluent is constantly maintained at 7.5 ± 0.1. The SBR is successfully operated for 195 days at a nitrogen loading rate (NLR) of up to 2.82 kg·m-3.d-1, achieving a nitrite accumulation rate (NAR) of over 90%. The high-throughput sequencing shows that the ratio of Nitrosomonas, the dominant species, is up to 29.83%.
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Affiliation(s)
- Yun Duan
- College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi Province 030024, China.
| | - Yusheng Liu
- College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi Province 030024, China
| | - Mingmei Zhang
- College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi Province 030024, China
| | - Yangyang Li
- College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi Province 030024, China
| | - Wei Zhu
- College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi Province 030024, China
| | - Mengya Hao
- College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi Province 030024, China
| | - Shuya Ma
- College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi Province 030024, China
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8
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Campbell K, Wang J, Daniels M. Assessing activated sludge morphology and oxygen transfer performance using image analysis. Chemosphere 2019; 223:694-703. [PMID: 30802835 DOI: 10.1016/j.chemosphere.2019.02.088] [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: 12/13/2018] [Revised: 02/08/2019] [Accepted: 02/14/2019] [Indexed: 06/09/2023]
Abstract
The morphology of the microbial communities can have dramatic impacts on not only the treatment performance, but also the energy use performance of an activated sludge process. In this research, we developed and calibrated an image analysis technique to determine key morphological parameters such as the floc diameter and the specific filament length (SFL) and discovered that the SFL has significant impacts on sludge floc size, the specific extracellular polymeric substances production, the settleability, mixed liquor viscosity, and oxygen transfer efficiency. When the SFL increased from 2.5 × 109 μm g-1 to 6.0 × 1010 μm g-1, the apparent viscosity normalized by the mixed liquor suspended solids concentration increased by 67%, and the oxygen transfer efficiency decreased by 29%. A long solids retention time (SRT) of 40 day reduced SFL, improved sludge settling performance, and improved oxygen transfer efficiency as compared to shorter SRTs of 10 and 20 day. The findings underscore the need to assess microbial morphology when quantifying the treatment performance and energy performance of activated sludge processes.
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Affiliation(s)
- Ken Campbell
- Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, MO, USA
| | - Jianmin Wang
- Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, MO, USA.
| | - Margo Daniels
- Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, Rolla, MO, USA
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9
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Liu X, Zhang K, Fan L, Luo H, Jiang M, Anderson BC, Li M, Huang B, Yu L, He G, Wang J, Pu A. Intermittent micro-aeration control of methane emissions from an integrated vertical-flow constructed wetland during agricultural domestic wastewater treatment. Environ Sci Pollut Res Int 2018; 25:24426-24444. [PMID: 29909533 DOI: 10.1007/s11356-018-2226-5] [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: 06/24/2017] [Accepted: 05/04/2018] [Indexed: 06/08/2023]
Abstract
It is very important to control methane emissions to mitigate global warming. An intermittent micro-aeration control system was used to control methane emissions from an integrated vertical-flow constructed wetland (IVCW) to treat agricultural domestic wastewater pollution in this study. The optimized intermittent micro-aeration conditions were a 20-min aeration time and 340-min non-aeration time, 3.9 m3 h-1 aeration intensity, evenly distributed micro-aeration diffusers at the tank bottom, and an aeration period of every 6 h. Methane flux emission by intermittent micro-aeration was decreased by 60.7% under the optimized conditions. The average oxygen transfer efficiency was 26.73%. The control of CH4 emission from IVCWs was most strongly influenced by the intermittent micro-aeration diffuser distribution, followed by aeration intensity, aeration time, and water depth. Scaling up of IVCWs is feasible in rural areas by using intermittent micro-aeration control as a mitigation measure for methane gas emissions for climate change.
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Affiliation(s)
- Xiaoling Liu
- Sichuan Water Conservancy Vocational College, Chengdu, 611231, China
| | - Ke Zhang
- College of Civil Engineering, Sichuan Agricultural University, Chengdu, 611830, China
| | - Liangqian Fan
- College of Civil Engineering, Sichuan Agricultural University, Chengdu, 611830, China
| | - Hongbing Luo
- College of Civil Engineering, Sichuan Agricultural University, Chengdu, 611830, China.
| | - Mingshu Jiang
- Sichuan Company of China Post Insurance, Chengdu, 610016, China
| | - Bruce C Anderson
- Department of Civil Engineering, Queen's University, Kingston, K7L 3N6, Canada
| | - Mei Li
- School of Urban and Rural Construction, Chengdu University, Chengdu, 610106, China
| | - Bo Huang
- Campus of Dujiangyan, Sichuan Agricultural University, Chengdu, 611830, China
| | - Lijuan Yu
- Campus of Dujiangyan, Sichuan Agricultural University, Chengdu, 611830, China
| | - Guozhu He
- Campus of Dujiangyan, Sichuan Agricultural University, Chengdu, 611830, China
| | - Jingting Wang
- College of Environmental Sciences, Sichuan Agricultural University, Chengdu, 611130, China
| | - Aiping Pu
- College of Environmental Sciences, Sichuan Agricultural University, Chengdu, 611130, China
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Wang S, Deng L, Zheng D, Wang L, Zhang Y, Yang H, Jiang Y, Huang F. Control of partial nitrification using pulse aeration for treating digested effluent of swine wastewater. Bioresour Technol 2018; 262:271-277. [PMID: 29715630 DOI: 10.1016/j.biortech.2018.04.084] [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: 02/18/2018] [Revised: 04/14/2018] [Accepted: 04/20/2018] [Indexed: 06/08/2023]
Abstract
Three sequencing batch reactors (SBRs) were used to investigate the influence of pulse frequencies on the partial nitrification (PN) process in this study. At a total aeration time of 6 min each hour, the aerated frequencies of R1, R2 and R3 were 6, 3 and 2 time h-1. During the steady period (117-143d), the nitrite accumulation rates (NARs) were 90.80%, 90.71% and 90.23% in R1, R2 and R3, respectively, indicating a steady nitritation was acquired. Activity measurements of the sludge samples taken at day 138 showed the activity of nitrite oxidating bacteria (NOB) was 0, indicating NOBs were successfully suppressed. The ratio of NO2--N to NH4+-N in the effluent of R3 was 1.35, which most closely matched the influent of Anammox process. However, the energy efficiency evaluation showed that R1 had the highest actual oxygen transfer efficiency (AOTE) and dynamical efficiency (DE).
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Affiliation(s)
- Shuang Wang
- Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China
| | - Liangwei Deng
- Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China.
| | - Dan Zheng
- Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China
| | - Lan Wang
- Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China
| | - Yunhong Zhang
- Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China
| | - Hongnan Yang
- Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China
| | - Yiqi Jiang
- Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China
| | - Fangyu Huang
- Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China
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11
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Freeman AI, Surridge BWJ, Matthews M, Stewart M, Haygarth PM. New approaches to enhance pollutant removal in artificially aerated wastewater treatment systems. Sci Total Environ 2018; 627:1182-1194. [PMID: 30857083 DOI: 10.1016/j.scitotenv.2018.01.261] [Citation(s) in RCA: 5] [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] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 01/25/2018] [Accepted: 01/25/2018] [Indexed: 06/09/2023]
Abstract
Freshwater ecosystems sustain human society through the provision of a range of services. However, the status of these ecosystems is threatened by a multitude of pressures, including point sources of wastewater. Future treatment of wastewater will increasingly require new forms of decentralised infrastructure. The research reported here sought to enhance pollutant removal within a novel wastewater treatment technology, based on un-planted, artificially aerated, horizontal subsurface flow constructed wetlands. The potential for these systems to treat de-icer contaminated runoff from airports, a source of wastewater that is likely to grow in importance alongside the expansion of air travel and under future climate scenarios, was evaluated. A new configuration for the delivery of air to aerated treatment systems was developed and tested, based on a phased-aeration approach. This new aeration approach significantly improved pollutant removal efficiency compared to alternative aeration configurations, achieving >90% removal of influent load for COD, BOD5 and TOC. Optimised operating conditions under phased aeration were also determined. Based on a hydraulic retention time of 1.5 d and a pollutant mass loading rate of 0.10 kg d-1 m-2 BOD5, >95% BOD5 removal, alongside final effluent BOD5 concentrations <21 mg L-1, could be achieved from an influent characterised by a BOD5 concentration > 800 mg L-1. Key controls on oxygen transfer efficiency within the aerated treatment system were also determined, revealing that standard oxygen transfer efficiency was inversely related to aeration rate between 1 L and 3 L min-1 and positively related to bed media depth between 1500 mm and 3000 mm. The research reported here highlights the potential for optimisation and subsequent widespread application of the aerated wetland technology, in order to protect and restore freshwater ecosystems and the services that they provide to human society.
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Affiliation(s)
- Andrew I Freeman
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Ben W J Surridge
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
| | - Mike Matthews
- Peak Associates Environmental Consultants Ltd., Lancaster Office, Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Mark Stewart
- Manchester Airports Group Plc, Manchester Airport, Water Services Department, Building 30, M90 1AA, UK
| | - Philip M Haygarth
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
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