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Haaksman VA, van Dijk EJH, Al-Zuhairy S, Mulders M, Loosdrecht MCMV, Pronk M. Utilizing anaerobic substrate distribution for growth of aerobic granular sludge in continuous-flow reactors. WATER RESEARCH 2024; 257:121531. [PMID: 38701553 DOI: 10.1016/j.watres.2024.121531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 03/24/2024] [Accepted: 03/26/2024] [Indexed: 05/05/2024]
Abstract
The development of continuous flow reactors (CFRs) employing aerobic granular sludge (AGS) for the retrofit of existing wastewater treatment plants (WWTPs) using a continuous-flow activated sludge (CFAS) system has garnered increasing interest. This follows the worldwide adoption of AGS technology in sequencing batch reactors (SBRs). The better settleability of AGS compared to AS allows for process intensification of existing wastewater treatment plants without the difficult conversion of often relatively shallow CFRs to deeper AGS-SBRs. To retrofit existing CFAS systems with AGS, achieving both increased hydraulic capacity and enhanced biological nutrient removal necessitates the formation of granular sludge based on the same selective pressures applied in AGS-SBRs. Previous efforts have focussed mainly on the selective wasting of flocculent sludge and retaining granular sludge to drive aerobic granulation. In this study a pilot-scale CFR was developed to best mimic the implementation of the granulation mechanisms of full-scale AGS-SBRs. The pilot-scale reactor was fed with pre-settled municipal wastewater. We established metrics to assess the degree to which the proposed mechanisms were implemented in the pilot-scale CFR and compared them to data from full-scale AGS-SBRs, specifically with respect to the anaerobic distribution of granule forming substrates (GFS). The selective pressures for granular sludge formation were implemented through inclusion of anaerobic upflow selectors with a water depth of 2.5 meters, which yielded a sludge with properties similar to AGS from full-scale SBRs. In comparison to the CFAS system at Harnaschpolder WWTP treating the same pre-settled wastewater, a more than twofold increase in volumetric removal capacity for both phosphorus and nitrogen was achieved. The use of a completely mixed anaerobic selector, as opposed to an anaerobic upflow selector, caused a shift in EBPR activity from the largest towards the smallest size class, while nitrification was majorly unaffected. Anaerobic selective feeding via bottom-feeding is, therefore, favorable for the long-term stability of AGS, especially for less acidified wastewater. The research underlines the potential of AGS for enhancing the hydraulic and biological treatment capacity of existing CFAS systems.
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Affiliation(s)
- Viktor A Haaksman
- Delfluent Services, Peuldreef 4, Den Hoorn, 2635 BX, The Netherlands.
| | | | - Salah Al-Zuhairy
- Delfluent Services, Peuldreef 4, Den Hoorn, 2635 BX, The Netherlands
| | - Michel Mulders
- Delfluent Services, Peuldreef 4, Den Hoorn, 2635 BX, The Netherlands
| | - Mark C M van Loosdrecht
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, Delft, 2629 HZ, The Netherlands
| | - Mario Pronk
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, Delft, 2629 HZ, The Netherlands; Royal HaskoningDHV, Laan 1914 35, Amersfoort, 3800 AL, The Netherlands.
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2
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Haaksman VA, Schouteren M, van Loosdrecht MCM, Pronk M. Impact of the anaerobic feeding mode on substrate distribution in aerobic granular sludge. WATER RESEARCH 2023; 233:119803. [PMID: 36870106 DOI: 10.1016/j.watres.2023.119803] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 01/20/2023] [Accepted: 02/24/2023] [Indexed: 06/18/2023]
Abstract
There is a growing interest to implement aerobic granular sludge (AGS) in existing conventional activated sludge (CAS) systems with a continuous flow-through configuration. The mode of anaerobic contact of raw sewage with the sludge is an important aspect in the adaptation of CAS systems to accommodate AGS. It remains unclear how the distribution of substrate over the sludge by a conventional anaerobic selector compares to the distribution via bottom-feeding applied in sequencing batch reactors (SBRs). This study investigated the effect of the anaerobic contact mode on the substrate (and storage) distribution by operating two lab-scale SBRs; one with the traditional bottom-feeding through a settled sludge bed similar to full-scale AGS systems, and one where the synthetic wastewater was fed as a pulse at the start of the anaerobic phase while the reactor was mixed through sparging of nitrogen gas (mimicking a plug-flow anaerobic selector in continuous flow-through systems). The distribution of the substrate over the sludge particle population was quantified via PHA analysis, combined with the obtained granule size distribution. Bottom-feeding was found to primarily direct substrate towards the large granular size classes (i.e. large volume and close to the bottom), while completely mixed pulse-feeding gives a more equal distribution of substrate over all granule sizes (i.e. surface area dependant). The anaerobic contact mode directly controls the substrate distribution over the different granule sizes, irrespective of the solids retention time of a granule as an entity. Preferential feeding of the larger granules will enhance and stabilise the granulation compared to pulse-feeding, certainly under less advantageous conditions imposed by real sewage.
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Affiliation(s)
- V A Haaksman
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, Delft, 2629 HZ, The Netherlands.
| | - M Schouteren
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, Delft, 2629 HZ, The Netherlands
| | - M C M van Loosdrecht
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, Delft, 2629 HZ, The Netherlands
| | - M Pronk
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, Delft, 2629 HZ, The Netherlands; Royal HaskoningDHV, Laan 1914 35, Amersfoort, 3800 AL, The Netherlands
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3
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Tsertou E, Caluwé M, Goossens K, Dobbeleers T, Dockx L, Poelmans S, Suazo KS, Dries J. Is building up substrate during anaerobic feeding necessary for granulation? WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2022; 86:763-776. [PMID: 36038975 DOI: 10.2166/wst.2022.236] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
For a successful granulation process in activated sludge systems, the stimulation of slow growing organisms such as glycogen accumulating microorganisms (GAOs) is a key factor. Here we show that the introduction of an anaerobic feast followed by an aerobic famine phase successfully transforms bulking sludge, caused by the abundance of genus Kouleothrix, to a hybrid floccular-granular sludge. Two sequencing batch reactors (SBRs) were operated for 228 days treating the same industrial wastewater derived from the cleaning of trucks transporting liquid food (the cargo consists of approximately 70% chocolate and 30% beer). By respectively applying a fast and slow feeding in two parallel SBRs, different degrees of substrate build-up were achieved in the two reactors during the feast phase. The F/M ratio over the feeding time was 1.41 ± 0.48 and 0.57 ± 0.16 kg COD·(kg VSS*d)-1 for the fast-fed and the slow-fed SBR respectively. Our results demonstrate that substrate build-up during the anaerobic selection step is not necessary to obtain well-settling granular-like sludge.
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Affiliation(s)
- Eirini Tsertou
- Research Group BioWAVE, Biochemical Wastewater Valorization & Engineering, Faculty of Applied Engineering, University of Antwerp, Campus Groenenborger, Groenenborgerlaan 171-2020, Antwerp E-mail:
| | - Michel Caluwé
- Research Group BioWAVE, Biochemical Wastewater Valorization & Engineering, Faculty of Applied Engineering, University of Antwerp, Campus Groenenborger, Groenenborgerlaan 171-2020, Antwerp E-mail:
| | - Koen Goossens
- Research Group BioWAVE, Biochemical Wastewater Valorization & Engineering, Faculty of Applied Engineering, University of Antwerp, Campus Groenenborger, Groenenborgerlaan 171-2020, Antwerp E-mail:
| | - Thomas Dobbeleers
- Research Group BioWAVE, Biochemical Wastewater Valorization & Engineering, Faculty of Applied Engineering, University of Antwerp, Campus Groenenborger, Groenenborgerlaan 171-2020, Antwerp E-mail:
| | - Lennert Dockx
- Research Group BioWAVE, Biochemical Wastewater Valorization & Engineering, Faculty of Applied Engineering, University of Antwerp, Campus Groenenborger, Groenenborgerlaan 171-2020, Antwerp E-mail:
| | - Sven Poelmans
- Research Group BioWAVE, Biochemical Wastewater Valorization & Engineering, Faculty of Applied Engineering, University of Antwerp, Campus Groenenborger, Groenenborgerlaan 171-2020, Antwerp E-mail:
| | - Karina Seguel Suazo
- Research Group BioWAVE, Biochemical Wastewater Valorization & Engineering, Faculty of Applied Engineering, University of Antwerp, Campus Groenenborger, Groenenborgerlaan 171-2020, Antwerp E-mail:
| | - Jan Dries
- Research Group BioWAVE, Biochemical Wastewater Valorization & Engineering, Faculty of Applied Engineering, University of Antwerp, Campus Groenenborger, Groenenborgerlaan 171-2020, Antwerp E-mail:
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4
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Caluwé M, Goossens K, Seguel Suazo K, Tsertou E, Dries J. Granulation strategies applied to industrial wastewater treatment: from lab to full-scale. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2022; 85:2761-2771. [PMID: 35576267 DOI: 10.2166/wst.2022.129] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
About one third of the industrial activated sludge (AS) plants worldwide suffer from bad settling sludge, often caused by filamentous bulking phenomena. The present study investigated the effectiveness of a sludge granulation/densification strategy, based only on a metabolic selection mechanism, to eliminate sludge bulking in a sequencing batch reactor (SBR) treating real industrial wastewater. The wastewater originated from a tank truck cleaning company transporting chocolate and beer. The proposed strategy involved the introduction of a slow unaerated/anaerobic feeding step in the SBR operation. On lab-scale, the new feeding strategy resulted in (1) excellent settling with a sludge volume index (SVI) decreasing from more than 300 mL·g-1 to 100 mL·g-1 and lower, (2) the elimination of sludge bulking genera and (3) the significant enrichment of glycogen-accumulating organisms (GAO), mainly Defluviicoccus and Candidatus Competibacter, and this in less than 80 days. The feeding strategy was then applied to the full-scale installation, yielding similar results: a stable average SVI of 37 mL·g-1 was reached after approximately 150 days. Full granulation was however not reached, which warrants further optimization. The present study shows that the proposed strategy can easily be applied in existing SBR systems to solve the problem of sludge bulking.
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Affiliation(s)
- M Caluwé
- Research group BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium E-mail:
| | - K Goossens
- Research group BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium E-mail:
| | - K Seguel Suazo
- Research group BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium E-mail:
| | - E Tsertou
- Research group BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium E-mail:
| | - J Dries
- Research group BioWAVE, Biochemical Wastewater Valorization and Engineering, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium E-mail:
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Demirkaya E, Ciftcioglu B, Ozyildiz G, Zengin GE, Pala-Ozkok I, Cokgor E, Tas DO. Comprehensive evaluation of starter culture impact on the bioreactor performance and microbial kinetics. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2021.108233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Haaksman VA, Mirghorayshi M, van Loosdrecht MCM, Pronk M. Impact of aerobic availability of readily biodegradable COD on morphological stability of aerobic granular sludge. WATER RESEARCH 2020; 187:116402. [PMID: 32956938 DOI: 10.1016/j.watres.2020.116402] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 09/04/2020] [Accepted: 09/05/2020] [Indexed: 06/11/2023]
Abstract
Operational disturbances in aerobic granular sludge (AGS) systems can result in aerobic availability of readily biodegradable COD (rbCOD). Different from activated sludge, morphological consequences on the short and long term are not well described in literature. This study investigated the effect of incomplete anaerobic uptake of acetate on the morphological and process stability of AGS using a lab-scale reactor. A fraction of the total acetate load was dosed aerobically, which was increased stepwise while monitoring granular morphology. A good granular morphology and an SVI of 40 ml/g were obtained during initial enrichment and maintained for ≤20% aerobic acetate load dosed at 4 mg COD/g VSS/h. Biological phosphorus removal efficiency was initially unaffected, but the aerobic acetate dosage rate did decrease the aerobic phosphate uptake rate. This led to loss of phosphorus removal for >20% aerobic acetate load dosed at 8 mg COD/g VSS/h over the course of 12 days. Subsequently, significant outgrowth formed on the granular surfaces and developed over time into finger-like structures. Under these high aerobic acetate loads the SVI increased to 80 ml/g and resulted in significant biomass washout due to deteriorating settling properties of the sludge. The sludge settleability and biological phosphorus removal recovered 10 days after aerobic feeding of acetate was stopped. Aerobic presence of rbCOD can be tolerated if mostly anaerobic acetate uptake is maintained, thereby ensuring stable granular morphology and good settleability. The high enrichment of phosphate accumulating organisms in the granular sludge through bottom-feeding and selective wasting of flocs makes aerobic granular sludge resilient to morphological deterioration in aerobic presence of rbCOD.
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Affiliation(s)
- V A Haaksman
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, Delft 2629 HZ, Netherlands.
| | - M Mirghorayshi
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, Delft 2629 HZ, Netherlands; Environment Research Center (ERC), Department of Applied Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran
| | - M C M van Loosdrecht
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, Delft 2629 HZ, Netherlands
| | - M Pronk
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, Delft 2629 HZ, Netherlands; Royal HaskoningDHV, Laan 1914 35, Amersfoort 3800 AL, Netherlands
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7
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Li BB, Peng ZY, Zhi LL, Li HB, Zheng KK, Li J. Distribution and diversity of filamentous bacteria in wastewater treatment plants exhibiting foaming of Taihu Lake Basin, China. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 267:115644. [PMID: 33254706 DOI: 10.1016/j.envpol.2020.115644] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 09/09/2020] [Accepted: 09/10/2020] [Indexed: 06/12/2023]
Abstract
Foaming caused by filamentous bacteria in activated sludge (AS) is a common phenomenon in municipal wastewater treatment plants (WWTPs) in Taihu Lake Basin of South China. In this study, total bacterial and filamentous bacterial communities were comprehensively characterized in AS and foams from eight municipal WWTPs by high-throughput sequencing technology. Results showed that alpha diversities of total bacterial communities in foams were obviously lower than those in AS samples. The bacterial community structures were significantly different between WWTPs rather than sample types (AS vs. foam). For most WWTPs, the Actinobacteria phylum was highly enriched in foams and the most abundant genera in foams were common mycolata. Sixteen filamentous bacteria were identified against the improved bulking and foaming bacteria (BFB) database. Abundance and composition of BFB in different WWTPs and different sample types were significantly different. 'Nostocoida limicola' I Trichococcus and Microthrix were generally dominant in AS samples. The dominant BFB in foams were associated with Microthrix, Skermania, Gordonia, and Mycobacterium. A new Defluviicoccus spp. in cluster III was identified in severe and continuous foams. Moreover, dominant BFB in stable and continuous foams with light level in one typical WWTP were diverse, even, and dynamic. Bacterial co-occurrence network analysis implied that the bacterial community of AS was more sensitive to disturbance than that of foam.
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Affiliation(s)
- Bing-Bing Li
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Zhi-Ying Peng
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Li-Ling Zhi
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Huai-Bo Li
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Kai-Kai Zheng
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China
| | - Ji Li
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi, 214122, China; Jiangsu Engineering Laboratory for Biomass Energy and Carbon Reduction Technology, Jiangnan University, Wuxi, 214122, China; Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou, 215009, China.
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8
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Shen Y, Huang DM, Chen YP, Yan P, Gao X. New insight into filamentous sludge bulking during wastewater treatment: Surface characteristics and thermodynamics. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 712:135795. [PMID: 31866048 DOI: 10.1016/j.scitotenv.2019.135795] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 11/22/2019] [Accepted: 11/25/2019] [Indexed: 06/10/2023]
Abstract
Although there have been many studies on filamentary bulking of activated sludge, it has been revealed that there is still a gap in the microscopic mechanism of filamentary bulking. In this study, the surface characteristics and thermodynamics of sludge floc were investigated to reveal the mechanism of filamentous sludge bulking. The results showed that the EPS content gradually decreased from 71.09 mg/g VSS to 40.00 mg/g VSS and the protein (PN) content of the EPS significantly decreased from 64.10 mg/g VSS to 35.85 mg/g VSS during sludge bulking. The variation in the EPS and its components led to a decrease in the relative hydrophobicity of sludge and an increase in surface negative charge; then, deterioration of the flocculation setteability of sludge flocs occurred. The electric double layer (WR) was the main force determining the aggregation of sludge during sludge bulking. The total energy of the interaction (WT) increased during sludge bulking, which led to an increase in the difficulty of sludge accumulation. This study is useful for understanding the filamentous bulking of sludge within an activated sludge process.
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Affiliation(s)
- Yu Shen
- National Research Base of Intelligent Manufacturing Service, Chongqing Key Laboratory of Catalysis and New Environmental Materials, Chongqing Technology and Business University, Chongqing 400067, China; Chongqing South-to-Thais Environmental Protection Technology Research Institute Co., Ltd., Chongqing 400067, China
| | - Dong-Mei Huang
- National Research Base of Intelligent Manufacturing Service, Chongqing Key Laboratory of Catalysis and New Environmental Materials, Chongqing Technology and Business University, Chongqing 400067, China; Chongqing South-to-Thais Environmental Protection Technology Research Institute Co., Ltd., Chongqing 400067, China
| | - You-Peng Chen
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
| | - Peng Yan
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
| | - Xu Gao
- National Research Base of Intelligent Manufacturing Service, Chongqing Key Laboratory of Catalysis and New Environmental Materials, Chongqing Technology and Business University, Chongqing 400067, China
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Soft Sensor Application in Identification of the Activated Sludge Bulking Considering the Technological and Economical Aspects of Smart Systems Functioning. SENSORS 2020; 20:s20071941. [PMID: 32235669 PMCID: PMC7180765 DOI: 10.3390/s20071941] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 03/24/2020] [Accepted: 03/25/2020] [Indexed: 12/28/2022]
Abstract
The paper presented the methodology for the construction of a soft sensor used for activated sludge bulking identification. Devising such solutions fits within the current trends and development of a smart system and infrastructure within smart cities. In order to optimize the selection of the data-mining method depending on the data collected within a wastewater treatment plant (WWTP), a number of methods were considered, including: artificial neural networks, support vector machines, random forests, boosted trees, and logistic regression. The analysis conducted sought the combinations of independent variables for which the devised soft sensor is characterized with high accuracy and at a relatively low cost of determination. With the measurement results pertaining to the quantity and quality of wastewater as well as the temperature in the activated sludge chambers, a good fit can be achieved with the boosted trees method. In order to simplify the selection of an optimal method for the identification of activated sludge bulking depending on the model requirements and the data collected within the WWTP, an original system of weight estimation was proposed, enabling a reduction in the number of independent variables in a model—quantity and quality of wastewater, operational parameters, and the cost of conducting measurements.
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10
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Jobbágy A, Weinpel T, Bakos V, Vánkos Z. Use of floating seals to exclude oxygen penetration in non-aerated selectors. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2019; 80:357-364. [PMID: 31537772 DOI: 10.2166/wst.2019.280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
It is widely assumed that non-aerated selectors are very efficient in nutrient removal, and especially anaerobic basins may largely contribute to good sludge settleability as well. However, based on results measured in full-scale, this paper draws attention to the fact that with decreasing availability of readily biodegradable carbon source (rbCOD) being experienced worldwide, oxygen penetration into non-aerated basins through the uncovered surface may no longer be considered negligible. When the oxygen mass transfer is significant compared to the available influent rbCOD, non-aerated selectors should be regarded as basins with low dissolved oxygen (low DO) concentrations that may underperform with respect to nutrient removal and favor the growth of filaments, especially during low-loaded conditions. In order to fully exclude oxygen penetration, floating seals have been developed and applied at the North-Budapest Wastewater Treatment Plant in Hungary. Comparative full-scale studies showed prevention of significant amounts of influent rbCOD loss (up to 60 mg/L) through the application of this new technology. This amount of saved, non-oxidised but fermented carbon source could be accordingly used for enhancing biological P-removal. Due to the elimination of microaerophilic conditions, the undesirable growth of filamentous bacteria could also be avoided, leading to significantly better activated sludge settling.
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Affiliation(s)
- A Jobbágy
- Department of Applied Biotechnology and Food Science, Budapest University of Technology and Economics, Szent Gellért tér 4, H-1111 Budapest, Hungary E-mail:
| | - T Weinpel
- Department of Applied Biotechnology and Food Science, Budapest University of Technology and Economics, Szent Gellért tér 4, H-1111 Budapest, Hungary E-mail:
| | - V Bakos
- Department of Applied Biotechnology and Food Science, Budapest University of Technology and Economics, Szent Gellért tér 4, H-1111 Budapest, Hungary E-mail:
| | - Zs Vánkos
- Department of Applied Biotechnology and Food Science, Budapest University of Technology and Economics, Szent Gellért tér 4, H-1111 Budapest, Hungary E-mail:
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Gabarró J, Guivernau M, Burgos L, Garanto O, Bonmatí A. Startup strategy for nitrogen removal via nitrite in a BAF system. Bioprocess Biosyst Eng 2018; 42:233-243. [PMID: 30367248 DOI: 10.1007/s00449-018-2028-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 10/17/2018] [Indexed: 10/28/2022]
Abstract
A biological aerated filter (BAF) pilot plant consisting of two reactors (aerobic and anoxic one) was used to determine a strategy to remove nitrogen via nitrite. RNA/DNA analysis was performed to assess microbial activity and support chemical results. In less than 13 days the pilot plant was able to remove COD and suspended solids. Nitrogen removal via nitrite pathway could not be observed until day 130 when the empty bed contact time (EBCT) was set at 0.71 h. Nitrite was detected in the aerated BAF effluent but never nitrate. qPCR of amoA gene from RNA and DNA extracts of the aerobic biofilm confirmed that ammonia oxidizing bacteria (AOB) were present from the beginning of the operation but not active. AOB activity increased with time, reaching stability from operational day 124. The combination of both, low EBCT together with high OLR, has been demonstrated to be a feasible strategy to startup a BAF to achieve nitrogen removal via nitrite.
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Affiliation(s)
- Jordi Gabarró
- GIRO, Institute of Agrifood Research and Technology (IRTA), Torre Marimon, Caldes de Montbui, E08140, Barcelona, Catalonia, Spain.,TELWE S.A., Camprodon 49, 17240, Llagostera, Catalonia, Spain
| | - Miriam Guivernau
- GIRO, Institute of Agrifood Research and Technology (IRTA), Torre Marimon, Caldes de Montbui, E08140, Barcelona, Catalonia, Spain
| | - Laura Burgos
- GIRO, Institute of Agrifood Research and Technology (IRTA), Torre Marimon, Caldes de Montbui, E08140, Barcelona, Catalonia, Spain
| | - Oswald Garanto
- PESA Medio Ambiente, Avinguda de la Generalitat, 216, 08174, Sant Cugat del Vallès, Catalonia, Spain
| | - August Bonmatí
- GIRO, Institute of Agrifood Research and Technology (IRTA), Torre Marimon, Caldes de Montbui, E08140, Barcelona, Catalonia, Spain.
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12
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Meunier C, Henriet O, Schoonbroodt B, Boeur JM, Mahillon J, Henry P. Influence of feeding pattern and hydraulic selection pressure to control filamentous bulking in biological treatment of dairy wastewaters. BIORESOURCE TECHNOLOGY 2016; 221:300-309. [PMID: 27643739 DOI: 10.1016/j.biortech.2016.09.052] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 09/09/2016] [Accepted: 09/12/2016] [Indexed: 06/06/2023]
Abstract
In sequencing batch reactors (SBRs) treating dairy wastewaters, the overgrowth of filamentous bacteria is a frequent cause of operational problems. The present study aimed at understanding to what extent the operating conditions of a SBR can be optimized to convert a bulking activated sludge into a well-settling biomass at low aeration velocity. The abundance of filament morphotypes and floc-formers able to store biopolymers were analysed by PCR-DGGE and 16S amplicon sequencing. The results indicated that a combination of an anaerobic-microaerated feeding pattern with a low selective pressure was beneficial to supress filamentous overgrowth and to form aerobic granules, while increasing the efficiency of suspended solid removal. Average removal efficiencies for total chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were 94±2%, 95±1% and 83±13%, respectively.
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Affiliation(s)
- Christophe Meunier
- CEBEDEAU, Research and Expertise Center for Water, Allée de la Découverte 11 (B53), Quartier Polytech 1, B-4000 Liège, Belgium.
| | - Olivier Henriet
- Laboratory of Food and Environmental Microbiology, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Bastien Schoonbroodt
- CEBEDEAU, Research and Expertise Center for Water, Allée de la Découverte 11 (B53), Quartier Polytech 1, B-4000 Liège, Belgium
| | - Jean-Marc Boeur
- CEBEDEAU, Research and Expertise Center for Water, Allée de la Découverte 11 (B53), Quartier Polytech 1, B-4000 Liège, Belgium
| | - Jacques Mahillon
- Laboratory of Food and Environmental Microbiology, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Paul Henry
- CEBEDEAU, Research and Expertise Center for Water, Allée de la Découverte 11 (B53), Quartier Polytech 1, B-4000 Liège, Belgium
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13
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Nguyen VL, He X, de Los Reyes FL. Quantifying in situ growth rate of a filamentous bacterial species in activated sludge using rRNA:rDNA ratio. FEMS Microbiol Lett 2016; 363:fnw255. [PMID: 27974391 DOI: 10.1093/femsle/fnw255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Revised: 07/28/2016] [Accepted: 11/08/2016] [Indexed: 11/14/2022] Open
Abstract
If the in situ growth rate of filamentous bacteria in activated sludge can be quantified, researchers can more accurately assess the effect of operating conditions on the growth of filaments and improve the mathematical modeling of filamentous bulking. We developed a method to quantify the in situ specific growth rate of Sphaerotilus natans (a model filament) in activated sludge using the species-specific 16S rRNA:rDNA ratio. Primers targeting the 16S rRNA of S. natans were designed, and real-time PCR and RT-PCR were used to quantify DNA and RNA levels of S. natans, respectively. A positive linear relationship was found between the rRNA:rDNA ratio (from 440 to 4500) and the specific growth rate of S. natans (from 0.036 to 0.172 h-1) using chemostat experiments. The in situ growth rates of S. natans in activated sludge samples from three water reclamation facilities were quantified, illustrating how the approach can be applied in a complex environment such as activated sludge.
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Affiliation(s)
| | - Xia He
- Department of Civil, Construction and Environmental Engineering, North Carolina State University, Raleigh, NC 27695-7908, USA
| | - Francis L de Los Reyes
- Department of Civil, Construction and Environmental Engineering, North Carolina State University, Raleigh, NC 27695-7908, USA
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14
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Insights into microbial diversity in wastewater treatment systems: How far have we come? Biotechnol Adv 2016; 34:790-802. [DOI: 10.1016/j.biotechadv.2016.04.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 02/15/2016] [Accepted: 04/07/2016] [Indexed: 11/16/2022]
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15
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Regmi P, Bunce R, Miller MW, Park H, Chandran K, Wett B, Murthy S, Bott CB. Ammonia-based intermittent aeration control optimized for efficient nitrogen removal. Biotechnol Bioeng 2015; 112:2060-7. [DOI: 10.1002/bit.25611] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 04/02/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Pusker Regmi
- Brown and Caldwell; 1600 Duke Street, Suite 310 Alexandria Virginia 22314
| | | | - Mark W. Miller
- Civil and Environment Engineering Department; Virginia Tech; Blacksburg Virginia
| | - Hongkeun Park
- Department of Earth and Environmental Engineering; Columbia University; New York City New York
| | - Kartik Chandran
- Department of Earth and Environmental Engineering; Columbia University; New York City New York
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16
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Asvapathanagul P, Olson BH, Gedalanga PB, Hashemi A, Huang Z, La J. Identification and quantification of Thiothrix eikelboomii using qPCR for early detection of bulking incidents in a full-scale water reclamation plant. Appl Microbiol Biotechnol 2015; 99:4045-57. [DOI: 10.1007/s00253-014-6230-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 11/10/2014] [Accepted: 11/12/2014] [Indexed: 11/24/2022]
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17
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Azimi Y, Allen DG, Farnood RR. Enhancing disinfection by advanced oxidation under UV irradiation in polyphosphate-containing wastewater flocs. WATER RESEARCH 2014; 54:179-187. [PMID: 24568787 DOI: 10.1016/j.watres.2014.01.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 01/03/2014] [Accepted: 01/06/2014] [Indexed: 06/03/2023]
Abstract
In this paper, the role of naturally occurring polyphosphate in enhancing the ultraviolet disinfection of wastewater flocs is examined. It was found that polyphosphate, which accumulates naturally within the wastewater flocs in the enhanced biological phosphorus removal process, is capable of producing hydroxyl radicals under UV irradiation and hence causing the photoreactive disinfection of microorganisms embedded within flocs. This phenomenon is likely responsible for the improved UV disinfection of the biological nutrient removal (BNR) effluent compared to that of conventional activated sludge effluent by as much as 1 log. A mathematical model is developed that combines the chemical disinfection by hydroxyl radical formation within flocs, together with the direct inactivation of microorganisms by UV irradiation. The proposed model is able to quantitatively explain the observed improvement in the UV disinfection of the BNR effluents. This study shows that the chemical composition of wastewater flocs could have a significant positive impact on their UV disinfection by inducing the production of oxidative species.
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Affiliation(s)
- Y Azimi
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, Canada M5S3E5
| | - D G Allen
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, Canada M5S3E5
| | - R R Farnood
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, Canada M5S3E5.
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18
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Guo F, Zhang T. Profiling bulking and foaming bacteria in activated sludge by high throughput sequencing. WATER RESEARCH 2012; 46:2772-82. [PMID: 22406202 DOI: 10.1016/j.watres.2012.02.039] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 02/11/2012] [Accepted: 02/17/2012] [Indexed: 05/13/2023]
Abstract
Bulking and foaming bacteria (BFB) are notorious in wastewater treatment although they are always presented in the normal activated sludge and playing certain roles other than being harmful. Previous studies using microscopy or conventional molecular methods could hardly get the full profile of the BFB in the normal activated sludge. In this study, high throughput sequencing was adopted to investigate the BFB community, which was sub-dominant in activated sludge from 14 global wastewater treatment plants. The full-length 16S rRNA gene sequences of BFB groups were collected from previous studies to build a database for local BLAST and subsequent taxonomic assignment. The total BFB percentage in each sample ranged from 1.86% to 8.99% according to the 16S rRNA gene V4 pyrotags detected at the BLAST similarity cutoff of 97%. The most abundant and frequent BFB groups are 'Nostocoida limicola' I and II, Mycobacterium fortuitum, Type 1863, and 'Microthrix parvicella'. The BFB among the activated sludge samples were both biogeographically and technological distributed to some extent. An extending application was performed to evaluate and design oligonucleotides probes based on the rich information of high similar sequences. Our study also gave an exemplified case of investigation on the specific sub-dominant functional groups in complex bacterial communities revealed by high throughput sequencing.
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Affiliation(s)
- Feng Guo
- Environmental Biotechnology Laboratory, The University of Hong Kong, Hong Kong SAR, China
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19
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Brault JM, Whalen P, Stuart P. Early warning signs of bulking in an activated sludge system through interpretation of ATP data in a systems analysis context. ENVIRONMENTAL TECHNOLOGY 2011; 32:1649-1660. [PMID: 22329156 DOI: 10.1080/09593330.2010.547874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A research project was undertaken at an integrated thermomechanical pulp and paper mill in Canada to evaluate the use of adenosine triphosphate (ATP) monitoring methods in order to identify the potential for operational problems related to microbiological aspects of activated sludge. The specific filamentous bulking ATP (fbATP) ratio is an emerging measurement technique that measures the proportion of flocs that have bulking potential by filtering a sample through a 250 microm mesh and measuring the ATP in the retentate. For the host mill in this study, the specific fbATP measurement provides early warning signs of bulking, at 1.0 to 1.5 times the sludge age, before poor settling occurs. A possible bulking scenario was identified in which the initiator was the overflow of an upstream tank containing high BOD whitewater, resulting in spikes of organic acids to the treatment and promoting the proliferation of certain types of filamentous bacteria. A storage response by filamentous bacteria to these high readily biodegradable substrate conditions was monitored with fbATP. By predicting the onset of bulking conditions, this technique can potentially assist operators to make corrective actions proactively.
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Affiliation(s)
- Jean-Martin Brault
- NSERC Environmental Design Engineering Chair, Department of Chemical Engineering, Ecole Polytechnique de Montreal, Pavilion André Aisenstadt, 2920 Chemin de la Tour, Montreal, Quebec, Canada, H3T 1J7
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20
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Martins AMP, Karahan O, van Loosdrecht MCM. Effect of polymeric substrate on sludge settleability. WATER RESEARCH 2011; 45:263-273. [PMID: 20696456 DOI: 10.1016/j.watres.2010.07.055] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Revised: 07/13/2010] [Accepted: 07/18/2010] [Indexed: 05/29/2023]
Abstract
The study aims to evaluate the role of a polymeric substrate (starch) on sludge settleability. Despite being an important COD component of the wastewater, the relationship between polymeric substrates and bulking sludge has been hardly studied. The polymers are hydrolysed at a rate smaller than the consumption rate of monomers. This means that the soluble substrate resulting from hydrolysis is likely to be present at growth rate limiting concentrations. According to the kinetic selection theory this leads to bulking sludge. However, a recently postulated theory suggests that, strong diffusion limited micro-gradients of substrate concentration inside flocs lead to bulking sludge, and not a low substrate concentration as such. If the polymeric COD is first incorporated in the sludge floc and afterwards hydrolysed in the sludge floc then there is essentially no substrate gradient inside the biological flocs. The experiments showed that conditions leading to bulking sludge with monomers (glucose) did not lead to bulking when starch was used. A bulking sludge event was even cured just by substituting the monomer with starch. These results are clearly in line with a diffusion gradient--based theory for bulking sludge. Nevertheless, flocs growing on starch are more open, fluffy and porous than flocs formed on maltose or glucose, most likely because the starch needs to be hydrolysed at the surface of the micro-colonies forming the flocculated sludge. Some additional observations on occurrence of filamentous bacteria in oxygen diffusion limited systems are also discussed in this manuscript.
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Affiliation(s)
- António M P Martins
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
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21
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Liao BQ, Lin HJ, Langevin SP, Gao WJ, Leppard GG. Effects of temperature and dissolved oxygen on sludge properties and their role in bioflocculation and settling. WATER RESEARCH 2011; 45:509-20. [PMID: 20875910 DOI: 10.1016/j.watres.2010.09.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2010] [Revised: 08/30/2010] [Accepted: 09/09/2010] [Indexed: 05/26/2023]
Abstract
Effects of temperature (mesophilic (35 °C) vs. thermophilic (55 °C)) and dissolved oxygen (DO) concentration (under thermophilic conditions) on sludge properties and their role in bioflocculation and settling were studied using well-controlled sequencing batch reactors fed with a synthetic wastewater comprised of glucose and inorganic nutrients. Under a similar DO level, thermophilic sludge had a poorer bioflocculating ability and settleability than that of mesophilic sludge. Under a thermophilic condition, an increase in DO level led to a poorer settleability and a slightly improved bioflocculating ability. A poorer settleability was related to a higher level of filaments. Analysis of bound extracellular polymeric substances (EPS) indicates that thermophilic sludge had a higher level of total bound EPS content than that of mesophilic sludge under a similar DO level, and an increase in DO resulted in an increase in total bound EPS content in thermophilic sludge. Surface analysis of sludge by X-ray photoelectron spectroscopy (XPS) suggests that significant differences in the surface concentrations of elements N, C, O were observed between thermophilic and mesophilic sludge, implying significant differences in bound EPS composition. The results of gel permeation chromatography indicate that the weight-averaged molecular weight (M(w)) of bound EPS covered a range of 1159 Da to 13220 Da. The distribution of EPS "species" at floc surfaces was shown by transmission electron microscopy (TEM) to be uneven; different kinds of nanoscale materials were distributed in a patchy manner at the floc-water interface. The results suggest that it is the role of specific EPS molecules rather than the quantity of bound EPS that determine the difference in bioflocculation behavior between thermophilic and mesophilic sludge. The strategy of increasing the DO level could not solve the biomass separation problems associated with thermophilic sludge.
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Affiliation(s)
- B Q Liao
- Department of Chemical Engineering, Lakehead University, Thunder Bay, ON, Canada.
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22
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Gray DMD, De Lange VP, Chien MH, Esquer MA, Shao YJ. Investigating the fundamental basis for selectors to improve activated sludge settling. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2010; 82:541-555. [PMID: 20572462 DOI: 10.2175/106143009x12529484815791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Aerobic, anoxic, and anaerobic selectors have become popular for controlling filamentous bulking in activated sludge systems; however, selectors are not always successful. Regression analyses of data collected from 48 full-scale wastewater treatment plants, with operating selectors, provided a method for ranking the importance of selector operating and design parameters (with respect to their influence on activated sludge settleability) and suggests optimum numerical ranges for these parameters for best selector performance. Selectors do not appear to control filamentous bulking in long mean cell residence time (MCRT) plants. Further, the elimination of all selector zones may help to control bulking in these plants. However, other design/operating parameters were shown to influence activated sludge settleability in long-MCRT plants. Aerobic selectors in short-MCRT plants can control filamentous bulking, if they are small enough to produce a biochemical oxygen demand (BOD) concentration gradient. Anoxic and anaerobic selectors can control filamentous bulking in short-MCRT plants, if the selector volume is large enough and/or the selector mixed-liquor suspended solids concentration is high enough. These unaerated selector systems do not appear to benefit from a BOD concentration gradient as the aerobic selectors in short-MCRT plants do. Although anaerobic/anoxic selector compartmentalization in these plants appears to improve settleability, this presumably is because of reduced selector short-circuiting.
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Affiliation(s)
- Donald M D Gray
- East Bay Municipal Utility District, Oakland, California 94607, USA.
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23
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PENG Z, PENG Y, GUI L, LIU X. Competition for Single Carbon Source Between Denitrification and Phosphorus Release in Sludge under Anoxic Condition. Chin J Chem Eng 2010. [DOI: 10.1016/s1004-9541(10)60245-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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24
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Flores-Alsina X, Comas J, Rodriguez-Roda I, Gernaey KV, Rosen C. Including the effects of filamentous bulking sludge during the simulation of wastewater treatment plants using a risk assessment model. WATER RESEARCH 2009; 43:4527-4538. [PMID: 19695661 DOI: 10.1016/j.watres.2009.07.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 07/26/2009] [Accepted: 07/31/2009] [Indexed: 05/28/2023]
Abstract
The main objective of this paper is to demonstrate how including the occurrence of filamentous bulking sludge in a secondary clarifier model will affect the predicted process performance during the simulation of WWTPs. The IWA Benchmark Simulation Model No. 2 (BSM2) is hereby used as a simulation case study. Practically, the proposed approach includes a risk assessment model based on a knowledge-based decision tree to detect favourable conditions for the development of filamentous bulking sludge. Once such conditions are detected, the settling characteristics of the secondary clarifier model are automatically changed during the simulation by modifying the settling model parameters to mimic the effect of growth of filamentous bacteria. The simulation results demonstrate that including effects of filamentous bulking in the secondary clarifier model results in a more realistic plant performance. Particularly, during the periods when the conditions for the development of filamentous bulking sludge are favourable--leading to poor activated sludge compaction, low return and waste TSS concentrations and difficulties in maintaining the biomass in the aeration basins--a subsequent reduction in overall pollution removal efficiency is observed. Also, a scenario analysis is conducted to examine i) the influence of sludge retention time (SRT), the external recirculation flow rate (Q(r)) and the air flow rate in the bioreactor (modelled as k(L)a) as factors promoting bulking sludge, and ii) the effect on the model predictions when the settling properties are changed due to a possible proliferation of filamentous microorganisms. Finally, the potentially adverse effects of certain operational procedures are highlighted, since such effects are normally not considered by state-of-the-art models that do not include microbiology-related solids separation problems.
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Affiliation(s)
- Xavier Flores-Alsina
- Laboratory of Chemical and Environmental Engineering, University of Girona, Montilivi Campus s/n, Girona, Spain.
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25
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Stricker AE, Lishman L, Barrie A. Effects of fluctuating iron dosage on nitrification in integrated fixed film and conventional activated sludge processes. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2009; 81:907-921. [PMID: 19860147 DOI: 10.2175/106143008x274275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
An integrated fixed-film activated sludge (IFFAS) process with four media cells is operating in parallel with a conventional activated sludge (CAS) train at Lakeview Wastewater Treatment Plant (Ontario, Canada). During winter 2007, an intensive sampling campaign was conducted to monitor the temporal and spatial variations of the nitrification capacity within the two plug-flow reactors. At the beginning of the six-week study, the CAS train was partially nitrifying, whereas the IFFAS train was nitrifying completely using the first two IFFAS cells only. Within one week, the CAS train lost nitrification because of a drop in solids retention time and pH caused by the onset of iron overdosing. When the IFFAS train received an iron spike, the carriers at the injection point (first cell) became iron-coated and lost 80% of their nitrification capacity. However, this train maintained its total nitrification capacity using the reserve capacity in the three remaining cells.
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26
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Stricker AE, Barrie A, Maas CLA, Fernandes W, Lishman L. Comparison of performance and operation of side-by-side integrated fixed-film and conventional activated sludge processes at demonstration scale. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2009; 81:219-232. [PMID: 19378652 DOI: 10.2175/106143008x325692] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A full-scale demonstration of an integrated fixed-film activated sludge (IFFAS) process with floating carriers has been conducted in Ontario, Canada, since August 2003. In this study, data collected on-site from July 2005 to December 2006 are analyzed and compared with the performance of a conventional activated sludge train operated in parallel. Both trains received similar loadings and maintained comparable mixed liquor concentrations; however, the IFFAS had 50% more biomass when the attached growth was considered. In the winter, the conventional train operated at the critical solids retention time (SRT) and had fluctuating partial nitrification. The IFFAS nitrified more consistently and had a doubled average capacity. In the summer, the suspended SRT was less limiting, and the benefit of IFFAS for nitrification was marginal. The lessons learned from the operational requirements and challenges of the IFFAS process (air flow, carrier management, and seasonal foaming) are discussed, and design recommendations are proposed for whole plant retrofit.
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27
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Ciğgin AS, Karahan O, Orhon D. Effect of high nitrate concentration on PHB storage in sequencing batch reactor under anoxic conditions. BIORESOURCE TECHNOLOGY 2009; 100:1376-1382. [PMID: 18842401 DOI: 10.1016/j.biortech.2008.08.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2008] [Revised: 08/20/2008] [Accepted: 08/21/2008] [Indexed: 05/26/2023]
Abstract
The study investigated effect of high influent nitrate concentration on poly-beta-hydroxybutyrate, (PHB), storage in a sequencing batch reactor, (SBR), under anoxic conditions. Acetate was fed as pulse during anoxic phase, sustained with external nitrate feeding. SBR operation involved three runs at steady state with COD/N ratios of 3.84, 2.93 and 1.54 gCOD/gN, where external nitrate concentrations gradually increased from 50 mg N/l to 114 mg N/l and 226 mg N/l, in 1st, 2nd and 3rd runs, respectively. In 1st run, acetate was fully converted into PHB with the storage yield value of 0.57-0.59 gCOD/gCOD, calculated both in terms of PHB formation and NO(X) utilization, confirming storage was the sole substrate utilization mechanism. In the following runs, PHB formation was reduced and the storage yield based on PHB dropped down to 0.40 and 0.33 gCOD/gCOD with increasing influent nitrate concentrations, indicating that higher portions of acetate were diverted to simultaneous direct growth. The observations suggested that nitrite accumulation detected at low COD/N ratios was responsible for inhibition of PHB storage.
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Affiliation(s)
- Asli S Ciğgin
- Environmental Engineering Department, Faculty of Civil Engineering, Istanbul Technical University, Maslak, Istanbul, Turkey
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28
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Xin G, Gough HL, Stensel HD. Effect of anoxic selector configuration on sludge volume index control and bacterial population fingerprinting. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2008; 80:2228-2240. [PMID: 19146100 DOI: 10.2175/106143008x325700] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The effect of single-stage and 4-stage anoxic selectors and an anoxic/aerobic sequencing batch reactor (SBR) on the removal of readily biodegradable chemical oxygen demand (rbCOD) and slowly biodegradable COD (sbCOD) and on filamentous growth and sludge settleability was studied. Microbial community fingerprinting in the three selector configurations was done using automated ribosomal intergenic spacer analysis. Nostocoida limicola II and type 1851 filamentous bacteria were observed in all systems. The diluted sludge volume index (DSVI) decreased with increased selector staging. The rbCOD was almost completely removed in all selectors, and the lower DSVI values with increased selector staging were the result of greater sbCOD removal in the selector. The plug-flow kinetics in the SBR aerobic phase also improved DSVI. The bacteria community composition in the 4-stage selector system was found to be more similar to that for the SBR than for the single-stage selector.
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Affiliation(s)
- Gang Xin
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington 98195, USA
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29
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Schuler AJ, Jassby D. Filament content threshold for activated sludge bulking: artifact or reality? WATER RESEARCH 2007; 41:4349-56. [PMID: 17825872 DOI: 10.1016/j.watres.2007.06.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 06/01/2007] [Accepted: 06/10/2007] [Indexed: 05/17/2023]
Abstract
An often-noted feature of activated sludge settleability is the existence of a threshold content of filamentous bacteria, below which filaments have a relatively small effect on settleability, and above which settleability is much more sensitive to filament content. This concept has historically been based on an apparent inflection point in settleability/filament content curves. However, this was demonstrated to be an artifact of data presentation on semi-logarithmic scales. Analyses of several published data sets indicated that there was little or no evidence of a threshold effect when data were presented on linear scales, particularly around the 150 mL/g sludge volume index (SVI) "threshold". Rather, there appears to be a generally continuous (and often nearly linear) relationship between filament content and SVI, suggesting that the threshold effect, as commonly perceived, is not accurate. A modified empirical model of filament content and settleability was also presented.
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Affiliation(s)
- Andrew J Schuler
- Department of Civil and Environmental Engineering, University of New Mexico, Albuquerque, NM 87131-0001, USA.
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30
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Ju LK, Huang L, Trivedi H. Simultaneous nitrification, denitrification, and phosphorus removal in single-tank low-dissolved-oxygen systems under cyclic aeration. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2007; 79:912-20. [PMID: 17824538 DOI: 10.2175/106143007x175942] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Simultaneous nitrification and denitrification (SND or SNdN) may occur at low dissolved oxygen concentrations. In this study, bench-scale (approximately 6 L) bioreactors treating a continuous feed of synthetic wastewater were used to evaluate the effects of solids retention time and low dissolved oxygen concentration, under cyclic aeration, on the removal of organics, nitrogen, and phosphorus. The cyclic aeration was carried out with repeated cycles of 1 hour at a higher dissolved oxygen concentration (HDO) and 30 minutes at a lower (or zero) dissolved oxygen concentration (LDO). Compared with aeration at constant dissolved oxygen concentrations, the cyclic aeration, when operated with proper combinations of HDO and LDO, produced better-settling sludge and more complete nitrogen and phosphorus removal. For nitrogen removal, the advantage resulted from the more readily available nitrate and nitrite (generated by nitrification during the HDO period) for denitrification (during the LDO period). For phosphorus removal, the advantage of cyclic aeration came from the development of a higher population of polyphosphate-accumulating organisms, as indicated by the higher phosphorus contents in the sludge solids of the cyclically aerated systems. Nitrite shunt was also observed to occur in the LDO systems. Higher ratios of nitrite to nitrate were found in the systems of lower HDO (and, to less dependency, higher LDO), suggesting that the nitrite shunt took place mainly because of the disrupted nitrification at lower HDO. The study results indicated that the HDO used should be kept reasonably high (approximately 0.8 mg/L) or the HDO period prolonged, to promote adequate nitrification, and the LDO kept low (< or =0.2 mg/L), to achieve more complete denitrification and higher phosphorus removal. The above findings in the laboratory systems find strong support from the results obtained in full-scale plant implementation. Two plant case studies using the cyclic low-dissolved-oxygen aeration for creating and maintaining SND are also presented.
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Affiliation(s)
- Lu-Kwang Ju
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325-3906, USA.
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31
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Huang L, Ju LK. Sludge settling and online NAD(P)H fluorescence profiles in wastewater treatment bioreactors operated at low dissolved oxygen concentrations. WATER RESEARCH 2007; 41:1877-84. [PMID: 17363027 DOI: 10.1016/j.watres.2007.01.040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Revised: 01/19/2007] [Accepted: 01/26/2007] [Indexed: 05/14/2023]
Abstract
Biological nitrogen removal via simultaneous nitrification and denitrification (SND) may be achieved in the single-tank bioreactors operated at low dissolved oxygen concentrations (DO). The continuous-stirred tank reactor (CSTR) configuration and the low DO environments employed are; however, more conducive to growth of filamentous bacteria and, thus, poor sludge settling in clarifiers. In this work, a synthetic wastewater was treated in bench-scale (approximately 6L) bioreactors under either cyclic or constant-rate aeration, at various sludge retention times (SRT) and DO. The objective was to evaluate the effects of these factors on the sludge settling indicated by sludge volume index. The cyclic aeration was carried out by alternating the aeration between a higher rate for 1h and a lower (or zero) rate for 30 min. In different experiments, the DO during the period of higher aeration (HDO) was 0.4, 0.6, 0.8, or 2.0 mg/L and the DO during lower aeration (LDO) was 0.0 or 0.2mg/L. The sludge established under the cyclic aeration was found to settle better than that under constant-rate aeration. Shortening SRT also improved the sludge settling significantly. NAD(P)H fluorescence profiles in these bioreactors were monitored using an online fluorometer. A procedure was developed to quantitatively describe the metabolic state of sludge's heterotrophic population on a 0-1 scale using the fluorescence profile, with "0" corresponding to the fully anoxic-denitrifying state and "1" to the fully aerobic state.
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Affiliation(s)
- Lin Huang
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325-3906, USA
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Ciğgin AS, Karahan O, Orhon D. Effect of feeding pattern on biochemical storage by activated sludge under anoxic conditions. WATER RESEARCH 2007; 41:924-34. [PMID: 17223159 DOI: 10.1016/j.watres.2006.11.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Revised: 11/10/2006] [Accepted: 11/10/2006] [Indexed: 05/13/2023]
Abstract
This study investigated the effect of feeding pattern on bacterial storage under anoxic conditions, emphasizing previous adaptation of biomass to a long term feeding condition, under steady-state operation. Storage was evaluated in a sequencing batch reactor (SBR) system operated in a sequence of anoxic/aerobic phases, fed with acetate as the sole carbon source during anoxic conditions. The experimental results indicated that biochemical storage of acetate as PHB occurred when substrate was fed as a pulse, while acetate was removed mostly through direct microbial growth under continuous feeding. For pulse feeding, the anoxic yield, Y(STOD) was calculated as 0.58mg COD (mgCOD)(-1) in two different ways, using mass balances on acetate utilization, PHB generation and nitrate consumption. This value was supported by parallel batch tests and similar results in the literature. Similarly, the rate coefficient for storage under anoxic conditions, k(STOD) was computed as 9.3day(-1) based on basic stoichiometry and model calibration of experimental data. Batch tests conducted with biomass adapted to different feeding patterns showed that substrate storage was insignificant when the feed was added continuously at low concentrations, even if the biomass was previously adapted to storage. Similarly biomass acclimated to continuous feeding could not store the excess substrate although fed instantly. For the operating conditions selected for the study, storage response was significant only with a microbial culture with metabolic activities previously adapted to storage and with short-term substrate feeding at high concentrations.
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Affiliation(s)
- Asli S Ciğgin
- Faculty of Civil Engineering, Environmental Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
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