1
|
Zhang Z, Huang Z, Li H, Wang D, Yao Y, Dong K. Impact of Nitrate on the Removal of Pollutants from Water in Reducing Gas-Based Membrane Biofilm Reactors: A Review. MEMBRANES 2024; 14:109. [PMID: 38786943 PMCID: PMC11123063 DOI: 10.3390/membranes14050109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2024] [Revised: 04/11/2024] [Accepted: 05/07/2024] [Indexed: 05/25/2024]
Abstract
The membrane biofilm reactor (MBfR) is a novel wastewater treatment technology, garnering attention due to its high gas utilization rate and effective pollutant removal capability. This paper outlines the working mechanism, advantages, and disadvantages of MBfR, and the denitrification pathways, assessing the efficacy of MBfR in removing oxidized pollutants (sulfate (SO4-), perchlorate (ClO4-)), heavy metal ions (chromates (Cr(VI)), selenates (Se(VI))), and organic pollutants (tetracycline (TC), p-chloronitrobenzene (p-CNB)), and delves into the role of related microorganisms. Specifically, through the addition of nitrates (NO3-), this paper analyzes its impact on the removal efficiency of other pollutants and explores the changes in microbial communities. The results of the study show that NO3- inhibits the removal of other pollutants (oxidizing pollutants, heavy metal ions and organic pollutants), etc., in the simultaneous removal of multiple pollutants by MBfR.
Collapse
Affiliation(s)
- Zhiheng Zhang
- College of Environmental Science and Engineering, Guilin University of Technology, 319 Yanshan Street, Guilin 541006, China; (Z.Z.); (Z.H.); (H.L.); (D.W.)
- Guangxi Collaborative Innovation Center for Water Pollution Control and Safety in Karst Area, Guilin University of Technology, Guilin 541006, China
- Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, Guilin 541006, China
| | - Zhian Huang
- College of Environmental Science and Engineering, Guilin University of Technology, 319 Yanshan Street, Guilin 541006, China; (Z.Z.); (Z.H.); (H.L.); (D.W.)
- Guangxi Collaborative Innovation Center for Water Pollution Control and Safety in Karst Area, Guilin University of Technology, Guilin 541006, China
- Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, Guilin 541006, China
| | - Haixiang Li
- College of Environmental Science and Engineering, Guilin University of Technology, 319 Yanshan Street, Guilin 541006, China; (Z.Z.); (Z.H.); (H.L.); (D.W.)
- Guangxi Collaborative Innovation Center for Water Pollution Control and Safety in Karst Area, Guilin University of Technology, Guilin 541006, China
- Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, Guilin 541006, China
| | - Dunqiu Wang
- College of Environmental Science and Engineering, Guilin University of Technology, 319 Yanshan Street, Guilin 541006, China; (Z.Z.); (Z.H.); (H.L.); (D.W.)
- Guangxi Collaborative Innovation Center for Water Pollution Control and Safety in Karst Area, Guilin University of Technology, Guilin 541006, China
- Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, Guilin 541006, China
| | - Yi Yao
- College of Environmental Science and Engineering, Guilin University of Technology, 319 Yanshan Street, Guilin 541006, China; (Z.Z.); (Z.H.); (H.L.); (D.W.)
- Guangxi Collaborative Innovation Center for Water Pollution Control and Safety in Karst Area, Guilin University of Technology, Guilin 541006, China
- Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, Guilin 541006, China
| | - Kun Dong
- College of Environmental Science and Engineering, Guilin University of Technology, 319 Yanshan Street, Guilin 541006, China; (Z.Z.); (Z.H.); (H.L.); (D.W.)
- Guangxi Collaborative Innovation Center for Water Pollution Control and Safety in Karst Area, Guilin University of Technology, Guilin 541006, China
- Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, Guilin 541006, China
- Guangxi Engineering Research Center of Comprehensive Treatment for Agricultural Non-Point Source Pollution, Guilin 541006, China
- Modern Industry College of Ecology and Environmental Protection, Guilin University of Technology, Guilin 541006, China
| |
Collapse
|
2
|
Li S, Duan L, Song Y, Hermanowicz SW. High-Density Microarray Analysis of Microbial Community Structures in Membrane Bioreactor at Short Sludge Retention Time. MEMBRANES 2023; 13:146. [PMID: 36837649 PMCID: PMC9965995 DOI: 10.3390/membranes13020146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/14/2023] [Accepted: 01/20/2023] [Indexed: 06/18/2023]
Abstract
Membrane bioreactors (MBR) have become prevalent in wastewater treatment because of their high effluent quality and low sludge generation. Sludge retention time (SRT) is an important parameter in the operation of MBR, and it has a direct effect on the microbial community. In this study, microarrays were used to analyze the microbial communities of three different MBRs at short SRTs. The results showed that MBR at SRT 5 days (CS5) has the highest operational taxonomic units (OTUs) richness, but the lowest diversity and uniformity compared to SRT 3 days at continuous CS3 and the sequencing batch (SS3). Proteobacteria were the dominant phylum of three reactors. Bacteroidetes were the second dominant phylum in MBRs at the continuous model, instead of Actinobacteria at the sequencing model. At the class level, the dominant group of Proteobacteria exhibited a remarkable difference between the three MBRs. γ-Proteobacteria was the dominant group in CS5 and CS3, while α-Proteobacteria was the main group in SS3. The samples from the three MBRs had similar compositions of α-, β- and δ-Proteobacteria. However, γ-Proteobacteria showed different community compositions at the order level between the three MBRs. Enterobacteriales were the dominant group in CS5 and CS3, while Pseudomonadales were the dominant group in SS3. The bacterial community concentration of SRT 5 days was generally higher than that of the other two MBRs. The community composition of CS5 was significantly different from that of CS3 and SS3, and the phylogenetic relationships of the three MBRs were relatively different.
Collapse
Affiliation(s)
- Shilong Li
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Liang Duan
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710, USA
| | - Yonghui Song
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Slawomir W. Hermanowicz
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710, USA
| |
Collapse
|
3
|
Bai Y, Wu YH, Wang YH, Tong X, Zhao XH, Ikuno N, Hu HY. Membrane fouling potential of the denitrification filter effluent and the control mechanism by ozonation in the process of wastewater reclamation. WATER RESEARCH 2020; 173:115591. [PMID: 32062226 DOI: 10.1016/j.watres.2020.115591] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 06/10/2023]
Abstract
A process of denitrification filter (DNF) coupled with ultrafiltration (UF) and ozonation (DNF-UF-O3) has been widely applied to advanced nitrogen removal for wastewater reclamation. Despite of the effective removal of nitrogen by DNF, the influence of DNF stage on the operation of UF was still unclear. In this study, a laboratory filtration system was used to investigate the membrane fouling potential of DNF effluent and the fouling control of ozonation. The membrane fouling potential was proved to be increased significantly after DNF stage and alleviated with ozonation treatment. With the help of UV-vis, fluorescence spectroscopy, scanning electron microscopy (SEM) and molecular weight (MW) analysis, the change of DOM component characteristics was proved to be in accordance with the change of fouling potential. The water samples were further fractionated into six hydrophobic/hydrophilic acidic/basic/neutral fractions, among which hydrophobic acids (HOA) and hydrophobic neutrals (HON) dominated the membrane fouling potential of DNF effluent. Detailed study of each fraction revealed that higher MW components in HOA and HON played a crucial role in the fouling of UF membrane. The dominant component of membrane fouling could be degraded and removed by ozonation, and therefore significant fouling alleviation was achieved. These results indicated that in the process of wastewater reclamation, besides conventional water quality indexes, more detailed water features should also be taken into consideration to optimize the whole process. Moreover, the control effects by ozonation could be monitored simply according to the change of specific UV absorbance (SUVA) and fluorescence intensity as surrogates in engineering applications. According to these results, a modified DNF-O3-UF process with O3 dosage of 3 mg/L was proposed simply by reversing the sequence of UF and O3 with no more infrastructure. This modified DNF-O3-UF process was expected to enlarge the produce capacity of reclaimed water with much lower electricity costs and chemical consumption.
Collapse
Affiliation(s)
- Yuan Bai
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing, 100084, PR China
| | - Yin-Hu Wu
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing, 100084, PR China.
| | - Yun-Hong Wang
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing, 100084, PR China
| | - Xin Tong
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing, 100084, PR China
| | - Xue-Hao Zhao
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing, 100084, PR China
| | - Nozomu Ikuno
- Kurita Water Industries Ltd., Nakano-ku, Tokyo, 164-0001, Japan
| | - Hong-Ying Hu
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing, 100084, PR China; Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Tsinghua-Berkeley Shenzhen Institute, Shenzhen, 518055, PR China.
| |
Collapse
|
4
|
Mechanism of Membrane Fouling Control by HMBR: Effect of Microbial Community on EPS. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17051681. [PMID: 32150812 PMCID: PMC7084492 DOI: 10.3390/ijerph17051681] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 02/29/2020] [Accepted: 03/01/2020] [Indexed: 11/16/2022]
Abstract
A hybrid membrane bioreactor (HMBR) employing activated sludge and biofilm simultaneously is proved to represent a good performance on membrane fouling control compared to conventional membrane bioreactor (CMBR) by reducing extracellular polymeric substances (EPS), especially bound EPS (B-EPS). In order to better understand the mechanism of membrane fouling control by the HMBR in regard of microbial community composition, a pilot scale HMBR operated to treat domestic wastewater for six months, and a CMBR operated at the same time as control group. Results showed that HMBR can effectively control membrane fouling. When transmembrane pressure reached 0.1 MPa, the membrane module in the HMBR operated for about 26.7% longer than that in the CMBR. In the HMBR, the quantity of EPS was significantly lower than that in the CMBR. In this paper, soluble EPS was also found to have a close relationship with cake layer resistance. The species richness and diversity in the HMBR were higher than those in the CMBR, and a certain difference between the compositions of microbial communities in the two reactors was confirmed. Therefore, the difference in microbial community compositions may be the direct reason why EPS in the HMBR was lower than that in the CMBR.
Collapse
|
5
|
Viet ND, Cho J, Yoon Y, Jang A. Enhancing the removal efficiency of osmotic membrane bioreactors: A comprehensive review of influencing parameters and hybrid configurations. CHEMOSPHERE 2019; 236:124363. [PMID: 31325824 DOI: 10.1016/j.chemosphere.2019.124363] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 06/30/2019] [Accepted: 07/12/2019] [Indexed: 06/10/2023]
Abstract
The amount of research conducted on osmotic membrane bioreactors (OMBRs) has increased over the past decade because of the advantages of these reactors over conventional membrane bioreactors (MBRs). OMBR process is a hybrid process involving a forward osmosis membrane and biologically activated sludge. It is a promising technology to reduce membrane fouling, enhance effluent water quality, and lower energy consumption compared to conventional MBR processes. Eleven years since the OMBR process was first proposed, about 60 papers regarding the OMBR process have been published. In this article, we address recent advances in OMBR technology based on a review of the literature. Typical factors that influence the performance of the OMBR process are discussed to provide a clear understanding of the current state of this technology. We also provide a critical review of OMBR applications in organic matter, nutrient, and micropollutant removal as well as direct recovery of nutrients from wastewater. We propose several hybrid configurations that can enhance the removal efficiency of OMBR systems. Finally, we present potential research directions for future OMBR research.
Collapse
Affiliation(s)
- Nguyen Duc Viet
- Graduate School of Water Resources, Sungkyunkwan University, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Jaeweon Cho
- School of Urban and Environmental Engineering, Ulsan Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 689-798, Republic of Korea
| | - Yeomin Yoon
- Department of Civil and Environmental Engineering, University of South Carolina, Columbia, 300 Main Street, SC, 29208, USA
| | - Am Jang
- Graduate School of Water Resources, Sungkyunkwan University, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea.
| |
Collapse
|
6
|
Wei D, Yan T, Zhang K, Chen Y, Wu N, Du B, Wei Q. Qualitative and quantitative analysis of extracellular polymeric substances in partial nitrification and full nitrification reactors. BIORESOURCE TECHNOLOGY 2017; 240:171-176. [PMID: 28279609 DOI: 10.1016/j.biortech.2017.02.115] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/23/2017] [Accepted: 02/24/2017] [Indexed: 06/06/2023]
Abstract
In present study, two column-type sequencing batch reactors with alternative anoxic/aerobic phases were operated and compared under partial nitrification and full nitrification modes by controlling different dissolved oxygen (DO) conditions. During steady state, the characterizations of extracellular polymeric substances (EPS) from two reactors were qualitatively and quantitatively analyzed through chemical and spectroscopic approaches. Data implied that partial nitrification reactor had relatively higher total nitrogen (TN) removal efficiency and loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) contents. According to excitation emission matrix (EEM) spectra, LB-EPS and TB-EPS from two kinds of reactors expressed similar fluorescence peak locations but different intensities. Fluorescence regional integration (FRI) further suggested that Region IV was the main fraction in both types of EPS fractions. Moreover, TB-EPS exhibited a greater number of molecular weight fractions than those of LB-EPS. Both EPS fractions had similar functional groups, which represented the complex nature of EPS compositions.
Collapse
Affiliation(s)
- Dong Wei
- School of Resources and Environment, University of Jinan, Jinan 250022, PR China
| | - Tao Yan
- School of Resources and Environment, University of Jinan, Jinan 250022, PR China
| | - Keyi Zhang
- School of Resources and Environment, University of Jinan, Jinan 250022, PR China
| | - Ya Chen
- School of Resources and Environment, University of Jinan, Jinan 250022, PR China
| | - Na Wu
- School of Resources and Environment, University of Jinan, Jinan 250022, PR China
| | - Bin Du
- School of Resources and Environment, University of Jinan, Jinan 250022, PR China.
| | - Qin Wei
- Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, PR China
| |
Collapse
|
7
|
Vanysacker L, Boerjan B, Declerck P, Vankelecom IFJ. Biofouling ecology as a means to better understand membrane biofouling. Appl Microbiol Biotechnol 2014; 98:8047-72. [DOI: 10.1007/s00253-014-5921-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 06/24/2014] [Accepted: 06/25/2014] [Indexed: 10/24/2022]
|
8
|
Lin H, Zhang M, Wang F, Meng F, Liao BQ, Hong H, Chen J, Gao W. A critical review of extracellular polymeric substances (EPSs) in membrane bioreactors: Characteristics, roles in membrane fouling and control strategies. J Memb Sci 2014. [DOI: 10.1016/j.memsci.2014.02.034] [Citation(s) in RCA: 490] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
9
|
Microbial relevant fouling in membrane bioreactors: influencing factors, characterization, and fouling control. MEMBRANES 2012; 2:565-84. [PMID: 24958297 PMCID: PMC4021913 DOI: 10.3390/membranes2030565] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 07/20/2012] [Accepted: 08/09/2012] [Indexed: 11/17/2022]
Abstract
Microorganisms in membrane bioreactors (MBRs) play important roles on degradation of organic/inorganic substances in wastewaters, while microbial deposition/growth and microbial product accumulation on membranes potentially induce membrane fouling. Generally, there is a need to characterize membrane foulants and to determine their relations to the evolution of membrane fouling in order to identify a suitable fouling control approach in MBRs. This review summarized the factors in MBRs that influence microbial behaviors (community compositions, physical properties, and microbial products). The state-of-the-art techniques to characterize biofoulants in MBRs were reported. The strategies for controlling microbial relevant fouling were discussed and the future studies on membrane fouling mechanisms in MBRs were proposed.
Collapse
|
10
|
Van den Broeck R, Van Dierdonck J, Nijskens P, Dotremont C, Krzeminski P, van der Graaf J, van Lier J, Van Impe J, Smets I. The influence of solids retention time on activated sludge bioflocculation and membrane fouling in a membrane bioreactor (MBR). J Memb Sci 2012. [DOI: 10.1016/j.memsci.2012.01.028] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
11
|
Yang XL, Song HL, Lu JL, Fu DF, Cheng B. Influence of diatomite addition on membrane fouling and performance in a submerged membrane bioreactor. BIORESOURCE TECHNOLOGY 2010; 101:9178-9184. [PMID: 20685114 DOI: 10.1016/j.biortech.2010.07.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 07/06/2010] [Accepted: 07/10/2010] [Indexed: 05/29/2023]
Abstract
This paper examined the effect of diatomite addition on membrane fouling and process performance in an anoxic/oxic submerged membrane bioreactor (A/O MBR). Particle size distribution, molecular weight distribution and microbial activity have been investigated to characterize the sludge mixed liquor. Results show that diatomite addition is a reliable and effective approach in terms of both membrane fouling mitigation and pollutants removal improvement. The MBR system with diatomite addition of 50 mg/L enhanced the removal of COD, TN and TP by 0.9%, 6.9% and 31.2%, respectively, as compared to the control MBR (without diatomite addition). The NH(4)-N removal always maintained at a high level of over 98% irrespective of diatomite addition. Due to the hybrid effect of adsorption and co-precipitation on fine colloids and dissolved organic matter (DOM) from the addition of diatomite, a reduction in foulants amount, an increase in microbial floc size and an improvement in sludge settleability have been achieved simultaneously. As a result, the membrane fouling rate was mitigated successfully.
Collapse
Affiliation(s)
- Xiao-Li Yang
- School of Civil Engineering, Southeast University, Nanjing 210096, PR China
| | | | | | | | | |
Collapse
|
12
|
|
13
|
Kim M, Nakhla G. Comparative studies on membrane fouling between two membrane-based biological nutrient removal systems. J Memb Sci 2009. [DOI: 10.1016/j.memsci.2009.01.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
14
|
Katagiri N, Chujo K, Takeuchi A, Iritani E, Kawasaki K. Effect of BOD Loading on Solid-Liquid Separation Properties of Activated Sludge. KAGAKU KOGAKU RONBUN 2009. [DOI: 10.1252/kakoronbunshu.35.99] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Kuniko Chujo
- Department of Chemical Engineering, Nagoya University
| | | | - Eiji Iritani
- Department of Chemical Engineering, Nagoya University
| | | |
Collapse
|
15
|
|
16
|
Lee WN, Chang IS, Hwang BK, Park PK, Lee CH, Huang X. Changes in biofilm architecture with addition of membrane fouling reducer in a membrane bioreactor. Process Biochem 2007. [DOI: 10.1016/j.procbio.2006.12.003] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
17
|
Jin YL, Lee WN, Lee CH, Chang IS, Huang X, Swaminathan T. Effect of DO concentration on biofilm structure and membrane filterability in submerged membrane bioreactor. WATER RESEARCH 2006; 40:2829-36. [PMID: 16859730 DOI: 10.1016/j.watres.2006.05.040] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2005] [Revised: 05/05/2006] [Accepted: 05/26/2006] [Indexed: 05/11/2023]
Abstract
The structures of biofilms deposited on the membrane surface under different dissolved oxygen (DO) conditions were characterized to identify its relation to membrane filterability in membrane bioreactors (MBR). The rate of membrane fouling for the low DO (LDO) reactor was 7.5 times faster than that for the high DO (HDO) reactor. Even though the biofilm deposited on the membrane surface in the HDO was thicker than in the LDO at the operating terminated (TMP reached 30 Kpa), biofilm resistance in both reactors were similar. Exactly, specific cake resistance of the HDO was lower than that of the LDO. Difference in biofilm characteristics as a result of different DO level was main factor affecting biofouling for both MBRs. The number of small particles ranging from 2-5mum in the biofilm as well as in the bulk solution for the LDO was greater than those for the HDO. The small particles in the bulk solution of the LDO more preferentially deposited on the membrane surface than those of HDO did. Hence, the biofilm porosity in the LDO (0.65) was smaller than that in HDO (0.85). The reduced porosity of LDO biofilm resulted in lower filterability than the HDO. The porosity data obtained from analysis of images of biofilm using confocal scanning laser microscopy (CLSM) was verified in terms of specific cake resistance (alpha) by comparing the experimentally measured values with the semi-theoretically computed values.
Collapse
Affiliation(s)
- Yu-Lan Jin
- School of Chemical and Biological Engineering, Seoul National University, San 56-1 Shimlim-dong, Kawanak gu, Seoul 151-744, Republic of Korea
| | | | | | | | | | | |
Collapse
|