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A Metagenomic Insight into Biofilm Populations in Industrial Water Systems Using a New, Real Time Biomonitoring Technology
Delegard, A.*, Denvir, A.**
*Chem-Aqua/Mohawk Labs, 2730 Carl Road, Irving, TX 75062
**Chem-Aqua/Mohawk Labs, 2730 Carl Road, Irving, TX 75062 Keywords: Biomonitoring; Metagenomics; Corrosion Summary of key findings
Within the last 10 years academic and industrial researchers have advanced our understanding into the important roles biofilms play in our water handling and distribution systems. Biofilms are ubiquitous, representing the preferred environment for microorganisms to survive, protecting them from harsh chemical treatments, predators, sheer stress, and other external pressures. Within the biofilm matrixes bacteria thrive, consuming nutrients, and producing metabolites that are responsible for the loss in heat transfer function of critical components, along with creating a corrosive environment within our water handling systems. Using a new biofilm monitoring technology we collected samples from 26 unique industrial water handling systems across the United States. This allowed for examination of not only a diverse geographical biofilm set; but also, how sesasonal changes caused variances within biofilm samples collected from the same water handling system. Using metagenomic sequence analysis we investigated the variation of the bacterial populations within these biofilms. The data has provided a new understanding and insight on the phylogenetically and metabolically distinct species the reside with these biofilms, helping in the development of new anti-biofilm approaches to minimize
microbial-influenced corrosion and heat transfer loss.
Background and relevance
From our nation’s infrastructure made from concrete, metal, and plastic to sophisticated implantable medical devives we are in a constant battle to combat the effects of corrosion. It is estimated that close to $2 trillion is spent globally replacing corroded structures and equipment and an additional $8 billion is spent on corrosion inhibition and prevention stratigies [1, 2]. Around 20% of corrosion related issues are as a result of microbial influenced corrosion or MIC [3]. MIC is a type of corrosion that occurs when a consortium of bacteria, fungi, or algae, existing within a biofilm on a surface influence or accelerate the rate at which that surface degrades [4]. In recent years research into the structure and formation of multispecies biofilms indicates that every biofilm is unique and is a product of its
surrounding environment at that specific time and place. The interactions between the bacterial species residing inside the biofilm and the substrate on which the biofilm is formed is the main reason MIC one of the most difficult forms of corrosion to combat. To better understand the true nature of biofilms and the role they play in the corrosion process there is a need for a test or procedure that will allow for the identification of the hundreds of phylogenetically and metabolically different species residing in the biofilm under a specific set of growth conditions. With the emergence of molecular methods such as real time PCR [5], microarray gene chips [6], T-RFLP analysis [7] and pyrosequencing [8] researchers have been able to gain an unprecenented insight into the nature of biofilms collected from sites
experiencing MIC. Unfortunately the inability to collect samples in a reproducible and repeatable manner together with the cost associated with the tests have limited the widescale adoption of the molecular approaches. Using a new biomonitoring technology we have been able to address these limitations. The biomonitor unit takes a side stream of water from a flow assembly and by controlling the flow rate through the transparent biofilm detection tube is able to produce the perfect environment to promote biofilm growth. The amount of light passing through the
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detector tube is measured and recorded as the Biofouling Index or BFI. The sensitivity of this device is such that it can detect the formation of nascent biofilms on the surface of the biofilm detection tube and monitor development all the way through maturation. The unique feature of this system is that unlike other biomonitoring devices this technology allows for the easy removal of the biofilm containing tubing for containment and transport to the laboratory for analysis. The biofilm detection tube can be removed (and replaced with a clean one) without stopping the operation of the biomonitoring device itself. Twenty-six biomonitoring units were deployed at sixteen sites throughout the United States. Over a year we collected biofilm growth data along with the corresponding biofilm samples using these biomonitoring units which provided a geographically diverse and seasonally variable biofilm sample set on which we could investigate changes in bacterial populations over time and with different water handing system operating conditions.
Results
The biofilm samples were collected from each site every 30 days and subjected to a series of analytical procedures, microscope imaging, heterotrophic plate counts, carbohydrate analysis, DNA quantification and next generation sequencing.
The data collected from the biomonitoring units coupled with the carbohydrate analysis showed that 64% had relatively low biofilm formed on the detection tube less than 95µg/cm2, 24% had high biofilm growth between 95µg/cm2 and 150µg/cm2, and 12% had excessively high biofilm growth on the detection tube greater than 150 µg/cm2. In addition to processing the biofilm detection tubes for carbohydrate content they were also processed to isolate and quantify DNA.
The analysis of the isolated DNA showed that as the carbohydrate content within the tubes increased the amount of purified DNA also increased. The trends observed in the data showed that low final BFI correlated to minimal fouling, low carbohydrate content and low DNA content.
Figure 1.1 is a snapshot of the the different types of bacteria collected from cooling towers in different locations across the country for the same month of the year. Sites in California, Texas, Georgia, South Carolina, Florida, and New York City are represented in the bar chart. A total combined 116 phylotypes are represented in the charts. The chart clearly shows the wide diversity identified across all of these biofilm samples and the high prevelance of bacteria associated with MIC in all the systems.
Discussion
The data collected during this study is opening a door into a new way to look at biofilm
formation and phylotype diversity across a broad spectrum of industrial water handling systems.
The results of our have studies have produced some very interesting and surprising findings. A snap shot of the phylogenetic diversity of the biofilms collect over the course of this study showed that they differed enormously from site to site across the country. With 116 phylotypes total identified across all systems this study has shown that biofilms in industrial water handling systems are very unique and are a product of a total system operational environment rather than just a biocide control program.
The data collected showed that operation of these systems and the biocide control program did impact the rate at which the biofilms were formed in the biofilm detector tube; however, the extensive biodiversity and the large number of phylotypes observed within the biofilm samples requires a greater understanding of the broader operational environmental conditions before we can adequately explain why these species are present in the system and how they impact overall system operations.
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Figure 1.1 Bar charts showing the percentage of the different phylotypes identified by pair end sequencing of the 16S rRNA gene for biofilms collected from sites in California, Texas, Georgia, South Carolina, Florida, and New York on the same month of the year. The different phylotypes are represented by the different colors on the charts.
References
K.A. Zarasvand, V.R. Rai, (2014), Microorganisms: Induction and Inhibition of Corrosion in Metals, International Biodeterioration and Biodegradation, 87, 66-74
N. Kip, J.A. van Veen, (2015), Mini Review: The Dual Role of Micorbes in Corrosion, The ISME Journal, 9, 542-551
J. Wen, K. Zhao, T. Gu, I.I. Raad, (2009), A Green Biocide Enhancer for the Treatment of Sulfate-Reducing Bacteria (SRB) Biofilms on Carbon Steel Surfaces Using Gluteraldehyde, International Biodeterioration and Biodegradation, 63, 1102-1106
K. Li, M. Whitfield, K.J. van Vilet, (2010), Beating the Bugs: Roles of Microbial Biofilms in Corrosion, http://kjvvgroup.mit.edu/wp-
content/uploads/2010/06/Li_Whitfield_VanVliet_Biofilm_Corrosionsmallpdf.com_.pdf
5 G. Schaule, T. Griebe, H.C. Flemming, (1999), Steps in Biofilm Sampling and Characterization in Biofouling Cases, Microbially Influenced Corrosion of Industrial materials-Biocorrosion Network-, (Mulheim an der Ruhr, Germany, Biocorrosion 99-02, 1999)
Z. He, T. Gentry, C. Schadt, L. Wu, J. Liebich, S. Chong, Z. Huang, W. Wu, B. Gu, P. Jardine, C. Criddle, (2007), GeoChip: A Comprehensive Microarray for Investigating Biogeochemical, Ecological, and Environmental Processes, ISME, 1, 66-77
R.E. Hicks, (2009), Assessing the Role of Microorganisms in the Accelerated Corrosion of Port Transportation Infrastructure in the Duiluth-Superior Harbor Cura Reporter, Spring/Summer, 4-10 H, Sun, B. Shi, Y. Bai, D. Wang,(2014), Bacterial Communities Developed Under Different Water Supply Conditions in a Distribution System”, Science of the Total Environment, 472, 99-107
95 Presenting Author
Angela Delegard Senior Research Scientist Chem-Aqua/Mohawk Labs
Is the presenting author an IWA Young Water Professional? Y/N (i.e. an IWA member under 35 years of age) No
Bio: Angela Delegard is a Senior Research Scientist at Chem-Aqua/Mohawk Labs. As a molecular biologist she evaluates novel methods to treat microorganisms and serves as lead scientist for the biomonitoring research program using a suite of techniques to characterize and document changes in biofilm populations collected at cooling system sites throughout the country.
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Algal-sludge membrane bioreactor (As-MBR) for sustainable municipal wastewater treatment
Senatore, V.*, Castrogiovanni, F.*, Corpuz, M.V.A.**, Borea, L.*, Zarra, T.*, Belgiorno, V.*, Ballesteros Jr., F.C.***, Naddeo, V.*
* Sanitary Environmental Engineering Division (SEED), Department of Civil Engineering, University of Salerno, via Giovanni Paolo II, Fisciano, SA, Italy
** Environmental Engineering Program, National Graduate School of Engineering, University of the Philippines, 1101 Diliman, Quezon City, Philippines
*** Department of Chemical Engineering, University of the Philippines, Diliman, Quezon City, 1101 Philippines Keywords: Wastewater; Membrane Bioreactor; Microalgae
Summary of key findings
Algal-sludge membrane bioreactors (As-MBR) gained increasing interest due to high efficiency shown to treat wastewater. This study implemented a hollow fiber membrane as membrane module and algal- bacterial inoculum. The present works aims to study the effects of algal and bacterial consortium on the performance of an aerobic membrane bioreactor (MBR) in terms of nutrients (N and P) and chemical oxygen demand (COD) removal and, on membrane fouling. During 30 days of continuous running, the As-MBR system achieved COD, NH4-N and PO4-P removal of 98%, 81.5% and 37%, respectively. Soluble microbial product (SMP) and extracellular polymeric substances (EPS) were decreased by
≈15% due to the inoculation of algae respect to conventional MBR. SMP and EPS reduction had a positive impact on membrane operation showing higher permeability and longer operation cycle.
Background and relevance
Novel algae-based wastewater treatment has gained tremendous attention during the last two decades due to the possibility of produce biofuels and high value bio-compounds from microalgal biomass (Shahid et al., 2020). Algal and bacterial synergism has been applied in algal-sludge membrane bioreactor (As-MBR) for the simultaneously remove of nutrients (N and P) and chemical oxygen demand (COD) (Ishizaki et al., 2017).
The objective of this study is the evaluation of a novel As-MBR for simultaneous COD and nutrients (N and P) removals from synthetic municipal wastewater in a single stage. Synthetic municipal wastewater was prepared based on Borea et al., (2019) procedure. Chlorella Vulgaris microalgae cultivated in a photobioreactor (PBR) were used as microalgae strain. Bacteria consortium was sampled in the activate sludge recirculation system at WWTP in Salerno and was acclimatized for 30 days. Inoculated ratio (algae/bacteria) of 1:5 was used according to Sun et al., (2020).
Syntetich wastewater was continuously fed into the As-MBR with a working volume of 15 L, containing a hollow fiber ultrafiltration membrane module with a nominal pore diameter of 0.04 µm and an effective membrane surface area of 0.05 m2 (Figure 1.1). A compressor was istalled to guarantee good mixing and maintain optimum level of DO (dissolved oxygen) concentration.
The As-MBR was operated with a 12 h:12 h dark-light cycle (i.e. LED lights turned on from 9 am to 9pm and turned off from 9pm to 9am). A light intensity of 80 µmol m-2 s-1 was irradiate by using 3 LED bulbs.
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4 4
4
4
Figure 1.1 As-MBR experimental set-up
The As-MBR system was operated using a 10 minute filtration cycle (10 mins. Filtration + 1 min.
backwashing) with permeate flow rate of 15 LMH. The sludge was maintained inside the reactor during the 30 days of continuously treatment process.
Turbidimeter (HACH 2100N) was utilized to measure the turbidity. Temperature, pH and dissolved oxygen (DO) concentration were measured with a multiparametric probe (Hanna Instruments, Padova, Italy, HI2838). Standard methods (APAT and CNR-IRSA, 2003) were used to obtain COD and nutrients concentration.
Results
Results highlight that the symbiosis of algae and bacteria exhibited more remarkable impacts on nutrients removal than MBR activate sludge based system.
As-MBR showed average removal efficiencies of COD, ammonia nitrogen (NH +-N) and ortophosphate (PO 3−-P) of 98%, 81.5% and 37%, respectively, comparable to a previous study (Sun et al., 2020). The average COD removal efficiencies were not significantly different from conventional MBR. Microalgae, e.g. Chlorella Vulgaris, use ammonium (NH +) as nitrogen source (Gentili, 2014). As reported by Wu et al., (2020) microalgae contribute significantly to the enhancement of ammonium removal. Secondly, PO43− removal was enhanced by the biological uptake of phosphorus by the microalgae biomass (Arias et al., 2018). The mean PO 3- removal in the As-MBR was higher by 10% than that in the conventional MBR (Ahmed et al., 2008).
In Table 1.1 the average parameter turbidity, pH and DO measured in the As-MBR during the 30 days of running are reported. As can be seen in Table 1.1 a drastic reduction of the turbidity was achived from 2350 NTU (reactor) to 0.28 NTU (permeate).
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Algae and activated sludge biomass demonstrate a membrane fouling reduction in the As-MBR compared to the conventional MBR (Millanar-Marfa et al., 2018).
SMP and EPS were considered to be the main causes of membrane fouling in MBRs (Ishizaki et al., 2017). Indeed, SMP and EPS concentrations were lower in the MBRs with algae-activated sludge biomass than in those with only activated sludge. As reported in Figure 1.2 the EPSc, EPSp, SMPc and SMPp concentrations were 4.12, 18.25, 8.21 and 8.95 mg/gSSV resulting lower than in the study reported by (Kampouris et al., 2018). Moreover, As-MBR exhibited a fouling rate of 1.80 ΔTMP/dt (kPa/day) that is lower than the fouling rate (8.10 ΔTMP/dt (kPa/day)) reported by Borea et al., (2019) in a conventional MBR.
Figure 1.2 Membrane fouling precursors concentrations, carbohydrate fraction of extracellular polymeric substances (EPSc), protein fraction of EPS (EPSp), protein fraction of soluble microbial product (SMPp) and carbohydrate fraction of SMP (SMPc).
Discussion
As-MBR showed that it is possible to realize wastewater treatment by combing algae and bacteria in a MBR. The CO2/O2 exchange between algae and bacteria makes the process more sustainable than the conventional one by decreasing CO2 emissions in atmosphere, as well as, reduction of oxygen demands due to the production of O2 by microalgae. Moreover, algal biomass could be converted into biofuels, and many other applications such as feed and fertilizers. Microalgae have great effects on the variation of growth environment, flocs properties and fouling formation. This study demonstrated that As-MBR is a promising technology that could achieve a high quality effluent treating COD and nutrients in one single step, as well as, reducing the membrane fouling.
References
APAT and CNR-IRSA. (2003), Metodi analitici per le acque. Manuali e Linee Guida 29/2003.
Ahmed, Z., Lim, B. R., Cho, J., Song, K. G., Kim, K. P., & Ahn, K. H. (2008). Biological nitrogen and phosphorus removal and changes in microbial community structure in a membrane bioreactor: Effect of different carbon sources. Water Research.
https://doi.org/10.1016/j.watres.2007.06.062
Arias, D. M., Solé-Bundó, M., Garfí, M., Ferrer, I., García, J., & Uggetti, E. (2018). Integrating microalgae tertiary treatment into activated sludge systems for energy and nutrients recovery from wastewater. Bioresource Technology.
https://doi.org/10.1016/j.biortech.2017.09.123
Borea, L., Ensano, B. M. B., Hasan, S. W., Balakrishnan, M., Belgiorno, V., de Luna, M. D. G., Ballesteros, F. C., & Naddeo, V. (2019). Are pharmaceuticals removal and membrane fouling in electromembrane bioreactor affected by current density? Science of the Total Environment, 692, 732–740. https://doi.org/10.1016/j.scitotenv.2019.07.149
Gentili, F. G. (2014). Microalgal biomass and lipid production in mixed municipal, dairy, pulp and paper wastewater together with added flue gases. Bioresource Technology, 169, 27–32. https://doi.org/https://doi.org/10.1016/j.biortech.2014.06.061 Ishizaki, S., Sugiyama, R., & Okabe, S. (2017). Membrane fouling induced by AHL-mediated soluble microbial product
(SMP) formation by fouling-causing bacteria co-cultured with fouling-enhancing bacteria. Scientific Reports.
https://doi.org/10.1038/s41598-017-09023-5
Kampouris, I. D., Karayannakidis, P. D., Banti, D. C., Sakoula, D., Konstantinidis, D., Yiangou, M., & Samaras, P. E. (2018).
Evaluation of a novel quorum quenching strain for MBR biofouling mitigation. Water Research.
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https://doi.org/10.1016/j.watres.2018.06.030
Millanar-Marfa, J. M. J., Borea, L., de Luna, M. D. G., Ballesteros, F. C., Belgiorno, V., & Naddeo, V. (2018). Fouling mitigation and wastewater treatment enhancement through the application of an electro moving bed membrane bioreactor (eMB-MBR). Membranes. https://doi.org/10.3390/membranes8040116
Shahid, A., Malik, S., Zhu, H., Xu, J., Nawaz, M. Z., Nawaz, S., Asraful Alam, M., & Mehmood, M. A. (2020). Cultivating microalgae in wastewater for biomass production, pollutant removal, and atmospheric carbon mitigation; a review. Science of the Total Environment. https://doi.org/10.1016/j.scitotenv.2019.135303
Sun, L., Ma, J., Li, L., Tian, Y., Zhang, Z., Liao, H., Li, J., Tang, W., & He, D. (2020). Exploring the essential factors of performance improvement in sludge membrane bioreactor technology coupled with symbiotic algae. Water Research.
https://doi.org/10.1016/j.watres.2020.115843
Wu, W., Zhang, X., Qin, L., Li, X., Meng, Q., Shen, C., & Zhang, G. (2020). Enhanced MPBR with polyvinylpyrrolidone- graphene oxide/PVDF hollow fiber membrane for efficient ammonia nitrogen wastewater treatment and high-density Chlorella cultivation. Chemical Engineering Journal, 379(July 2019), 122368. https://doi.org/10.1016/j.cej.2019.122368
Presenting Author
Mr. Senatore Ph.D Student
Sanitary Environmental Engineering Division (SEED), Department of Civil Engineering, University of Salerno, via Giovanni Paolo II, Fisciano, SA, Italy Is the presenting author an IWA Young Water Professional? No (i.e. an IWA member under 35 years of age)
Bio: I am Vincenzo Senatore, Ph.D student in Environmental Engineering at Sanitary Environmental Engineering Division (SEED), University of Salerno (Italy).
My research field is focused on carbon dioxide capture and utilization (CCU) and wastewater treatment by algal-bacterial membrane bioreactor (MBR).
Specifically, my topic concerns implementation of photobioreactors for CO2
capture, valorization of algae biomass and optimization of algal-bacteria bioreactor for nutrient removal.
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Blocking Biofilm Formation in Anaerobic and Aerobic Environments by Facultative Quorum Quenchers
Shah, SSA.*, Choo, KH.**
* Department of Environmental Engineering, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea.
** Department of Environmental Engineering, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
** Advanced Institute of Water Industry, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea
Keywords: Membrane bioreactor; Quorum quenching; Biofouling Summary of key findings
The isolation and characterization of novel facultative QQ bacteria from anaerobic digester sludge were conducted. Two indigenous bacterial isolates (KS2 and KS10) exhibited endogenous QQ activity in degrading the signal molecule C8-HSL. They produced different types of enzyme (lactonase by KS2 and acylase by KS10). KS2 had a more rapid growth rate under anaerobic conditions than did KS10.
The two QQ strains were both able to efficiently inhibit biofilm formation induced by Pseudomonas aeruginosa (PAO1), aerobic MBR sludge, and anaerobic digester sludge. The facultative QQ strains are thus considered useful for biofouling control in both aerobic and anaerobic MBRs.
Figure 1. Graphical abstract of the reserch findings.
Background and relevance
Membrane bioreactor (MBR) technology is a highly efficient wastewater treatment approach that merges biological processes with membrane filtration to produce high-quality effluent (Gu et al., 2018;
Maqbool et al., 2015; Meng et al., 2017; Shi et al., 2017; Waheed et al., 2017). However, bacterial growth in the form of a biofilm on the membrane surface, referred to as biofouling, is a significant drawback that needs to be overcome in order to make MBR more practical and cost- effective for use in field applications, in addition to other fouling factors associated with particle deposition and gel layer formation (Meng et al., 2009; Nam et al., 2017; Teng et al., 2019). Various physicochemical methods have been developed to solve the biofouling problem, such as air scouring/backwashing (Chae et al., 2006), chemically enhanced backwashing (Zsirai et al., 2012), and subcritical flux operation (Chu et al., 2014; Wang et al., 2008), but the natural biofouling process has
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remained a difficult problem to overcome (Weerasekara et al., 2016; Weerasekara et al., 2014).
Biofouling is known to be closely linked to quorum sensing (QS), which is a form of microbial cell-to- cell communication that acts through small diffusible signal molecules (Parsek and Greenberg, 2005;
Waters and Bassler, 2005). Several recent methodologies have been proposed to disrupt bacterial QS systems, otherwise known as quorum quenching (QQ), particularly in the context of biofilm formation (Whitehead et al., 2001). QQ based on the degradation of signal molecules such as N-acylhomoserine lactones (AHLs) and autoinducer-2 has been applied to aerobic MBRs using enzymes, bacteria, and fungi (Köse-Mutlu et al., 2019; Lee et al., 2018). Anaerobic MBRs are also used in wastewater treatment because of their lower energy requirements and lower sludge production (Smith et al., 2012;
Stuckey, 2012; Su et al., 2019), but biofouling is a lot more serious in these reactors, which exhibit different fouling patterns than those observed in aerobic MBRs (Ahmed and Lan, 2012; Meng et al., 2017; Xiong et al., 2016).
Figure 2. Effects of KS2 and KS10 strains on biofilm formation caused by QS bacterium PAO1, aerobic activated sludge, and anaerobic digester sludge.
Results
Quorum quenching (QQ), the disruption of microbial communication, has proven to be effective as an innovative anti-biofouling strategy for membrane bioreactors (MBRs). However, QQ bacteria for anaerobic environments have not been extensively analyzed in previous research. This study thus investigated facultative QQ bacterial strains that exhibit potential for use in aerobic and anaerobic MBRs. Two novel QQ strains from the genus Pseudomonas (KS2 and KS10) were isolated from anaerobic digester sludge using signal molecules as the sole carbon source. The two QQ strains exhibited significant signal molecule degradation depending on the oxygen levels and demonstrated endogenous QQ activity, with KS2 producing lactonase and KS10 producing acylase. The QQ strains significantly reduced the formation of the biofilm generated by both Pseudomonas aeruginosa (PAO1) and real sludge. Facultative QQ strains have the potential to offer a more flexible option for effective biofouling control in both aerobic and anaerobic MBRs.
References
Maqbool, T., et al., Membrane biofouling retardation and improved sludge characteristics using quorum quenching bacteria in submerged membrane bioreactor. Journal of Membrane Science, 2015. 483: p. 75-83.
Meng, F., et al., Fouling in membrane bioreactors: An updated review. Water Research, 2017. 114: p. 151-180.
Waheed, H., et al., Insights into quorum quenching mechanisms to control membrane biofouling under changing organic loading rates. Chemosphere, 2017. 182: p. 40-47.
Shi, L., X. Gao, and W. Li, A new species of Homoneura (Euhomoneura) from northern China (Diptera, Lauxaniidae). ZooKeys, 2017. 725: p. 71-78.
Gu, Y., et al., Fate of pharmaceuticals during membrane bioreactor treatment: Status and perspectives.
Bioresource Technology, 2018. 268: p. 733-748.
Meng, F., et al., Recent advances in membrane bioreactors (MBRs): Membrane fouling and membrane material.
Water Research, 2009. 43(6): p. 1489-1512.
Nam, K., et al., Interpretation and diagnosis of fouling progress in membrane bioreactor plants using a periodic pattern recognition method. Korean Journal of Chemical Engineering, 2017. 34(11): p. 2966-2977.
Chae, S.-R., et al., Mitigated membrane fouling in a vertical submerged membrane bioreactor (VSMBR). Journal of Membrane Science, 2006. 280(1): p. 572-581.
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Zsirai, T., et al., Efficacy of relaxation, backflushing, chemical cleaning and clogging removal for an immersed hollow fibre membrane bioreactor. Water Research, 2012. 46(14): p. 4499-4507.
Wang, Z., et al., Membrane fouling in a submerged membrane bioreactor (MBR) under sub-critical flux operation:
Membrane foulant and gel layer characterization. Journal of Membrane Science, 2008. 325(1): p. 238-244.
Chu, H., et al., Dynamic membrane bioreactor for wastewater treatment: Operation, critical flux, and dynamic membrane structure. Journal of Membrane Science, 2014. 450: p. 265-271.
Weerasekara, N.A., K.-H. Choo, and C.-H. Lee, Biofouling control: Bacterial quorum quenching versus chlorination in membrane bioreactors. Water Research, 2016. 103: p. 293-301.
Weerasekara, N.A., K.-H. Choo, and C.-H. Lee, Hybridization of physical cleaning and quorum quenching to minimize membrane biofouling and energy consumption in a membrane bioreactor. Water Research, 2014. 67: p.
1-10.
Parsek, M.R. and E.P. Greenberg, Sociomicrobiology: the connections between quorum sensing and biofilms.
Trends in Microbiology, 2005. 13(1): p. 27-33.
Waters, C.M. and B.L. Bassler, Quorum sensing: cell-to-cell communication in bacteria. Annual Review of Cell and Developmental Biology, 2005. 21: p. 319-346.
Whitehead, N.A., M. Welch, and G.P.C. Salmond, Silencing the majority. Nature Biotechnology, 2001. 19: p. 735.
Lee, K., et al., Quorum sensing and quenching in membrane bioreactors: Opportunities and challenges for biofouling control. Bioresource Technology, 2018. 270: p. 656-668.
Köse-Mutlu, B., et al., Quorum quenching for effective control of biofouling in membrane bioreactor: A
comprehensive review of approaches, applications, and challenges. Environmental Engineering Research, 2019.
24(4): p. 543-558.
Smith, A.L., et al., Perspectives on anaerobic membrane bioreactor treatment of domestic wastewater: A critical review. Bioresource Technology, 2012. 122: p. 149-159.
Stuckey, D.C., Recent developments in anaerobic membrane reactors. Bioresource Technology, 2012. 122: p.
137-148.
Su, X., et al., Impact of resuscitation promoting factor (Rpf) in membrane bioreactor treating high-saline phenolic wastewater: Performance robustness and Rpf-responsive bacterial populations. Chemical Engineering Journal, 2019. 357: p. 715-723.
Ahmed, F.N. and C.Q. Lan, Treatment of landfill leachate using membrane bioreactors: A review. Desalination, 2012. 287: p. 41-54.
Xiong, Y., M. Harb, and P.-Y. Hong, Characterization of biofoulants illustrates different membrane fouling mechanisms for aerobic and anaerobic membrane bioreactors. Separation and Purification Technology, 2016.
157: p. 192-202.
Ma, H., et al., The diversity, distribution and function of N-acyl-homoserine lactone (AHL) in industrial anaerobic granular sludge. Bioresource Technology, 2018. 247: p. 116-124.
Feng, H., et al., Where are signal molecules likely to be located in anaerobic granular sludge? Water Research, 2014. 50: p. 1-9.
Liu, J., et al., Quorum quenching in anaerobic membrane bioreactor for fouling control. Water Research, 2019.
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Presenting Author
Syed Salman Ali Shah PhD Student
Department of Environmental Engineering, Kyungpook National University, South Korea
Is the presenting author an IWA Young Water Professional? Y/N N
Bio: Syed Salman Ali Shah completed his MSc in Environmental Engineering from Kyungpook National University in 2020, and BSc in Chemical Engineering from University of Engineering and Technology (UET) Peshawar, Pakistan in 2016. In addition, he has 1 year industrial experience in process industry and is currently enrolled a PhD student at the Department of Environmental
Engineering, Kyungpook National University, South Korea.