Biofilm Dynamics In Drinking Water Biofiltration Downstream Nanofiltration Biofouling

Natural organic matter (NOM) is a concern in many surface waters and must be removed by water treatment processes for cost-effective production of safe and aesthetically pleasing drinking water. Biological filtration is an appealing NOM removal method due to its simplicity and low maintenance requirements. Biofiltration is not traditionally used in water treatment headworks, however biofiltration without pretreatment (BFwp) breaks with common practice to function as both particle and biodegradable NOM removal as a 1st stage process. BFwp makes use of indigenous microbial populations embedded in a biofilm matrix to remove biodegradable organic matter (BOM) from raw source water. This configuration is a viable pretreatment strategy for both low and high pressure membrane filtration due to its ability to remove both particulate and soluble BOM, thereby mitigating biofouling on the membrane surface. Biofouling has been described as the "Achille's heel" of membrane filtration (Flemming et al., 1997) due to its effects of increased operational cost and shortened membrane life-span. Therefore, a targeted effort is needed to understand how biofilter ecology affects performance both in the biofilter and downstream in membrane filtration units. Two parallel pilot scale BFwp units with dual-media were used in the current study for a seasonal characterisation of biofilter microbial dynamics and performance. Refurbishment of the biofilter pilot plant was performed by Dr. Ahmed Elhadidy and Brad Wilson, former students of the NSERC chair in water treatment. The current seasonal characterization spanned 14 months and made use of both new sample material as well as archived samples from Dr. Elhadidy. Biofilter media biomass was assessed using both adenosine tri-phosphate (ATP) and flow cytometric methods. Total protein, carbohydrate and free DNA of the media biofilm extracellular polymeric substances (EPS) were determined. Polymerase Chain Reaction - Denaturing Gradient Gel Electrophoresis (PCR-DGGE) was used to create microbial community fingerprint profiles of the biofilter feed and media. It was found that source water quality played a significant role in shaping BFwp microbial communities. Multivariate analysis of the PCR-DGGE fingerprints showed a media biofilm community shift occurred in response to high ammonia, high low molecular weight acids (LMW-acids) concentrations in the raw feed during January-February 2015. This low temperature, high ammonia and LMW-acids induced shift was accompanied by a rise in media biomass and EPS. Lower DOC and biopolymer removals were observed during the January-February 2015 community shift, however this was attributed largely to the effects which lower feed temperatures have on microbial biodegradation kinetics. No differences were found in community structures between media types, depths, or biofilter columns, however source water exhibited lower diversities and markedly different community structure than those of media biofilms. It was determined that media diversity and richness were high and did not exhibit seasonal fluctuations. As such these parameters could not be reliably related to biofilter DOC and biopolymer removal performance. In his investigation of biofiltration as a pretreatment for nanofiltration (NF), Dr. Elhadidy archived samples for molecular analysis that were used in the current study. PCR-DGGE was performed on extracted DNA from source water, media, and fouled membrane samples for bacteria, archaea, and fungi. Archaea were present in all samples, however their abundance was roughly 1000 fold less than bacteria, which made it difficult to assess their significance in the biofiltration and NF processes. Fungi were only screened for in one media and one source water sample during method development; both samples were positive. Archaeal community organisation was similar to that of bacteria during the autumn BF-NF experiment, however no community organisation was discernible during the winter experiment. Bacterial community structures from the autumn experiment showed that fouled NF membranes fed raw water clustered together with biofilter media, indicating feed water rather than substrate material influences bacterial community organisation. Comparatively, NF membranes fed with biofilter effluent produced a cluster of drastically dissimilar bacterial communities, which corresponded with improved flux and reduced biofoulant biomass. The microbial communities of biofiltration exhibited dynamic responses to feed water quality in both the seasonal and the nanofiltration studies. Biomass and EPS were highly correlated and their levels changed in response to community shifts, which in the seasonal and nanofiltration studies, were precipitated by changes in feed ammonia and BOM.

Biofiltration is a promising green drinking water treatment technology that can reduce the concentration of biodegradable organic matter (BOM) in water. Direct biofiltration or biofiltration without pretreatment (BFwp) limits the use of chemicals such as coagulants or ozone commonly employed with conventional biofiltration, making BFWP a more environmental friendly pre-treatment. BFWP was proven to be an efficient pretreatment to reduce fouling of low pressure membranes, and can also improve the biological stability of the final treated drinking water to limit bacterial regrowth in the distribution system. One major operational problem for high pressure membranes (i.e. nanofiltration and reverse osmosis membranes) is membrane biofouling due to biofilm growth inside the feed channel of the membrane module, resulting in higher energy requirements and more frequent membrane cleaning. BFWP can potentially be applied to reduce biofouling of nanofiltration membranes, which can reduce the energy requirements of high pressure membranes. Three pilot-scale parallel biologically active filters with different empty bed contact times, and bench-scale nanofiltration membrane fouling simulators, were designed and constructed in this study. A challenging surface water source (the Grand River in Kitchener, ON) was used as source water for the investigation. Initial work assessed the effect of biofiltration on the treated water quality and how the biofilter performance is affected by changes in water temperature. A protocol was developed to better characterize the biofilter attached biomass and extracellular polymeric substances (EPS), in order to understand their possible relationship to biofilter performance. Flow cytometry was applied to measure both planktonic cell concentrations in water and also to perform assimilable organic carbon (AOC) analysis using a natural microbial inoculum. BFWP was found to be an efficient pre-treatment for the removal of large molecular weight biopolymers and AOC over a wide range of water temperatures. Lower water temperatures had a significant impact on biopolymer removal, unlike AOC which was efficiently removed at lower water temperatures, and this proved the robustness of such a pre-treatment technology. Other fractions of the natural organic matter (NOM) such as humic substances, buildings blocks and low molecular weight organics were removed to a lower extent than biopolymers or AOC. Empty bed contact time (EBCT) as a design parameter had a limited effect on the biofilter performance. Most of the observed removal for BOM and total cell count happened at the shortest EBCT of 8 minutes, and increasing the EBCT up to 24 minutes had a significant but less proportional impact on biofilter performance. Regarding biofilter attached biomass, no direct linkage was found between biofilter performance and attached biofilter biomass characteristics using any of the commonly used analytical methods such as adenosine triphosphate (ATP) or biofilm cell count, however, cellular ATP content was found to be indicative of biofilm activity. Biofilm EPS composition was not related to biofilter performance but it was largely affected by the water temperature. Through community level physiological profiling (CLPP) analysis it was evident that the microbial community was changing due to a drop in water temperature, however, this was a minor effect and it is likely that the overall drop in biomass activity was the main reason behind the drop in biofilter performance. Finally, BFWP was tested as a potential pre-treatment technology to control high pressure membrane biofouling, which is a major operational problem. BFWP was able to reduce the amount of available nutrients measured as AOC, reduce the presence of conditioning molecules such as large molecular weight biopolymers, and modify the microbial community of the feed water. A 16 minute EBCT biofilter was able to extend the lifetime of nanofiltration membranes by more than 200% compared to the river water without biofiltration, both at low and high water temperature conditions. The 16 minute EBCT biofilter performance was also comparable to that of a full scale conventional biofilter with prior coagulation, sedimentation and ozonation. The biofiltration pre-treatment efficiently affected the amount of biomass present in the biofouling layer and affected the biofilm microbial community as determined using CLPP analysis. The findings of this study provide the basis upon which further and larger scale testing of the BFWP as a pre-treatment for membrane applications can be done. A sound technology could include a hybrid membrane system with a high pressure membrane proceeded with a low pressure membrane. BFWP can then be used at the start of the treatment train to limit both low pressure membrane fouling at the same time limit the biofouling of the pressure membrane. This treatment train can provide a high water quality with limited footprint compared to conventional treatment trains and long service time. Monitoring of the treatment unit performance can be efficiently done using some of the proposed analytical methods presented in the study, such as AOC monitoring and flow cytometry to study microbiological water quality and biofilter biomass. Fluorescence spectroscopy and size exclusion chromatography can also be used to monitor large molecular weight biopolymers, which are responsible for several operational problems in water treatment in general and specifically for membrane applications.

Microbial growth and contamination ("Biofouling") in water systems represents a significant threat to the quality of waters produced for the microelectronic, pharmaceutical, petroleum, paper, food and other manufacturing industries. Biofouling can lead to biologically induced corrosion ("Biocorrosion"), which can cause severe damage to the equipment. Both biofouling and biocorrosion are frequently not recognized in time, underestimated, or linked with the wrong causes. The book represents a new approach by introducing biofilm properties and dynamics as basic principles of biofouling and biocorrosion, thus providing a better understanding and the means of fighting the undesired effects of biofilms. The most important features are: Case histories of biofouling in water treatment.- Detection and monitoring of biofouling.- Reverse osmosis membrane biofouling.- Biocide efficacy and biofouling control.- Plant design considerations for preventing biofouling.- Case histories of biocorrosion.- Detection, monitoring, control and prevention of biocorrosion.- Fundamentals of biofouling and biocorrosion mechanisms.

Aquatic Ecosystems and Microbial Biofilms: Significance, Dynamics, Prevention and Control provides a systematic introduction and review of state-of-the-art information on microbial biofilms in aquatic ecosystems and their control. The book is designed and developed to understand the microbial biofilms in aquatic ecosystems, their role, and the control strategies. The contents of the book are well discussed to get state-of-art knowledge on various topics such as the role of biofilms in marine ecosystems, microbial biofilms, and drinking water systems, biofilms in biofouling and biocorrosion, beneficial aspects of biofilms such as biogeochemical cycling, wastewater treatment, and in biodeterioration of organic materials. This book also provides comprehensive knowledge and in-depth scientific information on the role of biofilms and their contribution to antibiotic resistance, and also advanced technologies to understand biofilms such as metagenomics. The book offers comprehensive coverage of the most essential topics, including: Microbial biofilms in aquatic ecosystems. New horizons to understand the role of biofilms in biofouling and corrosion and their control measures. Beneficial role of aquatic biofilms such as in biogeochemical cycling,wastewater treatment, and biodeterioration of organic materials. Various strategies to collaborate interdisciplinary schemes worldwide to design and develop new methods for cleaner drinking water, and information on advanced techniques such as metagenomics to understand the diversity and functional role of aquatic biofilms. This book serves as a reference book for scientific investigators who would like to study biofilms in aquatic ecosystems, as well as researchers developing methodology in this field to study biofilm formation in aquatic ecosystems, their advantages and disadvantages, and control strategies.

The development of biofilms and their role in public health - particularly drinking water - is often overlooked. Ideal for anyone interested in water related issues, Microbiological Aspects of Biofilms and Drinking Water presents an overview of the public health effects associated with drinking water. It highlights the microbiological aspects relat

The central theme of the book is the flow of information from experimental approaches in biofilm research to simulation and modeling of complex wastewater systems. Probably the greatest challenge in wastewater research lies in using the methods and the results obtained in one scientific discipline to design intelligent experiments in other disciplines, and eventually to improve the knowledge base the practitioner needs to run wastewater treatment plants. The purpose of Biofilms in Wastewater Treatment is to provide engineers with the knowledge needed to apply the new insights gained by researchers. The authors provide an authoritative insight into the function of biofilms on a technical and on a lab-scale, cover some of the exciting new basic microbiological and wastewater engineering research involving molecular biology techniques and microscopy, and discuss recent attempts to predict the development of biofilms. This book is divided into 3 sections: Modeling and Simulation; Architecture, Population Structure and Function; and From Fundamentals to Practical Application, which all start with a scientific question. Individual chapters attempt to answer the question and present different angles of looking at problems. In addition there is an extensive glossary to familiarize the non-expert with unfamiliar terminology used by microbiologists and computational scientists. The colour plate section of this book can be downloaded by clicking here. (PDF Format 1 MB)

Until now, techniques for studying biofilms- the cellular colonies that live in drinking water systems, wastewater operations, even ground and surface water- have been limited. Yet during the last decade, biofilms have become a critical element in water quality preservation systems, a key component of wastewater treatment biological reactions and t

This book provides a state-of-the-art assessment on a variety of biofiltration water treatment systems from studies conducted around the world. The authors collectively represent a perspective from 23 countries and include academics/researchers, biofiltration system users, designers, and manufacturers. Progress in Slow Sand and Alternative Biofiltration Processes - Further Developments and Applications offers technical information and discussion to provide perspective on the biological and physical factors affecting the performance of slow sand filtration and biological filtration processes. Chapters were submitted from the 5th International Slow Sand and Alternative Biological Filtration Conference, Nagoya, Japan in June 2014. Authors: Nobutada Nakamoto, Shinshu University, Japan, Nigel Graham, Imperial College London, UK, M. Robin Collins, University of New Hampshire, Durham, NH, USA and Rolf Gimbel,Universität Duisburg, Essen, Germany.