Meta-Omics Studies of Microbial Communities in Hollow Fiber Membrane Biofilm Reactors Treating Contaminants in Water Resources: Recent Advances
Department of Microbiology, University of Kalyani, Kalyani, India.
Oxidized materials such as nitrate, sulfate, perchlorate, selenate, chromate, and trichloroethene are prime contaminants of drinking water and wastewater. Presently, removal of such oxidized contaminants from water resources by biological reduction processes has been successfully incorporated in various water treatment facilities. One of such technologies is membrane biofilm reactor (MBfR). In this system, biofilm of microorganisms is allowed to form on the outer surface of hollow fiber membrane and gaseous substrates are allowed to enter the lumen of the hollow fiber that is delivered to biofilms by diffusion through membrane wall. Some MBfRs deliver gasses (H2 or CH4) to the biofilm as electron donors where oxidized contaminants in water act as electron acceptor and get reduced. When O2 is delivered reduced contaminants (benzene, toluene, and surfactants) are oxidized. The performance of the MBfR principally depends on the structure and function of microorganisms in the complex biofilm community. Biofilm microbial community composition and function can be managed by adjusting the operating parameters (membrane type, gas pressure, and surface loadings) of MBfR. Thus, to design and operate successful MBfR better understanding the functions of diverse microbial populations and their interactions with operating environments is prime essential. Recent advancements in “meta-omics” technologies (metagenomics, metatranscriptomics, and metaproteomics) for the analysis of microbiome have greatly enhanced such understanding. This chapter summarizes recent findings of biofilm microbial communities, physiology of key functional microbes, and responses of key microbes and genes to changes of environmental factors or operating parameters in different MBfRs targeting removal of different contaminants from drinking water and wastewater. Efforts are also given to highlight how the omics results have been integrated into the performance data for determination of optimal environmental and biotechnological parameters and improvement of contaminants removal efficiency.
Keywords: Membrane biofilm reactor, hollow fiber membrane, oxidized contaminants removal, wastewater, drinking water, microbial community, gaseous electron donor, meta-omics.