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Chapter 19 : Biofilms in the Water Industry
This chapter outlines fundamental— and often special —characteristics of biofilm systems in the water industry. Building on these fundamentals, the describes how the water industry uses biofilms as the heart of technology that improves water quality. Finally, it highlights the ways in which biofilms cause problems in the water industry and strategies to counter the problems. Having multiple donors and acceptors means that multiple-species biofilms are normal in the water industry. The donor and acceptor substrates present in the water select the bacteria that can inhabit the biofilm. Therefore, microbial ecology is the dominant biological science needed to understand and control biofilms in the water industry. Methanogenesis accomplishes two goals. The first and most fundamental goal is to transfer all the electron equivalents in organic matter (i.e., the biochemical oxygen demand (BOD)) to CH4, which is a valuable energy resource. The second goal is to digest (or destroy) organic solids when the BOD is present in solid form. As waste-solids disposal is expensive, destroying solids is a major advantage. Although the issues are similar to those for drinking water, they are complicated by the reality that the manufacturing processes often add easily biodegraded substrates to make the products. As it often is impossible to have biologically stable process water, industries have developed elaborate clean-in-place systems that are used between product batches, and they also use a wide range of antimicrobial agents to minimize microbial growth in the process water and in the products.