The below article is courtesy of http://biofilmbook.hypertextbookshop.com. It demonstrates two practical uses of a bacterial biofilm. Normally people encounter biofilm (slim) and really don’t know what it is. We all have seen it in it’s worst light. Having a bacterial biofilm on our hydro tanks does pose certain physical problems. It could clog pump lines, for example. But it also has it’s benefits. It is a nitrification dynamo turning organic carbon complexes into simple, soluable nutrients while keeping bacterial pathogens at bay.

Water and Wastewater Treatment

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Engineers have taken advantage of natural biofilm environmental activity in developing water-cleaning systems. Biofilms have been used successfully in water and wastewater treatment for over a century. English engineers developed the first sand filter treatment methods for both water and wastewater treatment in the 1860s. In these filtration systems the surfaces of the filter media act as a support for microbial attachment and growth, resulting in a biofilm adapted to using the organic matter found in that particular water. The end result of biological filtration is a conversion of organic carbon in the water into bacterial biomass. Ideally, this biomass is immobilized on the filter media and removed during the backwash cycle.

Drinking water and treated wastewater that have been subjected to microbial activity in a controlled manner in a treatment plant are more “biologically stable” and therefore less likely to contribute to microbial proliferation downstream in distribution system or receiving water. Biologically treated water typically has lower disinfectant demand and disinfection by-product formation potential than conventionally treated water if the source water is high in organic carbon. As drinking water utilities move to using ozone as a primary disinfectant and for taste/odor/color control, biological filters may be necessary to reduce the concentrations of biodegradable organic carbon entering the distribution system.

Remediation of contaminated soil and groundwater

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In soil, biofilm morphology can be highly variable, ranging from patchy discontinuous colonies to thick continuous films, depending on environmental conditions. When toxic organic contaminants (i.e. gasoline, fuel oil, chlorinated solvents) are accidentally released underground, the native soil bacterial population will, to the degree possible, adjust their ecological composition in order to use the organic contaminants as a food source. This process is commonly referred to as “bioremediation” and if successful, potentially has the ability to render initially toxic organic material into harmless by-products. Typical biofilm cell densities found in the vicinity of contaminated ground water sites vary from around 105 to 108 cells per gram of soil.

Bioremediation has emerged as a technology of choice for remediating groundwater and soil at many sites contaminated with hazardous wastes. Bioremediation results in 1) the reduction of both contaminant concentration and mass for many subsurface contaminants (e.g., petroleum hydrocarbons, chlorinated organics and nitroaromatics) and/or 2) a beneficial phase transfer or speciation change (e.g., for heavy metals and radionuclides). Subsurface bioremediation is controlled by abiotic geochemical and transport phenomena, including multiphase flow, convective mass transport, adsorption/desorption, and phase partitioning, as well as biotic processes, such as microbial biomass growth and contaminant metabolism.

Above article courtesy of http://biofilmbook.hypertextbookshop.com