Wastewater Treatment: Role of Microbial Biofilm and Their Biotechnological Advances

Wastewater Treatment: Role of Microbial Biofilm and Their Biotechnological Advances

Deepika Rajwar (G. B. Pant University of Agriculture and Technology, India), Mamta Bisht (Indian Agricultural Research Institute, India) and J. P. N. Rai (G. B. Pant University of Agriculture and Technology, India)
Copyright: © 2018 |Pages: 13
DOI: 10.4018/978-1-5225-3126-5.ch010
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In recent years, stringent discharge standards prior to the release of effluent into the water bodies have led to implementation of diverse advanced biological treatment processes in various industries. Biological treatment is a fundamental part of industrial wastewater treatment, contains soluble inorganic/organic pollutants. Being a cost-effective process, biological treatment has an economic advantage over chemical and physical processes. It employs a range of microorganisms which as a community form a microbial biofilm. Microbial biofilm provides a diverse range of micro-niches to microbial communities and protection from physical agitation to support metabolic potential and functional stability. Currently, biofilms are applied in wastewater treatment, degradation of toxic waste in water and soil and production of various commercial products. Intensive exploration has proved the importance of biofilm as a highly promising biotechnology, especially in wastewater treatment.
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Microbial Biofilm

A microbial biofilm is a group of surface-associated microbial cells enclosed in an extracellular matrix containing polymeric substances (Ghannoum and O’Toole, 2004). Extracellular polymeric substances (EPS) are primary matrix material that accounts for 50 to 90% of the entire organic carbon of a biofilm (Flemming et al., 2000). EPS is composed of polysaccharides but may vary chemically and physically. The polysaccharides are neutral or anionic, such as EPS of gram-negative bacteria is consisted of uronic acids (D-glucuronic, D-galacturonic, and mannuronic acids) which provides anionic characteristics to the biofilm (Sutherland, 2001). The anionic nature of EPS attracts divalent cations (magnesium and calcium) which makes cross-link structures with the polymer that provides larger binding force to a biofilm (Flemming et al., 2000). However, EPS of some gram-positive bacteria is cationic, for example, Staphylococci. On the other hand, the amount of EPS production differs among the organisms and it increases as biofilm grows (Leriche, 2000); however, several factors like nutrient status of the medium, accessible carbon and limited nitrogen or phosphate sources affect EPS production (Sutherland, 2001).

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