Advantages And Disadvantages Of Heterotrophic Nitrification

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CHAPTER 2 Review of Literature This chapter describes about biological methods of ammonical nitrogen removal processes from waste waters, their advantages and disadvantages compared to heterotrophic bacterial ammonia removal processes. These methods include both aerobic and anaerobic methods of ammonical nitrogen removal, their drawbacks in view of performance, literature studies on simultaneous heterotrophic nitrification and aerobic denitrification, immobilization studies including materials for immobilization, heterotrophic nitrifiers and aerobic denitrifiers and their reactor studies. Biological process The biological process involves autotrophic as well as heterotrophic microbial processes for nitrogen removal. Recently scientists discovered…show more content…
The oxidized nitrogenous compounds (nitrite or nitrate) are reduced to gaseous nitrogen by heterotrophic microorganisms that use nitrite or nitrate instead of oxygen as electron acceptor and organic matter as carbon and energy. Denitrification is common among the gram negative bacteria such as Pseudomonas, Alcaligenes, Paracoccus and Thiobacillus. Some gram positive bacteria (like Bacillus) and a few halophillic archaeal microorganisms (Haloferax denitrificans) are able to denitrify (Kim et al., 2005, Cyplik et al., 2007). Denitrification is a slow process particularly for industrial wastewaters that contains high concentrations of nitrate (Foglar et al., 2005) but the process gained huge interest as it is environment friendly and cost…show more content…
In comparison to conventional nitrification and denitrification, Anammox bacteria requires no external carbon source, they take carbon dioxide from water, 50% less oxygen, therefore low operation costs (Tal et al., 2006). These bacteria belong to the order planctomycetales. They are the most primitive group of bacteria and occupy the base of the bacterial tree. They are gram negative, uncultivable, first isolated through density gradient centrifugation (Van de graaf et al., 1996, Strous et al., 2002). Their distinctive phenotypic characteristics involve red color, budding production, crateriform structure on the cell surface, intracellular compartment, anammoxosome, intra cytoplasmic membrane containing ladder lane lipids (Van de graaf et al., 1996, Linsey et al., 2001, Sininghe Damste et al., 2002). They have a coccoid shape with a diameter of less than 1µm and generation time of 10-30 days (Van Niftrik et al.,

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