2. Biogeochemical Cycling Bacteria and Nutrient Dynamics in Waste Stabilization Pond System

Wastewater generated from different sources creates environmental problems after entering the aquatic ecosystem due to its heavy organic load and other undesirable toxicants. As a consequence, biological and chemical oxygen demand increases with depletion of oxygen level of water; all the biotic organisms suffer from stress-related symptoms often reaching to lethal limits. However, wastewater may become a useful resource for various economic-driven activities. Wastewater reuse is primarily dependent on the microbial degradation of different nutrients present in sewage. Thus, biogeochemical cycling bacteria have profound role on the decomposition, degradation and regeneration of nutrients from organic sewage water. Thus, the metabolism and turnover of the whole sewage-fed ponds are regulated by nutrient cycling and energy flow in the trophic level. Waste stabilization pond has been recognized as effective treatment system with removal of as high as 90–95% dissolved organic matter and reducing pathogens through microbial activities under aerobic and anaerobic conditions in trickling filter, activated sludge processes, etc. Interactions within and between carbon, nitrogen and phosphorus pools in nutrient cycles of wastewater-fed ponds ultimately result in nutrient removal from wastewater. A series of waste stabilization ponds (anaerobic, facultative and maturation) in which the detritus food chain is dominant over the grazing food chain is popular. It is evident that microbial activities play a crucial role in nutrient recovery from wastewater through microbial degradation of organic load leading to increased biological production while accelerating the enhancement of water quality through microbial-driven ecological processes.