The Fate of Organic Pollutants and Their Microbial Degradation in Water Bodies

Globally, organic substances are one of the major pollutants in the contamination of water bodies. Some of the major sources of organic pollutants are domestic sewage, industrial effluent from various industries like the pharmaceutical industry, pulp and paper, coalmines, food processing, fertilizers, and agricultural run-off containing pesticides. Input from these sources leads to changes in the physicochemical properties of water bodies, thereby putting stress on aquatic ecosystems or water bodies. These changes induce a change in pH, temperature, total suspended solids (TSSs), total dissolved solids (TDSs), dissolved oxygen (DO), and other properties. Previous studies revealed that biodegradable compounds tend to deplete DO content of a water body. Organic contaminants are degraded in water bodies through various transformation processes in the natural environment such as photodegradation, biodegradation, microbial degradation, and enzymatic degradation. The present chapter describes various sources and types of organic pollutants, associated problems, and different methods of pollutant removal with a special emphasis on microbial degradation. Some advanced and efficient technologies such as photocatalytic degradation and advanced oxidation technologies are discussed. During the past few decades, the natural attenuation method has generally been used for pollutant removal, which is a combination of chemical and biological processes. Changing environmental conditions during the natural attenuation process results in the acceleration of pollutant degrading microbial communities with special reference to the emerging contaminant (EC). The biodegradation pattern of such contaminations is not yet understood, and thus, provides a good scope for the inculcation of different methods, which could prove to be sustainable and energy-efficient. Organic pollutants are naturally degraded into the environment, however, degradation always has a certain upper limit, which seems to be passed under current environmental conditions. This phenomenon may result in an increase of organic contaminants into water bodies. Therefore, utmost care is required before the discharge of organic pollutants into water bodies.