Biological wastewater treatment technology: Advancement and drawbacks

Abstract Biological wastewater treatment is a modern technique in which wastewater is treated with microorganisms instead of chemicals. In this way, we try to prevent the adverse effects caused by chemical treatment of wastewater such as chemical accumulation in water bodies or algal blooming. In biological wastewater treatment, many aerobic as well as anaerobic microorganisms can be used in various methods to reduce different types of pollutants present in water and to reduce biochemical oxygen demand of water. Activated sludge is also a very important part of the biological treatment of wastewater as it is used as inoculum to start the microbial reactions in wastewater treatment plants. Various techniques of biological wastewater treatment can be used to remove a variety of pollutants from wastewater such as conventional activated sludge process, membrane bioreactors, or trickling filter process. Biological wastewater treatment is a slow process and requires a large area to treat and store water, which leads to high capital and operating cost. Biological wastewater treatment produces some unwanted microorganisms that produce gases and bad odor. This treated effluents containing water cannot be released into water bodies as it can cause a change in physicochemical properties of water, which ultimately leads to a decrease in the aquatic animal population. Biological treatment of wastewater eliminates organic pollutants but not all types of pollutants such as detergents, cosmetic wastes, etc. This chapter provides an overview of advanced biological methods used for treating wastewater and also highlights the various drawbacks associated with these methods.