An Overview on Recent Developments in Biological and Hybrid Wastewater Treatment Technology in India

Conventional biological wastewater treatments are broadly classified as suspended growth and attached growth treatments. The biomass is suspended in wastewater in suspended growth processes. It is attached as a slime layer to packings or rotating discs in attached growth processes. In attached growth processes microorganisms have large surface area for growth. Attached growth processes are costly and have high oxygen requirements. Activated sludge processes are suspended growth processes for biological treatment of water. Microorganisms consume the organic matter to purify the wastewater. The biological methods can also be aerobic and anaerobic. Anaerobic water treatment is utilized for very high organic loading and produces methane. Due to odour problems, this method is underutilized. Advancement in technology to intensify the processes is a key research area in wastewater treatment technology. Reductions in cost, area and time have been the driving forces for innovations in biological treatment technologies. Combining the advantages of one biological treatment process with other technologies such as membrane separation, advanced oxidation with UV light, ozone treatment, and biosorption for wastewater treatment are widely investigated research topics in wastewater engineering. Investigations of biological treatment in recent past are focused on optimization of process parameters and combining the biological treatment processes to obtain high percent removal of the pollutants along with modelling of the removal mechanism. This book chapter sheds light on the recent investigations on biological treatments along with an overview of treatment methodologies with a focus on research, investigations and initiatives in India.