Anaerobic Digestion and the Characterization of Variability of Agricultural and Municipal Waste for its Efficient Valorization Potential

“Waste” is any undesirable product that results from anthropogenic activities. Such unwanted items must be disposed of as they cause a nuisance to the environment and human health. Numerous approaches are being employed, comprising both aerobic and anaerobic treatments. However, anaerobic treatment offers more benefits as compared to aerobic ones. Anaerobic digestion is the degradation and stabilization of organic materials by microbial organisms under anaerobic conditions, which results in the formation of biogas and microbial biomass. One of the biggest biological sectors with the highest biomass production is agriculture, which can provide a significant bioeconomy input. Bioeconomic strategies based on agriculture waste management can stop the underuse of livestock manure and the careless or random burning of crop residues to guarantee food and health security, waste valorization to produce products with added value, farmer’s livelihood, youth employment opportunities, and agriculture sustainability. Wastewater is unsuitable water that is generated when freshwater is deliberately used for several purposes. Most of the environmental issues are the result of improper management of water. The need of the hour is to remove impurities from wastewater before it is released into the natural sources of water such as rivers, lakes, and oceans. For sustainable development, it is necessary to treat wastewater and reuse it so that the load on freshwater decreases. Anaerobic wastewater treatment can be used in psychrophilic and thermophilic temperature ranges in addition to mesophilic ones. This chapter discusses the current knowledge regarding anaerobic treatment in water management, wastewater, and its sources, types, and factors affecting digestion, and its treatment.