Microbiological and enzymatic treatments for utilizing agricultural and food processing wastes

Agricultural and food industry wastes include both solids and liquids that pose potentially severe pollution problems and are subject to increasing governmental regulations. In this presentation, emphasis is placed on microbiological and enzymatic processes for recovering animal feeds, food additives, chemicals and fuels from these wastes. Under aerobic conditions, carbohydrates, lipids and proteins in wastes can be converted by microorganisms to yield microbial biomass or single‐cell proteins to be used for animal feeds or human foods. Also, they can serve as substrates for producing chemicals or enzymes, or for enzymatic conversion to sugar syrups, fatty acids, or amino acids. Under anaerobic conditions, wastes containing carbohydrates, lipids, and proteins can be digested to yield methane. Also ethanol or organic acids can be produced from carbohydrates by anaerobic microbiological processes. Key considerations in determining the advisability of utilizing these wastes include the following: cost of utilization, seasonality and quantities of wastes, availability of appropriate technologies, existence of markets and market value of recovered products including fuel value.