Anaerobic Digestion Essay

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Anaerobic Digestion is broken down in 4 steps. These four steps are Hydrolysis, Acidogenesis, Acetogenesi and Methanogenesis. The first stage is hydrolysis. Hydrolysis is a process used to break down larger polymers in the presence of water, and often of an acidic catalyst. This is a very essential part of hydrolysis as biomass consists of very large organic molecules and for this process to work efficiently we must break the large particles down into smaller particles. Think of it the same way our stomach works, before we digest the food that we eat, we must break it down. The large polymers, mainly consisting of proteins, fats and carbohydrates are broken down into amino acids, fatty acids and simple sugars. During this process hydrogen and acetate are also produced. These byproducts will be used in a later anaerobic digestion stage. After hydrolysis, though the molecules have decreased in size, it is still not small enough and must be broken down further. This is when the next process comes in. In Acidogenesis we bring in acidogenic microorganisms to aid in the breakdown of the organic material. These fermentative bacterica produce an acidic environment within the tank. These bacteria will further break down the material into ammonia, H2, CO2, H2S, and shorter volatile fatty acids,but alas it is still too big for methane production! So, we go to our next stage to help break it down more. This process is called Acetogenesis. Acetogenesis is the creation of acetate, which is a derivative of acetic acid. To do this we must use more microorganisms. They catabolise most of the product in created from the previous process into acetic acid, CO2 and H2. Acetogens break down biomass to a point to which it is acceptable to create methane. In the last process called Methangenisis. This is when methanogens create methane from the final products of the previous stage as

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