Design and Construction of Five Gallon Anaerobic Digesters

This project discusses the design, construction, and testing of a laboratory scale anaerobic digestion reactors. It included four digesters and two gas measurement devices. The outside dimensions of the digester were 22 inch tall with a 10.5 inch diameter. They were constructed from schedule 40 PVC pipe, with a wall thickness of 0.5 inches. They were designed to be filled with 20 liters of digester feed stock, at a height of 16 inches from the bottom, leaving 5 inches of head space above the digester feed for biogas accumulation. Two of the reactors were heated with Hydrofarm seedling heating pads controlled by Hydrofarm thermostat that operate at a maximum temperature of 42°C. Two digesters were complete mixed reactors mixed with a mixing paddle. Two digesters were fixed film digesters, packed with media, and mixed with a peristaltic pump. The gas produced by the digesters was piped to the gas measurement tipping meters and the volume of gas was recorded on a data logger in 90 ml intervals