Anaerobic digestion method and apparatus for sewage sludge

摘要

To provide a method and an apparatus for anaerobically digesting sewage treatment sludge, in each of which the environment of an in-tank agitating/mixing type reaction tank is adjusted so that dispersed bacteria become dominant species and the amount of methane gas to be generated and the concentration (partial pressure) of the methane gas can be increased.SOLUTION: In the method and the apparatus for anaerobically digesting sewage treatment sludge, the sewage treatment sludge, which comprises the first sedimented sludge sedimented in a first sedimentation basin of a sewage treatment plant and/or the excess sludge withdrawn from a biological treatment reaction tank, is digested anaerobically in an anaerobic digestion tank 3. At least one water quality index value of the temperature, pH, ORP, M alkalinity and volatile fatty acid concentration of the sludge to be introduced into the anaerobic digestion tank 3 or the sludge in the anaerobic digestion tank. When at least one of the measured water quality index values is deviated from a predetermined range, an additive containing at least one of Fe, Cu, Zn, Mg, Mn, K, Ca, Ni, Mo, Se, S, V, Cr, I and Co is added thereto.SELECTED DRAWING: Figure 1