The invention discloses a method for producing
biogas through two-phase anaerobic
fermentation of piggery
wastewater. The method comprises steps as follows: the piggery
wastewater flows into an adjusting tank to be uniformly stirred after impurities are filtered by a
grating tank; uniformly stirred
wastewater in the adjusting tank flows into an acidification tank for high-temperature hydrolytic
acidification treatment, and an acidizing fluid is obtained; the acidizing fluid is pumped into a black film
biogas digester to be fermented to produce
biogas; biogas is purified and connected with a biogas power generator for power generation; the biogas power generator, a
heat exchanger and a hot water tank are connected sequentially and are used for recovering
waste heat produced by power generation, forming hot water and sending the hot water to an acidification tank to increase the temperature. By means of the method, acidification and
hydrolysis of
organic matter in the piggery wastewaterare promoted, the gas producing efficiency and the gas output of the black film biogas digester are increased, and the problem of difficulty in
slag discharge of the black film biogas digester is solved; the obtained biogas residues are used for producing
compound organic fertilizer, the biogas is used for power generation,
waste heat of power generation is used for acidification and
hydrolysis, and the method has good ecological benefits and
economic benefits and is applicable to large-scale
pig farms.