The invention relates to a multistage
anaerobic digestion strengthened gas production method mainly comprising the steps of front-stage
anaerobic digestion, high-temperature and high-pressure
thermal hydrolysis and back-stage
anaerobic digestion. After
sludge is subjected to the front-stage anaerobic
digestion treatment, easily-degraded organic matters are sufficiently decomposed and converted into
marsh gas, the residual part mainly comprises difficultly-biodegraded organic matters and
facultative bacteria which adapt to the anaerobic environment and can not be digested and utilized, and the organic matters account for over 50% of the total organic matters in the
sludge and
restrict the development of anaerobic
digestion. The discharged material subjected to the front-stage anaerobic
digestion is subjected to the high-temperature and high-pressure
thermal hydrolysis treatment to force a
cell wall to crack, substances in a
cell to be dissolved out and a
colloid structure of an
extracellular polymer to be broken, so that parts of difficultly-biodegraded organic matters are converted into the easily-degraded organic matters; the
sludge subjected to the
thermal hydrolysis treatment is added into a back-stage anaerobic digestion
system to further realize the degradation and anaerobic gas production of the organic matters. By using the multistage anaerobic digestion strengthened gas production method, the degradation rate and gas
production rate of the organic matters in the sludge are radically increased, the quantity and volume of the sludge are reduced, the sludge stabilizing effect is enhanced, and the quality of anaerobic digestion sludge is improved.