Anaerobic Co-Digestion Of Municipal Solid Waste And Anaerobic Waste Sludge

This thesis explores in the mesophilic anaerobic co-digestion of municipal biochemical solid waste (MBSW)and anaerobic waste sludge. We use one stage anaerobic digestion., and carry through two experiments. The one is the mesophilic anaerobic co-digestion of MBSW and anaerobic waste sludge, with different OLR, and the other experiment is controlling pH to a suitable scope for the methane bacteria.The results of the different OLR mesophilic anaerobic co-digestion show that pH of the two digestion systems automatically raised to 7.0 with the OLR 0.5 g·VS/L·d and 1.0 g·VS/L·d. The acidifications were reversible. The acidification was inreversible for another higher than OLR of 1.5 g·VS/L·d, which accompanied an accumulation of VFA and acid inhibition.The higher the OLR of digestion system was , the lower the acidification point was. The removal of VFAs were obvious with the OLR 0.5 g·VS/L·d and 1.0 g·VS/L·d of the digestion systems, but the removal of ammonia nitrogen and COD were not much. The concentration of ammonia, VFAs, COD were very high in the digestion system, whose OLR was higher than 1.5 g·VS /L·d.Controlling pH to a suitable scope, for the methane bacteria is important, in the co-digestion process of MBSW and anaerobic waste sludge.The result shows that the solid material of the digestion system decomposed more completely by controlling about pH7 , and provided the favorable substrates to subsequent methanogensis, the cumulative gas production and the methane gas concentration was higher. That controlling pH to suitable scope can promote the removal of ammonia nitrogen and COD, shorted the time of hydrolysis and acidogenesis, increases the hydrolysis and acidogenesis rates, ensures that the methanogenic reaction be taken .