Two Phase Anaerobic Degestion Of Shredded And Dewatered Household Kitchen Waste

The production of municipal solid waste continues to rise rapidly with the development of cities and towns in China.However,most residents are used to mixing KW with other domestic refuse.The mixture was disposed in landfills or incinerated,practices associated with different issues,such as rising costs of waste disposal,lack of space,leaching,public environmental concern and emission of toxic and greenhouse effect gases.In order to separate KW from domestic garbage effectively and propose a recycling application,this study use household shredding-dewatering equipment developed earlier to separate solid part of KW.Anaerobic digestion(AD)in solid-liquid system is a promising process to treat with the separated KW.The operation conditions and treatment effects were investigated.In this study,the practicability of household shredding-dewatering equipment was tested.The treatment effect of kitchen waste,the main properties of solid materials produced and wastewater were investigated.The results showed that the weight and volume reduction rate were 15~30% and 40~60%,the TS and VS of solid material were 15~30% and 80~90%,and the BMP of solid part was 536 NmL/gVS.The wastewater produced during treatment had no significant effect on the quantity and quality of domestic sewage.The leachate amount,leaching frequency and substrate type on effects of solid-state acid production were investigated.The results showed that biogas production was positively affected by leachate spreading,especially when leachate amount was 1:2(the ratio of leachate volume to substrate volume)and leaching frequency was 4 times per day.The semi-continuous liquid methane production test showed that the maximum OLR was 4.3 gCOD/(L·d)and the daily gas production was 69-83 mL.When the concentration of additional NaCl was 2500 mg/L,the cumulative gas production was 487 mL.When the concentration of additional NaCl was 10000 mg/L,the gas production decreased significantly.When TAN concentration was 2500~3000 mg/L,the maximum cumulative gas production was 455 mL,and when TAN was more than 3850 mg/L,it resulted in gas production inhibition.Through the continuous operation test of solid-liquid anaerobic digestion system,the optimum operating parameters,such as solid hydrolysis period and hydraulic retention time of liquid phase were determined.The results also showed that the solid-liquid anaerobic digestion system could run for 28 days continuously,with stable gas production,high methane content of 45~68%.The average VS reduction rate of kitchen waste substrate was 47.5%,and the weight and volume reduction rate were 34% and 48% respectively.The COD and VFAs reduction rate of the methanogenic reactor were 56.4% and 45.7%.