Wet Anaerobic Digestion Of Wheat Straw And Combined Dry Anaerobic Digestion Of Wheat Straw And Municipal Solid Waste

The production of crop straw and municipal solid waste in China increased annually.The pollution is becoming more and more serious,and the accompanied safety risks can not be ignored.The treatment and utilization of straw and municipal solid waste have been an urgent task.Anaerobic digestion,which can produce clean biomass energy and bio fertilizer,has been paid more and more attention to society.In this paper,the technologies of wet anaerobic digestion of wheat straw and combined anaerobic digestion of wheat straw and municipal solid waste have been studied.The results are as follows:1.Study on wet anaerobic digestion of wheat straw was carried out.The effects of different temperature(38?,42?)and different frequency of feeding and discharging(feeding and discharging every day,feeding and discharging every two days)on the performance of anaerobic digestion of wheat straw were studied.The results showed that:The methane production of wheat straw at 42 ? was higher than that of at 38?,In different feeding frequence,the biomethane production rate of 42? were 17.2%and 11.7%higher than that of 38?,respectively.The biomethane production rate of per VS of feeding every two days were 19.0%and 13.4%higher than that of feeding every day,respectively.2.Studied the biomethane production of wet anaerobic digestion in different pretreatment(LFD,4%NaOH,2%KOH+2%NH3·H2O),different temperature(38?,42 ?)and different frequency of feeding and discharging(feeding and discharging every day,feeding and discharging every two days)in pilot-scale.The results showed that:The biomethane yield under the pretreatment of 2%KOH+2%NH3·H2O is higtest,which was 261.38 mL.gVS-1 and was 4.9%higher than that of 4%NaOH pretreatment.The biomethane production rate of per VS of LFD pretreatment was approximately equal to that of 4%NaOH pretreatment.Increasing the temperature would lead to increasing the biomethane production.When the temperature of anaerobic digestion increased from 38? to 42 ?,the biomethane production rate of per VS of feeding every day increased from 260 mL·gVS-1 to 279.17 mL·gVS-1,the biomethane production rate of per VS of feeding every 2 day increased from 263.51 mL·gVS-1 to 288.76 mL·gVS-1.The frequency of feeding has little influence on methane production.At 38 ? and 42 ?,the biomethane production rate of per VS of feeding every 2 day were only 1.4%and 3.4%higher than that of feeding every day.3.A pilot study on combined dry anaerobic digestion of wheat straw and municipal solid waste was carried out.Studied the start-up and semi-continuous operation of dry anaerobic digestion and their performance of anaerobic digestion.The results showed that:under the conditions of 38 ??TS20%?inoculation rate was 30%,the reactor could start successfully.When the HRT was 25d,TS was 25%,and inoculated with material after digestion,inoculation rate was 300%,the reactor could stable operation.In the semi-continuous stable stage,the methane content was 58%,the volumetric gas production rate was 0.65 L·L-1·d-1,the pH of anaerobic digestion system was maintained at about 7.45,VFA and ammonia nitrogen were 8007 mg·L-1 and 2142 mg·L-1,respectively,which exceeded the inhibitory concentration,but did not inhibit the production of meghine.