Analysis Of The Methanogens Abundance And Effect Of The Food Waste And Sludge Co-digestion Process

The methanogenic anaerobic digestion system of sewage sludge and food wasteco-digestion will have a more abroad prospects for development,which is an method thatwastes could be transformed to resources. But during the digestive process, PH, ammonianitrogen and other factors affect the methane production rate and efficiency by inhibitingmethanogens′activity. The inhibition of methanogens can be effectively reduced, with thefermentation substrate treated by denitrification process.Relevant research still stays on themacro control, changes of methanogens abundance in the digestive prosess and analysis ofdigestion effect and parameter were seldom referred to.The study changed the secondaryfermentation parameters on the basis of denitrification process and the results of previousstudies, optimized the FISH operating conditions, analysisd the methanogens abundancechanges and the process parameters and effects during the digestive process,results showedthat:(1) The percentage of methanogen had the same change trend when the mixing ratiowas not equally during the one-time static fermentation, and the percentage of methanogenreached a steady state about12.5%eventually. During the same stage, no correlationshowed in the abundance of methane-producing bacteria as the mixing ratio increased.Themain factors that affected the changes of methanogens were VFA and PH.(2) The secondary fermentation, the abundance of methane-producing bacteria ofmixing ratio under the two stage reactor increased significantly after the fermentationsubstrate of the primary reactor was treated by denitrification process, up to about threetimes the level of the primary reactor.While the mixing ratio fixed, the abundance ofmethane-producing bacteria did not show revelant correlation as the second reactor dosingrate increased.(3) Analysis on the abundance of methane-producing bacteria and the digestion effectin the steady state of the optimal dosing rate of its each mixing ratio showed that, themixing ratio of1:3, dosing rate of14%of the operating conditions got the highest activityof methanogenic bacteria, but not the highest organics removal rate; while the mixing ratio1:4, dosing16%has the higher activity of methanogens, the larger number ofmethanogens,the better process results, and less time needed to a stablity; VFAconcentration was4610mg/L at the condition of mixing ratio1:5, the dosing rate16%, and methane performance of the process was inhibited. Impact of ammonia was largest to thethree operating parameters.(4) The best condition of the issue as: mixing ratio1:4, dosing rate of the secondaryreactor16%. The methanogenic condition was suitable,PH, ammonia, VFA were8.07,2050mg/L,633.8mg/L;methanogenic bacteria activity was relatively high, abundance ofmethane-producing bacteria was39.1%; process effect was better, VS removal, methaneproduction per day, SCODCrwere51.4%,8140mL,9562mg/L; a shorter time about65dwas needed to reach the desired stability.