The Research On Co-digestion Of Restaurant Garbage Leachate And Sewage Sludge

Urban sludge and kitchen garbage were top two difficult to deal with urban wastepollution,which have been two major more and more serious problem in urbanconstruction. Based on the characteristics of high organic matter content and C/N ratioof restaurant garbage leachate in the Chongqing area and the low heating value(VS/TSbetween25%~25%) and C/N ratio of sewage sludge,Co-digestion of sewage sludgeand garbage leachate was investigated to overcome the disadvantages of the treatmentof sewage sludge and garbage leachate. Meanwhile,optimization of co-digestive gascondition and the mechanism of co-digestion of leachate and sewage sludge wasobtained.The results showed that the addition of restaurant garbage leachate enhanced boththe biogas production and the removal rate of VS. After the addition of vegetablebiomass wasteand decomposed kitchen waste, The cumulative methane production foraddition of leachate of vegetable biomass waste and decomposed kitchen waste were542.3and2102.2mL, respectively, which were1.2and4.6times of the digestion ofsludge without leachate．The addition of leachate also enhanced the removal of VS/TS,15.3%for vegetable waste addition while26.3%for restaurant garbage leachateaddition. The SCOD concentration after digestion varied from182mg/L to408mg/L,and additions of leachates hardly affected the quality of effluent.The optimal experiment about the mixed volume ratio of sludge and decomposedkitchen waste leachate was conducted, the standard condtion, the largest cumulativemethaneproductionwas1853.9mL under the volume ratio of10:1condition.Respectively, under the volume ratio of10:1,20:1,40:1and60:1condition, themaximum unit methane yield were1.012,1.058,0.782and0.2945L/g VS. But due to theinfluence of initial pH of the added leachate, which caused initial gas production rateunder the volume ratio of10:1condition was too low. Adjusting the initial pH of garbageleachate could effectively avoid the low initial pH of system caused by the problem ofinitial low digestive efficiency in the digestive bottle.Garbage composting time has a certain influence on the feature of the landfillleachate, and the concentration of COD, TN, NH4+-N of the restaurant garbage leachatewere both very high, accordingly, their concentration offered upgrade firstly thandescending latter tendency along with the compostingprocess. In the middle of refuse compost, the concentration of TCOD and TN reached maximum, respectively,3.85×105mg/L and1526.8mg/L, and the C/N ratio of the vegetable biomass waste leachateand decomposed kitchen waste leachate were20and226. In addition, the wastecomposting time also has some influence to combined digestion gas production, amongthem, The cumulative methane yield was the lagest,1267.3mL,in the middle ofcompost (20days).At this point, the maximum unit methane yield was1.058mg/L, andthe removal rate of VS/TS was21%, which would be caused bythat the C/N ratio in thisperiod was the highest and biodegradable organic matter content was high.Analysis ofPCR-DGGEprofiles showed that the addition of leachate mademoreobvious changes in the microbial species and amount.Some dominant bacterium wasfound. All other experimental conditions compared with sludge anaerobic digestionalone, which not only found a common bacteria species, but also their respectiveadvantage microflora in each reactor. Among them, the changes of mixture’s volume forthe system have a more pronouncedeffect oncommunity diversity ofmicroorganismsthan the effect of garbage composting time.Meanwhile,with more stripe number andbrighter on light-dark intensity.