Study On Semi-dry Anaerobic Co-digestion Of Food Waste And Cow Dung

In today’s shortage of energy and scarce of resources, due to theeffective treatment of food waste, manure and other organic waste can not only reduceenvironmental pollution, protect human health, but also better produce biogas andother renewable energy sources to alleviate the energy problem,it get more and moreattention. Domestic and foreign scholars through a joint study found that thecombinedanaerobic fermentationeffect of organic mixture is often better than the effect of asinglematerial.At present the study on the food waste focus on wet fermentation,Itproduce large amounts of biogas slurry, not only a waste of water resources, At thesame time caused by biogas slurry processing difficulties.This subject of mixedanaerobic fermentation based on food waste, fruit＆vegetable wastes and cow dung,While using high concentrations of semi-dry mesophilic fermentation process toreducing water consumption while reducing biogas slurry yield, By orthogonal testmethod,study the anaerobic fermentation characteristics of food waste, fruit＆vegetable wastes and cow dung with different mixture ratio, provide experimentalbasis for the future offood waste treatment project.Through the research, found:(1)In the food waste and cow dung (by mass) anaerobic fermentation is carriedout with1:4,2:3,3:2,4:1, when the content of food waste is dominant, reach to3:2thefermented liquid pH valued decreased rapidly and unable to recover, then anaerobicfermentation can not proceed smoothly. When proportion of food waste is lower,theanaerobic fermentation can proceed smoothly and has a higher gas productionyield.So the food waste with cow dung ratio in test should not be greater than the2:3range selected.when the food waste and cow dungmixed orthogonaltest accordingto TS15%,16.5%,18%, food waste/cow dung （by TS）1/4,7/18,9/16, biogasslurry added20%,30%,35%. While the whole fermentation process, mainly useacetic acid followed by butyrate acid to produce methane.so for food waste and cowdung mixed semi-dry anaerobic fermentation, the best conditions is food waste: cowdung=1:4, TS=15%,biogas slurry=35%.when (the food waste+fruit＆vegetable)+cow dung hybrid anaerobicfermentation system using mainly butyrate acid followed by acetic acid.Add fruit andvegetable wastes is not conducive to the acid hydrolysis step, and reduce the stability of the system, the (food waste+fruits and vegetables) and cow dung mixed semi-dryanaerobic fermentation conditions for optimum ratio=1:4, TS=16.5%, biogasslurry=35%.(2) Tests found that mixed material ratio has the most effect on the fermentation.Producting gas rules of group with the same ratio are similarity, pH changeis consistent, and have similar average methane content.With the food waste increasedaverage methane content decreased and the pH value of the feedsolution decreased faster. Higher TS concentration lead to the slower growth, slowstart of the cumulative gas production of anaerobic fermentation, at the same time, thehigh concentration fermentation liquid is easy to acidification and is not conduciveto the fermentation process.The amount of slurry has a significant effect on theaverage content of methane, the higher biogas slurry the bettergasproduction.(3) The test of45days, results that the food waste mixed with cow dung cananaerobic ferment of high concentration of TS15%-18%,C/N about20,andthenthebiogasyield achieve312.84mL/gVS, the methaneyield achieve145mL/gVS, thedegradation rate of food waste achieve39.91%.