Research On Anaerobic Fermentation Characteristics Of Food Waste

With the development of food services in China, the amount and type of food waste isincreasing rapidly. Nowadays, food waste takes more and more proportions in consist of cityrubbish. It’s becoming a sharp question that how to prevent and control the pollution of foodwaste in the process of production, transport, storage and disposal, and it gradually becomesthe burden of environmental protection work.Food waste is rich in water, organic compounds in total solid. Under the properconditions, food waste can be as good matrix for the metabolism of microbe’s growth.Anaerobic fermentation project has the advantages of recycling, lower energy consumption inits process. Therefore, anaerobic fermentation project is the reasonable way to solve theproblem of utilization of food waste，and it becomes focus in the field of the research in recentyears.In this thesis, lots of experiments were carried out to analyze biogas production rule inthe anaerobic fermentation of basic components of food. The Effect of different proportion offood waste on the thermophilic anaerobic digestion was studied through measuring totalbiogas production and methane content. The characteristics and process conditions ofanaerobic fermentation of food waste were studied, and the effect of quality scores in rawmaterials, inoculation concentration, moisture content on biogas production efficiency in theprocess of anaerobic fermentation were also explored. After quadratic general rotary unitizeddesign, mathematical models of total biogas production and three factors were constructed. Atlast, the optimum anaerobic fermentation conditions, which can offer academic support forfood waste utilization, had been obtained.The results are as follows:(1) Characteristics of biogas production in each group were significant. In allexperiments, the range of total biogas production is3985mL, biogas production rate is51mL/gTS, and methane content is49.9%. In all days of the anaerobic digestion, the total biogasproduction(8400ml),biogas production rate(140.94ml/g) and CH4content(49.9%) of group10were the maximum, so proportion of m(rice):m(napkin):m(meat)=4:4:2is the best.(2) Add appropriate urea can obviously increase the hydrolysis, enhancing the efficiencyof anaerobic fermentation of food waste. After comprehensive comparison of pH value,concentration of VFAs, methane content, accumulative biogas production, quality score for about1.25%of the urea added group has the highest efficiency in anaerobic fermentation offood waste.(3) Higher inoculation concentration can shorten the time of methane production phase,but too higher inoculation concentration may reduce the efficiency of microbe in the use offood waste, leading to a smaller biogas production. The test shows that the optimum ofinoculation concentration is around50%.(4) The effect of moisture content on anaerobic fermentation of food waste mainlyembodies in the influence of highest daily biogas production time, and lasting time during thebiogas stabilization stage. The test shows that the optimum of moisture content is around90%.(5) Choosing quality ratio of food waste and urea, inoculation concentration, moisturecontent as influence factors, using quadratic general rotary unitized design, a second-ordermathematical model was seted up by response surface methodology. So, the processparameters of anaerobic fermentation of food waste are: quality ratio of food waste and urea(85.62:1), inoculation concentration (50.15%), moisture content (92.39%).