Acclimatization And Bioaugmentation Of Methanogenic Propionate Microbial Consortia For Kitchen Waste Anaerobic Fermentation

The high water content,high organic content and perishability of food waste in China have determined that food waste is not only a serious source of pollution in the city,but also a kind of biomass resources with broad prospects.The use of anaerobic fermentation methane production process to treat kitchen waste can achieve its harmless and resource treatment.However,in the anaerobic fermentation engineering of kitchen waste,there is often a problem of acid inhibition,which leads to the difficulty in raising the concentration of fermentation and low gas production efficiency,which restricts the further popularization and application of the anaerobic fermentation process.In this paper,propionic acid methanogenic bacteria were domesticated and enriched with propionic acid as the sole carbon source.At the same time,the microorganism community was optimized by microoxygen treatment,and the microorganism community in the microorganism was analyzed.The abundance of functional genes was compared by means of macrogenomics,and the internal characteristics of the biofortified bactericide were understood.Then,the problem of acid inhibition in food waste anaerobic fermentation was bioaugmented.The effect of kinetic methanogenic bacteria on batch anaerobic fermentation of kitchen waste was studied,and the efficiency of semi continuous kitchen waste fermentation in the step type improvement of organic load and the change law of microbial community were analyzed by macrogenomics.The main results of the paper are as follows:?1?A high efficient methanogenic bacteria of propionic acid can be obtained with propionic acid as the carbon source and the concentration of propionic acid.The methanogenic bacteria of propionic acid treated by micro oxygen have shown a better effect in the adaptation period,which is similar to that of the reactor that has not been treated in the stable period.The methane production per gram of VS was between 440 ml and 450 ml.Syntrophobacter,Smithella,Mesotoga and Thermovirg in methanogenic bacteria of propionic acid in R1,R2 reactor are all the dominant strains in the reactor.The results of functional gene analysis showed that 10.01%of the bacterial genes in the propionic acid producing system were involved in membrane transport in R1,8.79%in carbon metabolism,8.95%in amino acid metabolism,and 6.57%in energy metabolism.In R2,8.75%participated in membrane transport,8.91%participated in carbohydrate metabolism,8.75%participated in amino acid metabolism,and 6.65%participated in energy metabolism,and the growth of bacteria in R2 was more stable.?2?Adding methanogenic bacteria to the anaerobic fermentation system of food waste with different concentrations.The final cumulative methane production of 1 gVS kitchen waste adding 0,0.5,1 gVS and 3 gVS kitchen waste with 0,0.5,and 1 gVS agents was 426.7,377.6,362.2,338.5,372.2 and319.45 mL/gVS_added,respectively.The cumulative methane production of 1gVS kitchen waste is highest under the condition of 1 gVS inoculant addition.The cumulative methane production of 3 gVS kitchen waste is highest under the condition of 0.5 gVS inoculant addition.This indicated that adding proper amount of bio enhanced inoculants increased the utilization rate of propionic acid and increased the methane production of anaerobic reactor.The fitting results of the modified Gompertz equation showed that the maximum methane production rate of the system was obtained by adding 0.5 gVS bacteria to the other methods,and the test showed that the more the inoculants added,the shorter the delay period of the batch anaerobic fermentation.?3?By adding propionic acid producing methanogens to the anaerobic fermentation system of semi continuous kitchen waste,the maximum OLR and gas production performance between the reactors were analyzed and compared.The maximum load carrying capacity of the control group without adding propionic methanogens was 1.5 gVS/L/d.The experimental group of methanogenic inoculum with propionic acid added with microaerobic treatment can carry organic load of 3 gVS/L/d,and the reactor is stable inside,which can continue to increase organic loading.The maximum loading capacity of the experimental group was 2.5 gVS/L/d.By comparing the similarity of the three reactors with the level of microbe,it showed that the addition of propionic acid methane producing bacteria could change the population structure in the reactor,increase the abundances of methanogenic bacteria using propionic acid,and enhance the ability of using propionic acid in the reactor.