Research On The Anaerobic Fermentation Of Food Waste And Resource Untilization Of Biogas Residue

In recent years,the level of urbanization and the improvement of people's living standards have caused a large number of food wastes.The imperfect treatment facilities have led to environmental pollution and harm to human health.Therefore,the treatment of food waste has become an urgent problem to be solved.For anaerobic fermentation,food waste is an ideal raw material.The use of food waste anaerobic fermentation for methane production,while realizing the resource utilization of food waste,also solves the problem of energy shortage.At present,the anaerobic treatment of food waste mainly utilizes the CSTR(Continuouslystirred tank reactor),but in engineering applications,there are disadvantages such as dilution pretreatment before fermentation and solid-liquid separation after fermentation.Disadvantages for CSTR researchers have proposed a LBR(Leach bed reactor),which can overcome the problems currently existing in CSTR engineering applications.In addition,biogas residue will be produced after the LBR fermentation is completed,and the recycling of the biogas residue is also a problem that needs to be solved at present.This article studies from the following aspects:LBR was used for anaerobic fermentation of food waste.The methane volume fraction,daily methane production,cumulative methanogenesis,COD and VFA were used as indicators to investigate the backflow and reflux frequency of different leachate for LBR anaerobic fermentation of food waste.The effect then determines the optimal fermentation conditions for the LBR.In order to clarify the conversion of carbon in the LBR inner substrate,carbon balance analysis was performed on LBR fermentation.The leachate reflux and reflux frequency have a significant effect on the fermentation of LBR,which together ensure the smooth progress of LBR fermentation.When the leachate return flow rate is 4 L/d and the reflux frequency is 12 times/d,the cumulative methanogenic amount reaches 17.98 L,the TS methanogenic rate is 136.57 mL/gTS,and the cumulative concentration of COD and VFA at the end of fermentation is in all conditions the lowest were 3380 mg/L and 285.8 mg/L respectively.At the same time,the LBR carbon balance results show that 4.7%~7.54% of the carbon in the substrate is converted into the gas phase,and 10.04%~54.3% of the carbon is converted into the liquid phase,and 31.6%~70.1% of the carbon remains in the carbon.In the solid phase,1.57% to 12.32% of the carbon becomes other.Comparing the gas production effect of LBR and CSTR fermentation,the cumulative concentration of COD and VFA,and examining the L5(the leachate return flow rate 4 L/d and the reflux frequency 12 times/d)with the best gas production in CSTR and LBR and the gas production effect The worst L3(2 L/d and 24 times/d)differences in microbial community structure,in turn to determine the reactor suitable for anaerobic fermentation of food waste.The cumulative methane production of CSTR is 10.87 L,the cumulative concentration of COD at the end of fermentation is 44300 mg/L,and the cumulative concentration of VFA is 34072.9 mg/L.Compared with the results obtained under the above optimal conditions of LBR,the cumulative methane production of CSTR is lower than that of LBR.The cumulative concentration of COD and VFA is higher than that of LBR.At the level of bacterial community structure,the dominant bacteria in LBR and CSTR are not much different,but there are differences in the dominant genus of CSTR,L3 and L5 at the genus level,indicating that different reactors are different from the same reactor(LBR).The fermentation conditions affect the dominant bacteria of the bacteria in the system.At the level of archaeal community structure,both L3 and L5 are occupied by Euryarchaeota with a relative abundance of 99%.In addition to Euryarchaeota,there are a relative abundance of 7.99% Verrucomicrobia and 1.74% Thaumarchaeota in CSTR,indicating that different reactors are ancient.The dominant bacteria in the bacterial community will have a certain impact.At the level of archaeal genus,there are differences in the dominant genus of CSTR,L3 and L5.The dominant genus of L5 is acetate nutrient-type Methanothrix,and the dominant genus of L3 and CSTR are hydrogen-nutrient methanogens.In the anaerobic digestion process,70% of the methane production comes from the methanation pathway of acetic acid.Therefore,for L5,the methanogenic state of acetic acid type is the best,which makes the methanogenesis best.Analysis shows that LBR is more suitable for anaerobic fermentation of food waste than CSTR.The feasibility analysis of biogas residue fertilizer was carried out.The growth and quality of Chinese cabbage were used as indicators to investigate the effects of non-fertilizer,inorganic fertilizer,biogas residue and biogas residue inorganic compound fertilizer on the growth and quality of Chinese cabbage.The nutrient content and heavy metal content in the biogas residue are in line with the organic fertilizer standard(NY525-2012),so it is feasible and safe to make the biogas residue into organic fertilizer.Different fertilizations will promote the growth and quality of Chinese cabbage.Biogas residue inorganic compound fertilizer can increase the budding rate and yield of Chinese cabbage,increase vitamin C content and soluble sugar content,and also reduce nitrate content,which can promote the quality and yield of Chinese cabbage.