Study On Aerobic Composting Effect Based On Different Ventilation Frequency Reactor

In the field of organic waste fertilizer utilization,reactor composting is an inevitable trend to replace the traditional extensive composting,and the research on ventilation technology in reactor composting is the focus of recent years.With the help of self-designed small fermentation equipment,this paper discusses the experimental research on the same initial conditions but only changing the ventilation mode,and sets up three different intermittent ventilation modes: High frequency ventilation treatment(GW,ventilation for 30 minutes and stop for 30 minutes),low frequency ventilation treatment(DW,ventilation for 30 minutes and stop for 60 minutes)and frequency conversion ventilation treatment(BW,different ventilation frequencies are used in the heating and cooling stages of compost).By means of chemical and biological analysis methods,the change rules of physical and chemical factors,microflora and humus fluorescence spectrum in the composting process were analyzed,and the three ventilation methods were comprehensively evaluated.Based on the small ventilation parameter optimization test,the best ventilation method was selected for practical verification in the composting process of large reactor.The main results of this test are as follows:1.The compost temperature,water content,p H,EC,total nitrogen,total phosphorus,total potassium,nitrate nitrogen,ammonium nitrogen,GI value,and fulminic acid concentration value showed different changes under different ventilation frequency treatment.Under the three treatments,the compost temperature reached more than 55℃,and the high temperature lasted for more than 4 days.The high temperature of DW treatment exceeded 70℃,and the secondary heating phenomenon appeared in the compost process under BW treatment.The p H value was stable between 8.2 and 8.52 in the later stage of composting.The content of organic matter decreased gradually,and the content of organic matter decreased from 47% to 32% under DW treatment.Under GW treatment,there was a negative correlation between p H value and the content of organic matter,and the correlation coefficient was-0.785.In the high temperature stage,the production of ammonium nitrogen is higher,and DW treatment is more helpful to reduce the loss of nitrogen.The contents of total phosphorus and total potassium in the late composting period were less than 2%,and DW treatment was beneficial to the formation of total potassium.The EC value showed a trend of increasing first and then decreasing.The water content decreased by more than 30%;GI value reached more than 85% at the later stage of composting,and there was a negative correlation between GI(seed germination index)and water content of the three ventilation treatments.The concentration of fulfulic acid in the three ventilation treatments all showed a decreasing trend,the position of fluorescence peak changed,and the relative content of substance(Pi.N)corresponding to substance III in UV fluorescence FA region all increased,indicating that all three treatments could effectively promote the fermentation of compost,among which DW treatment was the best.2.In the high temperature stage of compost,the microbial flora showed different changes under different ventilation treatments.The Chao1 index of the three treatments showed a downward trend,which were GW(720.23),BW(747.15)and DW(627.72)respectively on the 7th day of composting.There were obvious differences in the structure of microflora among the three treatments.Based on the phylum level,a total of 23 phyla were detected,with 4 dominant phyla,including Actinobacteria,Firmicutesp,Proteobacteria and Bacteroidetes.A total of 355 bacteria genera were detected based on the analysis of the genus level,including 13 dominant bacteria genera.Atopostipes,Corynebacterium and Erysipelothrix were dominant bacteria genera in the early stage of composting.The relative abundance of Atopostipes and Erysipelothrix under low frequency treatment reached 11.5% and 12%.Fasttidiosipila and Pseudogracilibacillus were the dominant species in the first four days of composting,and their relative abundance did not exceed5.5%.Oceanobacillus and Bacillus were the dominant bacteria in the high temperature stage of composting,and the relative abundance of Oceanobacillus was significantly different in different composting days.In the analysis of the correlation between environmental factors and microflora(RDA),nitrate nitrogen was an important factor affecting the microflora in the high temperature stage of composting fermentation,and the explanation amount of NN(nitrate nitrogen)was 32.8%(P=0.0094).3.The results showed that DW treatment ventilation(30 minutes,stop 60 minutes)was beneficial to the fermentation of compost.The large-scale reactor test adopted the ventilation method of DW treatment,the temperature of the test compost reached above 55℃,GI value reached 94.11%,reached the standard of decomposing,and the decomposing period was basically 7 ～ 10 days.