| The increase in the output of municipal solid waste and the increase in the proportion of food waste make the problem of food waste disposal imminent.Anaerobic digestion can produce renewable energy and is a better choice for solid waste treatment.Current studies about one-atage high solid anaerobic digestion of food waste mainly concern about low OLR,which results in the inefficient of the digestion process,and high OLR often buring up severe acidification problems,which become the main factor which restricts its development.This study uses a horizontal anaerobic digestion system with less additional appendixs and have high economic benefits to treat high solid food waste.Firstly,on the basis of the optimization of OLR feeding frequency was optimized too.At the same time,the horizontal flow reactor was started.Through the monitoring of gas production,process stability,substrate changes and other parameters of different systems combined with gas production fitting conclusion,biological testing results to get the characteristics of different systems.Under the experimental conditions,the system under the OLR of 10.71 kg VS·m-3·d-1 has the highest cumulative methane production,with an average methane yield of 0.270 L·g-1VS·d-1,the total number of methanogenic archaea in the system is 17.81% and 23.98% higher than the OLR under 8.93?13.39 kg VS·m-3·d-1,which is the direct reason for the best methane production.The system could remain stable under this OLR.Fitting results also indicate that it is the maximum OLR without acidification.Under the same OLR,the cumulative methane production is 21.15% and 11.63% higher than that of F1 and F2 when feeding frequency is F3.During the digestion process,the highest methanogenic rate reached 0.400 L·g-1VS·d-1,and average value is 0.342 0.270 L·g-1VS·d-1.Gas production efficiency and the ammonia nitrogen suppression threshold of the system significantly improved by increasing the feeding frequency.In addition,the daily average concentration of propionic acid in the system of F2 and F3 was reduced by 102% and 165% respectively compared with F1,thus significantly improved the stability.Apart from that,methanogens increased by 14.23% for F3 compared to F1.During the operation period of the horizontal flow reactor,no suppression due to various factors.The average methane yield is 0.363 L·g-1VS·d-1,and the volumetric methane yield reaches 5.685 L·L-1·d-1.When OLR increased to 13.80 kg VS·m-3·d-1,SCOD fluctuated greatly,and TVFAs rapidly increased to 7.500 g COD·L-1,indicating that the reactor had reached the maximum OLR.Data fitting results showed that the theoretical maximum methane yield under high-load anaerobic digestion is 0.5276 L·g VS-1,first-order hydrolysis rate constant is 0.1368 d-1,and established the structureeffect relationship equation.Gas production fitting results showed that the highest gas production,the highest methane production,the maximum gas production rate,and the maximum methane production rate first decrease and then increase with the increase of the OLR.The composition and structure of microorganisms in different positions of the horizontal flow reactor in the direction of advancement are different,mainly reflected in the community structure and population abundance of archaeal bacteria,archaea species more in the middle than the two ends,bacteria species opposite.Studies have shown that single-phase anaerobic digestion of high-solids food waste can be carried out sommthly under high OLR,and the stability of the system can be improved through the improvement of the operation mode.Horizontal flow reactor is used to treat food waste with good gas production effect and high volumetric gas production rate.The research results of this paper are expected to provide theoretical support for the efficiency of food waste engineering treatment. |
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