Study On The Selection And Mechanism Of Energy-saving Ventilation Methods For Landfill Leachate Treatment By Combined Evaporation

The continuous development of mankind and the increase in demand for shortterm consumer goods have led to a rapid increase in waste production and have had a strong impact on the environment.The amount of urban domestic waste produced in China is increasing year by year,with an increase rate of about 10%,and a large amount of landfill leachate is generated.In recent years,the most commonly used process for the treatment of landfill leachate in China is the two-stage DTRO(Disc-Tube Reverse Osmosis)process,which is a relatively mature leachate treatment process,but it leads to more complex pollutants and higher concentration of organic substances.In order to deal with the more costly and more difficult concentrates,it is urgent to study the method of processing the concentrates.Bioevaporation is a recent emerging technology for the treatment of high-concentration organic wastewater.This technology utilizes the metabolic heat released by the aerobic degradation of organic matter contained in highconcentration organic wastewater under the action of microorganisms to evaporate the water in the wastewater.Simultaneous removal of organic matter and moisture in concentrated wastewater.In this study,biofilm sponges were used as microbial carriers and bulking agents,kitchen waste as supplemental carbon source,and bio-evaporation treatment of landfill leachate two-stage DTRO concentrate.This paper explores the use of more efficient and energy-saving intermittent ventilation for bio-evaporation,which has significant benefits for energy savings.The content of hemicellulose,cellulose and lignin,the activity of key enzymes,the change of community structure of microorganisms,the distribution of dead bacteria and energy balance were studied during the process of biological evaporation.Oxygen is supplied to the reactor by intermittently ventilating differently set frequency,and compared with the traditional continuous ventilation method,it is more efficient to optimize the ventilation for 10 minutes and stop the ventilation for 20 minutes(good removal effect on moisture and organic matter).And energy-saving ventilation.The total amount of moisture removed by the intermittent ventilation method is 91% of continuous ventilation,the total amount of VS removal is 88%,and the electricity consumption is only 56%.It is an economical ventilation method and provides a reference for engineering application.Using the optimized ventilation method and contrasting with continuous ventilation,experiments were performed in two large reactors.Samples were taken at temperatures(heating 30°C,50°C,maximum temperature,temperature drop 50°C,and 30°C)to determine the enzyme activity at each temperature node.The content of organic matter and the proportion of viable bacteria were calculated and the energy balance was calculated separately.Under the condition of intermittent ventilation,the content of hemicellulose showed a trend of first increase and then decrease.The change trend of cellulose content increased first and then decreased;the change trend of lignin content continued to increase.The trends of dehydrogenase and protease activity were similar in both ventilation modes.The activity of dehydrogenase first increased and then decreased,reaching a maximum at 37-42°C.Protease activity increases with increasing temperature and reaches a maximum at the highest temperature.Both proteobacteria and proteobacteria dominated in the whole process of bioevaporation under two ventilation methods,and showed a decreasing trend with the progress of bioevaporation.Through the principal component analysis,the differences in the microbial community structure of the three samples under intermittent ventilation were greater than under continuous ventilation.The metabolic activity of methanogenesis is stronger than that of continuous ventilation under intermittent ventilation.The methanogenic metabolism is the third stage of anaerobic fermentation.In the absence of intermittent ventilation in the air,the metabolism of methanogen is even more prosperous;autophagy-yeast is The continuous ventilation is stronger than the intermittent ventilation,and the yeast is facultative aerobic microorganisms,so there is more under sufficient continuous ventilation of oxygen.In the process of biological evaporation under both ventilation conditions,the optical density of live bacteria was higher than that of dead bacteria,and the optical density of live bacteria in the high temperature period was greater than the temperature increase period and the cool-down period.Through energy balance calculation,the energy consumed by evaporation of bio-evaporation water under continuous ventilation and intermittent ventilation accounted for 64.44% and 63.43% of the heat generated by VS respectively,which is similar to the previously reported 70%.