Sludge Biological Drying Process Based On Exogenous Microorganism Enhancement And The Mechanism Of Bacterial Community Successio

At present,the output of urban sludge is increasing year by year,while the phenomenon of"value water and neglect sludge"still exists,and the most important step of sludge’s treatment and disposal is dewatering and drying process of sludge.This study proposes a sludge biochemical process based on exogenous microorganisms to make up for the shortcomings of the current sludge bio-drying technology and discussed the comparative experiment of sludge bio-drying with or without adding the concentrated mixed bacteria solution and setting different conditioners.Meanwhile,the bio-drying mechanism of sludge was analyzed by bacterial community analysis and programmed death of bacterial cells,and the effects of different deodorization methods on sludge drying effect and the odor emission were investigated.Finally,a large-scale production test of sludge bio-drying process with concentrated mixed bacteria solution was studied in low temperature environment,and the changes of physicochemical properties and nitrogen indexes of the pile were analyzed,which provided a theoretical basis for the application of sludge bio-drying technology.The drying effect and mechanism of sludge bio-drying process with adding exogenous microorganism and different bulking agents were studied to solve the problem of high moisture content of dehydrated sludge.Using the core material in the high temperature period of the sludge composting process to cultivate the concentrated mixed bacteria solution,and setting up different bulking agents to carry out bio-drying experiments to analyze the changes of indicators such as the temperature and moisture content of the pile and explain the bio-drying mechanism from the microbial level by analyzing the changes of bacterial community and programmed death of bacterial cells in different periods.The results showed that the new drying process with the addition of the concentrated mixed bacteria solution and wheat straw as bulking agents had the best effect,with the maximum temperature reaching 70.5℃and the high temperature period remaining 104 h,and the water content decreased to below 50%.The bacterial community analysis showed that exogenous microorganisms significantly changed the bacterial colony structure of the pile,and thermophilic bacteria such as Bacillus and Geobacillus became the dominant bacteria in high temperature environment.Annexin-V and PI double staining were used to analyze the bacterial death in the pile.The pile added with the concentrated mixed bacteria solution maintained its active through the altruistic mechanism of partial bacterial active death to stay active and improve the drying efficiency.This study could provide reference for the understanding of bio-drying mechanism and the application of continuous bio-drying process of sludge.Aiming at the problem that the odor emission during the bio-drying process of sludge was easy to cause the secondary pollution,the purpose of this study was to reduce NH₃emissions from the desiccated pile at the source by setting different deodorization methods.The change laws of temperature,moisture content and nitrogen conversion during drying process added deodorant bacteria liquid and biochar powder were explored on the basis of adding the concentrated mixed bacteria solution and setting up the biological drying experiment with wheat straw as bulking agents.The results showed that both deodorizing methods had certain deodorization effect.The NH₃ emission peak was 97.9mg/m³ and475.09mg/m³ in the pile with deodorant solution and biochar powder respectively.The desiccated pile with deodorizing bacteria solution had the best deodorization and a certain desiccated effect.The desiccated pile with biochar powder had deodorization effect to a certain extent,but had the best desiccated effect,and the moisture content after drying was49.6%.Based on the above analysis,adding deodorizing bacteria solution is the optimal deodorization method in sludge bio-drying test,which has lower cost,more convenient operation and less influence on bio-drying effect of sludge.Bio-drying technology of sludge has been widely studied in the laboratory,but there are few studies on large-scale pilot study and application.In this experiment,the 200-ton sludge pilot experiment was carried out in a low-temperature open air environment to investigate the sludge’s bio-drying effect of adding the concentrated mixed bacteria solution and deodorizing bacteria liquid in winter.Meanwhile,analyzing the environmental impact during the application process of this technology,and the results showed that the bio-drying process of sludge with the addition of the concentrated mixed bacteria solution in low temperature environment started successfully.On the third day,it reached the high temperature stage,and the final water content dropped below 40%,and the bio-drying effect of sludge was obvious.In the pilot test process,the maximum NH₃ emission in the pile was 71.29mg/m³,and the emission was greatly reduced,with good effect of innocent treatment and stabilization.The biological desiccation product has the potential of resource utilization.The bio-drying product has the potential of resource utilization.After mechanical compression,it is made into biomass fuel,and finally it is incinerated to make the sludge resource utilization and produce certain economic benefits.