Study On Microbial Community Of Earthworm Sludge Systerm

Sludge was the inevitable result of sewage treatment.The production of urban sludge was more than 20 million tons per year and improper handling would cause secondary pollution.The traditional methods of sludge disposal could lead to waste of resources and environmental risks.The earthworm treatment sludge technology was considered as sustainable utilization of processing technology.It was could be converted sludge to a more stable material based on earthworms and microorganisms with function of organic matter in sludge.Although microorganisms were the main decomposers of organic matter,earthworm significantly affected microbial characteristics and population structure.This study established a sludge-earthworm system with earthworm and wetland sludge,and designed three processing experiment:earthworm-sludge disposal directly,carbon source and antibiotics sludge treatment.The microbial community structure and composition of sludge and vermicompost was analyzed by high-throughput sequencing technology and the earthworm biomass,sludge bacteria,sludge fertility and changes of heavy metalscontent were analysized.The following conclusions were obtained:?1?Through the monitoring of system's efficiency,it was found that earthworms could adapt to the environment of sludge,the growth of earthworms in the cellulose was the best.The content of nitrogen and potassium increased,the phosphorus content did't change significantly in sludge treated by carbon,.The content of nitrogen was decreased,the phosphorus and potassium did't change significantly in sludge treated by antibiotics.The degradation of organic matter was higher than that of antibiotics.The total number of bacteria was significantly increased,and the number of bacteria in lactose sludge was increased as much as 9.10�10⁶ CFU/m L.In antibiotics experiments,the total number was significantly lower than that of the control group without earthworms,all under 6.5�10⁶ CFU/mL.?2?TheHigh-throughputsequencingresultswereshowedthat Gammaproteobacteria and Flavobacteriia were inherent bacterium in vermicompost.Sphingobacteriia,Alphaproteobacteria,Betaproteobacteria,Actinobacteria and Anaerolineael were common bacterium.The bacterial community structure of sludge was affected by earthworm activity and the carbon source and antibiotics.Bacteroidetes in the sludge with Streptomyces were relatively stable,Firmicutes and Chloroflexi were relatively stable,Gammaproteobacteria were the most common bacteria in sludge.?3?Different treatments had a great effect on the species of bacteria in the vermicompost.The dominant species of the three fungi were the Aeromonas spp.and the Flavobacterium spp.,but the difference in category were significant.In addition,Shewanella putrefaciens,Lactococcus piscium,Enterococcus hirae and Bacillus toyonensis were the most important bacteria in vermicompost,which were affected by carbon source greatly.The addition of antibiotics in the new bacteria accounted for a larger proportion,including Acinetobacter johnsonii,Luteolibacter luojiensis,Sphingobacterium faecium,Flavobacteriu maquaticum and Flavobacterium spartansii.The genus Terrimonas spp.,Sphingomonas spp.,Streptomyces spp.and Azyme spp.reducted or disappeared significantly.?4?It could be concluded that activity of earthworm could reduced the number of pathogens and increased the number and quantity of bacteria associated with the sludge treatment.15 species associated with the sludge treatment process was found,including Nitrosospira multiformis and Bacillus toyonensis with nitrification,Gemmatimonas phototrophica and Acinetobacter johnsoniirelated with dephosphorization,Sphingobacterium faecium and Dehalogenimonas alkenigignens with degradation of organic matter;A variety of bacteria related to carbohydrate degradation were found in the carbon source experiment,Lactococcus plantarum and Lactococcus piscium could fermented glucose or lactose,Hydrogenispora ethanolica could ferment glucose,galactose and starch;A variety of bacterias were found to be resistant to antibiotics such as Lactococcus piscium and Bacillus toyonensis,which were resistant to chloramphenicol,Flavobacterium resistens was strongly resistant to chloramphenicol and streptomycin.Tetracycline and penicillin have less toxic effects on Pseudomonas alkylphenolica.