The Construction Of Protease-producing Mixed Bacterial Strain And Its Influence On The Composition Of The Remaining Sludge Flora Of Alkaline Fermentation

According to the development of the wastewater treatment development,sewage sludge increased year by year in the city,the sludge piled up at random has affected people's lives,sewage treatment after the remaining brought a great burden to the environment.Excess sludge alkaline anaerobic fermentation processing not only can improve the decomposition of excess sludge,but also can reduce the cost of sludge treatment,provide vital significance to improve the yield and quality of the sludge treatment problem.In this research,analyse the microbial community in sludge,the pure culture was obtained from the sample by classical microorganism separation and purification technology,the screened strains were identified through morphological characteristics,physiological and biochemical features as well as molecular biology method.Afterwards,by identification,HD-A is Bacillus sp.and HD-B is Bacillus subtilis..The functional strains were subjected to fermentation condition study and complex test,Under such conditions,the maximum activity of protease enzyme reached to 1749.8U/mL.The protease enzyme activity was improved to 60.3% pre-optimization strains.Mixed bacteria to the sludge in a continuous fermentation,using gas chromatography(GC)to determination the yield of the volatile fatty acid(VFAs).It can be seen that,sludge volatile under alkaline conditions of continuous fermentation acid production is 8.3 times the normal fermentation sludge.Access mixed bacteria HD-A and HD-B continuous fermentation of volatile acid sludge output up to 3098 mg/L,than the strains of the amount of volatile acid sludge increased 1.4 times than that of without any treatment sludge yield increased 15 times of volatile acid.At the same time use the PCR-DGGE technique observed different fermentation time treatment of residual sludge bacterial population is changing,access to the mixed bacteria,obvious changes have taken place in the flora composition of sludge,the high protease strains will decompose the not easily protein hydrolysis to small molecule organic matter,improve the sludge in the diversity of population.It was showed that the thirteen bands are Bacillus sp.,Bacillus subtilis,Clostridium thermosuccinogene,Pseudoxanthomonas spadix,uncultured bacterum.In this experiment,showed that these uncultured bacteria had close relationship with Bacillus sp.The inoculated strain HD-A and HD-B is also obtain the survival.