The Affect Of Thermophilic Bacteria On Aerobic Composting Of Municipal Sewage Sludge

Because of its unique heat resistant mechanism and broad application value, thermophilic.bacteria become the hot topic of the domestic research. The author screen to two strains, which can grow in 70℃, named strain L and J from the soil sample separation in high temperature.Sequencing on 16 S r DNA of strain L and J, the analysis showed that strain L and J have the similarity of 99% with thermus thermophilus. Strain L, gram-negative, aerobic, glucose oxidation, contact enzyme test, v.p, hydrolysis of the starch are all positive; gelatin liquefaction, indole test are all negative, growth temperature range 45-75℃, identified as thermus.flavus. Strain J, gram-negative, aerobic, glucose oxidation, contact enzyme, gelatin liquefaction are all positive, nitrate reduction, v.p, indole test are all negative, growth temperature range 45-75℃,identified as thermus thermophilus.It research that the best fermentation conditions of strain L and J. The best carbon sources of strain L is beef extract, the best nitrogen source is peptone, carbon nitrogen ratio is 1:3, the comparison of the growth factor: speed >temperature >p H > beef extract, the best optimum combination of strain L is temperature 60℃, p H8.0, beef extract content 2.0%, 150r/min. The best carbon sources of strain J is beef extract, the best nitrogen source is gelatin, carbon nitrogen ratio is 1:2, the comparison of the growth factor: p H>temperature>beef extract>speed, the best optimum combination of strain J is temperature 70℃, p H7.0, beef extract content 0.4%, 150r/min.Strain L and J, which is as the exogenous thermophilic bacteria, added to the aerobic process by a single or combinations. During composing, we research temperature, p H, water content, the quantity of thermophilic bacteria, the quantity of normal bacteria, the activity of hydrogen peroxide enzyme, organic matter, budding degrees and the change of GI index. The results show that adding to strain L and J, it reached to high temperature earlier 4 days than the contrast, maintained a long time. The water content, organic matter and plant toxic reduced a large margin. The quantity of thermophilic bacteria and the activity of hydrogen peroxide enzyme are increased. The change of p H and normal termperature is not big. It suggest that strain L and J can accelerate to compost rotten speed, shorten the process of compost reaction, improve the benefits of organic fertilizer production, optimize the composting process.Sum up, screen thermophilic bacteria can provide more strain resources, research the optimal condition can provide more theory, with the form of exogenous microorganisms added to the city of sludge aerobic process, it provide a new thought and theory basis for the application of thermophilic bacteria and the treatment of sludge.