Microbial Dehydrogenase Activity In The Low-temperature Reactor

Sewage treatment is becoming more and more important in the environmental problems. In winter, the temperature of cold area of our country is very low, it may cause low efficiency of sewage treatment. This research aims to improve the treatment of low-temperature sewage by immobilizing psychrotrophs to the treatment system. The activities of dehydrogenase of the psychrotrophs were measured and the factors related to dehydrogenase activity were also discussed in this paper.By immobilization, the removal rates of COD and BOD in low-temperature sewage were efficiently improved, COD removal rates reached to 82.89%, and BOD removal rate was 90%. The activity of dehydrogenase in system were also measured, the results showed that from 4℃to 45℃, the biofilms were proved to be able to catalyze the reaction. The optimal temperature of enzyme was around 30℃, optional pH is from 7.5 to 9.0, the optional reaction time is 3 hours at 30℃and 8 hours at 4℃respectively.The low temperature biofilm was composed of physchrotrophs, Through the experiments of isolation and identification, 8 strains of physchrotrophs were obtained from biofilm, they are Comamonas,Flavobacterium,Arthrobacter,Bacillus,Micrococcus,Pseudomonas,Achromobacter and Vibrio.All the microbial colonies in biofilm showed the dehydrogenase activity at low temperature, but with different activity, which are related to their growth rate. The pH, time and temperature were considered as the main factors which affect the activity of dehydrogenase of phychrotrophs in our experiments. The conclusion was made that the 8 strains were all detected with catalyzed activity during the range of temperature from 4℃to 45℃, the optional temperature was 20℃to 30℃, optional pH were found from 7.0 to 9.0, and the reaction time of S3 was the shortest , S2 and S4's were the longest.In the proper conditions, the 8 strains of psychrotrophs were all with a certain enzyme activeity, Among them, strain S3 was the highest, it was about 14.64 mgTF/gSS. strain S4 and strain S6 were the second, they were 13.34 mgTF/gSS and 12.76 mgTF/gSS respectively, but strain S1 was the smallest, only 2.59 mgTF/gSS. Above all, by adding immobilized psychrotrophs to the low-temperature sewage treatment system, the treatment effect of sewage in cold area could be improved greatly. The low temperature microorganisms on biofilm possess dehydrogenase activity from 4℃to 45℃, so they can perform well in both low temperature and normal temperature . In addition, strains S3, S4 and S6 have good dehydrogenase activity, it is expected that they can be used in the low-temperature treatment system.