Research Of Separation And Identification Of Psychrotrophs From ESBR And Biological Enhancement Of ESBR In Low Temperature

The mechanism of biological wastewater treatment process, which the main process used in China, is to remove the organic by biooxidation by micro-organisms. It has generally accepted that the predominant bacteria used in wastewater treatment are mesophilic bacteria, which highly effective and active in normal temperature. But in north area of China, the sewage temperature always below 10℃in cold winter, the activity of biooxidation of mesophilic bacteria exist in activated sludge were strongly weaken by low temperature, and the organic removal efficiency drawdown significantly.In this research, we consider that the predominant bacteria in low temperature wastewater treatment in winter were cold-adapted microorganisms, the number of which increased as the temperature dropped more and more, but rarely high up to the number of mesophilic bacteria in normal temperature due to its low growth rate and the restriction of ecological factors, so that the total number and activity level of microorganism in activated sludge decreased. Therefore, the essential way to improve the efficiency of low temperature wastewater treatment is to enhance the effect of cold-adapted microorganisms, especially the psychrotrophs which can resist to the temperature fluctuation.Eight psychrotrophs with high activity in low temperature(5~15℃)were separated and selected from ESBR. The psychrotrophs were identified by morphological, physiological, and growing characteristics identification, then the result were compared with the ecological characteristics of known micro-organism record in Bergey's Manual of Determinative Bacteriology (Eighth Edition, 1984) and ensured that the eight psychrotrophs belong to Flavo-bacterium, Alcaligenes, Vibrio, Bacillus, Micrococcus, Psychrobacter, Veillonella and Pseudomonas, respectively.We drew the growth rate curves of each psychrotrophs in 5℃and 15℃, then the growth rate and generation time of psychrotrophs were calculated by the curves. It was shown that the value of growth rate and generation time retained at 0.049~0.074h-1 and 9.18~13.93h at 5℃, respectively, while the growth of mesophilic bacteria were very slow, even stopped at the same temperature. The...