The Study On Pollution Control Technology Of Circulating Water System In Coal Methanol Plant

Due to oxidation or aging of corrosion equipment,Methanol plant circulating water system cause a small amount of leakage of methanol, which will pollute cycle water system, produce fibrous substance, which is harmful for heat transfer speed and efficiency of circulating water for thermal system. In this experiment, the method of using methanol degrading bacteria to control the ecological niche of extracellular polysaccharide can inhibit the growth of fibrous substance, and alleviate the pollution problem of circulating water system from the source.This experiment identifies properties and structure of fibrous material screen the fibrous substance producing. it studies fermentation conditions, fermentation ecological relationship with selected methanol degrading bacteria and ecological relationship between circulating water system and the effect of microbial community structure changes in the study.Identification and screening results show that the fibrous material is bacterial cellulose.The strain of producing bacterial cellulose is Gluconacetobacter xylinus.The single factor experiment of G. xylinus fermentation conditions shows that G. xylinus has the highest yield in the 8th day,the most suitable pH is 5.0, When inoculation amount is 6%, it gets the largest quantity of bacterial cellulose(BC). When the methanol concentration is less than 50 ml/L by G. xylinus can survive. When methanol concentration is less than 35ml/L bacterial cellulose can be produced. When the concentration of methanol is 15ml/L, bacterial cellulose has the maximum yield.The Bacteria Bacillus amyloliquefaciens(abbreviated as B) and Pseudomonas sp.(abbreviated as P) were screened out for better methanol degradation. Respectively, with G. Xylinus., this two bacteria is put into the dynamic simulation of the methanol plant circulating water system. Through water quality monitoring the water quality, it is found that index is increasing with the increase of time. which strain P causes a increase of pH and chloride ion concentration with a decrease of turbidity, calcium hardness and total alkalinity and the CODcr is showing irregular. variation; strain B causes a decrease of system calcium hardness and total alkalinity with a increase of CODcr and chloride concentration, pH and turbidity shows irregular change.But the water quality index of experimental group and control group non-exist difference, and are all in the range of circulating water control index.The two strains have a certain effect of reducing production of bacterial cellulose. Therefore, strain P plays more effective role to inhibit the growth of G. xylinus and reduce production of bacterial cellulose.The PCR-TGGE technology analysis of microbial community structure of activated sludge shows that methanol degrading bacteria P and B are access to change the original microbial community structure, strain P replaces G. xylinus and becomes the dominant strains of system; strain B also inhibits the growth of G. Xylinus. It shows that methanol degrading bacteria could grow stably in the circulating water system, and seize the ecological niche of G. Xylinus to become the dominant species,which could inhibit the growth of bacterial cellulose and effectively alleviate the pollution problems of circulating water system.