煤制甲醇循环水系统中块状污垢的分析和控制

煤制甲醇厂的循环冷却水系统中因轻微泄漏出现泡沫和微小块状污垢,取样后通过光学显微观察、扫描电镜和化学显色分析表明,该污垢主要为细菌纤维素,并采用微生物学分离手段获得1株优势菌。经16S rDNA基因序列及BIOLOG碳源利用分析表明,该菌为木葡糖酸醋杆菌(Gluconacetobacter xylinus)。甲醇浓度和pH值对该菌产纤维素能力影响较大,甲醇浓度为15~25 mL/L时产纤维素最强,pH值为8~9时纤维素产量仅为pH值5.0时的50%。当与其他甲醇降解菌共同生长时,由于竞争性排除、生态位争夺等作用,该菌产纤维素能力下降超过37.9%。该发现为生物法控制煤制甲醇循环冷却水系统中的纤维素污垢提供科学依据。

ANALYSIS AND CONTROL OF COLLOIDAL FOULING FROM CIRCULATING WATER SYSTEM IN A COAL-TO-METHANOL PLANT

Foams and blocks were produced in the circulating water system of a coal-to-methanol plant due to slight leakage. The fouling was identified to be mainly bacterial cellulose after optical microscopic observation, scanning electron microscopy and chemical coloration analysis, from where a dominant strain was obstained by microbiological isolation. The strain was identified as a strain of Gluconacetobacter xylinus, according to 16S rDNA sequence and BIOLOG identification. Cellulose production of the strain were studied under different conditions. The results showed that pH and methanol concentration had a great influence on the cellulose production of the strain. Maximum cellulose production appeared when methanol concentration 15~25 mL/L, and the cellulose production with pH of 8 and 9 was only 50% of that with pH of 5.0. When co-growth with methanol-degrading bacteria, cellulose-producing ability of the strain decreased by 37.9%, owning to competitive exclusion and niche competition. This discovery provided a scientific basis for the biological control of cellulose fouling in the coal-to-methanol circulating water system.