生物破乳菌的筛选及发酵条件的优化

Selection of De-emulsification Strains and Optimization of Fermentation Conditions

摘要:

生物破乳剂的开发可以降低油田乳状液对石油工业和生态环境的负面影响并减少化学破乳剂的使用量。本研究建立了一套高效、便捷的破乳菌筛选方法, 并对破乳菌的特性进行研究。利用大庆油田受石油污染土壤作为菌种来源, 将Tween 60-water(0.072%, V/V)和Span 60-oil (0.028%, V/V)以6.5:3.5体积比配置出可以稳定200 h以上的O/W型乳状液, 用于破乳菌破乳效能的评价。经过分离纯化、血平板试验、排油试验和破乳试验最终筛选出2株24 h平均排油率在80%以上的优势破乳菌, 初步鉴定为芽孢杆菌属(Bascillus)。通过该破乳菌发酵条的件优化得到, 当温度为25°C, 摇床转数为160 r/min, pH值为9, 接菌量为20%时对该破乳菌生长速率最快, 积累发酵产物的量最多; 当温度为35°C, 摇床转数为120 r/min, pH值为9, 接菌量为2%时该破乳菌代谢产物的破乳活性最高。

Abstract:

Petroleum-field emulsions, which are produced in the process of exploration, production and recovery, represent a major environmental and processing problem for the petroleum industry. Biological demulsifier as a biological agent, will become a novel method of petroleum-field emulsions demulsifier instead of chemical demulsifier for its high efficiency, low cost, high adoptability, environment-friendly, repeated use. A set of high efficiency and convenient method was established to isolate de-emulsification strain and studied on the characteristics of the de-emulsification strains. A de-emulsification strains, isolated from a petroleum-contaminated site, was evaluated for its de-emulsification capabilities using a kerosene/water model emulsion system keeping stable for more than 200 hours which was mixed by stirring Tween 60-water (0.072%, V/V) and Span 60-oil (0.028%, V/V) at the ratio (oil:water) of 6.5:3.5. We have isolated two strains with high and steady de-emulsification activity by separation and purification, blood-plate test, excluding-oil test and de-emulsifying test. The average de-emulsification rates were more than 80.0% at 24 h. The two strains are both belonging to bacillus by traditional and molecular genetic identification. By optimizing the demulsification bacteria fermentation conditions, the fermentation conditions, which is the most suitable for accumulating the fermentation products, were determined as follows: temperature 25°C, stirring speed160 r/min, pH 9, inoculated quantities 20%. When the fermentation conditions were temperature 35°C, stirring speed120 r/min, pH 9, inoculated quantities 2%, the fermentation products appeared the highest activities of demulsification.