| Bio-demulsifier is one of biological agents with the advantages of high demulsificationefficiency, non-toxicity, non-secondary pollution, easily biodegradable and environmentallysafe, etc. Efficient bio-demulsifier can improve the dehydrationrate of crude emulsion andreduce the difficulty of crude waste water. Therefore, e nvironmental pollution will bereduced and human health can be protected. Instead of chemical demulsifier, bio-demulsifierhas high environmental and economic benefit.Two demulsifying strains with high and steady demulsification activity were isolated bya set of high efficiency and convenient method. For80%containing aqueous crude emulsions,the demulsification efficiency of strains can reach85%within12h. Thephysiological-biochemical characteristics of two strains were analyzed and two strains wereidentified by16S rDNA. The results indicated that one strain is Serratia marcescens, named asPRJ-1and the other is Bacillus mojavensis, named as PRJ-2. The serial generation testshowed that two strains had hereditary stability. Effects of demulsification efficiency andgrowth of the PRJ-1were investigated through demulsifying test and biomass estimation. Theoptimal cultivation conditions, optimum nutrient conditions and optimum demulsificationconditions were confirmed by demulsifying experiment. Cheap materials such as oilfieldsludge, workshop waste oil and edible waste oil were used as carbon sources to cultivatePRJ-1demulsifying bacteria. As a result, PRJ-1grew well in the waste oil and the growthspeed was faster than paraffin medium. The demulsification efficiency of nutrient solutionwas higher and dehydrated water was clearer.PRJ-1cultivation solution was centrifuged to contrast components demulsificationefficiency of cultivation solution, the result showed that strains cells and metabolin had highdemulsification ability. The metabolin was observed by microscope and analyzed by physicaland chemical methods. The protein turned out to be active constituent in metabolin.Combination study showed demulsifying bacteria PRJ-1had high efficient and stabledemulsification activity which was better than conventional chemical emulsifier. Highapplication value and wide applicability were confirmed, which reflected the superiority ofbio-demulsifier. Therefore, bio-demulsifier must have a spacious developmental market andhave profound significance in aspect of economy and environmentally safe. |
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