Production Of Bio-Demulsifiers By Using Waste Oil

Biodemulsifier, one mumber of bio surfactants, has been widely applied in the field of petrochemical industry and environmental enginneering due to its characteristics such as high-efficiency, easy-biodegradable, environment-friendly. However, high cost of traditional carbon sources such as liquid paraffin seriously limited its large scale production. Accordingly, production of biodemulsifier using cheap waste carbon sources has become the research focus of this field. This paper mainly studied on feasibility of production of biodemulsifier using waste food oil and waste diesel oil, inculding growth characteristics of biodemulsifier-producing bacterials, biodemulsifier properties and its active ingredients. The effect of carbon number of alkanes on bacterial cell growth and de-emulsifing capabilities was also premilinary studied, in the hope of solving high-cost problem, relieving environmental pollution caused by waste carbon sources, providing theoretic foundation of biodemulsifier synthesis mechanism. The main results are as followings.1. Using general strain separating method,6 strains were obtained from petroleum contaminated soils of Jiangsu oilfield. After surface tension method, oil spreading methods combined with demulsification test,1 strain named S-JS-1, was finally screened. This strain was identified as Dietzia sp. using 16S rDNA sequencing, physiological and biochemical test.2. Biodemulsifier-producing strains S-XJ-1 and S-JS-1 were cultivated on waste diesel oil and waste food oil. The results indicated that purified biodemulsifier produced by the two strains using waste diesel oil were 0.36 g/L and 0.23 g/L, respectively. CMC were 117 mg/L and 180 mg/L, showing a better surface activity than chemical surfactant SDS(2100 mg/L). Waste food oil was more suitable for strain S-JS-1 in producing biodemulsifier, the strain dry biomass was up to 2.6 g/L, reducing surface tension of distilled water from 72 mN/m to 30 mN/m.3. In order to investigate de-emulsifing capabilities of biodemulsifier produced using waste diesel oil and waste food oil. demulsification tests were conduced in W/O model emulsion. The results indicated 24h demulsification capabilities of biodemulsifier produced by strain S-XJ-1 and strain S-JS-1 using waste diesel oil were approximately 60%-70%, obviously better than HWS-1501 chemical demulsifer,24h demulsification capabilities of biodemulsifier produced by strain S-JS-1 using waste food oil was 60%-80%. TLC and FTIR analysis showed biodemulsifiers produced by strain S-XJ-1 and strain S-JS-1 were lipopeptides, anionic biosurfactants according to cationic-type identification.4. Strain S-XJ-1 and strain S-JS-1 were cultivated on complex carbon resource consisting of C12、C14、C16、C18、C20 n-alkanes and waste diesel oil. The effect of carbon number of alkanes on strain biomass, surface tension, de-emulsifing capabilities and carbon source consumption ratio were studied compared with waste diesel oil. The results showed that strain S-XJ-1 biomass, surface activity, de-emulsifing capabilities and carbon source comsumption were increased when carbon number of alkanes increased, while strain S-JS-1 biomass, surface activity, de-emulsifing capabilities were initially decreased, then increased with C16 complex alkane as the center. In addition, strain biomass, surface activity, de-emulsifing capabilities and carbon source consumption ratio were optimized when the two strain growed on C20 complex alkane, similar to waste diesel oil. Therefore, strain S-XJ-1 and strain S-JS-1 mainly utilized C20 alkane of waste diesel oil in producing biodemulsifier.