| Rhamnolipid, one of the most important biosurfactants, can exhibit excellent surface/interfacial activity at low concentrations. It has excellent properties on washing, emulsification, solubilization, wetting, permeation and etc. As a natural product, it is a non-polluting surfactant with high biodegradability. Nowadays, with the achievement on using cheap raw materials and advanced fermentation technology, the cost of rhamnolipid has drastically decreased. Based on its unique properties, rhamnolipid has the potential to replace/partly replace traditional surfactants in washing industry.This paper investigated the potential applicability of rhamnolipid secreted by Pseudomonas aeruginosa in washing industry. The study includes the following aspects:Firstly, this paper evaluated the applicability of rhamnolipid as hard surface and laundry detergent. Compared with SDS and SDBS, rhamnolipid was found to sustain higher cleaning efficiency on removing oily stain from the hard surface and showed great compatibility with hard water. Besides, the presence of rhamnolipid at10%(m/m) in the laundry detergent increased the removal efficiency of oil and protein stain from fabrics by over10%. Moreover, the tests on foaming and biodegradability showed that rhamnolipid performed lower foaming ability and superiority on biodegradability over SDS and SDBS.Secondly, this paper evaluated the removal efficiency of diesel and white oil from drill cuttings with the presence of rhamnolipid, and the oil content finally met the national emission standard. The use of rhamnolipid under mechanical stirring removed49%of oil in the first cleaning step while the subsequent biodegradation (12days) using activated sludge could further remove93%of the residual oil. After the two-step treatment, the oil content reduced from11.2%to0.4%at a removal rate of96.4%. Lastly, the effect of rhamnolipid on the treatment of oily sludge was investigated. The treatment of oily sludge by rhamnolipid under an acidic environment could remove62.9%of water while could further remove about88%of solids under an alkaline environment. The washing process of solid particles from oil was recorded under microscope. After the two-step treatment, more than60%of oil was obtained at a purity of80%, a significantly improved purity in comparison of the original value of21%, which can be reused.Taken together, this thesis reveals the good surface activity and biodegradability of rhamnolipid as well as its excellent performance in household cleaning, drill cutting washing and the treatment of oily sludge, indicating its great potential in both industrial and household usage. |
