title: Enhanced treatment of waste frying oil in an activated sludge system by addition of crude rhamnolipid solution.
abstract: The presence of high-strength oil and grease (O&G) in wastewater poses serious challenges for environment. Addition of surfactant into the activated sludge bioreactor is feasible in reducing high concentrations of O&G via enhancing its bioavailability. In this paper, an aqueous biosurfactant solution of rhamnolipid as a cell-free culture broth of Pseudomonas aeruginosa zju.um1 was added into a batch of aerobic activated sludge system for treatment of the waste frying oil. This treatment was conducted on both bench and pilot-scales, whereas the removal efficiency of frying oil was determined by analyzing the residue concentration of O&G and chemical oxygen demand (COD). In the presence of varying concentrations of rhamnolipid from 22.5 mg/L to 90 mg/L, aerobic treatment for 30 h was enough to remove over 93% of O&G while this biodegradability was only 10% in the control system with the absence of rhamnolipids. The equivalent biodegradability was similarly obtained on COD under addition of rhamnolipid. Compared with bench studies, a higher treatment efficiency with the presence of rhamnolipids was achieved on a pilot-scale of activated sludge system, in which a short time of 12h was required for removing approximately 95% of O&G while the control treatment attained a low efficiency of 17%. Finally, foaming and biodegradability of rhamnolipids in activated sludge system were further examined in the whole treatment process. It seems that the addition of rhamnolipid-containing culture broth showed great potential for treatment of oily wastewater by activated sludge.
authors.affiliation: Department of Chemical Engineering and Biochemical Engineering, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Hongzi
authors.initials: H
authors.lastname: Zhang
authors.forename: Hai
authors.initials: H
authors.lastname: Xiang
authors.forename: Guoliang
authors.initials: G
authors.lastname: Zhang
authors.forename: Xia
authors.initials: X
authors.lastname: Cao
authors.forename: Qing
authors.initials: Q
authors.lastname: Meng
mesh_terms: D001673:Biodegradation, Environmental; D019649:Food Industry; D006017:Glycolipids / Q000737:chemistry*; D007220:Industrial Waste / Q000517:prevention & control*; D009821:Oils; D011550:Pseudomonas aeruginosa / Q000737:chemistry; D012722:Sewage; D013501:Surface-Active Agents; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D006017:Glycolipids; D007220:Industrial Waste; D009821:Oils; D012722:Sewage; D013501:Surface-Active Agents; C418382:rhamnolipid