Study on sludge expansion during treatment of salad oil manufacturing wastewater by yeast.
Five yeast strains, namely Rhodotorula rubra, Candida tropicalis, Candida utilis, Candida boidinii, Trichosporon cutaneum, were isolated from soil spots of a salad oil factory, and applied for continuous treatment of salad oil manufacturing wastewater. The oil and COD removal performance of the mixed cultures were comparable to the results other researchers obtained. Sludge expansion, accompanied with sludge morphology change from pseudomycelia to true mycelia, occurred during continuous treatment of wastewater. The true mycelia dominated sludge had a much higher water content and SVI value than that of the yeast pure cultures, although the two kinds of sludge had similar oil removal performance. A mold, Geotrichum candidum, was isolated from the expanded sludge, and was suspected to be a reason for sludge expansion. Addition of 0.3% sodium propionate into batch cultures degraded SVI value from around 100 to 60. In a continuous running, addition of 10 mg l-1 sodium hypochlorite decreased SVI value from over 200 to below 100. The yeast activity, however, was weakened to a large extent at the same time.
Zheng
S
S
State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
Yang
M
M
Lv
W
W
Liu
F
F
D007221:Industry; D010938:Plant Oils / Q000378:metabolism*; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D015003:Yeasts / Q000502:physiology*
D010938:Plant Oils; D012722:Sewage