title: Dissolved air flotation clarification of activated sludge and wastewaters from chemical industry.
abstract: Wastewaters from separate chemical factories are treated together in an extended aeration activated sludge plant. The factories produce chemicals for paper industry (e.g. starch), latexes and animal feed. The components of the wastewaters include styrene, tertiary butanol and vinyl acetate. Activated sludge is clarified by sedimentation. During winter time, when the water temperature was 3-12 degrees C, the clarification deteriorated causing carry over of suspended solids containing COD. Enhancement of suspended solids and COD removals was studied in a dissolved air flotation jar test unit. Flotation trials were conducted for activated sludge, sedimentation treated final effluent (tertiary treatment) and separate wastewater fractions. The need for chemicals, flocculation and amount of recycle water were judged according to the achieved removals. Dissolved air flotation was found well suited for the clarification of activated sludge, but not technically and economically feasible for the clarification of the wastewater streams before the activated sludge treatment.
authors.affiliation: Institute of Environmental Engineering and Biotechnology, Tampere University of Technology, Korkeakoulunkatu 4, FIN-33720 Tampere, Finland.
authors.forename: P
authors.initials: P
authors.lastname: Jokelat
authors.forename: J
authors.initials: J
authors.lastname: Immonen
mesh_terms: D000388:Air; D002617:Chemical Industry; D006112:Gravitation; D010316:Particle Size; D012995:Solubility; D014865:Waste Disposal, Fluid / Q000379:methods*; D014873:Water Pollutants / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods*
chemical_list: D014873:Water Pollutants