title: Comparison of biological and chemical treatment processes as cost-effective methods for elimination of benzoate in saline wastewaters.
abstract: Eight mixed cultures able to degrade benzoic acid under saline conditions were established and kinetic parameters were determined in batch processes with cultures SBM002 (0.5 g d(-1)·g oDM(-1)), SBM003 (0.7 g d(-1)·g oDM(-1)) and SBM007 (2.2 g d(-1)·g oDM(-1)) showing the highest degradation rates. Treatability of an industrial waste water (12 g L(-1) benzoic acid, 82 g L(-1) NaCl) by these cultures was proven in a fed-batch system (SBM002 & SBM003) and a continuous flow reactor (SBM007). The performance of the continuous flow reactor was 15-times higher compared to the fed-batch system due to the change of inocula, higher concentration of ammonia as nutrient and less accumulation of possibly toxic catecholic compounds. Average DOC reduction was found to be 98% at 100 g L(-1) NaCl and 1.2 g L(-1) benzoic acid under these conditions. Pre-treatment of the waste water via chemical precipitation by acidification to pH 3.5 diminished the concentration of benzoic acid to 2.1 g L(-1). In a combined chemical-biological process the volume of the bioreactor is reduced to 15% compared to a pure biological process. A comparison of operational costs for these three alternatives is presented.
authors.affiliation: Institute of Sanitary Engineering, Water Quality and Solid Waste Management, University of Stuttgart, D-70569 Stuttgart, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Kiel
authors.affiliation: Institute of Sanitary Engineering, Water Quality and Solid Waste Management, University of Stuttgart, D-70569 Stuttgart, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Dobslaw
authors.affiliation: Institute of Sanitary Engineering, Water Quality and Solid Waste Management, University of Stuttgart, D-70569 Stuttgart, Germany. Electronic address: karl-h.engesser@iswa.uni-stuttgart.de.
authors.forename: Karl-Heinrich
authors.initials: KH
authors.lastname: Engesser
mesh_terms: D001565:Benzoates / Q000737:chemistry* / Q000378:metabolism*; D001673:Biodegradation, Environmental; D011232:Chemical Precipitation; D014865:Waste Disposal, Fluid / Q000191:economics* / Q000379:methods*; D018508:Water Purification / Q000191:economics* / Q000379:methods*
chemical_list: D001565:Benzoates
keywords: Benzoate; Biodegradation; Chemical precipitation; Elimination; Saline conditions; Waste water treatment