TREATMENT OF PHENOLIC WASTE-WATER BY SEQUENCING BATCH REACTORS WITH AERATED AND UNAERATED FILLS

This paper presents the experimental results of a sequencing batch rea ctor (SBR) with aerated fill and an SBR with unaerated fill treating s ynthetic phenolic wastewater under identical conditions of influent ph enol concentration and aeration time. The performance of the two react ors was evaluated according to substrate removal efficiency, phenol pr ofiles, sludge settleability and effluent suspended solids concentrati on. At low influent phenol concentrations (e.g, <400 mg/l), the SBR wi th unaerated fill performed better than the SBR with aerated fill, in which there was a tendency for filamentous bacteria to develop. Howeve r, when the influent phenol concentration was high (e.g, >800 mg/l), p henol accumulated during the fill period in the SBR with unaerated fil l became inhibitory to micro-organisms, This led to a reduction in sub strate removal efficiency and the growth of dispersed biomass. The sel ection of fill strategies for the SBR were dependent not only on the w astewater composition and biodegradability, but also on the concentrat ion of toxic organic matters in wastewaters. (C) 1997 Elsevier Science Ltd.