ORGANIC LOADING EFFECTS ON THE TREATMENT OF PHENOLIC WASTEWATERS BY SEQUENCING BATCH REACTORS

The biodegradability of high concentrations of phenol and o-cresol in wastewater and the impact of these toxicants on sludge settleability was investigated. Sequencing batch reactors were utilized to treat phenol and o-cresol aerobically at a hydraulic retention time of 1 day and a solids residence time of 14 days. The reactors achieved greater than 99.5% removal of phenol and o-cresol at toxicant loadings in the ranges of 0.1-0.8 kg phenol/m3 . d and 0.1-0.6 kg o-cresol/m3 . d. The average 5-day biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) removal efficiencies were approximately 99% and 94%, respectively. High toxicant loadings were not observed to hinder the biodegradability of other waste constituents, reflected by the effluent BOD5 being consistently less than 5mg/L, or impair sludge settleability because the effluent total suspended solids (TSS) and sludge volume index (SVI) were consistently approximately 12 mg/L and 80 mL/g, respectively.