START-UP OF SEQUENCING BATCH REACTORS FOR TOXIC WASTE-WATER TREATMENT

The start-up of sequencing batch reactors (SBR) for the treatment of phenol-bearing wastewater was achieved in about a week without any seeding, using the culture present in raw sewage only. The mixed liquor suspended solids (MLSS) concentration was grown to about 3000 mg/l without showing any inhibition effects at phenol concentrations as high as 800 mg/l. The effluent concentrations of phenol were consistently less than 0.5 mg/l during most of the start-up phase. The response of the SBR to shock loadings of phenol at concentrations up to 1600 mg/l was favorable and over 75% phenol removal was maintained at a hydraulic retention time of 1 day.