TOXICITY ASSESSMENT IN INHIBITION ON ANAEROBIC DEGRADATION OF CEPHRADINE BASED PHARMACEUTICAL EFFLUENT IN AN UP–FLOW ANAEROBIC FLUIDIZED BED REACTOR

During the production of Cephradine (a main constituent of anti-osmotic drug) a large quantity of concentrated effluent was produced. The main polluting compounds in this effluent are Cephradine, acetic acid and ammonia. The chemical oxygen demand (COD) of wastewater was varying from 12000 to 14000 mg/L. In the present study, two methanogenic cultures were grown in the presence of effluent as sole carbon or together with a mixture of volatile fatty acids (VFA). Both batch cultures produced methane from VFA after 148 days in the presence of Cephradine up to a concentration of 96 mg/L in a first experiment, without significant activity inhibition. After several transfers, one of the cultures tolerated higher effluent concentrations. Only that culture, originating from industrial effluents contaminated with Cephradine and ammonia, was able to remove Cephradine to a maximum COD concentration of 212 mg/L with propionate and acetate as intermediate compounds. Continuous biodegradation was carried out using a GAC upflow anaerobic fluidized bed reactor with the acclimated culture and maximum Cephradine concentration of 212 mg/L. With a mixture of effluent: VFA at a COD ratio of 2:1, a reduction of 83.5% was obtained when operating at an hydraulic retention time (HRT) of 0.72 days and at influent concentration of 212 mg/L. When operating under the same conditions, in the absence of VFA, around 63% reduction of Cephradine concentration was obtained, although 90% concentration was attained at influent concentration of 1050 mg/L at a HRT of 0.83 days.