Phenol is present in wastewater from a number of industries, including coal conversion, petroleum refining, resins and plastics, dyes, textiles, mining, and pulp and paper. The removal of phenol from industrial wastewater is an important practical problem. In this study, a crude preparation of laccase was produced by the lignolytic fungi, Pleurotus ostreatus, by solid-state fermentation using wheat straw as the substrate. We then studied the removal of phenol from refinery effluents, at laboratory scale, by the laccase-containing broth concentrated using ultrafiltration (NMWCO = 50,000). The results showed that laccase nearly completely removed the phenol in the solutions spiked with 25 to 400 mg/L of phenol. Similar results were obtained with real samples from either refinery wastewater treatment plant or sour water effluent. The results indicated that the enzymatic treatment is effective over a wide range of pH and the phenol removal was not significantly different in systems with and without aeration. The enzyme addition strategy was also studied. Multiple additions in small quantities were more effective than a single addition at the beginning of the treatment process. The responsible mechanisms are being studied currently.
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