Fenton oxidative treatment of petroleum refinery wastewater: process optimization and sludge characterization

Sludge generation is one of the major concerns in Fenton treatment of recalcitrant wastewaters. In this work, mineralization (reduction of Dissolved Organic Carbon (DOC)) of petroleum refinery effluent (PRE) and the accompanying sludge generated in treating PRE was investigated. The mineralization level of 53% at optimum conditions produced 0.16 L of wet sludge per litre of wastewater. Further investigation of the sludge properties was conducted to assess the ease of handling and potential reuse of the sludge. For this purpose, sludge generated at studied conditions exceeding 30% DOC reduction were characterized by sludge volume index (SVI), sludge settling rates (Vs) and volumes of settled sludge within the first 30 minutes (SSV30). High Vs (approximate to 0.16 cm s(-1)) and low SVI (<100 mL g(-1)) and SSV30 (<50 min s(-1)) values indicated that the sludge has good settling and compaction properties. The results confirmed that the sludge generated could be managed systematically with appropriate operating conditions.