Treatment of dairy wastewater using anaerobic and solar photocatalytic methods

The present study was aimed to treat the dairy wastewater by using anaerobic and solar photocatalytic oxidation methods. The anaerobic treatment was carried out in a laboratory scale hybrid upflow anaerobic sludge blanket reactor (HUASB) with a working volume of 5.9 L. It was operated at organic loading rate (OLR) varying from 8 to 20 kg COD/m(3) day for a period of 110 days. The maximum loading rate of the anaerobic reactor was found to be 19.2 kg COD/m(3) day and the corresponding chemical oxygen demand (COD) removal at this OLR was 84%. The anaerobically treated wastewater at an OLR of 19.2 kg COD/m(3) day was subjected to secondary solar photocatalytic oxidation treatment. The optimum pH and catalyst loading for the solar photochemical oxidation was found to be 5 and 300 mg/L, respectively. The secondary solar photocatalytic oxidation using TiO2 removed 62% of the COD from primary anaerobic treatment. Integration of anaerobic and solar photocatalytic treatment resulted in 95% removal of COD from the dairy wastewater. The findings suggest that anaerobic treatment followed by solar photo catalytic oxidation would be a promising alternative for the treatment of dairy wastewater. (c) 2008 Published by Elsevier Ltd.