Techno-economical assessment of coupling Fenton/biological processes for the treatment of a pharmaceutical wastewater

A wastewater coming from a pharmaceutical plant of chemical organic synthesis with a TOC of ca 1.4 g/L and low biodegradability has been treated by coupling of advanced Fenton oxidation process and subsequent biological treatment. The influence of the reaction temperature, the hydrogen peroxide concentration and the iron/copper loadings as catalysts in the Fenton process were studied. A moderate oxidant concentration (7.5 mgH(2)O(2)/ mgTOC) and a temperature of 70 degrees C enhanced the biodegradability of the wastewater with a TOC reduction of ca. 35%. A subsequent biological treatment operating with HRT and SRT of 2 days and 20 days, respectively, allowed increasing the TOC removal above 90%. The oxidant concentration and the reaction temperature of Fenton process as pre-treatment to increase biodegradability were significantly lower than the values of the Fenton process currently implemented in the pharmaceutical plant to achieve an almost complete mineralization of the organic matter (21.4 mgH(2)O(2)/mgTOC and 120 degrees C, respectively). The techno-economical evaluation of the coupling Fenton/biological system compared to the Fenton process as unique treatment, showed that the lower oxidant uptake of the Fenton process for the coupling system is economically more profitable than using an excess of oxidant and a higher reaction temperature for the intensive Fenton process.