An integrated approach of solar photocatalytic and biological treatment of N-containing organic compounds in wastewater*

Abstract

In the present study the integration of TiO2-assisted solar photocatalysis and biological treatment for the degradation of organic nitrogen containing pyrazinamide (antituberculosis drug) synthesis process effluent is investigated. The experimental results showed that a considerable increase in the degradation efficiency of N-containing compounds is obtained by integration of photocatalysis and biological treatment when compared to either biological or photocatalysis treatment alone. The optimization parameter like amount of photocatalyst (TiO2 Degussa-P-25) was performed for photocatalytic treatment under solar irradiation. Furthermore BOD5/COD ratios were also evaluated. The optimum catalyst (wt.%) of 0.35 TiO2, and 40 times dilution are found to be optimum for achieving a maximum of 76, 83, 80% of COD, color and TOC removals respectively and an improved BOD5/COD ratio of 0.3 to 0.7 in a duration of 24 h. Also the formation of increased from 10 to 44 mg L−1 within 20 h of photocatalytic treatment. The effluent subjected to biological treatment for five days (120 h) has resulted 43% COD removal only, whereas the treatment method using integrated approach resulted a 91% COD removal in a duration of 44 h.