Combination of Fenton and Biological Oxidation for Treatment of Heavily Polluted Fermentation Waste Broth

Andreja Žgajnar Gotvajn* and Jana Zagorc-Končan 
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, Ljubljana, Slovenia, 

The aim of our work was to study the biotreatability of heavily polluted pharmaceutical fermentation broth (COD value of 124,500 mg·L–1) as well as application of Fenton oxidation for effective pretreatment. Because waste broth expressed biodegradability (BOD5/COD ratio was 0.40), biological treatment was the first choice. At the same time, in preliminary ready biodegradability assessment test, diluted broth degraded 65% as well it was not toxic to mixed bacterial culture of activated sludge. Further experiments in pilot laboratory biological treatment plant confirm acceptable treatment efficiency up to 0.01 vol% of the broth added (76%). However, we had considered additional pretreatment method to be able to enhance biotreatability. Fenton procedure was optimised in batch reactor using different concentrations of Fe2+, H2O2, temperatures (40/45 °C), as well as different retention times (up to 30 minutes). The highest treatment efficiency reached only 44% according to COD, but ready biodegradability of the sample increased (82%). Fenton oxidation was confirmed as possible method for pretreatment of broth, because it slightly enhanced biodegradability, it reduced organic pollution and formed products were non-toxic. We have focused our future work into a study on optimisation of applied procedure for improving biotreatability of the investigated broth.

Key words: biodegradability, biological treatment, pharmaceutical waste broth, Fenton oxidation, toxicity