Humic substances in bioremediation of industrial wastewater—Mitigation of inhibition of activated sludge caused by phenol and formaldehyde

Abstract

This paper describes studies on the effect of humic substances on bioremediation of industrial wastewater, heavily contaminated with formaldehyde and phenol, using aerobic respirometry. Returned activated sludge (RAS) was the source of biomass. Respirometric data and non-linear regression analysis indicated that the system complied with the Haldane model for inhibitory wastes. It has been found that an addition of humate at the dose of 2000 mg/L substantially reduced this inhibitory effect, resulting in an increase of biological oxygen uptake and in a better removal of both, phenol and formaldehyde. The results show that an application of humic substances to mitigate an inhibition of the activated sludge in wastewater treatment plants may be an attractive alternative to the use of activated carbon or specialized sorbents.