Degradation of personal care products in wastewater treatment plants

Biodegradation rates vary widely between wastewater treatment plants

The non-restricted production and use of pharmaceuticals and personal care products (PPCPs) has led to their presence in effluents from treatment plants, which can pose a threat to aquatic organisms downstream. This study analysed the breakdown of six common chemicals in four Danish treatment plants. The findings shed new light on the factors affecting removal of PPCPs from waste, showing that the composition of waste is more important than the design of the treatment plant.

Abstract

Degradation of PPCPs in activated sludge from different WWTPs in Denmark, Springer, Volume 24, Issue 10, pp 2073-2080, December 2015.

Pharmaceuticals and Personal care products (PPCPs) are often found in effluents from wastewater treatment plants (WWTPs) due to insufficient removal during wastewater treatment processes.

To understand the factors affecting the removal of PPCPs in classical activated sludge WWTPs, the present study was performed to assess the removal of frequently occurring pharmaceuticals (Naproxen, Fenoprofen, Ketoprofen, Dichlofenac, Carbamazepine) and the biocide Triclosan in activated sludge from four different Danish WWTPs. The respective degradation constants were compared to operational parameters previous shown to be of importance for degradation of micropollutants such as biomass concentration, and sludge retention time (SRT).

The most rapid degradation, was observed for NSAID pharmaceuticals (55-90% for Fenoprofen, 77-94% for Ketoprofen and 46-90% for Naproxen), followed by Triclosan (61-91%), while Dichlofenac and Carbamazepine were found to be persistent in the systems. Degradation rate constants were calculated as 0.0026-0.0407 for NSAID pharmaceuticals and 0.0022-0.0065 for triclosan. No relationships were observed between degradation rates and biomass concentrations in the diverse sludges. However, for the investigated PPCPs, the optimal SRT was within 14-20 days (for these values degradation of these PPCPs was the most efficient).

Though all of these parameters influence the degradation rate, none of them seems to be overall decisive. These observations indicate that the biological composition of the sludge is more important than the design parameters of the respective treatment plant.

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