Removal of hazardous micropollutants from treated wastewater using cyclodextrin bead polymer - A pilot demonstration case

Abstract

Increasing amount of micropollutants such as drugs, cosmetics and nutritional supplements detected in surface waters represents increasing risk to humans and to the whole environment. These hazardous materials deriving mostly from wastewaters often cannot be effectively removed by conventional water treatment technologies due to their persistence. Some of the innovative technologies use specific sorbents for their removal. Cyclodextrin-based sorbents have already proved to be efficient in laboratory-scale experiments, but no pilot-plant scale demonstration has been performed so far. We are the first who applied this sorption-technology as a tertiary treatment in a pilot-plant scale operating, biomachine-type municipal wastewater treatment plant. As a result of the treatment 7 of 9 typical micropollutants (estradiol, ethinyl estradiol, estriol, diclofenac, ibuprofen, bisphenol A and cholesterol) were removed with >80% efficiency from effluent (reducing their concentration from ∼5 μg/L to <0.001-1 μg/L). GC-MS analysis of water samples showed that many of the micropollutants were removed from the water within a short time, demonstrating the high potential of the applied cyclodextrin-based sorbent in micropollutant removal. The effect-based testing also confirmed the efficiency. There was a correlation between sorption efficacies and binding constants of micropollutant/cyclodextrin inclusion complexes, showing that among others also inclusion complex formation of pollutants with cyclodextrin played important role in sorption mechanism.

Keywords: Cyclodextrin polymer; Direct toxicity assessment; Emerging micropollutants; Pilot plant-scale sorption technology.