Removal of pharmaceuticals and ecotoxicological changes in wastewater using Trametes versicolor: A comparison of fungal stirred tank and trickle-bed bioreactors

Abstract

Hospital wastewater is loaded with pharmaceutically active compounds (PhACs), which sometimes end up in the environment unaltered due to the lack of effective and specific treatments. The use of white rot fungi, specifically Trametes versicolor, as a biological treatment has proven to be an effective and environmentally friendly technology to tackle this problem. However, only a few studies have dealt with the removal of pharmaceuticals from wastewater by immobilizing white rot fungi in a lignocellulosic substrate. In this work, two bioreactor configurations are utilized to treat both synthetic and real hospital wastewater by the use of T. versicolor. The stirred tank bioreactor (STB) was able to remove to a great extent 16 pharmaceuticals spiked in the synthetic wastewater (95.7%) and those naturally present in the hospital wastewater (85.0%). Nonetheless, acute toxicity tests with Daphnia magna and germination index with Lactuca sativa showed an increase in the general toxicity of both wastewater matrices after the treatment. On the other hand, a trickle-bed bioreactor (TBB), using fungal biomass immobilized on rice husks, achieved an elimination of 88.6% and 89.8% in synthetic and real wastewater, respectively. However, 73.3% of the removal was ascribed to adsorption to the bed’s biomass. Additionally, toxicological tests showed a decrease in the hospital wastewater’s toxicity after the treatment in the TBB. These findings suggest that the fungal fixed-bed reactor could be more suitable than the stirred tank reactor to remove pharmaceutical compounds from wastewater, since it was able to remove PhACs to a great extent and simultaneously detoxify real wastewater.