Fungal waste treats water waste: Enzymatic and non-enzymatic removal of organic micropollutants with spent mushroom substrate of Agaricus bisporus

Water bodies are increasingly contaminated with a diversity of organic micropollutants (OMPs). This impacts the quality of ecosystems due to their recalcitrant nature. In this study, we assessed the removal of OMPs by spent mushroom substrate (SMS) of the white button mushroom (Agaricus bisporus) and by its aqueous tea extract. Removal of acesulfame K, antipyrine, bentazon, caffeine, carbamazepine, chloridazon, clofibric acid, N,N-Diethyl-meta-toluamide (DEET), GenX, and PFOA by SMS and its tea was between 10-90% and 0-26%, respectively, in a 7-day period. Sorption to SMS particles was between 0-29%, which can thus not explain the removal difference between SMS and its tea, the latter lacking these particles. Removal of OMPs (except caffeine and PFOA) by SMS tea was not affected by heat treatment, which implies a non-enzymatic removal activity. By contrast, heat-treatment of SMS reduced OMP removal to <10% except for carbamazepine with a removal of 90%. These results indicate that OMP removal by SMS and its tea is mediated by both enzymatic and non-enzymatic activities. The presence of copper, manganese, and iron (0.03, 0.88, and 0.33 µg L-¹, respectively) as well as H₂O₂ (1.5 µM) in SMS tea indicated that the Fenton reaction represents (part of) the non-enzymatic activity. Indeed, the in vitro reconstituted Fenton reaction removed OMPs >50% better than the teas. From these data it is concluded that spent mushroom substrate of the white button mushroom, which is widely available as a waste-stream, can be used to purify water from OMPs.