Evaluating Fungus-Inoculated Biochar as a Cost-Effective, Sustainable Media for Stormwater Treatment

Abstract

Urban stormwater runoff is a leading contributor to water quality degradation in the U.S., negatively affecting both human and aquatic ecosystems. To mitigate these impacts, many cities have implemented green stormwater infrastructure like bioretention systems. However, the increase in acutely toxic organic contaminants transported by stormwater runoff has prompted the investigation of bioretention system media amendments to improve stormwater quality downstream. Previous studies have shown that biochar, mycoremediation, and phytoremediation serve as sustainable, effective mechanisms to remediate contaminated systems. Therefore, this study investigated the use of Mountain Crest Gardens (MCG) biochar, derived from pyrolyzed conifer softwood, as a contaminant sorbent and growth substrate for fungal degrader Trichoderma harzianum via fungal inoculation, to enhance the removal of common stormwater contaminants (sulfamethoxazole, benzotriazole, and acetaminophen). Additionally, this study evaluated the influence of T. harzianum-inoculated biochar on the plant health and phytoremediation capacity of the native perennial Juncus patens. Laboratory batch isotherm studies and an 18-week greenhouse mesocosm experiment revealed that T. harzianum-inoculated MCG biochar improved removal efficiency and sorption capacity across stormwater contaminants, in comparison to T. harzianum and MCG alone. The mesocosm study further demonstrated that Juncus patens enhanced the removal of all three contaminants in soils amended with TH@MCG biochar in comparison to mesocosms amended with T. harzianum or MCG only. These findings suggest that TH@MCG biochar, particularly when combined with Juncus patens, offers a promising approach for bioretention systems to sustainably treat stormwater runoff. Utilizing fungus-inoculated biochar alongside plants with phytoremediation potential presents a cost-effective, sustainable solution for remediating contaminated stormwater.