Coupled adsorption–biodegradation of trichloroethylene in groundwater using food waste-derived Polyhydroxyalkanoates (Pha) and pine wood biochar

This study investigates a novel coupled adsorption-biodegradation (CAB) system employing waste-derived polyhydroxyalkanoates (PHA) and pine wood biochar (PWB) for the remediation of groundwater contaminated with trichloroethylene (TCE). A mini pilot column reactor was operated for 164 days, integrating a distributed PWB zone and a raw PHA-rich biomass, sourced from food waste, as a slow-release electron donor for biological reductive dechlorination (BRD). The system achieved complete TCE removal and detoxification of cis-DCE and vinyl chloride (VC), even after volatile fatty acid (VFA) depletion. Notably, the use of raw PHA eliminated the fermentation lag phase, while the continuous PWB distribution increased contaminant residence time and sustained long-term BRD activity. Biomolecular analyses confirmed the enrichment of Dehalococcoides mccartyi and key reductive dehalogenase genes ( tceA, vcrA, bvcA ) in reactor zones where VC was completely removed. Furthermore, microbial community profiling revealed the presence of additional functional groups likely contributing to the bioprocesses within the system. These results demonstrate that combining adsorption with biodegradation using waste-based materials can enhance in situ remediation efficiency, offering a scalable and sustainable CAB strategy in line with circular economy principles. • A coupled adsorption and biodegradation process for TCE removal from water has been developed • Biochar from pinewood waste pyrolysis was the sorbent material • Raw PHA-rich biomass from organic waste has been used as source of electron donor • A biofilm of dechlorinating culture developed onto biochar for biological reductive dechlorination