Use of upcycled biosolids for bioremediation of groundwater contaminated with chlorinated solvents

Trichloroethene (TCE) is a widespread toxic groundwater contaminant; thus, the development of inexpensive and accessible remediation materials is needed. Bioremediation of TCE under field conditions often requires the addition of carbon amendments. This study examines the use of biosolids at a field site as a sustainable carbon-rich and microbial amendment. A trench with amendments was installed upstream of a TCE-contaminated site, which was filled with biosolids, limestone, and biochar. Field monitoring of water quality parameters was compared with microbial community changes in soil samples collected 9 months after amendment. The results showed that the TCE concentration decreased from 91 µg/L to below the detection limit, with the presence of TCE biodegradation products indicating anaerobic reductive dehalogenation occurring in the trench. Analysis of the microbial community data also provided predictions about the metabolic activities and showed the presence of acetogenic activity. This activity is required for complete TCE dehalogenation and suggests the presence of different dehalogenase enzymes that can contribute to the degradation of chlorinated contaminants. Thus, the application of the waste product for sustainable TCE bioremediation in the field was successful in decreasing the contaminant levels by upcycling an organic waste product (biosolids).