Project overview
Many stormwater ponds in the State of Minnesota contain polycyclic aromatic hydrocarbons (PAHs) in the sediment. Currently, a confined disposal facility is the main means of disposing dredged pond sediments contaminated with PAHs, the high costs of which are deterrent to routine maintenance of ponds. Earthworms have been found to enhance the degradation of petroleum products in soil, including PAHs. The proposed research study will investigate the use of earthworms in organic pollutant remediation systems (vermiremediation) as a cost-effective means of reducing PAH concentrations in stormwater pond sediments. Bench-scale experiments will be performed using prepared pond sediments that contain PAH levels representative of stormwater ponds in the Twin Cities Metro Area. The experiments will evaluate the reduction in PAH concentration possible with earthworms in comparison to the threshold concentration that requires the dredged material to be managed as a regulated solid waste and the time necessary to reach these levels. The results will be used to assess the feasibility of field implementation, including recommended methods, materials, maintenance, costs, and challenges involved.
Research questions
- Is it possible to reduce PAH concentrations in pond sediments using earthworms (vermiremediation) in a properly prepared environment, and if so, to what levels?
- Under what conditions (chemical constituent mix, natural microbial communities, sediment characteristics) and time scale can earthworms enhance degradation of PAHs in pond sediments?
- What is the feasibility of implementing a large-scale operation, including economically
procuring sufficient earthworm food stocks and the space for at-scale use of
vermiremediation?
Key innovations/contributions
This study will determine the feasibility of using earthworm remediation for treating PAHs in stormwater pond sediments.
What does this mean for Minnesota?
We are studying the use of earthworms for remediation of PAHs in pond sediments because we want to find out the extent to which earthworms reduce PAH concentrations in sediments to evaluate the feasibility and cost-effectiveness of vermiremediation so that stormwater pond managers can implement the technology in contaminated stromwater ponds which might provide cost savings on landfilling requirements and enable proper maintenance of ponds for better water quality performance.