Pilot Constructed wetland: treatment of chlorinated solvents and chlorobenzenes using a constructed wetland


Over the last year HMVT has tested the possibilities of using a constructed wetland type treatment for the treatment of groundwater contaminated with chlorinated solvents and chlorobenzenes. For the test we used our specially designed constructed wetland pilot test container. The equipment in this container allows for testing on site, using various constructed wetland types. With the equipment we can test various flow patterns in the wetland, various types of soil matrix of the wetland and various plant types.

 For this test we used a relatively organic rich soil matrix, anticipating on the required anaerobic conditions to achieve full degradation of the most important contaminants. The test started in December 2022 and was concluded in November 2023. An extensive monitoring was conducted during the tests. These included analyses on the water quality (e.g. physical chemical measurements such asthe oxygen content, redox-potential), chemicals within the water , the impact of evaporation and adsorption to soil and plants on the contaminant mass balance.

Looking into the results, after 5 months of stabilization PCE,TCE, DCE and VC were fully degraded from influent to effluent (>99%). Interestingly, despite lack of aerobic conditions measured in the waterflow, aerobically active microbes were abundantly present (DNA detection), and aerobically degradable contaminants were metabolized. This likely was a result from activity surrounding the plant roots, creating aerobic niches within the soil matrix. Chlorobenzenes were also fully degraded (100%). Effluent values were well below discharge limits.

Conducting the test has significantly reduced any uncertainties on the potential of a constructed wetland for the treatment of the contaminated groundwater on the site.. With the results of the tests, we have now a complete set of data to design a full scale constructed wetland, which appears to be very feasible for the site in question.

More information: constructed wetlands (HMVT)