PLANTECO Environmental Consultants, LLC was contracted by MSE Technology Applications to conduct a landfill leachate pilot treatment test. PLANTECO installed a microbial mat bioreactor and a Constructed Treatment Wetland (CTW) at Ft. Hood, TX based on our initial bench scale tests . The remediation system was designed to remove iron, manganese, boron and lead from the leachate.

The microbial mat bioreactor utilized a plate and shelf design consisting of five 20” x 24” shelves and a 30 gallon reservoir at the base of the reactor. The CTW was composed of 6 cells planted with duckweed, cattails, parrot feather, smartweed, bulrush and an aeration cell (Figure 1). 

After an equilibration period, leachate was continuously pumped into the CTW and bioreactor at flow rate of 1 and 2 gpm, respectively. Samples were periodically collected from ports installed at the outlets of the bioreactor and individual CTW cells. The test period was 4 days (96 hours). 

Results of the test were promising. Despite the high iron concentrations in the leachate, the system was able to remove an average of > 91.5% of iron. We feel the addition of an initial settling pond treated with lime would remove the bulk of the iron and result in a low-cost passive system to effectively remove leachate metals to below regulatory limits.