Landfill Leachate Treatment Wetland

Client: 
Ecowaste Industries Limited

Leachate is generated when precipitation percolates through the landfill and takes up organic and inorganic constituents from contents stored in the landfill.  The resulting leachate contains elevated concentrations of constituents such as ammonia nitrogen and suspended solids that may potentially be deleterious if released to the environment.  Ecowaste utilizes a combination of systems implemented and managed by SYLVIS to treat leachate.  The most recent addition is a pilot subsurface constructed wetland.

The pilot subsurface constructed wetland became operational in 2014 and is designed to treat 12% of the daily leachate production at the Ecowaste landfill.  The primary function of the wetland is to reduce the concentrations of ammonia nitrogen and suspended solids in the leachate.  The wetland consists of a vegetated variable surface bed (VVSB) which promotes biological uptake of nutrients and trace elements and a denitrification bed which converts nitrate to nitrogen gas, permanently removing the reactive nitrogen from the system.  The vegetation growing at the wetland is periodically harvested to ensure there is the export of nutrients and continued nutrient uptake. An aeration system has been installed in the VVSB to further improve the treatment of leachate.

This pilot subsurface constructed wetland demonstrates a long-term ability to reduce the level of contaminants to levels required under Ecowaste’s operational certificate. This systems allows for greater leachate treatment capacity using a smaller footprint as compared to other treatment methods.