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Project Location: McLean's Pit Landfill, Town of Greymouth, South Island, New Zealand
This case study summarizes initial results of the first field-scale application of Floating Island International's patented floating treatment wetland (FTW) technology to treat landfill leachate. Constructed of post-consumer polymer fibers and vegetated with native plants, FTWs mimic the ability of natural wetlands to clean water by bringing a "concentrated wetland effect" to any water body-in this case, several treatment lagoons.
Overview:
Landfill leachate is a problematic water stream to treat in New Zealand and worldwide. Greymouth is a town of approximately 3,000 people on the South Island. The town identified a need for improved treatment of its municipal landfill leachate, which is a dilute stream because of the area’s extremely high annual rainfall (3.5 m or 140 in).
Because of limited funding, lagoon improvements are being implemented in three stages. In Stage 1 (initial results are described below), FII licensee Kauri Park Ltd constructed and installed 288 m2 (3100 ft2) of FTWs to cover approximately 20% of the lagoon surface in half of the lagoons. In Stage 2, another 288 m2 (3100 ft2) will be constructed in the other half of the lagoons. In Stage 3, media for biofilm attachment will be added to the primary treatment lagoon that precedes the other lagoons, along with improved aeration, for enhanced nitrification (ammonia removal). The wetland plants being utilized are Carex virgata and Cyperus ustulatus.
Results:
Removal of total suspended solids (TSS) and color has been exceptional, as shown in the results table and first photo. The FTWs are also significantly removing total nitrogen and Biochemical Oxygen Demand (BOD). Operational data and detailed water quality data are still being collected and analyzed; however, the most recent data indicate that TSS removal has been improved by 89% when compared to pre-launch samples.
Conclusion:
Although the test is still in its early stages, initial results indicate that FTW technology is a viable and effective option for improving the quality of landfill leachate.
Installation Data
Results
link to PDF
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McLean's Pit Landfill
