Project Location: McLean’s Pit Landfill, Greymouth, New Zealand
Landfill leachate is a problematic water stream to treat. Greymouth is a town of approximately 3,000 people on the West Coast of 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). Although only 50% of the recommended volume of BioHavens was installed, the results enabled the city to reach its effluent goals without further investment.
Because of limited funding, lagoon improvements were intended to be implemented in three stages. In Stage 1 (results are described below), FII licensee Waterclean Technologies constructed and installed 288 m2 (3100 ft2) of BioHavens 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 used are Carex virgata and Cyperus ustulatus.
Removal of TSS and color pigment has been exceptional. The FTWs are also significantly removing total nitrogen and 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.
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Phase 1 of the project (50% of the recommended BioHaven volume) delivered sufficient improvement to bring the site back into compliance. BioHavens improved removal of total suspended solids (TSS), biochemical oxygen demand (BOD) and total nitrogen by 89%, 46% and 40% compared to pre-FTW conditions.
Location: Greymouth, New Zealand
Parameters Studied: TSS, Total Nitrogen, BOD
System Type: Lagoons
BioHaven Size: A total of 288 m2 (3,100 ft2); each of three ponds contains eight modules with 12 m2 of surface area
Water Source: Landfill leachate
Installation Date: November 2009
Flow Rate: Variable, with highest flows in the winter (rainy season)
Water Body Depth: 0.6 m (2 ft)
Water Body Area: Each pond is 40 m x 12 m (131 ft x 39 ft). There are six ponds, with BioHavens in three of them.
Improvement Compared to Pre-FTW
Total Nitrogen 40%