20-year landfill biogas deal agreed

The Milwaukee Metropolitan Sewerage Commission has approved a revised 20-year agreement with Waste Management to use biogas from the company’s Metro landfill in Franklin, Wisconsin, according to the Milwaukee Journal Sentinel.

An $11 million gas treatment plant will be built at the landfill site by the Milwaukee Metropolitan Sewerage District (MMSD). Waste Management will maintain a gas extraction system and build a pipeline to the Emerald Park Landfill operated by Advanced Disposal. From there, the gas will be transported to the MMSD’s Jones Island water treatment facility for use in powering the plant and drying sludge into Milorganite fertiliser.

Landfill biogas is released during the decomposition of waste by bacteria. About 50-55% of the gas is biomethane.

According to the Milwaukee Journal Sentinel, the new agreement will save district rate players up to $10 million over the 20 year contract. MMSD will pay Waste Management 36% of the market price for natural gas based on energy content, not volume, under the terms of the revised agreement.

Landfill gas is burnt in three turbines on Jones Island to generate electricity for the sewage treatment plant. Surplus heat from the turbines is used to dry off sewage sludge in the production of Milorganite fertiliser.