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Sioux City, Iowa wastewater RNG plant now operational

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Iowa’s second renewable natural gas (RNG) facility at Sioux City’s Wastewater Treatment Plant (WWTP) is now operational.

The facility was launched with support from Bartlett & West, a community-driven engineering firm, and DMT Clear Gas Solutions, a technology supplier for biogas conditioning and upgrading systems.

The water resource reclamation facility converts 800 standard cubic feet per minute (SCFM) of biogas to produce more than 99.5% pure RNG for direct injection into the natural gas pipeline. The project generates enough renewable energy equivalent to removing 2,900 vehicles from US roads for one year or replacing 1.5 million gallons of petrol annually.

The Sioux City WWTP treats around 15 million gallons of wastewater per day, serves more than 30 industries and five communities from three states including Iowa, Nebraska, and South Dakota.

This $11 million (€9 million) renewable energy project is a significant upgrade to the existing WWTP and offers major advantages such as greenhouse gas emission reduction, odour control, and revenue for the city. The project will also generate $4-7 million (€3.2-5.7 million) in city income after five years.

“DMT is thrilled with the plant’s completion,” said DMT general manager Robert Lems. “We would like to thank our hardworking team and partners like Bartlett & West for a successful collaboration.

“Many WWTPs already have on-site anaerobic digesters to treat sewage sludge but do not have the equipment to use the biogas they produce and flare the gas instead.

“Our proven technology can turn these potential facilities into a net energy producer rather than a consumer.”

Sioux City chose Bartlett & West as the wastewater treatment programme manager, which included leading teams of consultants and individuals in designing several improvement projects for the city.

Bartlett & West recommended improvements to the city’s AD system, using DMT’s Sulfurex®CR, a chemical desulphurisation unit, to remove hydrogen sulphide, and DMT’s three-stage Carborex®MS, a membrane separation technology, to extract CO2 from the methane stream.