Electricity self-sufficiency is the aim for sewage treatment plant

The Beijing Drainage Group plans to achieve electricity self-sufficiency at one of its sewage treatment plants in the capital as it works toward carbon neutral operations, the State-owned company has announced.

The plan has proved to be feasible following the long-term operation of a facility for disposing of sewage sludge in the company's Gaoantun sewage treatment plant in the capital's Chaoyang district.

The plant generates large amounts of methane through one of its disposal procedures that uses anaerobic digestion, in which microorganisms break down biodegradable material in the absence of oxygen, the company said.

Beijing Drainage plans to use the facility to dispose of 700 metric tons of sewage sludge and 550 tons of kitchen waste every day. That will see 3,000 cubic meters of methane generated per day in the Gaoantun plant, it said.

With the help of a methane-fired power generation facility with an installed capacity of 6 megawatts, the plant will produce 48 million kilowatt-hours of electricity a year, the company said.

The plant will also reduce carbon dioxide emissions by 29,000 tons per annum, the company added.

Established in 2016, the Gaoantun plant has the capacity to treat 200,000 cu m of sewage and 1,836 tons of sewage sludge a day.

On average, the plant consumes 132,000 kWh of electricity a day. "Once it goes into operation, the power-generation facility will not only meet the demands of the plant, but also output electricity to the grid," said Ge Yongtao, head of the production department at Beijing Drainage.

The facility is expected to make the Gaoantun plant the country's first such facility to achieve electricity self-sufficiency, he said.

The company said that all the power-generation equipment has been put in place, and it is undertaking administration procedures to green light its operation, it said.

Beijing Drainage added that it has also fully tapped the potential of the plant's rooftops for the development of solar energy.

Currently, the plant has 1.6 MW of installed capacity for solar energy generation, which can annually produce more than 1.8 million kWh of electricity and reduce carbon dioxide emissions by 1,105 tons, it said.