Nanning transforms urban waste into energy

At the Shuangding Circular Economy Industrial Park in Nanning, Guangxi Zhuang autonomous region, a waste treatment plant is challenging the conventional image of such facilities.

There is no pungent smell or smoke-filled sky. Instead, there is a garden-like compound and automated treatment lines that sort, incinerate and process urban waste, converting it into electricity, heat and construction materials.

The plant provides a glimpse into Guangxi's push to turn household garbage, kitchen waste, urban sludge and medical waste into usable resources via coordinated treatment facilities, rather than simply burying or discarding them. The Shuangding park, operational since late 2021, is the region's first facility of this kind.

Developed, built and operated by Guangxi Green City Environmental Development Group, a subsidiary of Nanning Jianning Water Investment Group, the park spans some 73 hectares. To date, around half of the site has been constructed, with total investment in the project estimated at 2.56 billion yuan ($379.33 million).

Chen Xuewen, deputy general manager of Nanning Jianning Water Investment Group, said the park is built around the principle of energy recycling, with its coordinated treatment system anchored by the incineration of household waste to generate electricity.

While electricity generated from waste incineration is fed into the national grid, residual heat is piped to facilities that treat organic waste, sludge and medical waste. "This improves overall energy efficiency," Chen said.

Equipped with three furnaces, the park's household waste incineration plant has a daily treatment capacity of 2,250 metric tons. Each ton of raw household waste processed can generate nearly 600 kilowatt-hours of electricity, roughly equivalent to the power consumption of a three-person household for three months, he added.

Great emphasis has been placed on reducing secondary pollution. A wastewater treatment facility with a daily capacity of 1,700 tons handles leachate, production wastewater and domestic sewage. After advanced treatment, the water is reused for cooling, landscaping and other production purposes within the park.

Slag left after incineration is processed to recover metals, while the remaining material is made into eco-friendly bricks or roadbed materials. Fly ash, which accounts for about 2 to 3 percent of incinerated waste, is stabilized and solidified before being sent to a designated landfill for safe disposal.

To control emissions, the park employs a seven-step flue gas purification system, integrating technologies including denitrification, deacidification and dust filtration. Chen said the facility's emission indicators are stricter than China's national standards and European Union limits.