NANCHANG, March 31 (Xinhua) -- In Jiujiang City, east China's Jiangxi Province, treated wastewater is being used for fish farming, industrial gas is being sold for profit, and scrap materials are being reintegrated into production. These practices are becoming increasingly common as local authorities and businesses intensify efforts to develop a circular economy.

At a steel plant in Hukou High-Tech Industrial Park, a pond of ornamental fish offers an unusual showcase of industrial recycling.

"It is hard to imagine that the water in this pond comes from treated wastewater from our industrial production," said Ou Yaohui, a staff worker of Jiujiang Steel, while pointing to a nearby treatment facility.

After multiple stages of treatment, wastewater is purified from murky to clear, Ou said. A portion is reused in production, while the rest is used for landscaping, cleaning and aquaculture.

The treatment comes at a cost, nearly four times that of water drawn from the Yangtze River. "As a riverside enterprise, we must balance ecological benefits with economic costs," said Nie Jianggen, head of the company's production command center, adding that the company's wastewater recycling rate has exceeded 98.5 percent.

In the petrochemical industrial park of Jiujiang Economic and Technological Development Zone, not far from the Yangtze River, a nearly two-kilometer pipeline connects a coal-to-hydrogen plant of Sinopec Jiujiang Petrochemical Company with Jiangxi Bazhen Energy Chemical Co., Ltd. The pipeline transports waste carbon dioxide for reuse following further treatment.

"The emissions can be compressed, purified and processed into food-grade liquefied carbon dioxide with a purity of over 99.99 percent," said Ao Huihua, general manager of Jiangxi Bazhen Energy Chemical Co., Ltd. The product is used in sectors including carbonated beverages, lithium-ion batteries and fertilizers.

The company recovered 102,800 tonnes of carbon dioxide last year, generating revenue of approximately 37 million yuan (about 5.35 million U.S. dollars) while helping reduce emissions, Ao said.

The company currently has an annual food-grade carbon dioxide production capacity of 120,000 tonnes and plans to expand capacity to meet market demand.

The waste-to-treasure story goes beyond carbon dioxide. A full circular economy industrial chain is taking shape at Shacheng Industrial Park in Chaisang District, where scrap steel is turned into precision moulds, while wood waste is processed into lightweight panels.

At Jiujiang Weiger Metal Manufacturing Co., Ltd., scrap aluminium is remelted into aluminium alloy ingots used in automobiles and home appliances.

Through recycling, waste materials re-enter the manufacturing process, ensuring that resources are fully utilized, said Zhu Meier, chairwoman of Weiger.

Last year, Weiger recycled over 40,000 tonnes of scrap aluminium, producing around 2,500 tonnes of aluminium alloy ingots per month, with an annual output value of 500 million yuan.

In recent years, Jiujiang, which stretches along 152 kilometers of the Yangtze River, China's longest river, has made significant progress in the circular economy.

By 2025, 168 key enterprises had passed cleaner production audits, reducing emissions by 25,600 tonnes. The city has also built 42 straw storage centers and 72 utilization enterprises, lifting the straw utilization rate to 95.43 percent, and achieved full harmless disposal of domestic waste.

The city's efforts underscore China's broader push to balance economic growth with environmental protection, particularly along the Yangtze River, a vital economic corridor that has come under huge ecological strain over recent decades.

"We are exploring a path towards becoming a 'zero-waste city' by optimizing industrial layout and extending the circular economy chain," said Fang Baoping, deputy director of the Jiujiang Municipal Bureau of Industry and Information Technology.