In Chengdong, our wastewater treatment plant soaks up the sun

We are spearheading a truly pioneering approach in China. Our revolutionary initiative, consisting of generating solar power by building solar panels into the infrastructure of treatment tanks, is contributing to the construction of a greener world.

In Jiangsu province, SUEZ and its local partner (Jiangsu Sino French Water Co. Ltd) are helping to improve the integrated water supply and drainage systems of the city of Changshu, contributing to our overall wastewater treatment and waste management solutions at local level. One of them is the Chengdong project, where we manage the wastewater network and treatment plant under a 30-year concession contract.

Spanning around 90 hectares and with a total capacity of 120,000 m³/day, the wastewater treatment plant (WWTP) serves a population of 461,400. The plant uses 30% of the recycled water in various ways, in particular to irrigate green spaces and roads.

Setting a new standard for renewable energy in WWTPs

However, where we are truly breaking new ground in terms of impact is the incorporation of solar panels into the existing infrastructure of biochemical treatment and sedimentation tanks. In summer last year we launched this original initiative to capitalise on solar energy by installing 7,700 photovoltaic modules covering a total of 34,000 sqm, thereby setting a new standard for renewable energy in WWTPs.

The new installation generates up to 4,000 MWh of green electricity per year, thus contributing to the plant’s clean energy ambitions. The excess energy generated, i.e. produced but surplus to the plant’s requirements, is fed back into the city's power grid. Our project substantially reduces the plant’s demands on the national grid and contributes to the decarbonisation of energy in the city of Changshu by cutting carbon dioxide emissions by 3,400 tonnes.

Our innovative project not only contributes to energy self-sufficiency, but the excess power can be reinjected into the grid to achieve substantial annual costs.

Tong Xiaofeng , Plant Manager

All the while efficiently reducing the wastewater treatment plant’s operating costs, the project also avoids the consumption of 1,300 tonnes of coal per year: a boost to the green, low-carbon and sustainable development of our joint venture.

Meanwhile, the implementation of SUEZ’ cutting edge technology in the neighbouring artificial wetland spanning 14,000 sqm (including a 4,500 sqm lake) constitutes a natural way of treating microorganisms and heavy metals. The 12.5 million m³ of recycled water that is produced each year is channelled back into the local ecosystem.

The ecological wetland today has today taken on the status of a wildlife sanctuary with an abundance of fish, ducks and vibrant plant life, illustrating the SUEZ vision of a harmonious balance between development and nature. The local government authority is drawing inspiration from our model to develop the “solar power + WWTP” model in other facilities, placing emphasis on reducing sludge, managing resources, using renewable energy and pursuing better environmental stewardship. Our goal is to find new ways of reducing carbon emissions in wastewater treatment and contribute to building a greener world.

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