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Suzhou Industrial Park sludge treatment project, source recycling model

China-Singapore Suzhou Industrial Park (“SIP”) is the national development zone, with a surface area of 288 km2, where 600,000 population and hundreds of domestic and international enterprises are located. In 2009, SUEZ NWS obtained the sludge treatment and recycling project of SIP. The concession contract of 30 years terms is to design, build and manage the first sludge treatment project of Jiangsu Province.
The mission

SIP is one of the best developed industrial zones in China. Along with its economic development, the Park also pays a lot of attention in terms of ecological and environmental protection. In order to secure the water environment of SIP and its surroundings and limit the impact of industrial pollution, the Park has built two wastewater treatment plants, with a total treatment capacity of 500,000 m³/day.

Sludge is the inevitable by-product generated during wastewater treatment process. It is usually in large volume, perishable, smelly and contains heavy metal, germs and hazardous components. It can seriously pollute the water body, soil, underground water and air, as well as impact the human health, if discharged to the environment without scientific treatment. Therefore, we must make it harmless, reduce and recycle, to avoid the secondary pollution.

500,000
m3/ day wastewater treated in SIP
600
tons sludge produced by the wastewater treatment plants
Our solution

Safe and Efficient INNODRY 2E® Process

SUEZ NWS applies INNODRY 2E® (two-phase sludge drying process), the patented technology of SUEZ in the sludge project of SIP. With such process, it can treat the sludge safely, reduce the energy consumption, and dry the sludge from 80% water content to 10%. Due to its high heat value, The dried sludge can be reused as an alternative fuel of coal.

Industry Synergy and Circular Economy

The sludge drying plant is located close to the co-generation plant, wastewater treatment plant. Through the synergy between the three plants, it really archives the concept of resource recycling.

 

Between Wastewater Treatment Plant and Sludge Drying Plant

  • The wet sludge of the Wastewater Plant is sent to the sludge drying plant for treatment;
  • The cooling water used during the sludge drying process is the reclaimed water from the wastewater plant.

 

Between Sludge Drying Plant and the Co-generation Plant

 

  • The excess heat from the co-generation plant is supplied to the sludge plant in the form of steam to dry sludge;
  • The dried sludge is reused as fuel to be burned in the co-generation plant;
  • The condensate generated during sludge drying process is sent to the co-generation plant as boiler water.
The results

Through the advanced INNODRY 2E® process from SUEZ as well as the industrial synergy, the sludge project in SIP turns the sludge, the by-product of WWTP to resources, which is a perfect example of circular economy.

Energy recovery

In SIP, the dry sludge after treatment is sent to the power station, as an alternative fuel, allowing to save about 24,000 tons standard coal and lowering CO2 emissions. It is estimated that 100,000 tons of sludge can generate energy equivalent to 6,000 tons of fuel oil.

Water savings:

The condensate generated during the sludge drying process is sent back to the power station to be reused for the boilers, which can save around 136,000 tons desalted water per year.

Material recovery

Bottom ash resulting from the incineration process is used by another industrialist in the park to produce cement, realizing the zero discharge of sludge disposal reducing by 20,000 tons of solid waste generated.

Low Energy Consumption:

This advanced drying technology with low energy consumption and high level safety and environment protection consume 40% less energy than the normal sludge drying process due to the cascade utilization of energy.

600
ton/ day sludge treatment capacity
90%
Solid content in sludge after being dried
24,000

ton standard

coal saved

136,000
m3/ year desalted water saved
20,000
ton solid waste reduced
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