Beside Beijing and Hong Kong, Shanghai is one of the most important industrial locations and market places in the People’s Republic of China. In the recent years, the city has had a remarkable growth spurt. Fifty years ago, about seven million people were living in the metropolitan area Shanghai, today the city has more than 25 million inhabitants. Along with the city’s growth came innumerable building projects with huge amounts of construction waste and other waste products. More and more of such material inevitably ended up also in the sewer system where it settled and started to cause problems.
As a preventive measure, the sediments in the sewers, such as debris and grit, are removed several times a year by suction trucks and transported to the sewage treatment works. But this procedure leads to batchwise overloading of machine components in the mechanical sewage treatment stage, such as screens or grit traps, which significantly impairs the function of these components. Ultimately, coarse particles end up in the primary clarifier with further negative impacts on the complete sewage treatment works.
To avoid these problems, the raw material delivered by the suction trucks can be treated centrally in a decoupled grit treatment plant to remove undesired coarse particles, wash out the mineral fraction and discharge the pre-treated raw material into the inlet to the sewage treatment plant. This offers the plant operator several benefits:
- Reduced solids load within the sewage treatment plant
- Avoid operational problems caused by solids load peaks
- Reduced disposal volumes due to the organics being washed out from the raw material