Innovative Strategies and Forward Thinking on the Development Trend of Urban Sludge Resource Utilization

With the widespread adoption of the activated sludge method for treating sewage wastewater around the world, the annual products production of urban sludge was very huge for the past few years in both developed and medium-income countries.The annual production of urban sludge in America and China was 7.2 and 6.2 million dry metric tons, respectively and it was significantly higher than that of most European countries.The urban sludge was rich in organics, heavy metals, phosphorus, and nitrogen, which was not only a great energy resources, but also generated the factors of environmental pollution.The European Green Deal issued by the European Union clearly proposed to decouple resource extraction from the economy and reached zero carbon emission by 2050, which meant that the wastes should be maximized to achieve the optimal use of energy resources.