In 2011, China's total sewage discharge has reached 48.24 billion tons, including 26.13 billion tons of urban domestic sewage and 22.11 billion tons of industrial wastewater. The COD emissions of 48.24 billion tons of wastewater can reach 13.392 million tons. If we use biological methods to treat 65% of the sewage, then the country will produce 8.47 million tons (dry mass) of sludge (calculated by 1t dry mass sludge = 0.38 million tons of wastewater). And if we assume that the water content of these sludges reaches 80%, then the quality of these sludges can reach 42.33 million tons. The treatment of sludge is so much that it can be seen that the sewage treatment plant faces difficulties in handling these sludges. The cost of sludge treatment and disposal mainly includes landfill fees, off-site transportation costs and on-site transmission costs.
The amount of sludge is the most cost-effective. If we actively carry out sewage treatment
technology, even if we only reduce the water content to half, then at least half of the country's transportation costs and landfill fees can be reduced, and 21.16 million tons of sludge can be reduced, resulting in a significant reduction in management costs. Therefore, sewage treatment technology has great application value.