The next 10 years will be the golden age of China's sewage treatment market, and thousands of sewage treatment plants will be built. Every sewage treatment plant discharges hundreds or even tens of thousands of tons of surplus sludge with a moisture content of about 99.2% every day. These huge quantities of sludge will become a problem that needs to be treated urgently in the future. Sludge treatment technology includes sludge concentration, dehydration and drying. The existing technology in China is basically sludge thickening and dewatering technology. After sludge thickening and dewatering, the water content of sludge can only be reduced to about 80%, while developed countries are gradually requiring the water content of sludge to be reduced to 20% - 30%. Therefore, efficient and economical sludge treatment technologies, including dehydration and drying technologies, will have a huge market.
With the improvement of sewage treatment rate, the output of sludge is also increasing, and the problem of sludge treatment and disposal is becoming more and more prominent.
About 800000 T / year of urban sewage treatment plant; It is estimated that 5.4 million tons of dry sludge (27 million tons of sludge with 80% water content) will be produced every year in the next five years; Less than 1 / 4 of the existing sewage treatment facilities have sludge stabilization treatment facilities, and few of the existing sludge digesters can operate normally, some of which are not in operation at all. In some places, the sludge is directly discharged without reasonable treatment and disposal, resulting in serious secondary pollution.
GB18918-2002 pollutant discharge standard for urban sewage treatment plants issued by the State Environmental Protection Administration was implemented on July 1, 2003, especially adding the content of sludge control standard. Experts believe that there is an urgent need to formulate and improve a series of supporting standards, such as fertilizer, building materials, construction soil and other relevant standards for sludge recycling, and the safety of sludge needs to be carefully studied.