Industry experts work together to treat sludge in China
With the acceleration of urban sewage treatment and the construction of sewage treatment facilities in China, the urban sewage treatment rate has been continuously improved, and the problem of safe treatment and disposal of sludge has become increasingly prominent, which has become a new problem and new challenge in sewage treatment and environmental treatment. According to statistics, from 1978 to 2004, the sludge sludge production of the national sewage treatment plant increased from 150 tons/day to 33,000 tons/day. Most sewage treatment plants lack sludge disposal facilities, and the sludge has not been safely disposed.
At the 6th Asia-Pacific Infrastructure Development Ministerial Forum and the 2nd China International Conference on Urban Water Development, a number of experts from enterprises and universities gathered together to discuss the “sludge treatment and resource technology”. A topic to carry out in-depth discussions and exchanges, to open a "prescription" for the problem of sludge treatment in China.
Status: sludge treatment is imminent
“At present, the daily sewage treatment capacity of Beijing sewage treatment plant is about 2100 tons, which produces a large amount of sludge. More than 80% of the sludge does not reach harmless disposal, and only one-fifth of the sludge is treated by composting. Nutrient soil, used for farmland and landscaping, but the degree of harmlessness of this simple composting sludge is also very low.” Yang Xiangping, general manager of Beijing Urban Drainage Group Co., Ltd. said that due to the construction of the early sewage treatment plant The construction of sludge treatment related facilities, the current sludge treatment has become a headache.
Conventional sludge technologies include sludge landfill, sludge composting, sludge drying, sludge incineration, etc., all of which have various problems. Sludge landfills will occupy a large amount of land and will also pollute the groundwater. Fertilizer sludge treatment will cause a series of problems such as burning seedlings, salt damage, pests and diseases, and weed seeds. In addition, due to the high moisture content of the sludge itself, the energy consumption during the treatment and disposal process is large.
Problem: There are many drawbacks
Yang Xiangping pointed out that sludge disposal should not over-emphasize resource utilization, and should adjust “resource-reduction-stabilization-harmlessness” to “stabilization-reduction-harmless-resource-resource” The stabilization and reduction of mud is the most important, followed by harmlessness and resource utilization. Hang Shizhen said that at present, the main body of responsibility for sludge treatment in China is not clear, and there is no reliable economic support system. The cost of sludge treatment is not included in the cost of the sewage treatment plant. In addition, the standard for sludge disposal in China is the highest in the world, but the actual level of treatment is not high. This standard system is very unreasonable.
At present, China's sludge treatment and disposal technology also has many problems. Professor Yan Jianhua of Zhejiang University pointed out that the treatment method of direct sludge incineration is an expedient measure. The existing sludge incineration disposal system has a low design level and lacks technical specifications for sludge incineration. And sludge drying and incineration system with independent intellectual property rights.
The pulse: the experts have prescribed prescriptions
In view of the problems existing in the current sludge treatment and disposal and resource utilization in China, the experts at the meeting gave their opinions and suggestions from different angles.
“The disposal of sludge should be tailored to the local conditions and diversified in technology, so that the amount of sludge produced and used can be balanced.” Hang Shizhen said that economically developed large cities and special areas can be burned by heat or anaerobic digestion + dehydration + drying. + The way to landfill. When heavy metals in small and medium-sized towns are not serious, the compost products should be actively developed for landscaping and soil improvement. When heavy metals do not exceed the standard, compost products are used in agriculture to replace part of the fertilizer. In addition, the use of sludge co-firing technology should be prudent, and it is necessary to fully test and formulate relevant standards and regulations. The sludge drying should be used as a building material for in-depth research and production tests of a certain scale. The sludge drying technology and engineering facilities should be studied. The government shall have corresponding responsibilities for sludge disposal work, and establish a planning, design, construction, and operation management procedures for simultaneous sludge disposal projects, and establish a regulatory agency for sludge safety disposal.
Yang Xiangping pointed out that it is necessary to establish relevant regulations and policies for sludge disposal according to China's national conditions, determine the standards and stage targets for sludge treatment, improve the supervision system for pipe network discharge and sludge safe disposal, and establish a special plan for sludge disposal. Increase the investment in sludge safe disposal facilities, implement relevant policies and funds for sludge disposal, and continuously develop and gradually absorb and promote new technologies of harmless and resource-based sludge disposal.
Chen Tongbin, a researcher at the Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, introduced the complete set of technologies for sludge automatic control composting and resource utilization. After many years of experiments and case studies by Professor Chen and his team, this technology has matured. The sludge automatic control composting treatment and resource system can stabilize the organic matter in the sludge, improve the physical properties of the sludge, and reduce the moisture content of the sludge through biological dehydration. At the same time, the system can effectively deodorize through the treatment. Kill harmful organisms, degrade organic matter, and achieve harmlessness. Professor Chen pointed out that China's sludge treatment market has huge demand. This technology can effectively treat sludge and make up for the shortage of fertilizer, which has broad industrialization prospects.
Professor Zhao Qingliang from the School of Municipal and Environmental Engineering of Harbin Institute of Technology combined with his own research and summarized the key technologies for energy saving and consumption reduction in sludge treatment and disposal of urban sewage plants. The first is to improve and innovate the treatment process, increase the anaerobic digestion pretreatment process, and destroy the complex structure of the sludge itself. Second, it is necessary to develop new materials to replace polyacrylamide and polyaluminum chloride, which are difficult to biodegrade and may produce twice. Contaminated substances; the third is to develop new equipment; the fourth is to maximize the recycling of energy.