"Where has the huge amount of urban sludge gone?" Professor Chen Riyuan, director of the Resources and Environment Work Committee of the Guangdong Provincial Party Committee of the People's Democratic Progressive Movement, told Nanfang Weekend that if this question was raised, environmental protection departments in many cities would be difficult to answer.
Urban sewage treatment After the plant is put into operation, a large amount of sludge will be produced every day. They do not have enough land for sanitary landfill, the chain of transforming into resources is short, and most cities do not have dry incineration, etc Sludge treatment Disposal process. But these sludge "disappeared". Where did they go?
It was precisely out of this concern that the Guangdong Provincial Committee of the Democratic Progressive Movement submitted the Proposal on Promoting the Standardized Treatment and Resource Utilization of Municipal Sludge in China to the CPPCC Guangdong Provincial Committee in 2007 (which was later approved by the Central Committee of the Democratic Progressive Movement as a key research project in 2008, and its results were submitted to the 2009 National Political Association as a proposal).
In fact, in recent years, with the continuous improvement of urban sewage treatment rate, the potential pollution hazard of sludge to the ecological environment and the threat to the health of residents have become increasingly prominent. Sludge treatment is imminent.
This issue has also attracted the attention of managers. In February 2009, the Ministry of Housing and Urban Rural Development, the Ministry of Environmental Protection and the Ministry of Science and Technology jointly released the Technical Policy for Sludge Treatment, Disposal and Pollution Prevention in Urban Sewage Treatment Plants (Trial), which is known as "the sign of sludge coming into the government's sight".
Pollution control and pollution generation
According to Professor Yan Jianhua from the Thermal Energy Engineering Research Institute of Zhejiang University, sludge is the concentration of pollutants in the sewage treatment process. The sludge has high moisture content, is prone to corruption, has foul smell, and contains heavy metals, "three causing" organic pollutants, etc. Random stacking or simple treatment will pose a high risk of secondary pollution, which will damage soil, atmosphere and water resources. After some heavy metals in sludge seep into groundwater, they may return to the table through the food chain such as fish and shrimp. "If scientific treatment is not carried out now, it will have an irreparable impact on future generations".
As for the harm of sludge pollution, Wang Li, the head of Changchun Zhenyu Protein Regeneration Technology Research Institute, gave an example, saying that even flies and insects could not grow after the surrounding environment of a municipal sludge treatment plant was polluted. Employees engaged in fecal disposal in the early stage even suffered from various strange diseases such as eye ulceration.
However, the pollution of harmful components in sludge to the environment often takes a long time to show. It is this concealment that has made government departments and the public ignore the harmfulness of sludge and the urgency of its treatment for a long time.
From the perspective of investment, the investment in sludge disposal of urban sewage treatment plants in China only accounts for about 20% of the total investment in sewage treatment plants. In the planning and construction of early sewage treatment plants, sludge treatment is often simplified and ignored, and even the built sludge treatment facilities are left idle for a long time to save costs. In some developed countries such as Europe, America and Japan, sewage and sludge treatment are regarded as two subsystems to solve urban water pollution problems, and the investment in sludge treatment accounts for 50% - 70% of the total investment in sewage treatment plant construction.
Chen Riyuan introduced that the sludge in many cities in China has been abandoned without effective treatment. It has even been dumped into rivers and oceans, creating more serious secondary pollution. "This is the answer to 'Where has the pollution gone?'" Chen Riyuan said.
"Policy is the key to sludge treatment"
The overseas sludge treatment and disposal technology system has been relatively mature. In China, many scientific research institutions have also carried out research on sludge reduction, land use, drying and incineration. However, associate professor Jiang Jianguo, director of the Solid Waste Control Research Institute of the Department of Environmental Science and Engineering of Tsinghua University, believes that the technology that meets the national conditions of low investment in sludge treatment in China is not yet mature, "The research focuses on how to reduce the moisture content of sludge at the lowest cost before and during sludge dewatering". He believed that the technical route of sludge treatment should be adapted to local conditions. "The key to sludge treatment is not technology, but policy. Only when the policy problem is solved can the problems of technology, equipment, management and investment be solved." said Wen Yibo, president of Beijing Sound Environmental Protection Group. Existing national policies do not have complete technical indicators for organic pollutants, pathogens and heavy metals in sludge treatment. Moreover, for a long time, the responsibility subject of sludge treatment and disposal is unknown and the responsibilities are not divided, which leads to its operability and implementation strength being greatly reduced, and there is no way to talk about supervision. "Unclear subject of responsibility is the key factor that restricts the management system of sludge treatment and disposal to be straightened out." Fu Tao, director of the Water Industry Policy Research Center of Tsinghua University, believes that the unclear subject of responsibility is due to the nature of the traditional sewage treatment plant and the overemphasis on "resourcefulness" rather than social responsibility.
Although the pilot policy has made relevant provisions on many issues of sludge treatment and disposal, there is still no specific operational implementation plan and supporting policies. How to promote the effective implementation of the pilot policy? Yan Jianhua suggested that at the national level, engineering technical specifications and environmental protection standards corresponding to sludge treatment technology should be introduced. At the local level, corresponding supporting policies should be formulated in terms of construction investment, comprehensive utilization of sludge, fees, price subsidies, etc.
Who will pay for the huge cost?
Dr. Zhong Lijin, from the Water Policy Research Center of Tsinghua University, told the reporter that the cost of sludge treatment and disposal would be different if different technology routes were adopted. The investment and construction cost of domestic sludge treatment is generally 100000 to 300000 yuan/ton, and the operation cost is about 200-400 yuan/ton, while the sewage treatment plant is basically unable to bear this huge cost. However, at present, the sewage treatment fee system in China does not consider the sludge treatment and disposal fees. Even if there is, it only includes the sludge dewatering (that is, wet sludge dewatering into sludge with a moisture content of 85%) and clearing and transportation fees.
The pilot policy clearly points out that "sewage treatment fee shall include the operating cost of sludge treatment and disposal". However, there are no specific rules on the collection amount, financial subsidies and use supervision of sludge treatment fees. For example, Jiangsu Province adjusted the sewage treatment fee in Taihu Lake area to 1.3-1.6 yuan on average last year, from which no less than 0.2 yuan/ton was extracted for sludge disposal. In the opinion on sludge disposal issued later, it was again required to draw a certain proportion of funds from sewage treatment fees for sludge disposal. Relatively speaking, many provinces and cities have no regulations on this.
Wen Yibo said that the national competent department should formulate a reasonable standard for sludge treatment and disposal fees and government financial subsidies, and each region can fluctuate up and down according to local sludge scale, treatment degree, environmental impact and other factors. However, it is still "new" for residents to be included in the main body of sewage discharge, and the awareness of sewage payment still needs a process. "At present, the domestic financial subsidy for sludge treatment is between 180-250 yuan/ton. If a part of the sewage treatment fee is set aside for sludge treatment, the sludge treatment and disposal project will have certain economic benefits, and social funds will be willing to invest in it. The government departments can formulate rules of the game for this." Professor Chen Riyuan is optimistic about the diversified investment and operation of sludge projects. Solid liquid separation equipment To solve this problem. If Solid-liquid separation If the industry standards fail to meet the requirements, the situation of pollution generation and pollution discharge will never be solved
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