Compared to the society's concern for sewage treatment and atmospheric treatment, sludge treatment seems to have received less attention. However, at the 2010 Advanced Technology Forum for Water Industry, the participants agreed that if the sludge treatment problem is not solved, it will “delay†the pollution reduction and bring great trouble to environmental management. "If we do not dispose of the sludge generated during the treatment of sewage, nearly 50% of the COD (chemical oxygen demand) will be transferred to the environment in another form," said Yang Xiangping, vice president of the China Urban Water Supply and Drainage Association.
“Where did the huge amount of sludge go?†At the National Committee of the Chinese People's Political Consultative Conference last year, some members put forward proposals for standardized treatment and resource utilization of sludge. It is understood that the sludge of many cities and industrial enterprises in China has been abandoned without proper treatment, and has even been dumped into rivers and seas, causing serious secondary pollution.
With the increasing attention paid to sewage treatment, almost all cities and large enterprises are building sewage treatment plants. However, Wang Hongchen, deputy director of the School of Environment of the People's University of China, said that the large increase in sludge production has been accompanied by a continuous increase in sewage treatment rates. Sludge is the concentration of pollutants in the sewage treatment process. Sludge has a high moisture content and contains heavy metals, organic pollutants, etc. It is highly risky for secondary pollution by stacking or simply disposing of it. It can damage soil, atmosphere and water resources. Some harmful substances in the sludge may also enter groundwater. Through the food chain of fish, shrimp, etc., back to the table.
However, the pollution of the harmful components in the sludge to the environment often takes a long time to show. It is this concealment that makes government departments and people ignore the dangers of sludge and the urgency of its governance for a long time.
From an investment point of view, China's sewage treatment plant investment in sludge disposal accounts for only about 20% of the total investment in the sewage treatment plant. In the planning and construction of early sewage treatment plants, sludge treatment is often simplified and neglected, and even the completed sludge treatment facilities are idle for long periods to save costs. In developed countries, the treatment of sewage and sludge is considered as two subsystems to solve the water pollution problem. The investment in sludge treatment accounts for 50% to 70% of the total investment in the sewage treatment plant.
The sludge produced by petroleum and chemical companies is also very different from urban sludge and often contains a large amount of toxic and hazardous production waste. For example, the sludge of a petrochemical company's sewage treatment plant mainly comes from the sludge in the grease trap pool, the scum produced by flocculants in the flotation tank, and the remaining activated sludge in the aeration biochemical unit, commonly known as “three mudsâ€. Among them, oil-containing sludge is the most difficult to handle and has the greatest impact on the environment. A petrochemical wastewater treatment plant with a treatment capacity of 20,000 cubic meters per day will produce about 200,000 cubic meters of “three muds†with a water content of 99.5% per year. Oily oily sludge in the oil fields are all within the scope of hazardous waste management. If these sludges are not properly handled, the threat to the environment is undoubtedly enormous.
No matter whether it is the sludge treatment of cities or industrial enterprises, it is inseparable from chemical technology. At present, many research institutes in China have studied related technologies and some petrochemical enterprises have also achieved results. For example, the drying technology of oily sludge has been implemented in companies such as Fushun Petrochemical. By implementing relevant chemical and biotechnologies, useful substances in the sludge can be extracted. In addition, sludge can also be used to produce fertilizers, building materials and other products.
On the whole, experts believe that the domestic sludge treatment industry is still in its infancy, and it is still in the stage of selecting which equipment and which technology route to choose. Sludge treatment technologies that are suitable for China's national conditions and policy requirements are not yet mature. It is necessary to introduce foreign technology and equipment, build a research platform, and devote themselves to exploring localized applicable technological processes.
Sludge needs to be treated in a large-scale manner, and in most cases, the intervention of enterprises, chemical and environmental protection companies should do something. In the eyes of entrepreneurs, at this stage, the sludge treatment industry security system is still missing, technical standards lag behind, industry supervision is not in place, and industrial policies are not perfect. These issues must be addressed and resolved. Among them, the lack of policies is the biggest obstacle to the development of the sludge treatment industry.
Wen Yibo, president of Beijing Sunde Environmental Protection Group, said that the key to sludge management is not technology but policy. Existing national policies do not have complete technical indicators for organic contaminants, heavy metals, etc. in sludge treatment. Moreover, for a long time, the main body responsible for sludge treatment is unclear and its responsibilities have not been divided, which has led to a reduction in its operability and execution, and supervision has no way of talking about.
Experts suggest that the state should issue engineering technical specifications and environmental protection standards corresponding to sludge treatment technologies. Local governments should also formulate corresponding supporting policies in terms of construction investment, comprehensive utilization of sludge, charges, and price subsidies. When formulating policies, the state must also consider the upstream and downstream industries. There must be preferential policies for investment and financing to ensure the investment of funds; there must also be standards for downstream production of clean energy and fertilizers, which will open the way for sludge disposal. Only in this way can we truly achieve the stabilization, harmlessness, reduction, and scale treatment of sludge.
“Where did the huge amount of sludge go?†At the National Committee of the Chinese People's Political Consultative Conference last year, some members put forward proposals for standardized treatment and resource utilization of sludge. It is understood that the sludge of many cities and industrial enterprises in China has been abandoned without proper treatment, and has even been dumped into rivers and seas, causing serious secondary pollution.
With the increasing attention paid to sewage treatment, almost all cities and large enterprises are building sewage treatment plants. However, Wang Hongchen, deputy director of the School of Environment of the People's University of China, said that the large increase in sludge production has been accompanied by a continuous increase in sewage treatment rates. Sludge is the concentration of pollutants in the sewage treatment process. Sludge has a high moisture content and contains heavy metals, organic pollutants, etc. It is highly risky for secondary pollution by stacking or simply disposing of it. It can damage soil, atmosphere and water resources. Some harmful substances in the sludge may also enter groundwater. Through the food chain of fish, shrimp, etc., back to the table.
However, the pollution of the harmful components in the sludge to the environment often takes a long time to show. It is this concealment that makes government departments and people ignore the dangers of sludge and the urgency of its governance for a long time.
From an investment point of view, China's sewage treatment plant investment in sludge disposal accounts for only about 20% of the total investment in the sewage treatment plant. In the planning and construction of early sewage treatment plants, sludge treatment is often simplified and neglected, and even the completed sludge treatment facilities are idle for long periods to save costs. In developed countries, the treatment of sewage and sludge is considered as two subsystems to solve the water pollution problem. The investment in sludge treatment accounts for 50% to 70% of the total investment in the sewage treatment plant.
The sludge produced by petroleum and chemical companies is also very different from urban sludge and often contains a large amount of toxic and hazardous production waste. For example, the sludge of a petrochemical company's sewage treatment plant mainly comes from the sludge in the grease trap pool, the scum produced by flocculants in the flotation tank, and the remaining activated sludge in the aeration biochemical unit, commonly known as “three mudsâ€. Among them, oil-containing sludge is the most difficult to handle and has the greatest impact on the environment. A petrochemical wastewater treatment plant with a treatment capacity of 20,000 cubic meters per day will produce about 200,000 cubic meters of “three muds†with a water content of 99.5% per year. Oily oily sludge in the oil fields are all within the scope of hazardous waste management. If these sludges are not properly handled, the threat to the environment is undoubtedly enormous.
No matter whether it is the sludge treatment of cities or industrial enterprises, it is inseparable from chemical technology. At present, many research institutes in China have studied related technologies and some petrochemical enterprises have also achieved results. For example, the drying technology of oily sludge has been implemented in companies such as Fushun Petrochemical. By implementing relevant chemical and biotechnologies, useful substances in the sludge can be extracted. In addition, sludge can also be used to produce fertilizers, building materials and other products.
On the whole, experts believe that the domestic sludge treatment industry is still in its infancy, and it is still in the stage of selecting which equipment and which technology route to choose. Sludge treatment technologies that are suitable for China's national conditions and policy requirements are not yet mature. It is necessary to introduce foreign technology and equipment, build a research platform, and devote themselves to exploring localized applicable technological processes.
Sludge needs to be treated in a large-scale manner, and in most cases, the intervention of enterprises, chemical and environmental protection companies should do something. In the eyes of entrepreneurs, at this stage, the sludge treatment industry security system is still missing, technical standards lag behind, industry supervision is not in place, and industrial policies are not perfect. These issues must be addressed and resolved. Among them, the lack of policies is the biggest obstacle to the development of the sludge treatment industry.
Wen Yibo, president of Beijing Sunde Environmental Protection Group, said that the key to sludge management is not technology but policy. Existing national policies do not have complete technical indicators for organic contaminants, heavy metals, etc. in sludge treatment. Moreover, for a long time, the main body responsible for sludge treatment is unclear and its responsibilities have not been divided, which has led to a reduction in its operability and execution, and supervision has no way of talking about.
Experts suggest that the state should issue engineering technical specifications and environmental protection standards corresponding to sludge treatment technologies. Local governments should also formulate corresponding supporting policies in terms of construction investment, comprehensive utilization of sludge, charges, and price subsidies. When formulating policies, the state must also consider the upstream and downstream industries. There must be preferential policies for investment and financing to ensure the investment of funds; there must also be standards for downstream production of clean energy and fertilizers, which will open the way for sludge disposal. Only in this way can we truly achieve the stabilization, harmlessness, reduction, and scale treatment of sludge.
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