Both major documents emphasize that it is necessary to build a "green and low-carbon benchmark plant for sewage treatment", what is a "benchmark"?|Sewage treatment with synergy of pollution reduction and carbon reduction(1)
On January 11, the "Opinions of the Central Committee of the Communist Party of China and the State Council on Comprehensively Promoting the Construction of a Beautiful China" (hereinafter referred to as the "Opinions") was released, proposing to "build a green and low-carbon benchmark plant for sewage treatment".
Not long ago, the National Development and Reform Commission, the Ministry of Housing and Urban-Rural Development, and the Ministry of Ecology and Environment jointly issued the "Implementation Opinions on Promoting the Synergy of Pollution Reduction and Carbon Reduction in Sewage Treatment" (Fa Gai Huan Zi [2023] No. 1714, hereinafter referred to as the "Implementation Opinions"), which has a more detailed explanation of this, that is, "100 green and low-carbon benchmark plants for sewage treatment with efficient recycling of energy resources will be built in 2025".
What is a "green and low-carbon benchmark" and what are the evaluation criteria? At present, there is no further explanation at the national level, but many enterprises are eager to try, and the enthusiasm to participate is very high, and professional analysis and guidance are urgently needed. To this end, the reporter interviewed experts in the field of water environment to discuss this issue.
Grasping the two keywords of "green" and "low-carbon" is indispensable
The concept of "green and low-carbon benchmark plants for sewage treatment" first appeared in the "Action to Improve the Level of Environmental Infrastructure Construction (2023-2025)" jointly issued by the National Development and Reform Commission and other three ministries and commissions in July 2023. The recently issued "Implementation Opinions" gave a timetable for the first time.
Wang Jiazhuo, deputy chief engineer of the China Academy of Urban Planning and Design, president of the Ecological Municipal Institute of the Chinese Academy of Planning and Design (Beijing) Planning and Design Co., Ltd., and a professor-level senior engineer, told this reporter: "Considering that there are still two years to go until 2025, these green and low-carbon benchmark plants should be selected from the sewage treatment plants that have been built. To select these 'benchmark factories', the selection criteria are very important. Obviously, there are two key words here, one is low-carbon, and the other is green. ”
The importance of "low carbon" is undeniable. Experts believe that compared with the previous documents on improving the quality and efficiency of sewage treatment, the biggest difference between the "Implementation Opinions" released this time is that it pays more attention to the carbon peak and carbon neutrality strategy and global warming.
The "Implementation Opinions" clearly put forward the reduction of greenhouse gas emissions. Scientifically carry out dredging and management of sewage pipe networks to reduce methane emissions. Support the use of biodegradable wastewater from upstream production enterprises as a supplement to the carbon source of downstream sewage treatment plants in accordance with laws and regulations. Strengthen the application of low-carbon technologies such as high-efficiency nitrogen and phosphorus removal to reduce the escape of nitrous oxide in the denitrification process.
"To measure whether a wastewater treatment plant is low-carbon, its carbon emissions must be assessed and measured, and there is no national standard for this," Wang said. Some time ago, the "Carbon Emission Reduction Assessment Standard for Urban Sewage Treatment Plants" issued by the China Urban Water Supply and Drainage Association can be used as a reference. ”
In addition, in 2022, the China Environmental Protection Industry Association issued the first low-carbon group standard in the field of sewage treatment in China - "Technical Specifications for Low-carbon Operation Evaluation of Sewage Treatment Plants" (T/CAEPI49 - 2022). This standard standardizes the carbon emission accounting methods and evaluation methods of sewage treatment enterprises, and can also be used as a reference.
At the same time, Wang Jiazhuo emphasized: "The green and low-carbon benchmark plant for sewage treatment is not equal to a low-carbon sewage treatment plant, and the relevant indicators of 'green' need to be considered in the selection criteria." The document clearly states that 'efficient recycling of energy resources' points out the general direction for the selection of 'green' related indicators. ”
What are the "clues" in the document that point to the direction of the "benchmark"?
The "Implementation Opinions" put forward that carrying out energy-saving and carbon-reduction transformation, reducing greenhouse gas emissions, and increasing scientific and technological support contain the connotation of "benchmark factory".
Hao Xiaoguang, an expert member of the Shanxi Provincial Urban Drainage Professional Committee, told reporters: "In terms of 'low carbon', under the premise of clarifying reasonable emission standards, the sewage treatment plant applying for benchmarking should have the ability to account for carbon emissions in the whole process." There is a complete monitoring and accounting system for the carbon emissions in the whole process of sewage treatment, which can clarify the carbon emissions of each link, so as to have the basis for low-carbon operation. Secondly, sewage treatment plants should take targeted greenhouse gas emission reduction measures and achieve certain emission reduction effects. For example, the transformation or new low-carbon operation of equipment and facilities, in the direction of resource recycling, new energy generation and utilization of investment and effectiveness. Finally, the sewage treatment plant should establish a refined management and control system, and apply data technology to complete low-carbon and energy-saving operation. ”
A senior expert in the field of water environment told reporters: "We analyzed the mainstream process technology of the sewage treatment plant in the Yangtze River basin and found that if it is only measured according to the water quality index, microfiltration, ultrafiltration, reverse osmosis and other membrane methods are good methods. However, considering carbon emissions, the membrane method uses power, and the power consumption is naturally more than that of the non-membrane method. From this point of view, the membrane method is not an ideal method for low carbon, and traditional methods such as microflocculation filtration have a much lower carbon footprint than the membrane method. Therefore, 'biochemical treatment + micro-flocculation filtration' can reduce carbon more than 'biochemical treatment + membrane filtration'. How to choose, it is necessary to further weigh the arguments. At present, in the selection of these 100 sewage treatment benchmark plants, there is still a lack of more detailed, operable, and followable supporting rules. It is not clear how much energy consumption, chemical use, and carbon emissions of the benchmark plant must reach to meet the requirements, but the general direction has been clear. ”
Wang Jiazhuo believes that the "Implementation Opinions" also put forward that it is necessary to "speed up the formulation of the national standard of "Collaborative Carbon Reduction Performance Evaluation of Urban Sewage Treatment", and carry out performance evaluation work in a timely manner. "Encourage benchmark factories to implement the integrated professional operation and maintenance of 'plant-network-river (lake)', and carry out the first trial of new ideas, new technologies and new equipment. "This also sets the stage for wastewater treatment plants that are interested in applying to become a benchmark.
