420 million kWh of electricity will be generated annually! How to "turn garbage into treasure"? This is done in Xi'an

Where did the garbage we sorted in daily life go? How are they disposed of? What can the resource utilization of garbage based on the harmless waste treatment facilities bring us?

Recently, the reporter walked into Gaoling District, Xi'anCircular Economy Industrial Park, through on-site visits to park enterprises, we can truly feel the magic of garbage turning waste into treasure.

01 Incineration of domestic waste can generate electricity by harmless treatment and incineration. The fermentation leachate can also be recycled for production water

"The park is still under construction, and the two companies that have been put into use are domestic waste harmless treatment plants andHarmless treatment of kitchen wastefactory. "A staff member of the Gaoling District Circular Economy Industrial Park Office told reporters that the Xi'an Gaoling Domestic Waste Harmless Treatment Plant that is going to be invested, constructed and operated by Xi'an Jingwei Kangheng Environmental Energy Co., Ltd.

When you walk into the Xi'an Gaoling Domestic Waste Harmless Treatment Factory, what catches your eyes is a clean and tidy environment. As a garbage disposal plant, there is no odor in the air. In response, the staff explained: "The entire process of waste incineration is sealed and there will be no odor under normal circumstances." In the central control room of the factory, technicians are remotely controlling the operation of incineration boilers, generators and other equipment in combination with surveillance video and real-time data. During the video surveillance, the reporter saw that garbage trucks were constantly dumping domestic garbage in the garbage storage pit on the unloading table.

In the garbage hoist control room on the 6th floor of the factory, staff member Shi Mengzhe was operating the crane grab bucket, grabbing the fermented garbage to the feed outlet, and sending it to the garbage incinerator for incineration. "If this 'claw' goes down, you can catch about 10 tons of garbage." Xu Yajun, deputy general manager of Xi'an Jingwei Kangheng Environmental Energy Co., Ltd., told reporters that the garbage sent just now has a large moisture content and is difficult to burn, so it needs to be fermented in the garbage storage pit.

"The leachate produced by waste fermentation is processed by the sewage treatment station in the factory and is completely recycled for production water, with zero emissions from the outside." Xu Yajun explained that the high-temperature flue gas generated by waste incineration can generate electricity through the steam recovered by waste heat boiler, and can also provide heat to users. After the flue gas purification system, the flue gas is treated with desulfurization, denitrification, dust removal and other processes. All environmental protection indicators fully comply with national standards and can be directly discharged.

“Waste incineration power generation, not only can effectively avoid secondary pollution, but also improve power supply. "Xu Yajun said that except for a small part of the electricity sent for self-use of the factory, all the remaining electricity is input to the State Grid. In terms of heating, it can meet the heat used by 10,000 households. According to the treatment scale of 2,250 tons/day, their annual power generation can reach 420 million kWh and the grid power capacity reaches 370 million kWh. The slag produced by incineration can be made into bricks and other building materials after being processed by the supporting slag treatment plant... Relying on the harmless treatment of garbage, they have truly turned domestic waste into treasures.

02 The harmless treatment of kitchen waste is separated by three-phase separation to separate slurry, organic solid slag and industrial-grade mixed oil

"The harmless treatment plant of kitchen waste is located in the middle of the core area of the park, covering an area of 60 acres and a daily treatment capacity of 500 tons, of which 300 tons are catering waste and 200 tons are kitchen waste." According to reports, the harmless treatment plant of Xi'an Gaoling Kitchen Waste is built and operated by Kangrun Environmental Protection Engineering Co., Ltd., Gaoling District, Xi'an. After it is put into production in April 2021, it is currently mainly receiving kitchen waste from nine areas including Gaoling District, Weiyang District, Yanliang District, Lintong District, and Xincheng District.

"After the project is completed and put into production, our factory's resource utilization rate has reached more than 98%, and the reduction has reached more than 90%. "Zhang Duling, general manager of Kangrun Environmental Protection Engineering Co., Ltd., Gaoling, Xi'an City, said that through the "pretreatment + anaerobic fermentation in the wet room medium temperature + biogas power generation" process, they can maximize the recycling of waste oil, organic matter, carbon, nitrogen and other resources in kitchen waste.

According to reports, after being sent to the treatment plant, kitchen waste will be pre-treated. Large impurities such as plastics and chopsticks will be separated out and inoculated to the harmless treatment plant for domestic waste. After the remaining organic matter is slurried, it is separated by heating treatment by three-phase (water phase, solid phase, and oil phase) to separate the slurry, organic solid slag and industrial-grade mixed oil. Among them, industrial-grade mixed oil can be provided to biodiesel plants to make biodiesel oil. The biogas generated by fermentation of the slurry into the anaerobic tank can be used to burn boilers and generate electricity, and provide heat and electricity for the factory area. The solid residue can be made into biological bacteria after being fermented through its own technology. After adding special bacterial strains, it can be dehydrated and dried and sold to feed additive companies or breeding companies.

"Garbage is a resource placed in the wrong place. After resource processing, it can return to society and play a role again." Zhang Duling said that relying on the current scale, they process 182,500 tons of kitchen waste annually and produce more than 5,000 tons of industrial-grade mixed oil annually. It is a project with a high degree of resource utilization in China. As the circular economy receives more and more attention, they responded to the call for garbage classification and used efficient and environmentally friendly waste treatment technology to help the development of the circular economy, which not only "reduces burden" for cities, but also provides energy for society, and also provides cities with blue skies and white clouds, and helps achieve the goal of "carbon neutrality and carbon meet standards". It is very meaningful.

03 Plan the "three major functional areas" to vigorously introduce high-end elements and continuously improve the circular economy chain

"The Xi'an Gaoling District Circular Economy Industrial Park under construction is located in the enclosed area of Jingkun Expressway, National Highway 210, National Highway 310 and Weiyang Road, with an area of more than 1,800 mu." A relevant person in charge of the Planning Section of the Gaoling Branch of the Xi'an Natural Resources and Planning Bureau told reporters that as a major people's livelihood project, the park plans to include the "three functional areas" of the centralized area for waste incineration and reuse, the high-tech circular industry demonstration area, and the centralized area for wastewater disposal and recycled water utilization.

With the continuous use of domestic waste and kitchen waste harmless treatment plants, the industrial park is currently steadily promoting the construction of Gaoling Second Sewage Treatment Plant and Gaoling Sludge Disposal Project. Among them, the investment in the Gaoling Second Sewage Treatment Plant project is estimated to be about 745 million yuan, the treatment scale can reach 100,000 tons/day, the water collection area is about 46 square kilometers, and the population is 200,000, and the long-term project is expected to reach 452,000 people; the investment in the Gaoling Sludge Safety Disposal Project project is estimated to be about 474 million yuan, and the disposal scale is 400 tons/day. The service scope is mainly to deal with sludge produced in Gaoling District, and it mainly accepts sludge from the first, second and eighth sewage treatment plants of Gaoling, a total of about 230 tons/day. The surplus part can accept sludge from other sources.

Medical waste disposal, as the "end" of epidemic prevention and control, is related to urban public safety. The Xi'an Medical Waste Centralized Disposal Center project with a total investment of 300 million yuan will be officially started in the Gaoling District Circular Economy Industrial Park in August this year, and it is expected to complete an investment of 100 million yuan this year. After completion in 2023, we will improve the environmental conditions of the medical and health industry in Xi'an, protect the natural environment on which people rely on to survive, and achieve sustainable economic and social development in terms of consolidating the results of epidemic prevention and control, strengthening the emergency command system for epidemic prevention, ensuring that all medical waste should be collected and all should be taken, and properly carrying out harmless and safe disposal.

In accordance with the strategic deployment of Gaoling District to build a "urban supply guarantee sector", Gaoling District Circular Economy Industrial Park will vigorously introduce high-end elements of the circular economy industry, further improve the circular economy chain, and ensure the efficient operation of the circular economy industrial park. On the basis of doing a good job in the classification, centralized recycling and standardized treatment of domestic waste, kitchen waste, and medical waste, it will actively develop derivative economies such as tourism and research and study integration. While significantly improving the ecological environment, it will accelerate the development of the circular economy and provide strong guarantees for urban operation.

Text: Xi'an Press All Media Reporter Liu Xiaoyun