
The social publicity and education base of domestic waste classification (Renhe base) located in Changsha No.1 waste transfer treatment plant is open to the public. (photo by all-media reporter Huang Qiqing)
As one of the 46 key cities of garbage sorting in China, Changsha has entered the "fast lane" of garbage sorting. The reporter learned from the mayor’s office meeting held on July 27 that by the end of June, the total amount of domestic garbage entering the municipal terminals in the city this year was 124. About 50,000 tons, an increase of 4. 42%, basically the same as the population growth rate, and the average annual growth rate of about 12% in previous years showed a significant slowdown trend.
Where did the kitchen waste and kitchen waste go? How can recyclable garbage be fully reused? In response to the public’s concerns, the reporter learned that Changsha is accelerating the construction of a classified recycling and disposal chain around the goal of garbage reduction, harmlessness and resource utilization. At the same time, Changsha actively introduced social resources to improve the specialization of garbage sorting, recycling and disposal.
More than 1 million tons of kitchen waste "turn waste into treasure"
At about 14: 00 every day, the collection and transportation personnel of Hunan United Kitchen Waste Treatment Co., Ltd. (hereinafter referred to as "United Kitchen") will arrive at Xihu Lou Hotel on Sanyi Avenue on time to recycle the kitchen waste generated at noon that day.
At the scene, two collection and transportation personnel dressed in overalls transported the kitchen waste packed in special recycling bins from the back kitchen one by one, fixed it on the hydraulic device on one side of the collection and transportation vehicle, and dumped the kitchen waste into the special collection vehicle. Subsequently, the collected kitchen waste is transported to the processing center of the joint kitchen, and is subjected to combined sorting, pulping, high-temperature cooking, solid-liquid separation and harmless treatment through special equipment.
Changsha is one of the earliest cities in China to build a collection, transportation and treatment project for kitchen waste. In 2017, Changsha became the first city in China to achieve full coverage of kitchen waste collection and transportation. At present, the city is about 2. 750,000 large, medium and small kitchen waste generating units have signed contracts and commitments for the collection, transportation and disposal of kitchen waste, with a daily collection, transportation and disposal capacity of 800 tons.
The random disposal of kitchen waste not only pollutes the environment, but also may be used by black-hearted vendors to refine "swill oil", which is harmful to public health. Through unified recycling, Changsha separated waste oil, waste water and waste residue from kitchen waste. Among them, the wastewater can be discharged up to the standard after treatment, and the biogas generated in the anaerobic fermentation process can also be used for power generation; The waste residue is made into high-protein feed raw materials by breeding fly maggots and black hydra, and biogas slurry biogas residue can be used as liquid and solid organic fertilizer for agriculture and forestry fertilization; The waste oil is processed into industrial-grade mixed oil and biodiesel for export to Europe.
According to statistics, since it was put into production in 2012, the project has collected and treated more than 1 million tons of kitchen waste, recycled more than 50,000 tons of kitchen waste oil, and the annual power generation exceeded 10 million kWh. The harmless treatment rate and resource utilization rate of kitchen waste reached 100%.
"The composition of kitchen waste in China is different from that in Japan or other developed countries, so it is difficult to copy the experience, which also requires us to study and explore more ways to treat kitchen waste harmlessly and resourcefully." Yi Zhigang, chairman of Hunan United Kitchen Waste Treatment Co., Ltd., said that at present, United Kitchen has more than 20 patented technologies for various kitchen waste treatment, resource utilization inventions and utility models. "Last year, we established the Organic Waste Recycling Research Institute, and introduced two academicians, yu long and Chen Xiaohong, to jointly build a cooperation base in Industry-University-Research, hoping to speed up the development of a set of technology that conforms to the characteristics of kitchen waste in China and can be replicated and promoted."
The first wet waste (kitchen waste) pretreatment project was completed in September.
Wet garbage represented by kitchen waste has high water content and large output, which is the focus of domestic waste classification and reduction. With the continuous expansion of domestic waste classification coverage, domestic waste in more and more communities in Changsha began to realize "dry-wet separation". Unrecoverable dry garbage will become the "raw material" for incineration power generation. What about the wet garbage such as leftovers, vegetable leaves and peels in residents’ homes?
In fact, Changsha took the first step to explore wet garbage disposal last year. At the beginning of 2018, Hunan Renhe Environmental Protection Technology Co., Ltd. carried out special equipment transformation and technical upgrading for two of the existing nine compression positions in Changsha No.1 Waste Transfer Treatment Plant. Wet waste was collected in special warehouses, pretreated with special equipment and transported by special car through squeezing and dehydration. Among them, the sewage will be discharged up to standard after treatment, and the dehydrated residue will be cleaned and burned.
"Of course, this is only a transitional plan for the initial phased design of domestic waste in Changsha." Hu Shiti, general manager of Hunan Renhe Environmental Protection Technology Co., Ltd. told the reporter that the first waste sorting wet waste (kitchen waste) pretreatment terminal facility in the city is under construction. The project is expected to complete the installation of the construction and treatment line in September this year and start trial operation in October, with a daily processing capacity of 2,000 tons.
It is understood that after the project is completed and put into production, the wet waste (kitchen waste) classified by citizens will be crushed, squeezed and separated here by special equipment, and the solid residue will be transported to the municipal solid waste treatment plant by special transfer vehicles for resource utilization; Part of the high-concentration organic wastewater will be treated in a collaborative pilot plant through the anaerobic nitrification system of kitchen waste for initial resource utilization. At the same time, the whole process of the project will be treated in an underground fully enclosed workshop to ensure that the treatment process meets the environmental protection requirements.
Create a garbage collection network online and offline
"We take ‘ Small blue box ’ For the delivery point, with ‘ Little Blue House ’ For the centralized collection point, take ‘ Little blue car ’ For the collection and transportation dispatching system, with ‘ Blue Island ’ A classified collection entity network was built for the sorting center, and with the online technical support of the big data smart cloud platform, a full-process recycling system was built for recyclables and harmful waste in the four categories of domestic waste. " According to Ming Guoying, chairman of Hunan Wanrong Technology Co., Ltd., 216 "Little Blue Houses" have been opened in Changsha County, and more than 5,320 tons of recyclable materials and harmful waste have been recycled and disposed of this year, with a total of 1. More than 50,000 tons. The reporter saw in the "Little Blue Room" that harmful waste and recyclable materials can be classified and recycled here. The administrator will also register points for residents according to the weight of recycled materials, and the points will be entered into the matching "Classified Together" WeChat official account, which can be used to exchange items online.
Garbage is a misplaced resource. It is understood that in order to solve the problem of garbage resource utilization, Wanrong Technology has developed a "three networks integration" recycling system of the Internet, garbage classification network and renewable resource network, as well as a terminal disposal system for urban classified garbage, which fully meets the current garbage classification work. (Changsha Evening News, all-media reporter Tang Chaozhao, intern Wang Jiru)