"The Upstream City, Beautiful Without Waste" Series of Reports - Hechuan District: Garbage, medical waste and sludge are more worry-free to "play" together
With the continuous acceleration of urbanization and the rapid development of industry, the amount of solid waste such as domestic waste, medical waste, and municipal sludge continues to grow.
Chongqing Hechuan Sanfeng New Energy Power Generation Co., Ltd. (hereinafter referred to as Hechuan Sanfeng) has found a "high temperature" convergence point on these three different solid wastes, explored a new path of multi-span collaborative disposal of solid waste, and realized land intensification and energy recycling.
Utilizing the "waste heat" of garbage The annual power generation capacity is 170 million kWh
On January 15th, the modern factory area of Hechuan Sanfeng was clean and tidy, without any peculiar smell, and the dirty scene and the stench of the garbage factory did not appear here. From time to time, domestic garbage transport vehicles arrive, and a large amount of domestic garbage is dumped into the garbage storage pit after being sent to the unloading platform. In the garbage storage pit, the giant steel claws of the garbage crane are flexibly grabbing the garbage, and the garbage piled up in the shape of a hill is stacked in partitions between these grabbings, and the leachate is leached after 3 to 5 days of full fermentation before being put into the incinerator for incineration.
Founded in May 2020 and a subsidiary of Chongqing Sanfeng Environmental Group Co., Ltd., Hechuan Sanfeng is designed to incinerate 1,000 tons of domestic waste per day and generate about 170 million kWh of electricity per year, which can meet the daily electricity needs of more than 80,000 urban households.
Centralized energy supply to improve energy efficiency
Before 2020, the domestic waste in Hechuan District was mainly sanitary landfill, and the leachate and odor generated in the landfill process needed to invest in the construction of pollution control facilities. Municipal sludge is mainly co-disposed of by cement kilns, which is affected by the staggered peak shutdown of the cement industry, resulting in the need for emergency disposal of municipal sludge in the jurisdiction during some time periods. In addition, there are no medical waste disposal facilities in Hechuan District, and existing medical waste can only be transported outside the district for disposal, which increases the cost of disposal. Hechuan District urgently needs to build domestic waste, municipal sludge and medical waste treatment facilities, improve the solid waste treatment system, and make up for shortcomings.
On January 15, in Hechuan District, Chongqing, the waste incineration and disposal of waste in the control center of Hechuan Sanfeng New Energy Power Generation Co., Ltd. were carried out in an orderly manner. Photo by Yu Changhai
The relevant person in charge of the Hechuan District Ecology and Environment Bureau said: "We have successful experience in co-disposal of solid waste in cement kilns, so it should also be feasible to rely on domestic waste incineration power generation projects to co-dispose of municipal sludge and medical waste." ”
Based on this, the Hechuan District Ecological Environment Bureau and Chongqing Sanfeng Environmental Group Co., Ltd. have docked and proposed a model of intensive land use, overall construction and recycling.
"Because of the infectious nature of medical waste, the main disposal method is high temperature sterilization, and the municipal sludge is difficult to use directly due to the high moisture content, so it needs to be dried and disposed of, and the disposal of both types of solid waste requires a heat source, which is our advantage. Feng Jin said that domestic waste incineration will produce a large amount of steam, which can not only be used for power generation, but also provide sufficient heat source for the treatment and disposal of medical waste and municipal sludge.
Co-disposal to improve the level of solid waste utilization
This bold idea became a reality in 2022: relying on the land for domestic waste incineration power generation, Hechuan Sanfeng Construction put into operation a 5 tons/day medical waste treatment project. The municipal sludge disposal project with a capacity of 125 tons/day will also start construction in 2023. By relying on the steam generated by the domestic waste incineration project to provide energy for it, replacing the new boiler burning fossil energy heating mode, the annual use of standard coal can be reduced by 1,700 tons, sulfur dioxide emissions by 3.78 tons, nitrogen oxides by 13.56 tons, and carbon emissions by 5,500 tons.
"Adding medical waste and municipal sludge disposal to the incineration power generation chain will not increase the pressure on the environment. Feng Jin introduced that after the waste gas generated in the process of medical waste and municipal sludge disposal is introduced into the incinerator through the pipeline, it is discharged up to the standard after being treated by pyrolysis + SNCR + semi-dry + dry + activated carbon adsorption + bag dust collector, and the wastewater generated is discharged into the sewage treatment station after disinfection, and is discharged up to the standard after pretreatment + UASB + MBR + STRO+ RO treatment, so as to avoid the repeated construction of pollution control facilities, and effectively reduce the operation and management costs in the later stage through centralized disposal. The disposed medical waste and dried sludge have a high calorific value, and they enter the domestic waste incinerator for incineration, and the incineration process can produce steam again to generate value.
"Compared with the traditional landfill method, this co-disposal model can not only reduce land use, save land resources, but also turn waste into treasure and increase economic benefits. Feng Jin said that the slag after waste incineration is recycled by means of cleaning and screening, and then handed over to downstream enterprises for brick making to realize the resource utilization of solid waste.
"The project has achieved intensive land use, synergy in waste disposal, and recycling in energy. At the same time, it extends the industrial chain of waste incineration, provides a foundation for building a comprehensive venous industry, and is also a new way to solve solid wastes such as domestic garbage, municipal sludge, and medical waste in our district. The relevant person in charge of the Hechuan District Ecological Environment Bureau said that in the next step, Hechuan District will take the construction of a "zero-waste city" as an opportunity to further improve the solid waste treatment and disposal system, continue to improve the level of solid waste resource utilization and harmless disposal capacity, and actively build a "zero-waste city" to build an example of Hechuan.
