I. Project Background

On December 16, 2024, Lanzhi Environmental Protection Company and Rucheng Aidefu Company signed the implementation contract for the Rucheng County 200-ton-per-day low-temperature pyrolysis incineration and resource utilization project for domestic waste. The project involves an additional investment of 30 million yuan. The key construction components of the project include demolishing the existing domestic waste treatment facilities within the current plant and adding a new production line for crushing, drying, pyrolysis, screening, and storage of domestic waste.

The core technology of the production line is provided by Shandong Nuotai Environmental Protection Technology Co., Ltd., a shareholder of Lanzhi Environmental Protection. Building on the existing plant facilities, power supply system, and leachate treatment system, Lanzhi Environmental Protection has carried out a comprehensive redesign and reconfiguration of the entire system, adding key equipment such as a new waste-to-charcoal drying and carbonization system, a flue gas treatment system, an electrical control system, a hot-air furnace system, and a charcoal powder screening and storage system.

The project has completed 168 hours of continuous, stable operation from June 25 to July 3, 2025, and has begun long-term, stable production as of July 8.

 

II. Technical Introduction

(1) Analysis of Technological Advancement

This technology divides the original incineration and gasification process of organic solid waste, which was previously carried out in a single furnace, into three distinct reactors: “drying + low-temperature oxygen-free carbonization + combustion of carbonized oil and gas.” Given the high moisture content and low calorific value characteristic of organic solid waste feedstock, the drying stage not only pre-dries municipal solid waste but also boosts the calorific value of the organic solid waste. The dried material is then subjected to thermal decomposition in a low-temperature oxygen-free carbonization reactor under an atmosphere completely isolated from air at a controlled temperature ranging from 300°C to 500°C. Leveraging the thermal instability of organic compounds present in the solid waste, this process converts the waste into high-calorific carbonized oil and gas (with a calorific value as high as 2800 kcal/Nm³) and biochar residue. Subsequently, the carbonized oil and gas undergoes complete combustion in a carbonized oil and gas combustion furnace. Due to its high calorific value, the adiabatic combustion temperature of the carbonized oil and gas can reach up to 1800°C. Consequently, the high temperature (850–1050°C) within the carbonized oil and gas combustion furnace is easily controllable. The outlet temperature of the high-temperature flue gas after combustion remains above 850°C, and the residence time at this temperature is maintained for at least 2 seconds. Afterwards, this high-temperature flue gas transfers heat via a wall-mounted heat exchanger to both the low-temperature oxygen-free carbonization reactor and the dryer, providing the necessary thermal energy for the oxygen-free carbonization and drying processes of the organic solid waste, thereby ensuring that the entire process runs continuously and stably.

The schematic diagram of the carbonization process for carbon-containing organic solid waste is shown below:

Schematic Diagram of the Carbonization Process for Carbon-Containing Solid Waste

This technical process has the following characteristics:

① Flexible processing capacity: Particularly well-suited for the reduction, harmless treatment, and resource utilization of organic solid wastes in areas not covered by biomass power plants or waste-to-energy plants in county towns, townships, and villages, thereby filling a gap in the organic solid waste treatment market in these regions.

② It has broad requirements regarding the calorific value of organic solid waste (even household waste with a calorific value of approximately 800 kcal/kg—waste that cannot be processed by conventional incineration—can be handled), sorting (raw waste from sanitation vehicles can be fed directly into the system), and particle size (biomass straw and other materials do not need to be pelletized or formed; they can simply be coarsely crushed).

③ Solves the dioxin treatment challenge at its source: The low-temperature, oxygen-free environment inside the carbonization machine eliminates the conditions necessary for the synthesis of dioxins—specifically, the metal oxide catalysts required for dioxin formation. Moreover, by capturing chlorine from the carbonization gas and oil, the concentration of chlorine in the flue gas is significantly reduced, enabling compliance with emission standards for dioxin levels in flue gas (＜0.1 ng/Nm³) without the need to install an activated carbon injection system in the flue gas purification system.

④ The carbonized oil and gas are combusted in the combustion chamber under precisely controlled temperatures (850–1050℃), achieving ultra-low NOx emissions in the flue gas.

⑤ Compared with other production modes such as waste-to-energy incineration and biomass power plants at the same scale, carbonization generates a smaller volume of flue gas, with dust concentrations in the flue gas below 200 mg/Nm³—an order of magnitude lower than the 3–5 g/Nm³ dust concentration typically emitted from grate-fired waste incinerators. After simple baghouse dust removal, various pollutants—including dust and heavy metals—can be brought into compliance with emission standards.

⑥ The solid biochar product exhibits stable properties, with low leaching toxicity of heavy metals (as heavy metals transform from unstable forms such as exchangeable forms to stable forms like residual forms under reducing conditions, nearly all heavy metals are immobilized in the char residue), and low concentrations of pollutants such as chlorine. It can therefore be used for gasification to produce hydrogen.

⑦ For raw materials such as waste, fully mechanized and automated recovery of resources—including iron, copper, aluminum, glass, sand, and gravel—is achieved, enabling 100% resource utilization, 100% reduction in waste volume, and 100% harmless treatment of domestic waste. In comparison to domestic waste, biomass straw-based materials have a simpler composition; after carbonization, the yield of carbon powder can exceed 70%, yielding significant economic benefits.

⑧ The technology is mature and reliable. Currently, our company has already constructed a demonstration project in Yiliang County, Yunnan Province—a 200-ton-per-day low-temperature oxygen-free carbonization facility for municipal solid waste. This project has achieved stable operation over an extended period and has processed approximately over 90,000 tons of municipal solid waste and other types of废弃物. In the Xiong'an New Area, we are building a 100-ton-per-day processing facility for raw materials such as leather, waste textiles, and reeds, which is being supported as a key R&D project under the guidance of relevant national authorities. Meanwhile, in Rucheng County, Hunan Province, we have established a 200-ton-per-day low-temperature carbonization line for municipal solid waste, which has now completed 168 hours of continuous production operation. This technology has undergone extensive industrial verification and demonstrates reliable performance and stability.

For raw materials such as biomass straw, which have a simpler composition compared to municipal solid waste, the biomass carbonization technology transforms the resulting carbonized product into one with properties similar to charcoal. While ensuring that the physical characteristics of the solid material—such as its particle size—are preserved, this process significantly increases the energy density of the material and maximizes the retention of its chemical energy. Taking 1 kg of biomass (on a dry basis) as an example, if its energy content (lower heating value) is 1.0 Q kcal, its energy density would be 1.0 Q kcal/kg. Through indirect heating pyrolysis, this biomass yields 0.3 kg of combustible gas and organic liquids, along with 0.7 kg of biochar. Compared to the original biomass and municipal solid waste, the mass energy density of biochar has increased to 1.28 Q kcal/kg.

In addition to the features mentioned above, biochar has the following advantages compared to conventional biomass:

1) The biochar produced by carbonization exhibits excellent pulverizability and consumes significantly less energy than direct pulverization of conventional biomass, thereby greatly reducing pulverization costs. In addition, the baking process can produce uniform, mm-sized spherical fine particles with outstanding flowability. These particles can be directly fed into existing gasification furnaces through their current feeding systems, enabling reactions to take place inside the furnace. This approach markedly enhances operational stability and equipment reliability.

2) Biochar is hydrophobic, meaning it won't expand, deteriorate, or become moldy when exposed to rain, making it easy to transport and store outdoors.

3) The distributed biochar production and centralized biochar powder gasification model, thanks to the increased volume and energy density of biochar powder, can significantly reduce transportation costs and expand the radius of material transport.

This process breaks through the technological bottlenecks of conventional biomass gasification and can simultaneously handle various types of biomass feedstocks, such as municipal solid waste, agricultural and forestry residues, and kitchen waste. By establishing a diversified and clean energy supply system, it holds significant practical importance for achieving the “dual-carbon” goals.

(2) This technology has been incorporated into the national guidelines for promotion and is currently being explained.

The low-temperature carbonization and incineration technology for biomass (municipal solid waste) and its resource utilization have been included in Guideline No. 13—Integrated Utilization Technologies and Equipment for Organic Waste—of the "National Catalogue of Advanced and Applicable Process Technologies and Equipment for Comprehensive Industrial Resource Utilization (2023 Edition)," specifically the "Oxygen-Free Low-Temperature Continuous Carbon Stripping Pyrolysis Technology for Urban and Rural Municipal Solid Waste." This technology also complies with Item 113—"Complete Sets of Equipment for Small- and Medium-Sized Municipal Solid Waste Incineration and Treatment"—under the "Catalogue of Major Environmental Protection Technologies and Equipment Encouraged for Development by the State (2023 Edition)." The project aligns with Sections 3.1.6—Manufacturing of Equipment for Waste Resource Utilization, 3.2.6—Waste Resource Utilization, and 6.4.8—Construction and Operation of Municipal Solid Waste Collection, Transportation, and Treatment Facilities—in the "Guidance Catalogue for Green and Low-Carbon Transformation Industries (2024 Edition)." Furthermore, it conforms to the energy and material conversion technologies for biomass thermochemical transformation within the resource recycling industry as listed in the "Catalogue of Promoted Green Technologies (2024 Edition)." This project’s technology has been incorporated into the 94th entry of the "List of Demonstration Projects for Advanced Green and Low-Carbon Technologies"—the demonstration project for producing green hydrogen and high-purity carbon dioxide from municipal solid waste.

(3) Economic Analysis

This technology features low investment intensity—approximately 450,000 yuan per ton—and relies relatively little on government subsidies. Moreover, through the sale of carbon powder and recovered resources, it can achieve full self-sufficiency and break even without external financial support. In addition, for waste treatment projects with capacities ranging from 300 to 400 tons per day, the total investment amounts to only about 120 to 180 million yuan, representing half the investment intensity required for waste-to-energy incineration projects, thus giving it strong market competitiveness.

Compared to conventional organic solid-waste treatment technologies, this technology eliminates the need for pre-sorting and produces a uniform charcoal powder that can be directly used as feedstock for downstream gasification, thereby reducing raw-material preprocessing costs. In contrast to the conventional solidification and pelletizing process, which incurs preprocessing costs of 157.8 yuan per ton—primarily due to electricity consumption—the low-temperature carbonization process entails costs of only 52 yuan per ton. Moreover, for the treatment of solid wastes such as biomass municipal waste, the production cost is approximately 45 yuan per ton, significantly lower than the 135.2 yuan per ton required for incineration-based power generation. As a result, this technology greatly enhances the project’s economic viability and feasibility.

 

III. Production and Operation Status of the Rucheng County Domestic Waste Treatment Project

The main equipment for the project was delivered to the project site on April 10, 2025, and installation work commenced immediately. After two months, the installation and single-unit cold commissioning of all equipment were completed, and all equipment has now met the conditions required for production operation.

 

Production plant and main equipment

 

On June 25, the company notified Rucheng County Sanitation Company that the first truckload of domestic waste had been delivered to the site. At 9:00 a.m., the feeding process was initiated. The domestic waste was fed into a shredder and then passed through a feeding system before entering a dryer, where its moisture content was controlled at around 20%. From there, the waste was conveyed via a screw conveyor into a carbonization machine, where an oxygen-free carbonization reaction took place. Under the guidance of our company’s technical team, biomass charcoal powder began to be produced starting at 4:00 p.m. on the 25th. By the 28th, the entire system had entered a stable production phase and ceased supplying fuel to the hot-air furnace (since stable production no longer requires fuel), thus achieving self-sustaining thermal balance.

 

Primary domestic waste

 

 

Project Production and Operation (June 25 – July 3)

 

During the commissioning and operation period (June 25 to July 3, lasting over 168 consecutive hours), approximately 240 tons of municipal solid waste were fed into the system, yielding about 50 tons of carbon powder.

IV. Future Project Planning and Industrial Layout

Based on the future operational and production conditions of the project, our company plans to establish a related technology R&D center at the project site. We will also carry out technological optimization efforts, develop distributed charcoal production, centralized hydrogen production, and build downstream industrial chains such as green ethanol and green ammonia, thereby enhancing economic value-added and improving profitability.