Introduction to Technologies for the Resource Utilization of Organic Hazardous Waste

According to the National Catalogue of Hazardous Wastes (2025 Edition) and relevant technical specifications, the treatment of hazardous wastes must be carried out in strict accordance with their hazardous characteristics—such as toxicity, corrosivity, flammability, reactivity, and infectivity—as well as their chemical composition, under a classified management system. The oxygen‑free pyrolysis technology developed by Jufeng Company is primarily suited for organic wastes, including those containing organic solvents, waste plastics, diatomaceous earth, metal scrap, and medical waste.

Anaerobic pyrolysis, also known as dry distillation or cracking, is a thermochemical decomposition process in which organic materials are heated indirectly under anaerobic or hypoxic conditions at high temperatures—typically between 350 and 800°C. The core principle involves using heat to break the chemical bonds of large‑molecular organic compounds, transforming them into small‑molecule combustible gases, liquid oils, and solid residues.

The fundamental difference between anaerobic pyrolysis and direct incineration (aerobic combustion) lies in the following: Anaerobic pyrolysis takes place in an oxygen‑free or oxygen‑deficient environment, where decomposition reactions occur, yielding fuel (gas and oil) and carbon. Incineration, on the other hand, occurs in an oxygen‑rich environment, where oxidation reactions take place, producing CO₂ and H₂O while directly releasing heat.

Process Flow of Hazardous Waste Pyrolysis for Harmless Treatment

I. Preprocessing and Feeding System:

Preprocessing: Based on the physical state of hazardous waste (solid, semi‑solid, or liquid), perform preprocessing operations such as crushing, mixing, blending, and dewatering to achieve a uniform particle size and calorific value suitable for pyrolysis. Feeding: Use sealed feeding devices such as screw extrusion feeders or hydraulic pushers to ensure a continuous and stable flow of material into the pyrolysis furnace while preventing air ingress and maintaining an oxygen‑free environment within the system.

2. Pyrolysis Reaction System:

Pre‑treated organic hazardous waste enters the pyrolysis reactor (rotary kiln, fixed bed, fluidized bed, etc.) from the top or side. The reactor is heated by an external fuel source—such as natural gas or self‑produced pyrolysis gas—and the internal temperature is precisely controlled within a preset range of 400–800°C. In an oxygen‑free environment, organic materials undergo thermal decomposition.

3. Product Separation and Collection System:

The pyrolysis products (oil–gas mixture) are discharged from the reactor and enter the condensation and separation system. 1. First, dust carried along with the stream is removed using a cyclone separator and similar equipment. 2. The mixture then flows into a condenser, where the condensable components—such as heavy oil and light oil—are condensed and collected in oil tanks. 3. The non-condensable fraction consists of pyrolysis synthesis gas, primarily composed of H₂, CH₄, CO, and other gases, which are collected in a gas holder or directly routed to the combustion system.

4. Residue Treatment System:

The solid residues remaining after pyrolysis—primarily carbon black, inorganic salts, and metal oxides—are discharged from the bottom of the reactor. After being cooled via a water seal or a screw discharge machine, the residues are subjected to testing. Since harmful substances such as heavy metals are immobilized within the residues and the organic content is extremely low, once they have been verified to meet the relevant standards, they can be utilized as resource‑based materials, such as building material additives, or safely landfilled.

5. Flue Gas Treatment System:

The combustible gases produced during pyrolysis are typically routed to a secondary combustion chamber, where they undergo complete combustion at high temperatures (≥1100°C) in the presence of ample air, effectively destroying any potentially harmful substances such as dioxins. The high‑temperature flue gas generated by combustion then enters a waste heat boiler to recover energy (producing steam or generating electricity). Next, the flue gas passes through a rapid quenching tower, where it is rapidly cooled to below 200°C within just one second, preventing the re‑synthesis of dioxins. Finally, the flue gas sequentially flows through a baghouse dust collector (to remove particulate matter), a scrubber (to remove acidic gases such as HCl and SO₂), and an activated carbon adsorption tower (to adsorb heavy metals and trace amounts of dioxins), ensuring that the final emissions meet or even exceed environmental standards.

Partial Reaction Equations for Hazardous Waste Pyrolysis Technology for Harmless Treatment

The composition of organic hazardous waste is extremely complex. Taking representative polymers (such as polyethylene PE found in plastics), cellulose, and typical organic compounds as examples:

Macromolecular chain scission (cleavage):

This is the primary reaction of pyrolysis, in which large‑molecular carbon chains undergo random cleavage under the influence of thermal energy, yielding small‑molecule alkanes, alkenes, and other hydrocarbons.

(C₆H₁₀O₅)n (cellulose/biomass) → Pyrolysis → Various small-molecule gases (H₂, CH₄, CO, etc.) + Tar (liquid hydrocarbons) + Coke

(C₂H₄)n (polyethylene) → Pyrolysis → C₂H₆ (ethane) + C₃H₈ (propane) + C₂H₄ (ethylene) + ... + heavy oil + carbon black

Dehydrogenation reaction:

In organic molecules, hydrogen atoms are removed to form unsaturated hydrocarbons and hydrogen gas.

C₂H₆ (ethane) → C₂H₄ (ethylene) + H₂

Aromatization reaction:

Small-molecule olefins and other compounds undergo cyclization and dehydrogenation reactions to form aromatic hydrocarbons such as benzene and toluene, which are important components of pyrolysis oil.

3CH₂=CH₂ (Ethylene) → C₆H₆ (Benzene) + 3H₂

Water–gas shift reaction:

It occurs when the material contains moisture or oxygen‑containing functional groups.

C + H₂O → CO + H₂

Transformation reaction:

CO + H₂O → CO₂ + H₂

Secondary reaction (at high temperatures):

Primary products will undergo further reactions such as cracking and condensation.

Heavy tar → Light oil products + Gas + Coke

Small-molecule hydrocarbons → Carbon black + H₂

Equipment for the Treatment of Organic Hazardous Waste – Some Photos

Thermal Cracking Equipment for Organic Pesticide Waste Salt from Pesticide Plants

Oiled diatomaceous earth and oiled soil oxygen‑free thermal cracking equipment  

Medical Waste Chain-Plate Pyrolysis Treatment Equipment