Common Animal Harmless Treatment Technologies in China

It is particularly important to select a treatment process that is technologically advanced and practical, with economical and simple equipment and low operating costs. In China, several commonly used harmless treatment technologies include:

It is particularly important to select a treatment process that is technologically advanced and practical, with economical and simple equipment and low operating costs. In China, several commonly used harmless treatment technologies include:
I. Incineration Disposal
　　Incineration is a treatment method that involves burning animal carcasses and can be applied to the harmless disposal of all dead animals. It includes direct incineration and carbonization incineration.
　　Technical Overview: Direct incineration involves using the heat from auxiliary fuels to directly heat and decompose deceased animals under oxygen‑rich conditions, ultimately converting them into ash and slag. Carbonization incineration, based on the principle of pyrolysis, transforms deceased animals into high‑temperature flue gases and stable solid char under anaerobic, high‑temperature conditions, with the resulting flue gases undergoing further combustion as part of the treatment process.
Incineration-based sterilization achieves significant volume reduction, operates rapidly, and requires a small footprint; the resulting solid carbonized residues can be recovered and reused. However, it entails high initial capital investment, substantial energy consumption, and relatively high operating costs.
　　Technical requirements: The carbonization temperature shall be maintained within the range of 550°C to 650°C, and the incineration temperature shall not be lower than 850°C. Prior to carbonization and incineration, deceased animals may be frozen and mechanically crushed, which can reduce carbonization time and lower operating costs. The carbonization furnace shall comply with the requirements specified in “Technical Requirements for Medical Waste Incinerators” (GB 19218).
　　Technical risks: During the carbonization process, flue gases containing pollutants such as particulate matter, hydrogen chloride, sulfur dioxide, nitrogen oxides, carbon monoxide, and dioxins are generated. Large dead animals must be frozen and crushed, which imposes stringent biosecurity requirements.
II. Chemical Treatment and Disposal
　　Rendering is a method of treating deceased animals using specialized equipment under conditions of high temperature and pressure, and it can be applied to the harmless disposal of all dead animals. It includes wet rendering, dry rendering, and alkaline hydrolysis.
1. Drying method:
　　Technology Overview: Dry rendering involves processing deceased animals within a sealed, high-pressure vessel by circulating a high-temperature heat source through the jacket to heat the material, yielding stable, sterilized products such as animal fats and dried animal proteins. This dry‑rendering technology offers relatively rapid processing, high product recovery rates, and a compact footprint; however, it entails substantial upfront capital investment, significant energy consumption, and slightly higher operating costs.
Technical requirements: The temperature during the drying and rendering process shall be no less than 134°C, the pressure no less than 0.3 MPa, and the duration no less than 4 hours. Prior to drying and rendering, dead animals may be frozen and mechanically broken down, which can reduce processing time and lower operating costs.
　　Technical risks: The thermal‑drying and rendering process must be carried out in high‑temperature, high‑pressure vessels, requiring strict adherence to safety protocols during operation. The treatment process is complex and places demanding requirements on operators.
2. Humidification method
　　Technology Overview: Hydrothermal processing involves subjecting deceased animals to high‑temperature, high‑pressure sterilization within a sealed, pressurized vessel by introducing superheated saturated steam. Following this, solid–liquid separation is performed: the solid fraction is crushed and dried, while the liquid phase undergoes oil–water separation and wastewater treatment. This hydrothermal processing technology offers rapid treatment, high product recovery rates, and a relatively small facility footprint; however, it requires a substantial initial capital investment and consumes comparatively little energy.
　　Technical requirements: The treatment temperature shall be no lower than 134°C, the pressure no lower than 0.3 MPa, and the duration no less than 4 hours. Prior to rendering, dead animals do not need to be comminuted, and the rendering time should be adjusted according to the size of the material and the pressure.
　　Technical risks: Humidification treatment must be carried out in a high-temperature, high-pressure vessel, and safety precautions must be observed during operation. The treatment process is complex and places high demands on operators.
3. Alkaline Hydrolysis Method
　　Technology Overview: This is a disposal process in which sodium hydroxide or potassium hydroxide is added to a sealed, high-pressure vessel to dissolve deceased animals into a sterile liquid containing peptides, amino acids, carbohydrates, soap-like substances, and other solid residues, followed by subsequent treatment. Alkaline hydrolysis offers relatively rapid processing, high product recoverability, a small facility footprint, and lower initial capital costs; however, it entails substantial energy consumption and higher operating expenses.
　　Technical requirements: Alkali hydrolysis must be carried out in a high-temperature, high-pressure vessel, and the added alkali is corrosive; safety precautions must be observed during operation.
　　Technical risks: The treatment process is complex and places high demands on operators. The technologies required for the utilization or disposal of the resulting sterile liquid waste and other solid residues are also highly demanding.
III. Biological Treatment
　　Biological disposal utilizes bio‑fermentation technology to treat animal carcasses and is applicable only to the harmless treatment of animals that have died from causes other than animal diseases. Following high‑temperature pre‑treatment, biological disposal can be employed for the harmless treatment of all dead animals.
　　Technical Overview: In the dead-animal reactor, microbial inocula are added along with auxiliary materials such as sawdust, straw, corn cobs, and rice husks. The cultivation conditions for the microorganisms are artificially simulated to initiate a biological reaction, leading to the decomposition of dead animals into products containing peptides, amino acids, carbohydrates, and saponins. The resulting degradation products are then subjected to downstream processing and comprehensive utilization.
　　Technical requirements: Biological treatment typically operates at temperatures between 55°C and 75°C. The high-temperature pre-treatment shall be conducted at a temperature of no less than 134°C, under a pressure of no less than 0.3 MPa, for a duration of at least 4 hours.
　　Technical risks: High requirements for epidemic prevention. Biological treatment following high-temperature pre‑treatment must be carried out in a high‑temperature, high‑pressure vessel, and safety precautions must be observed during operation. According to Clause 4.4.2.1 of the Ministry of Agriculture’s Document No. 34 [2013], “Animal carcasses and related animal products that have died from major animal epidemics or zoonotic diseases may not be treated using this method”; therefore, the scope of application for this approach is relatively limited.