7. Question: Is sludge hazardous waste?

Sludge is divided into domestic sewage sludge and industrial sewage sludge, with industrial sewage sludge further classified into general solid waste and hazardous waste.

Sludge needs to be analyzed; depending on the type of wastewater treated, it contains different pollutants. If it is sludge from domestic wastewater treatment plants and has a low moisture content, it can be disposed of as ordinary solid waste or used for landscaping. Sludge from chemical wastewater treatment plants, on the other hand, must be analyzed first

It has characteristics that allow it to be managed as ordinary solid waste. In the second category, sludge generated by treatment facilities designed specifically for industrial wastewater (or for treating a small amount of domestic sewage) may possess hazardous characteristics; therefore, it is necessary to determine such hazardous characteristics in accordance with the **List of Hazardous Wastes**, the **environmental protection standards – Technical Specifications for Identifying Hazardous Wastes**, and the relevant standards for identifying hazardous wastes. In the third category, public sewage treatment plants whose primary function is to treat domestic wastewater may also handle industrial wastewater, provided that such industrial wastewater can meet the **standards or local regulations regarding pollutant emissions before being discharged into the public sewage treatment system. In such cases, the sludge generated by these public sewage treatment plants can be managed in accordance with the provisions of Article 1. However, when there are significant changes in the discharge of industrial wastewater, the identification of hazardous characteristics shall be carried out in accordance with the provisions of Article 2. In the fourth category, when enterprises discharge industrial wastewater directly or indirectly outside their legal boundaries, the quality of the wastewater discharged must meet **or the local standards for pollutant discharge ； The sludge generated during wastewater treatment is a type of solid waste that is being produced, and its hazardous characteristics need to be determined. In the fifth category, the **List of Hazardous Wastes** issued in 1998 (Document No. Huan Fa [1998] 89) stipulates that clinical waste generated as a result of medical services provided by hospitals, medical centers, and clinics (including sludge from wastewater treatment) is considered hazardous waste (hospital clinical waste HW01). Paragraph 4.3.1 of the \"Emission Standards for Water Pollutants from Medical Institutions\" (GB18466-2005), which was issued in 2005, stipulates more explicitly that \"sludge from screens, septic tanks, and sewage treatment plants constitutes hazardous waste, and should be treated and disposed of as such.\" It is clearly unreasonable for this standard to classify septic tank waste and the like as hazardous waste. Therefore, the **List of Hazardous Wastes** revised and issued in 2008 (Order No. 1 issued by the Ministry of Environmental Protection and the National Development and Reform Commission) has removed \"sludge generated from the treatment of wastewater from medical institutions\" from the 1998 version of the List. In the 2016 and 2021 versions, there was no further mention of the sludge generated from the treatment of wastewater in medical institutions, which is not included in the management of medical waste or hazardous waste.

What is said makes sense; it’s not possible to generalize in this case. It is also necessary to take into account the policy documents issued by local authorities. Here, biochemical sludge is treated as solid waste, while the physical and chemical sludge discharged from sedimentation tanks and oil separation tanks is considered hazardous waste

Combine the **list of hazardous wastes with the assessment process for identifying hazardous wastes; those clearly described in the list are considered hazardous wastes, while those that are vague or uncertain require further assessment