The State Administration for Market Regulation and the Standardization Administration of China released GB/T 25031—2026, Sludge Quality for Brickmaking in Municipal Wastewater Treatment Plant Sludge Disposal, published on July 2, 2026 and effective from February 1, 2027, fully replacing the 2010 edition. The scope of application expands from "fired brick production" to "sludge brickmaking" (including non-fired bricks), and adds requirements for non-fired bricks made from separately incinerated ash, widening the resource recovery pathways. Pollutant limits and testing methods are upgraded in tandem, referencing current environmental standards such as HJ 1091 and GB 14554 to unify quality and pollution control benchmarks for the utilization of sludge in building materials.

1. Standard Upgrade: Full Coverage from "Fired Bricks" to "Brickmaking"

The most notable change in this revision is the comprehensive replacement of "sludge-based fired brick production" in the standard's title and scope with "sludge brickmaking". In terms of terminology, the new edition clarifies that "sludge brickmaking utilization" refers to treating sludge from municipal wastewater treatment plants and using it as a raw material to produce fired bricks and non-fired bricks — a seemingly minor wording change that formally brings rapidly expanding processes such as non-fired bricks and concrete blocks made from sludge incineration ash into the standard's scope, closing the old edition's coverage gap of "governing fired bricks but not non-fired bricks".

The responsible authority remains the Ministry of Housing and Urban-Rural Development, with the Shanghai Municipal Engineering Design Institute (Group) Co., Ltd. leading the drafting, joined by the Shanghai Municipal Drainage Monitoring Station, Shanghai Chengtou Wastewater Treatment, Shanghai Mengzhuan Energy-Saving Material Technology, Tongji University, and the Zibo Municipal Environmental Sanitation Service Center. Having been first issued in 2010, this is its first revision, reflecting the maturity of sludge-to-building-material technology routes and the demand for standardization since the "14th Five-Year Plan" period.

2. Updated Limits: Maximum Limits Set for Nine Categories of Pollutants

The new standard sets clear physical-chemical and pollutant control indicators for sludge used in brickmaking:

• Basic physical-chemical indicators — odor must be "free of irritating smell"; stabilization indicators must comply with GB 18918 or CJ/T 510; physical-chemical indicators limit pH 5~10 and moisture content no greater than 40%, controlling the stability of brick body forming and firing from the source.
• Maximum pollutant limits — calculated on a dry sludge basis (mg/kg): total cadmium 20, total mercury 5, total lead 300, total chromium 1000, total arsenic 75, total nickel 200, total zinc 4000, total copper 1500, mineral oil 3000, aligned with soil and building material environmental risk control requirements, upholding the baseline that "sludge goes into the brick but risks do not leave".
• Testing method upgrade — heavy metal testing shifts fully to the HJ series of methods (e.g., total cadmium/lead using HJ 787, total chromium using HJ 750, multi-element analysis using HJ 766, total nickel/copper using HJ 752), replacing the old edition's GB/T 17134~17141 series, improving data accuracy and regulatory comparability; testing frequency is set at at least once per quarter, with retesting required when the process or influent changes.

It is worth noting that the new edition removes several indicators from the old edition — loss on ignition, radionuclides, volatile phenols, total cyanide, hygienic indicators, and air pollutant emissions. This is not a relaxation of control, but rather a delegation of "brickmaking process emissions" uniformly to dedicated standards such as HJ 1091, Technical Guideline for Pollution Prevention and Control in the Recycling and Utilization of Solid Waste, and GB 14554, Emission Standard for Odor Pollutants, avoiding overlapping and duplicate requirements with clearer responsibilities.

3. Two Key Additions: Non-Fired Bricks and Emission Compliance

The new standard's two major additions in technical provisions directly respond to industry pain points:

• Non-fired bricks from separately incinerated ash — it clarifies that bottom ash from the independent incineration of municipal wastewater treatment plant sludge, as well as fly ash captured by waste heat boilers and dust removal facilities, can be used to produce non-fired bricks such as concrete blocks. This provides a standard basis for the disposal closed loop of "incineration as the backstop + ash-to-building-material utilization", especially benefiting cities with tight land availability and restricted landfill capacity.
• Whole-process emission compliance — it requires that during sludge brickmaking, air pollution control and the hazardous substance content of finished bricks comply with HJ 1091, and that odor emissions comply with GB 14554; it also stipulates that the mass mixing ratio of sludge (on an absolutely dry basis) to total brickmaking raw materials should preferably not exceed 10%, which may be appropriately raised when the process, emissions, and quality permit, balancing resource recovery rates with product safety.

4. Industry Significance: Sludge-to-Building-Material Enters a Fast Track of Standardization

According to industry statistics, China's municipal wastewater treatment plants produce tens of millions of tonnes of dewatered sludge each year, and land application and landfill space are increasingly constrained, making "treating waste with waste and turning sludge into materials" an important outlet. The new national standard, together with the simultaneously implemented Ecological Environment Code and the six-department "15th Five-Year Plan" for Solid Waste Pollution Prevention and Control, forms a policy synergy: at the front end, the primary responsibility of sludge treatment and disposal entities is clarified; in the middle, standards unify sludge quality and product thresholds; and at the end, emission guidelines hold the environmental baseline.

For equipment and engineering enterprises, the standard sends a clear signal — sludge pretreatment stabilization, integrated separate incineration and ash-to-brick production, online monitoring, and compliant emissions will become hard constraints for project compliance, while also nurturing a new market shifting from "single disposal" to "disposal + resource recovery products". For owner entities, before February 1, 2027, they should complete the alignment of sludge quality control systems, testing capacity, and supply chains (brick plant coordination) to avoid the passive situation after implementation of "sludge that is hard to use, or non-compliant when used".

TIANYI TECH Co., Ltd. (TIANYI LIMITED) focuses on technical and engineering services in wastewater treatment and water reuse, continuously following policy and standard developments in sludge resource recovery and reclaimed water utilization, and providing integrated solutions from process design to intelligent operation for cities and industrial parks.

Source: announcements of the State Administration for Market Regulation and the Standardization Administration of China; the standard text of GB/T 25031—2026, Sludge Quality for Brickmaking in Municipal Wastewater Treatment Plant Sludge Disposal; the National Standards Information Public Service Platform.