[Chinese Mainland] The First Guideline for the Development of Industrial Park Wastewater Discharge Standards Takes Effect on September 1: HJ 945.4—2026 Fills the Gap for Dedicated Standards

Key Fact: The Ministry of Ecology and Environment approved and issued the Technical Guideline for the Development of Water Pollutant Discharge Standards for Centralized Wastewater Treatment Facilities in Industrial Parks (HJ 945.4—2026), effective from 2026年9月1日, as a first-time release. Previously, centralized wastewater treatment facilities in China's industrial parks lacked dedicated discharge standards and mainly referred to the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918). The guideline uniformly specifies the basic principles, technical routes, classification methods, and text structure for standard development.

I. The Question That Has Long Been Avoided

Centralized wastewater treatment facilities in industrial parks are a rather unique presence in China's wastewater treatment system: they do not treat typical domestic sewage, yet have long applied discharge standards designed for domestic sewage; they do not serve residents, yet are regulated according to the logic of municipal wastewater treatment plants.

This mismatch has existed for a long time. The water quality characteristics of park wastewater—complex composition, poor biodegradability, high salinity, and possible presence of heavy metals and characteristic organic pollutants—differ greatly from municipal sewage. Using municipal standards to regulate them results in either mismatched indicators (park-specific characteristic pollutants are not on the limit list) or mismatched limits (conventional indicators are too loose to reflect the treatment requirements of industrial parks). The result is that localities have explored on their own, standards have varied widely, enterprises have been at a loss, and regulators have lacked a unified basis.

The release of HJ 945.4—2026 is precisely intended to establish a set of rules for this "each doing its own thing" development process: it does not directly specify discharge limits, but rather specifies how the limits should be set.

II. What the Guideline Specifies

As a "standard for standards," the content framework of HJ 945.4—2026 includes the following parts:

• Basic principles and technical routes—specifying the overall principles to be followed when developing water pollutant discharge standards for centralized wastewater treatment facilities in industrial parks, as well as the complete technical path from status quo investigation to limit determination.
• Development needs and classification—the leading industries, wastewater characteristics, and environmental functions of receiving water bodies vary greatly among different parks. The guideline requires classified treatment to avoid a one-size-fits-all approach.
• Determination of main technical content—including the drafting methods for core provisions such as screening of control items, methods for determining discharge limits, and requirements for monitoring and implementation supervision.
• Benefit and feasibility analysis of standard implementation—requiring comprehensive demonstration of environmental benefits, technical feasibility, and economic costs to avoid setting limits that "look good but cannot be achieved."
• Standard text structure and development notes—unifying the text structure and main content requirements of development notes, so that local standards are comparable and reviewable.

III. Why a "Guideline" Rather Than a "Standard"

This point deserves special explanation. The Ministry of Ecology and Environment did not choose to directly issue a nationally unified discharge standard for industrial park wastewater, but instead first issued a development guideline. Behind this is a pragmatic judgment about real-world complexity:

• Parks differ too greatly to unify limits—the characteristic pollutants of chemical parks are almost completely different from those of electroplating parks, printing and dyeing parks, and pharmaceutical parks. Forcibly unifying limits is neither scientific nor feasible.
• Delegating development authority to localities while centralizing methodology—by standardizing steps such as "needs analysis and classification," "determination of technical content," and "benefit and feasibility analysis," the guideline ensures that localities adapt to local conditions under the same methodology, retaining flexibility while preventing arbitrariness in standard development.
• Building the skeleton for the subsequent standards system—with a unified development method, park standards subsequently issued by localities can be compared horizontally and connected vertically, gradually forming a complete system.

In other words, this is an institutional design of establishing the rules first, then filling in the content.

IV. The Regulatory Environment Is Tightening Overall

HJ 945.4—2026 was not issued in isolation, but is part of the intensive adjustment of water environment regulatory systems in recent months:

• Ecological Environment Code of the People's Republic of China — effective from 2026年8月15日, ten laws including the Water Pollution Prevention and Control Law were simultaneously repealed. Article 302 explicitly stipulates that the sewage treatment fees collected shall be used for facility construction, operation, maintenance and harmless sludge treatment and disposal, and shall not be misappropriated for other purposes.
• Regulations on Urban Drainage and Sewage Treatment (State Council Decree No. 843) — effective simultaneously from 2026年8月15日, Article 33 stipulates that the sewage treatment fee rate shall not be lower than the cost of normal operation of sewage treatment facilities, with the shortfall subsidized by local governments; Article 37 stipulates that industrial production, urban greening, road cleaning, etc. shall give priority to the use of Reclaimed Water.
• GB 18918 Amendment — from 2026年3月1日, instantaneous value limits for four major pollutants (COD, ammonia nitrogen, Total Nitrogen, and Total Phosphorus) were added for urban sewage plants, narrowing the effluent compliance determination window from "daily average" to "real-time."

With these three lines advancing in parallel, the sources of compliance pressure for Industrial Park wastewater treatment have expanded from a single "end-of-pipe limit" to a three-dimensional constraint of "standards + laws + costs."

V. Three Practical Impacts on the Industry

• The upgrade pathway for park sewage plants will become clearer — with a unified methodology for standard formulation, the pace of local standard issuance will accelerate. Park sewage plants will shift from "not knowing what to upgrade to" to "knowing how the limits will be derived," providing a clearer basis for designing upgrade plans.
• Demand for characteristic pollutant treatment is rising — classified management means that local standards will add characteristic pollutant control items targeting dominant industries. Technologies for refractory and high-salinity wastewater, such as Advanced Oxidation, specialized adsorption, and salt separation and resource recovery, will gain greater application space.
• Monitoring and data capabilities become a prerequisite for compliance — both standard classification and limit determination are built on a solid investigation of influent water quality. Industrial Parks and enterprises need to establish comprehensive water quality ledgers and online monitoring systems, which directly drives demand for online monitoring instruments, SCADA platforms, and Smart Water services.

VI. TIANYI TECH's Perspective

TIANYI TECH believes that HJ 945.4—2026 may appear to be merely a "procedural" guideline, but its actual impact could be more far-reaching than a specific standard — it marks that Industrial Park wastewater treatment has bid farewell to the ambiguous state of "reference implementation" and entered a refined stage of "one park, one standard; classified management." For technology service enterprises, the real threshold is no longer knowing the standard limits, but being able to participate in and support the technical justification behind the limits: influent water quality characterization, feasible technology comparison and selection, and cost-benefit analysis. This is precisely the watershed between being a "construction crew" and becoming a "technology solution provider."

About TIANYI LIMITED

TIANYI LIMITED specializes in the fields of wastewater treatment, Reclaimed Water Reuse, and water resource recycling, providing one-stop services from process consulting, solution design, equipment integration, and engineering implementation to smart operation and maintenance. The company is committed to promoting wastewater resource recovery through technological innovation, helping industrial enterprises and municipal clients achieve multiple goals of water conservation and carbon reduction, compliant discharge, and sustainable development.

Source: Standard publication announcements on the official website of the Ministry of Ecology and Environment of the People's Republic of China (HJ 945.4—2026, implemented on 2026年9月1日), and comprehensive compilation of the full text of the Regulations on Urban Drainage and Sewage Treatment (State Council Decree No. 843) republished by the Tianjin Water Conservation and Water Treatment Research Association