[Mainland China] Implementation of the Ecological Environment Code Coupled with the Amendment to GB 18918: Municipal Wastewater Treatment Plants Enter the "Instantaneous Value Era"

Key Highlights: 2026年8月15日The "Ecological Environment Code of the People's Republic of China" has officially come into effect, marking the first time water pollution prevention and control has been incorporated into a codified system; the earlier-issued amendment to the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant" (GB 18918—2002) took effect on 2026年3月1日, adding 4 instantaneous values for Chemical Oxygen Demand, ammonia nitrogen, Total Nitrogen, and Total Phosphorus. With the dual reinforcement of the Code and mandatory standards, the industry has officially bid farewell to the old logic of "using daily averages to shield short-term exceedances."

I. Code Implementation: Water Pollution Prevention and Control Enters a Full-Chain Closed Loop

2026年3月12日, the Fourth Session of the 14th National People's Congress deliberated and passed the "Ecological Environment Code of the People's Republic of China," which took effect on 2026年8月15日. This is a landmark event marking China's ecological civilization construction entering a stage of codification, systematization, and rigidity.

For the wastewater treatment industry, the Code proposes full life-cycle closed-loop control of pollution sources, meaning the industry's positioning is shifting from "end-of-pipe treatment" to "full-chain proactive transformation." Complementing this is the simultaneous tightening of the standards system—2026年1月, the Ministry of Ecology and Environment and the State Administration for Market Regulation jointly issued the amendment to the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant" (GB 18918—2002), along with the "Discharge Standard of Water Pollutants for Food Processing and Manufacturing Industry" (GB 46817—2025), the "Discharge Standard of Water Pollutants for Slaughtering and Meat Processing Industry" (GB 13457—2025), and the "Discharge Standard of Water Pollutants for Alcoholic Beverage Manufacturing Industry" (GB 19821—2025), totaling 4 items of national water pollutant discharge standards.

II. Four Major Changes in the Amendment: From "Daily Average Compliance" to "All-Time Compliance"

• Addition of 4 instantaneous values—New instantaneous discharge limits for Chemical Oxygen Demand, ammonia nitrogen, Total Nitrogen, and Total Phosphorus; any instantaneous monitoring exceedance is deemed a violation, and daily averages are no longer allowed to mask short-term water quality fluctuations
• 3 indicators adjusted from daily averages to instantaneous values—pH, color, and fecal coliform count are now judged by instantaneous values, significantly refining regulatory granularity
• Differentiated control of fecal coliform count—Differentiated requirements are set based on different discharge destinations of effluent, avoiding "one-size-fits-all" excessive disinfection in non-reuse scenarios while safeguarding aquatic ecological safety
• Improved exceedance determination provisions—Providing grassroots enforcement with clearer and more operable technical basis

This set of adjustments directly addresses the real pain point of municipal wastewater plant operations: water quality is subject to objective fluctuations. The amendment restructures determination rules based on the principle of seeking truth from facts, both solidifying corporate responsibility and avoiding unreasonable penalties caused by instantaneous disturbances.

III. Three Direct Impacts on the Industry

First, operational precision requirements surge. Instantaneous value control requires wastewater plants to have stronger real-time response capabilities in aeration, chemical dosing, reflux, and other processes. Investment in online monitoring and automatic control will shift from "optional" to "mandatory." Both over-dosing and under-dosing may trigger instantaneous exceedances, and the fault tolerance margin for process control is greatly compressed.

Second, the disinfection process needs redesign. Differentiated control of fecal coliform count forces operators to match disinfection intensity to effluent destinations, seeking a balance between compliance and energy savings. This places higher demands on precise control of ultraviolet disinfection, sodium hypochlorite dosing, and other processes.

Third, existing facilities face a retrofit window. Under the Grade 1A standard, the old benchmarks of COD limit 50 mg/L and ammonia nitrogen 5 mg/L are being superseded by stricter instantaneous determination. For older plants with insufficient equalization tank capacity and weak shock resistance, demand for upgrading and storage/regulation retrofits will continue to be released.

IV. Recommendations for Operators

• Complete online monitoring coverage—Prioritize coverage of the four instantaneous value indicators: COD, ammonia nitrogen, Total Nitrogen, and Total Phosphorus, ensuring data traceability
• Strengthen shock resistance—Smooth influent fluctuations through equalization tank expansion, segregated collection, and source control
• Advance intelligent dosing and precise aeration—Replace empirical values with algorithms to reduce instantaneous exceedance risks and chemical/energy costs
• Establish an early warning–response closed loop—Incorporate instantaneous value warnings into daily scheduling to form a "minute-level" response mechanism

From "wastewater treatment plant" to "water resource circulation node," the dual thrust of policy and standards is already in place. Whoever can first make instantaneous value compliance a daily capability will seize the initiative in the next round of upgrading and resource recovery competition.

About TIANYI TECH

TIANYI LIMITED (Hong Kong TIANYI Technology Co., Ltd.) focuses on industrial water treatment and water resource reuse. Centered on three core products — Industrial Wastewater Treatment AI Agent, Industrial Water Reuse Optimization System, and Digital Twin for Industrial Water Systems — the company provides enterprises with full-chain services from water quality diagnosis and process optimization to intelligent operations, helping customers achieve stable compliance and cost reduction with efficiency improvement under stricter standards.

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