[Mainland China] Nanjing Chengdong Wastewater Treatment Plant Phase IV Expansion of 100,000 Tons/Day: Directly Targeting the Most Stringent Class A Standard of Jiangsu Province, the Plant Advances Toward 450,000 Tons/Day

Introduction: According to a report by Nanjing Daily 9 月 3 日, the Phase IV project of Nanjing Chengdong Wastewater Treatment Plant is under accelerated construction: with an expansion capacity of 10 万 tons/day and a total investment of approximately 4.0 亿 yuan, it is expected to be completed by 2026 年 11 月. Upon completion, the plant's total treatment capacity will reach 45 万 tons/day. The Phase IV project directly targets the strictest tier of Jiangsu Province discharge standards — Provincial Standard (DB32/4440—2022) Level A, setting a new benchmark for water environment governance and wastewater facility upgrading in Nanjing.

I. Urban Eastward Expansion Drives Capacity Increase: From 42 km² to 142 km²

When Phase I of Chengdong Wastewater Treatment Plant was completed in 2005 年, its service area covered only 42 km², serving approximately 25 万 people, with a treatment capacity of less than 10 万 tons/day. With Nanjing's eastward urban expansion and the rise of the Southern New Town, the plant's service area has now expanded to approximately 142 km², serving a population of about 110 万 people. During peak periods, the plant operates at full capacity, making capacity expansion imperative.

• Redundancy assurance — In light of the redundant demand from urban development and domestic water use, the Phase IV project has been designated as a mandatory "weakness remediation" project;
• Strictest in the province — Jiangsu Province previously issued the Discharge Standards for Pollutants from Municipal Wastewater Treatment Plants (DB32/4440—2022), imposing higher requirements on effluent quality. The existing three phases of the Chengdong plant currently discharge in compliance with the national Level A standard, and must comply with the Provincial Standard Level C from 2026 年 3 月 28 日. The Phase IV project directly targets the Provincial Standard Level A (the highest tier in the province);
• Full-chain treatment — Phase IV of the Chengdong plant is one of the 18 wastewater facility projects in Nanjing 2026 年 included as Category A in the urban construction plan, covering the entire wastewater treatment chain including new construction and expansion, pipeline network interconnection, storage tank construction, and comprehensive river channel treatment.

II. 23 New Structures Under Construction: Systematic Upgrading from the Influent Pump Station to the Micro-Flocculation Tank

According to on-site reports, at the Chengdong Plant Phase IV project site on 2026 年 8 月 14 日, 23 new structures — including the influent pump station, grit chamber, biological tank, and micro-flocculation tank — are being laid out sequentially within the 20.42 hectares of the plant's red line boundary. Pile foundation construction is underway in the biological tank area, while other areas are simultaneously advancing rebar tying, supervision inspection, and other processes.

• Process upgrading — Targeting the Provincial Standard Level A means strengthening nitrogen and phosphorus removal and advanced treatment units on the basis of conventional secondary biological treatment, ensuring stable effluent quality at a higher water quality grade;
• System expansion — After Phase IV is commissioned, the plant's total treatment capacity will reach 45 万 tons/day, matching the planned regional population growth and industrial carrying capacity;
• Intelligent operation — The new structures are equipped with more comprehensive automation and control systems, creating conditions for refined and digitalized operation.

III. "Dual-Channel" Parallel Operation: Jiangxinzhou Sewage Collection System Building Urban Resilience

Running in parallel with the Chengdong Plant Phase IV is another backbone project of Nanjing's sewage collection system — the Jiangxinzhou Sewage Collection System Second Channel, which achieved full-flow water conveyance in 5 月 this year, enabling "dual-channel" operation for sewage from over 170 万 residents in the main urban area, significantly enhancing the reliability and risk resistance of the sewage collection system.

• Channel redundancy — The dual-channel design means that when one channel undergoes maintenance or experiences a fault, sewage conveyance can still be ensured through the other channel, avoiding the risk of "chain break" pollution;
• Plant-network coordination — The Chengdong plant expansion, together with the Jiangxinzhou channel and the Xianlin sewage system pipeline network inspection and remediation projects, forms an integrated "plant–network–station" urban drainage resilience system;
• Water environment improvement — Capacity expansion and standard upgrading directly reduce the pollution load discharged into river channels, contributing to the continuous improvement of urban river water quality.

IV. Industry Insights: Higher-Tier Local Standards Driving the "Expansion + Upgrading" Dual-Wheel Transformation of Existing Plants

The case of Nanjing Chengdong Plant clearly demonstrates that stricter local discharge standards are becoming the "baton" guiding the upgrading of existing wastewater treatment plants. The existing Phases I and II of the Chengdong plant have been required to comply with Provincial Standard Level C since 2026 年 3 月, while Phase IV directly targets Provincial Standard Level A — reflecting a pragmatic path of "phased upgrading with progressively stricter standards" within the same plant site. Meanwhile, progress such as the Chengdong plant's expansion of 10 万 tons/day and the Jiangxinzhou Second Channel's 5 月 water conveyance also confirms that large-city wastewater facilities are transitioning from "having or not having" to "being better and more resilient."

For wastewater treatment and equipment service enterprises, the integrated renovation demand packaged as "capacity expansion + standard upgrading + smart operation & maintenance" is becoming the mainstream order format in the industry. Service providers capable of simultaneously delivering process upgrade design, core equipment supply, automation system integration, and long-term operation capabilities will take the lead in such high-standard, driver-driven projects.

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Source note: This article is compiled from public reports including Nanjing Daily and the Nanjing Municipal Water Affairs Bureau (2026 年 9 月).