What changes on 1 Sept 2025?
Vietnam’s new QCVN 40:2025/BTNMT lowers COD to 80 mg/L, BOD to 30 mg/L and color to 50 Pt-Co, effective Sept 2025. A 100 m³/h textile plant can comply with MBR + activated carbon at 0.34 USD/m³ OPEX and 1.1 M USD CAPEX. This regulation replaces TCVN 5945:2010 and represents the most significant tightening of industrial discharge standards in Vietnam’s history. For EHS managers in Bac Ninh and surrounding industrial hubs, the grace period for existing facilities is rapidly closing. The 2025 standard removes many of the "Class B" leniencies previously afforded to factories discharging into industrial zone sewers, as many Centralized Effluent Treatment Plants (CETPs) are now being held to the same stringent "Class A" limits before discharging into receiving water bodies.
The Law on Environmental Protection (LEP) 2020 introduces a critical financial risk: the penalty tariff. Under the new framework, any exceedance of the QCVN 40:2025 limits triggers an environmental fee calculated at 2× the standard rate for every day the violation persists. For a medium-sized facility discharging 2,400 m³ per day, a persistent 10% exceedance in COD could result in monthly fines exceeding 15,000 USD, in addition to the risk of a mandatory 3-month operational shutdown for remediation. The following table summarizes the primary numeric shifts that will dictate WWTP redesign requirements.
| Parameter | TCVN 5945:2010 (Class A) | QCVN 40:2025 (New Limit) | % Reduction |
|---|---|---|---|
| Chemical Oxygen Demand (COD) | 100 mg/L | 80 mg/L | 20% |
| Biochemical Oxygen Demand (BOD₅) | 50 mg/L | 30 mg/L | 40% |
| Total Suspended Solids (TSS) | 100 mg/L | 50 mg/L | 50% |
| Ammonium (NH₄⁺ as N) | 5 mg/L (variable) | 10 mg/L (fixed) | Tighter controls |
| Color (Pt-Co) | 100 | 50 | 50% |
Parameter table: 2025 vs 2010 side-by-side
The regulatory shift from the 2010 standards to the 2025 limits represents a 20% to 50% reduction in allowable concentrations for primary organic pollutants, necessitating a move toward advanced tertiary treatment. For an EHS manager preparing a board memo, the specific TCVN test methods are as critical as the limits themselves, as non-standard testing can lead to permit rejection. The 2025 standard mandates daily composite sampling for organic loads and strict weekly heavy metal analysis for high-risk sectors. This change will significantly impact industrial facilities, particularly those in high-risk sectors.
| Parameter | Unit | TCVN 5945:2010 | QCVN 40:2025 | Test Method (TCVN) |
|---|---|---|---|---|
| Temperature | °C | 40 | 40 | TCVN 4557:1988 |
| pH Value | - | 6 to 9 | 6 to 9 | TCVN 6492:2011 |
| BOD₅ (20°C) | mg/L | 50 | 30 | TCVN 6001-1:2008 |
| COD | mg/L | 100 | 80 | TCVN 6491:1999 |
| TSS | mg/L | 100 | 50 | TCVN 6625:2000 |
| Arsenic | mg/L | 0.1 | 0.05 | TCVN 6626:2000 |
| Mercury | mg/L | 0.01 | 0.005 | TCVN 7877:2008 |
| Color | Pt-Co | 100 | 50 | TCVN 6185:2015 |
Note: Sampling frequency requires a daily flow-proportional composite for COD/BOD and weekly grab samples for heavy metals (per Circular 10/2021/TT-BTNMT).
Which industries are classified high-risk?
Decree 08/2022/ND-CP identifies 16 specific industrial sectors that are categorized as "high risk" of environmental pollution, requiring stricter oversight and mandatory automated monitoring. If your facility falls into these categories, the 2025 deadline is non-negotiable, and your discharge permit renewal will be contingent upon proving that your existing WWTP can hit the 80 mg/L COD limit consistently. Even if your factory is located within an industrial zone in Bac Ninh that utilizes a CETP, you are still responsible for pre-treatment to ensure the CETP can meet its final discharge obligations under the new standard.
The high-risk list includes:
- Textile Dyeing: Specifically fabric and yarn dyeing, washing, and grinding operations.
- Food & Beverage: Seafood processing, tapioca starch production, sugar cane processing, and rubber latex.
- Chemicals: Production of chemical fertilizers, plant protection drugs, and basic chemicals.
- Heavy Industry: Metallurgical processing, mining, tanning, and oil refining.
- Pulp and Paper: Production of paper, pulp, and fiberboard (MDF/HDF).
For these sectors, the 2025 standards are not merely suggestions but triggers for the mandatory installation of online monitoring stations. Failure to comply with the full step-by-step compliance checklist by the enforcement date can result in the immediate revocation of your environmental license.
Proven treatment trains to hit the new limits
Achieving a Chemical Oxygen Demand (COD) of less than 80 mg/L for high-strength textile or food processing wastewater requires the integration of tertiary treatment or membrane-based biological processes. Standard activated sludge systems often struggle to maintain COD below 100 mg/L during peak loads. To guarantee compliance with QCVN 40:2025, engineers must look toward intensified biological treatment or polishing stages. For textile applications, incorporating a DAF unit for pre-treatment of fibers and oils is essential to protect downstream membranes.
| Treatment Train | Best For | Expected COD | Expected Color | Power Demand |
|---|---|---|---|---|
| Option A: DAF + MBR + UV | Textile, Food, Pharma | < 75 mg/L | < 40 Pt-Co | 0.9 kWh/m³ |
| Option B: CAS + Cloth Filter + PAC | General Manufacturing | < 65 mg/L | < 35 Pt-Co | 0.6 kWh/m³ |
| Option C: EGSB + MBBR + AC | Starch, Seafood, Beer | < 55 mg/L | < 30 Pt-Co | 1.2 kWh/m³ (net) |
Option A utilizes a package MBR that guarantees <80 mg/L COD by replacing secondary clarifiers with ultrafiltration membranes. This eliminates TSS-related COD carryover and allows for a higher Mixed Liquor Suspended Solids (MLSS) concentration, which improves the degradation of complex organics. Option B is a cost-effective retrofit for existing plants, adding Powdered Activated Carbon (PAC) and cloth-media filtration to polish effluent. Option C is designed for high-load organic wastewater, using an Expanded Granular Sludge Bed (EGSB) to recover biogas, which significantly offsets OPEX. For a deeper technical dive, see our head-to-head comparison of MBR and SBR for the same limits.
CAPEX and OPEX for a 100 m³/h plant
For a standard 100 m³/h industrial wastewater treatment plant (WWTP), the transition to QCVN 40:2025 compliance typically requires a capital expenditure (CAPEX) between 0.9 million and 1.3 million USD. This range is largely influenced by the choice of materials—specifically whether the MBR tankage and internal components are constructed from 304 stainless steel or epoxy-coated carbon steel. For foreign-invested factories in Bac Ninh, stainless steel is often preferred for its 20-year lifecycle, despite the 15% higher initial cost.
Operational expenditure (OPEX) is the primary concern for board approval. Based on Zhongsheng field data (2025), a compliant system averages between 0.28 and 0.34 USD per cubic meter treated. This breakdown includes:
- Power: 0.08 - 0.12 USD/m³ (Aeration and membrane scouring).
- Chemicals: 0.06 - 0.09 USD/m³ (Coagulants, pH adjustment, and membrane CIP).
- Maintenance: 0.05 - 0.07 USD/m³ (Including a 5-year membrane replacement fund).
- Sludge Disposal: 0.09 - 0.11 USD/m³ (Assuming dewatering to 20% dry solids).
The payback period for a new, high-efficiency system is typically 1.8 to 2.5 years. This calculation is defended by the avoidance of the 2× penalty tariff and the reduction in the annual environmental protection fee (EPF), which is now calculated based on the total mass of pollutants discharged. By lowering COD from 100 mg/L to 60 mg/L, a 100 m³/h plant reduces its annual EPF liability by approximately 22,000 USD.
Self-monitoring and reporting obligations
Under the Law on Environmental Protection (LEP) 2020, facilities with a discharge capacity exceeding 200 m³/day must install automated, continuous monitoring systems linked directly to provincial Departments of Natural Resources and Environment (DONRE). This system must track flow rate, temperature, pH, TSS
