DENR DAO 2021-19 Effluent Standards Explained: Complete Parameter Table
Published by WastewaterPH. Verified by PRC-licensed Environmental and Sanitary Engineers.
DENR Administrative Order (DAO) 2021-19 amended the General Effluent Standards for six specific parameters: Ammonia (NH3-N), Boron, Copper, Fecal Coliform, Phosphate, and Sulfate. The primary organic limits—Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and Total Suspended Solids (TSS)—remain unchanged under DAO 2016-08. To stay compliant, commercial buildings discharging into Class C rivers like Pasig must maintain BOD below 50 mg/L, COD below 100 mg/L, and Fecal Coliform under 400 MPN/100mL.
Why DAO 2021-19 Confuses Commercial Building Owners
When the DENR issued DAO 2021-19, many facility managers and developers assumed the entire table of DAO 2016-08 had been replaced. That assumption leads to costly engineering mistakes.
DAO 2021-19 is a surgical amendment. It adjusted six parameters where local water bodies required refined environmental thresholds. If your engineer tells you BOD or COD limits changed under 2021-19, verify their license. The 50 mg/L BOD ceiling for Class C waters has remained mandatory since 2016.
Official General Effluent Standards (DAO 2016-08 & DAO 2021-19)
| Parameter | Unit | Class B (Laguna Lake) | Class C (Pasig River) | Class SC (Manila Bay) | Governing Rule |
|---|---|---|---|---|---|
| BOD (5-day) | mg/L | 30 | 50 | 100 | DAO 2016-08 |
| COD | mg/L | 60 | 100 | 200 | DAO 2016-08 |
| TSS (Total Suspended Solids) | mg/L | 65 | 100 | 100 | DAO 2016-08 |
| Oil & Grease | mg/L | 5 | 5 | 10 | DAO 2016-08 |
| Ammonia (as NH3-N) | mg/L | 0.5 | 4.0 | 4.0 | DAO 2021-19 Amendment |
| Fecal Coliform | MPN/100mL | < 200 | < 400 | < 400 | DAO 2021-19 Amendment |
| Phosphate (as P) | mg/L | 0.5 | 1.0 | 4.0 | DAO 2021-19 Amendment |
| Surfactants (MBAS) | mg/L | 2.0 | 15.0 | 15.0 | DAO 2016-08 |
The Strong Wastewater Provision (BOD ≥ 3,000 mg/L)
One of the most consequential sections of DAO 2021-19 is the formalized regulation for Strong Wastewater.
If your establishment operates a food processing facility, commissary, beverage plant, or abattoir where raw influent BOD exceeds 3,000 mg/L, achieving a flat 50 mg/L standard in a single pass is mathematically unfeasible without staged anaerobic pre-digestion.
Under DAO 2021-19, qualifying facilities can apply for percentage removal benchmarks or adjusted GES limits. However, the Environmental Management Bureau (EMB) requires third-party laboratory verification, continuous composite sampling, and an approved Engineering Report signed by a PRC-licensed environmental engineer.
Why 3-Chamber Septic Tanks Guarantee a Notice of Violation
A traditional concrete septic tank provides primary physical settling only. Anaerobic bacteria break down solids slowly, yielding at most a 30% to 50% BOD reduction.
Raw domestic blackwater enters at 250 to 400 mg/L BOD. When it leaves a septic tank, the effluent still reads 150 to 250 mg/L BOD. That is three to five times higher than the legal 50 mg/L Class C limit. Furthermore, septic tanks do not sanitize fecal coliform. They discharge hundreds of thousands of coliform colonies into local drainage lines, directly violating the 400 MPN/100mL cap.
How NatureCare Mobile STP Solves DAO 2021-19 Compliance
For existing properties that cannot excavate their basements or parking lots, the NatureCare Mobile Containerized STP utilizes containerized Moving Bed Biofilm Reactor (MBBR) technology:
- Active Biofilm Carriers: Multi-chamber aeration with virgin HDPE biomedia delivering 95%+ BOD removal.
- Integrated Secondary Clarification: Rapid lamella plate settling that pushes TSS well below 30 mg/L.
- Automated Chlorine Dosing: Tertiary contact chamber reducing Fecal Coliform to < 100 MPN/100mL, exceeding Class B standards.
- 7 to 14 Day Deployment: Above-ground containerized installation without structural disruptions.
Frequently Asked Questions on DAO 2021-19
What is the main difference between DAO 2016-08 and DAO 2021-19?
DAO 2021-19 did not change BOD, COD, or TSS limits. Those remain under DAO 2016-08. DAO 2021-19 specifically updated effluent standards for six parameters: Ammonia (NH3-N), Boron, Copper, Fecal Coliform, Phosphate (as Phosphorus), and Sulfate.
What is the maximum allowable BOD for commercial buildings discharging into Pasig River?
For Class C water bodies like Pasig River, the maximum allowable BOD is 50 mg/L under DAO 2016-08. Discharging directly into Laguna de Bay (Class B) requires a stricter limit of 30 mg/L.
What is the fecal coliform standard under DAO 2021-19?
DAO 2021-19 sets fecal coliform limits at less than 200 MPN/100mL for Class B receiving waters and less than 400 MPN/100mL for Class C and Class SC receiving waters. A standard 3-chamber septic tank cannot achieve this without tertiary disinfection or an STP.
What happens if my establishment generates Strong Wastewater (BOD ≥ 3,000 mg/L)?
Under DAO 2021-19, establishments generating influent with BOD of 3,000 mg/L or higher (such as food processing or slaughterhouses) can apply for Strong Wastewater General Effluent Standards, but must submit formal technical documentation and an engineering verification report to the EMB.
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