DR Congo effluent discharge rules: permits and pre-treatment
For industrial sites in the Democratic Republic of the Congo, the starting point is not a nationwide COD, BOD or suspended-solids table. It is the discharge route, prior authorisation and site-specific conditions. The Water Law prohibits pollution and requires controls, but the national framework leaves detailed discharge criteria and control arrangements to implementing measures, permits and the responsible sanitation or water authorities.
Do not size a DAF in DR Congo against an assumed “national COD limit”. First establish whether the treated water will go to a public sewer, a watercourse, the ground, reuse or another route; then obtain the operator’s or authority’s written target. The applicable conditions can be site- and route-specific.
The Water Law No. 15/026 of 31 December 2015 provides the legal controls: it prohibits pollution, requires authorisation for relevant works and activities, requires pre-treatment of certain non-domestic sewer discharges, and requires self-monitoring for classified facilities. This page explains what that means for a treatment project.
What is and is not a national effluent limit
We have not found a primary-source, nationwide discharge schedule in the Water Law that can honestly be presented as one DRC-wide numerical table for COD, BOD5, TSS, oils or nutrients. That absence matters. A consultant’s generic table, a supplier’s proposal or a limit copied from a neighbouring country is not a defensible design basis.
That does not mean industrial discharge is unregulated. It means the compliance route is permit-led. The Water Law provides the prohibition and authorisation framework; the environmental and classified-installation regime requires assessment and control; and sewer discharges need authorisation from the local sanitation service manager. The final numbers must be confirmed in writing for the particular receiving route and facility.
Legal controls that affect an industrial treatment plant
| Issue | Water Law position | Practical consequence |
|---|---|---|
| Polluting a water resource | Article 19 prohibits discharges, flows, immersion, infiltration, deposits and other acts that pollute, alter or degrade water resources. | A factory cannot treat the receiving river, drain, wetland or groundwater as an unregulated outlet. |
| Works or activities affecting water | Article 23 requires prior authorisation for works, installations or activities that may affect water resources, including withdrawal or conditions of the source. | Confirm authorisation requirements before construction, abstraction, discharge arrangements or an outlet change. |
| Industrial use of public-domain water | Article 68 requires prior input from the water-resources administration for placement or extension of industrial units using water from the public domain. | Bring the treatment and discharge concept into the project approval process early, not after equipment is ordered. |
| Discharge to public sewer | Articles 90–95 address sanitation. Article 94 requires prior authorisation from the local sanitation service manager for non-domestic wastewater; pre-treatment is required where raw wastewater can hinder the sewer or treatment works. | Obtain the sewer acceptance limits from the local operator. A DAF is often the pre-treatment stage for FOG, floatables and suspended solids. |
| Classified installation discharge | Article 100 requires classified installations discharging to a water body or groundwater to self-monitor under conditions validated by the administration. | Specify sampling points, flow measurement, laboratory methods, retention of results and alarms as part of the project—not as an afterthought. |
Public sewer discharge: when pre-treatment is required
A public sewer connection does not remove the factory’s treatment duty. Article 94 is particularly important for food factories, abattoirs, beverage plants, edible-oil processing, laundries, vehicle washing, metal finishing and chemical production: non-domestic wastewater needs prior authorisation from the local sanitation service manager, and pre-treatment is required when the wastewater could interfere with the network or downstream works.
For a DAF project, ask the operator for limits and acceptance conditions for at least pH, temperature, flow and flow variation, total suspended solids, FOG / mineral oil, COD or BOD, detergents, sulphides, metals, toxic substances, sampling location and maximum allowable discharge rate. Also obtain the consequences of non-compliance and whether the operator requires automatic sampling or a monitoring manhole.
Surface-water or groundwater discharge: the higher-risk route
Where treated effluent will reach a river, stream, lake, wetland, groundwater or land infiltration system, design and approvals should be treated as an environmental permitting project. Article 19’s prohibition is broad, and the environmental framework adds impact-assessment and classified-facility controls. The receiving water, available assimilative capacity, nearby users, protected areas, seasonal flow and existing pollution loads may all matter to the authorised target.
The project team should therefore obtain a written discharge consent or regulator-approved target before fixing the process guarantee. A good target document identifies the receiving route, point coordinates, permissible parameters, units, averaging period, maximum values, sampling frequency, analytical method, reporting duty, bypass prohibition and any seasonal conditions.
What a DAF can and cannot guarantee
| Duty | DAF role | What to add if the permit is tighter |
|---|---|---|
| Free and emulsified fats, oils and grease | Usually the strongest DAF duty when pH, coagulant and polymer are properly set. | Equalisation, chemical optimisation, oil polishing or activated carbon where dissolved hydrocarbons control the result. |
| Suspended solids | Coagulation and flotation can remove most settleable and colloidal solids. | Sand, cloth or membrane filtration for a consistently very low final solids target. |
| Particulate COD / BOD | Removes only the fraction attached to suspended or floatable matter. | Biological treatment for the soluble organic fraction; measure filtered COD before selecting the process train. |
| Nitrogen and ammonia | DAF is not a biological nitrogen-removal process. | Nitrification/denitrification or another approved treatment route. |
| Metals | Can separate precipitated metals after pH adjustment and hydroxide/sulphide precipitation. | Dedicated metals treatment, polishing filtration and segregated streams; do not mix strong chelant streams blindly. |
The information to obtain before DAF sizing
- Discharge route: public sewer, surface water, groundwater, land application, reuse or tanker removal.
- Authority and operator: the entity that grants the authorisation and, for sewer discharge, the sanitation service manager.
- Written limits: parameters, units, average/max format, flow cap, monitoring point and sampling method.
- Influent data: 24-hour composite and peak samples; total and filtered COD; TSS; FOG; pH; temperature; conductivity; alkalinity; nutrients; metals and relevant toxic compounds.
- Flow pattern: hourly peaks, production shifts, CIP or wash-down releases, rainwater ingress and future expansion.
- Receiving-water evidence: where the route is environmental, baseline quality and seasonal conditions needed for the approval.
Environmental and classified-installation framework
The Water Law sits alongside the environmental framework, including Law No. 11/009 on fundamental environmental protection principles and the regulations governing classified installations. For a new industrial facility, major expansion or a discharge with significant environmental risk, confirm whether the environmental study, classified-facility approval and water authorisation should be coordinated as one permitting package.
Do not let the DAF supplier define the legal discharge point. The approval route defines the target; the wastewater data defines what fraction is treatable by flotation; only then can the treatment train, operating cost and compliance guarantee be specified properly.
Frequently asked questions
What is the COD discharge limit in DR Congo?
We do not publish one DRC-wide COD figure because the Water Law itself does not provide a universal national COD schedule that can be applied to every industrial route. Confirm the applicable written target with the permitting authority or sanitation operator for the specific site and discharge route.
Can a factory discharge industrial wastewater into a public sewer?
Not automatically. The Water Law requires prior authorisation by the local sanitation service manager for non-domestic wastewater, and requires pre-treatment when untreated wastewater can interfere with the sewer, people or the downstream works. Obtain the operator’s conditions in writing.
Does a DAF replace biological treatment?
Usually not where the authorised target requires substantial removal of soluble COD, BOD or ammonia. A DAF is excellent for FOG and suspended solids, and for the particulate portion of COD. The filtered-COD test shows how much organic load flotation can physically reach.
What monitoring should be built into a new plant?
At minimum, provide an accessible final sampling point, flow measurement and sample records. The permit or operator may also require pH, conductivity, turbidity, automatic composite sampling, alarms and laboratory reports. Article 100 makes self-monitoring material for classified installations.
Primary legal sources
- Democratic Republic of the Congo, Law No. 15/026 of 31 December 2015 relating to water — especially Articles 19, 23, 68, 90–95 and 100.
- Law No. 11/009 of 9 July 2011: fundamental principles on environmental protection.