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Effluent discharge limits across Africa

The number your plant has to hit is set by law, not by a supplier. This is an open reference to what each African jurisdiction actually requires — traced to the instrument, dated, and rechecked.

Three limits, not one

Almost every African jurisdiction sets different limits depending on where the effluent goes. Quoting “the COD limit” for a country without saying which route is the most common error we see in enquiries, and it changes the treatment plant by a factor of several.

Discharge route	Typically the	Why	What it means for a DAF
To sewer — into a municipal collection system	Loosest limits	A downstream municipal works will provide biological treatment; the limits exist to protect the sewer, the works and its operators	Often flotation alone is sufficient. FOG and TSS limits dominate; COD limits are generous or absent
To surface water — river, lake, sea outfall	Tightest limits	No further treatment follows; the receiving water is the environment	Flotation is a pretreatment stage only. Biological treatment almost always required behind it
To land or irrigation reuse	Different, not simply tighter	Salinity, sodium adsorption ratio, chloride and pathogens matter more than COD	Coagulant choice becomes critical — chloride-based products may breach an irrigation limit that a sulphate-based product would not

And sometimes limits are set by sector, not nationally

A structural point that catches out anyone assuming one national table per country. Nigeria, for example, does not set a single national industrial effluent standard. NESREA issues sector-specific regulations, so a chemicals or detergent plant and a pharmaceutical plant face different numbers for the same parameter — and a food and beverage plant faces a third set again.

Where a country works this way, the country page gives a table per sector rather than one table, and states which regulation applies to which industry. Asking “what is the COD limit in Nigeria” has no single answer, and any source that gives you one has not read the regulations.

The parameters that decide a flotation plant

Discharge consents typically list twenty to forty parameters. Six of them determine whether dissolved air flotation is the right process and how large it needs to be. The rest are usually met or missed elsewhere in the treatment train.

Parameter	What DAF does to it	Realistic reduction	If the limit is tighter than that
Fats, oils and grease	Removes free and emulsified FOG with correct coagulation	90–99%	Rarely a problem. FOG is flotation’s strongest duty
Total suspended solids	Removes coagulated solids	85–98%	Add filtration behind the DAF
COD	Removes only the particulate fraction	40–70% where particulate; 20–40% where largely soluble	Biological treatment is required. No coagulant regime substitutes for it
BOD₅	Follows COD — removes the particulate share	30–60%	Biological treatment required
Total phosphorus	Precipitates with an iron or aluminium coagulant	60–90%	Below about 0.3 mg/L, add a polishing filter. See ferric chloride dosing
pH	Changed by the coagulant, not by the flotation	Correctable	Add a pH loop. Note that acidic coagulants consume alkalinity and can breach a lower pH bound

Verified countries compared

Side by side, for the parameters that decide a flotation plant. Both columns are taken from the primary instrument, not from secondary summaries.

Parameter	Kenya LN 177/2024, environment	South Africa GN 665/2013, general limit	South Africa GN 665/2013, special limit
COD	50 mg/L	75 mg/L	30 mg/L
BOD₅	30 mg/L	Not specified in Table 2.1	Not specified in Table 2.1
Suspended solids	30 mg/L	25 mg/L	10 mg/L
Oil and grease	Nil; n-hexane extracts 30 mg/L fats, 5 mg/L mineral oil	2.5 mg/L	0 mg/L
pH	6.5–8.5 non-marine	5.5–9.5	5.5–7.5
Total phosphorus / ortho-P	2 mg/L total P	10 mg/L ortho-P	1 mg/L median, 2.5 max
Total nitrogen	2 mg/L	Ammonia as N 6, nitrate/nitrite as N 15	Ammonia as N 2, nitrate/nitrite as N 1.5
Dissolved iron	10 mg/L	0.3 mg/L	0.3 mg/L
Chloride	250 mg/L	Not specified; conductivity limited instead	Not specified; conductivity limited instead

Country coverage

All 54 African countries are listed below. Each is published as its governing instrument is read directly, so a country carries a link only once its schedule has been read line by line. Nothing here is a substitute for the current text of the law, and your local environmental consultant or regulator’s own confirmation takes precedence over this page.

North Africa

West Africa

Central Africa

East Africa

Southern Africa

Countries without a link have not yet had their governing instrument read directly, so no figures are published for them. If you need a specific country prioritised, tell us which and we will move it up the queue.

Why we are not publishing numbers yet

Building this reference began by searching for each country’s standards. Within the first few queries, two things happened that explain the approach above.

• A search for Kenyan effluent standards returned figures that belong to a Mauritian instrument from 2003, presented as though they were Kenyan.
• A second set of Kenyan figures appeared that contradicted the first, with no way to tell from the summaries which schedule either came from — discharge to land and discharge to surface water carry different numbers in the same regulation.

Both are ordinary research errors and both would have been invisible in a published table. That is the problem. A discharge limit is the design basis for a treatment plant and sometimes the basis of a compliance argument with a regulator. Getting it wrong is not an embarrassment to be corrected later; it is a plant built to the wrong specification.

So the rule for this section is simple: a number appears here only after the instrument that sets it has been read directly, and it carries the date it was read. If you need a specific country urgently, say so and we will prioritise it.

Frequently asked questions