Effluent discharge limits in Algeria
Algeria has a national industrial-effluent decree with a general table and category-specific tolerances. The detail matters: the base values are the default design floor, while some industrial categories have stated transitional or technology-related tolerances. Do not treat a tolerance as a permanent licence to pollute.
Algerian industrial liquid effluent is governed by Executive Decree No. 06-141 of 19 April 2006. The annex sets general maximum values including temperature 30 °C, pH 6.5–8.5, suspended solids 30 mg/L, BOD₅ 40 mg/L, COD 120 mg/L, oils and fats 20 mg/L, hydrocarbons 20 mg/L and total phosphate 2 mg/L.
The decree requires industrial installations to be designed, built and operated so the final effluent does not exceed the applicable annex values, with appropriate treatment installed to reduce pollution load. A DAF is highly relevant for solids, oils, fats and phosphorus; it is only the first stage where soluble COD must reach 120 mg/L.
The national industrial-effluent standard
Executive Decree No. 06-141 is the central reference for industrial liquid discharges. Article 4 places the obligation at the outlet of the installation, rather than allowing the operator to point to downstream dilution. It also requires an appropriate treatment device. The annex then identifies the standard values and, separately, tolerances relevant to particular industrial categories and technologies.
That structure means an industrial site must answer three questions before selecting treatment: what is the final receiving route; which category in the annex covers the activity; and whether the site has a written, lawful tolerance. A connection to a public sewer may also carry acceptance conditions from the network operator; direct environmental discharge must meet the decree and its permit conditions.
Core values for industrial liquid effluent
| Parameter | Maximum value | Relevance to a flotation plant |
|---|---|---|
| Temperature | 30 °C | Equalise or cool hot wash-down and process streams. |
| pH | 6.5–8.5 | Coagulant dosing consumes alkalinity; design final neutralisation. |
| Suspended solids (MES) | 30 mg/L | Achievable by DAF plus reliable final solids separation where influent is variable. |
| BOD₅ (DBO₅) | 40 mg/L | Requires biological treatment where organic load is materially soluble. |
| COD (DCO) | 120 mg/L | DAF removes the particulate fraction; biology or oxidation handles the rest. |
| Kjeldahl nitrogen | 40 mg/L | Confirm nitrogen form; nitrification may be required for ammonia. |
| Total phosphate | 2 mg/L | A good DAF duty: iron coagulant can precipitate phosphorus while forming floatable floc. |
| Oils and fats | 20 mg/L | DAF’s principal application in food, edible-oil and machinery effluents. |
| Hydrocarbons | 20 mg/L | Separate free oil first; then DAF with suitable chemistry. |
| Detergents | 2 mg/L | Surfactants affect bubble attachment and may require source control. |
| Anionic surfactants | 10 mg/L | Relevant to CIP, laundry and detergent manufacturing. |
| Free cyanide | 0.1 mg/L | Dedicated destruction treatment; never acidify a cyanide stream. |
| Phenols | 0.5 mg/L | Needs a specific treatment route, not flotation alone. |
| Active chlorine | 1.0 mg/L | Dechlorination may be required before biology or discharge. |
| Aluminium | 5 mg/L | Allow for residual where aluminium coagulant is used. |
| Iron | 5 mg/L | Provides headroom for iron coagulants but does not remove the need for pH control. |
| Cadmium / mercury / lead | 0.2 / 0.01 / 1.0 mg/L | Hydroxide/sulphide precipitation and final solids capture. |
| Chromium III / chromium VI | 3.0 / 0.1 mg/L | Reduce Cr(VI), then precipitate total chromium. |
| Copper / nickel / zinc | 3.0 / 5.0 / 5.0 mg/L | Metals treatment design must use actual soluble concentrations and pH curves. |
Sector tolerances and sewer connection
The decree expressly recognises that, because of technological characteristics, particular tolerances can apply by industrial category. This is not a reason to lift a generic table from an old report. The applicable category must be identified from the annex and the tolerance must be confirmed with the competent authority or network operator.
| Situation | Practical rule |
|---|---|
| Direct industrial discharge | Use the general annex as the starting basis, then confirm all category-specific parameters and permit conditions. |
| Existing installation with a stated tolerance | Obtain the exact annex category and written basis. Do not transfer a tolerance from another sector or site. |
| Public sewer connection | Confirm the admission conditions with the receiving operator. Protection of the sewer and municipal treatment works can require pre-treatment beyond the generic table. |
| Textile, tannery, refinery, metals or chemicals | Expect additional parameter focus: colour/surfactants, chromium/sulphide, hydrocarbons/phenols, or metals/cyanide respectively. |
What this means for DAF design in Algeria
- DAF directly addresses three headline numbers. With correct coagulation and flocculation it is the right front-end process for 20 mg/L oils and fats, 30 mg/L suspended solids and 2 mg/L total phosphate.
- COD 120 mg/L divides physical treatment from biological treatment. If influent COD is mainly fat, protein or other particulate matter, flotation does much of the reduction. If it is dissolved, a biological stage follows.
- Plan pH as an effluent parameter, not just a chemistry setting. A DAF often coagulates best near neutral pH; the same pH must still be 6.5–8.5 at final discharge.
- Metals are a treatment train of their own. DAF is useful for separating precipitated metal hydroxides, but it does not replace reduction of hexavalent chromium or source segregation of cyanide.
- Do not rely on dilution. Article 4 places responsibility on the industrial installation’s outlet. Equalisation is useful; deliberate dilution to create compliance is not treatment.
Source and verification
| Instrument | Executive Decree No. 06-141 of 19 April 2006 defining limit values for industrial liquid effluent discharges |
| Official publication | Journal officiel de la République algérienne, No. 26, 23 April 2006, p. 4 |
| Regulatory basis | Environmental protection and water framework, with industrial-category annexes and tolerances |
| Source | Official Journal of Algeria — No. 26 (PDF) · Algerian regulatory index |
| Checked | 7 August 2026 |
Frequently asked questions
What is the COD limit for industrial effluent in Algeria?
The general value in Executive Decree 06-141 is 120 mg/L COD (DCO). The same annex sets BOD₅ 40 mg/L and suspended solids 30 mg/L. Check whether the industrial category has a stated tolerance or additional parameter.
What is the oil and grease limit in Algeria?
The annex sets 20 mg/L for oils and fats and 20 mg/L for hydrocarbons. DAF is normally the correct physical-separation stage for both, provided the waste is properly equalised and chemically conditioned.
Can a DAF alone meet the Algerian COD limit?
Only where most of the COD is particulate or oil-bound. DAF does not remove dissolved sugars, alcohols, acids and other soluble organics well enough to guarantee 120 mg/L. A biological stage is required for a typical high-strength organic industrial stream.
Are the same values used for all Algerian industries?
The general annex applies, but the decree also contains technology and category-related tolerances. Confirm the exact category and any written permit or sewer conditions rather than applying a generic number by analogy.