Water treatment chemicals
A dissolved air flotation unit is a separator. The chemistry decides what there is to separate — and the chemistry has to keep arriving, month after month, at a landed price the plant can absorb. We supply it.
watertreatment.africa supplies water and wastewater treatment chemicals — inorganic coagulants, flocculant polymers, pH correction reagents, oxidants and antifoams — CIF to any African port, in drums, IBCs, bags or bulk. We supply to any plant, not only to units we have sold. A works running a competitor’s flotation cell, a lamella, a clarifier or a belt press is a normal customer.
Every consignment ships with a batch certificate of analysis, a safety data sheet in English or French, and the HS code stated on the proforma so the clearing agent is not guessing. Where a stream has not been jar tested, we would rather test it first than sell the wrong product twice.
What we supply
Each product page carries the specification we buy to, the active strength as supplied, the effective pH window, dose ranges by industry, storage and materials-of-construction notes, and the customs classification. Read them before you enquire — most sizing questions are answered there.
Inorganic coagulants
Flocculant polymers
pH correction, oxidants and process aids
Choosing between the coagulants
Price per tonne is the wrong comparison. The number that matters is cost per cubic metre treated, which depends on the dose your stream actually needs, the alkalinity the coagulant destroys, and the volume of sludge you then have to dispose of. A coagulant that is twice the price per tonne at a third of the dose is cheaper.
| Coagulant | Strength as supplied | Effective pH | Typical DAF dose | Alkalinity destroyed | Relative sludge | Where it wins |
|---|---|---|---|---|---|---|
| PAC | 10–11% Al₂O₃ liquid 28–30% powder | 5.5–9.0 | 50–300 mg/L liquid | Low ~0.1–0.3 mg CaCO₃/mg | Medium | Wide pH window, tolerant of cold and of operator error. The default. |
| ACH | 23–24% Al₂O₃ | 5.5–9.5 | 20–120 mg/L | Very low | Lowest | Low-alkalinity water; sites paying to dispose of sludge by the tonne. |
| Alum | 8% Al₂O₃ liquid 17% Al₂O₃ solid | 5.8–7.5 | 100–400 mg/L | High ~0.5 mg CaCO₃/mg | High | Cheapest landed cost where alkalinity is plentiful and pH is stable. |
| Ferric chloride | 38–42% FeCl₃ | 4.0–11.0 | 50–250 mg/L | High ~0.9 mg CaCO₃/mg | High | Phosphorus removal, sulphide precipitation, tannery and municipal duty. |
| Ferric sulphate | 11–12% Fe | 4.0–11.0 | 100–350 mg/L | High ~0.75 mg CaCO₃/mg | High | Ferric chemistry without chloride attack on 304/316 stainless. |
| Ferrous sulphate | 19–20% Fe as heptahydrate | 8.5–11.0 | 100–400 mg/L | Moderate | High | Cheap iron where the stream is already aerated or chlorinated. |
Starting doses by industry
These are the ranges we open a jar test with, expressed as product as supplied. They are not a substitute for the jar test — a dairy running a caustic CIP cycle and a dairy running an acid cycle can differ by a factor of three on the same nominal product.
| Industry | Dominant contaminant | First-choice coagulant | Coagulant dose | Polymer | Polymer dose | Coagulation pH |
|---|---|---|---|---|---|---|
| Dairy processing | Milk fat, casein | PAC | 80–250 mg/L | Anionic | 1–3 mg/L | 6.0–6.5 |
| Edible oil refining | Emulsified FOG, soapstock | Alum or PAC, acid split first | 150–400 mg/L | Anionic | 2–5 mg/L | 4.5–6.0 |
| Abattoir and meat | Fat, blood protein | PAC or ferric chloride | 100–300 mg/L | Cationic then anionic | 2–6 mg/L | 6.0–7.0 |
| Brewery and beverage | Yeast, trub, kieselguhr | PAC | 60–200 mg/L | Anionic | 1–3 mg/L | 6.0–7.0 |
| Pulp and paper | Fibre fines, fillers | PAC, often with bentonite | 40–150 mg/L | Cationic then anionic | 0.5–2 mg/L | 6.5–7.5 |
| Tannery and leather | Sulphide, chromium, protein | Ferric chloride | 150–400 mg/L | Anionic | 2–5 mg/L | 7.5–9.0 |
| Municipal primary | Settleable and colloidal solids | Ferric chloride or PAC | 30–120 mg/L | Anionic | 0.5–2 mg/L | 6.5–7.5 |
| Poultry processing | Fat, feather fines, protein | PAC | 100–300 mg/L | Cationic | 2–6 mg/L | 6.0–7.0 |
| Fish and seafood | Oil, protein, high chloride | PAC or ferric sulphate | 100–350 mg/L | Anionic | 2–5 mg/L | 6.0–7.0 |
| Textile dyeing | Dye colour, surfactant | PAC with decolouring polymer | 150–500 mg/L | Anionic | 2–5 mg/L | 6.5–8.0 |
| Mining and quarry | Mineral fines, clay | PAC or lime | 20–100 mg/L | Anionic, high MW | 5–25 g/t solids | 7.0–9.0 |
| Plastics recycling wash | Label fibre, ink, soil | PAC | 80–250 mg/L | Anionic | 1–4 mg/L | 6.5–7.5 |
How supply works
Converting between products
Most chemical switching decisions are made badly because two products are compared as supplied rather than as active metal. The conversion is arithmetic, and it usually changes the answer.
| Product | Active metal as supplied | 1 mg/L of product delivers | Dose to match 5 mg/L as Al or Fe |
|---|---|---|---|
| PAC, 10% Al₂O₃ liquid | 5.29% as Al | 0.053 mg/L Al | 95 mg/L |
| PAC, 30% Al₂O₃ powder | 15.9% as Al | 0.159 mg/L Al | 32 mg/L |
| ACH, 23% Al₂O₃ | 12.2% as Al | 0.122 mg/L Al | 41 mg/L |
| Alum, 8% Al₂O₃ liquid | 4.23% as Al | 0.042 mg/L Al | 118 mg/L |
| Alum, 17% Al₂O₃ solid | 9.0% as Al | 0.090 mg/L Al | 56 mg/L |
| Ferric chloride, 40% FeCl₃ | 13.8% as Fe | 0.138 mg/L Fe | 36 mg/L |
| Ferric sulphate, 12% Fe | 12.0% as Fe | 0.120 mg/L Fe | 42 mg/L |
| Ferrous sulphate heptahydrate | 20.1% as Fe | 0.201 mg/L Fe | 25 mg/L |
What we will tell you before you buy
Chemical supply is a recurring-revenue business, which gives every supplier an incentive to sell you more product than the plant needs. The honest counterweights:
- Overdosing is common and expensive. Past the charge-neutralisation point, additional coagulant re-stabilises the colloid and performance goes backwards while cost goes forwards. If your float has thinned as the dose went up, you are past the optimum.
- Chemistry cannot fix hydraulics. If the flocculation stage is too short, the recycle ratio too low, or the saturator under pressure, no coagulant will rescue it. Check the troubleshooting order before you change product.
- Soluble COD does not respond to coagulation. A brewery with 70% soluble COD will not meet a total-COD consent on flotation and chemistry alone, whatever is dosed.
- The cheapest tonne is rarely the cheapest cubic metre. Alum at a low landed price that consumes alkalinity you then have to buy back as caustic is a false economy on a low-alkalinity water.
- Freight dominates dilute products. Shipping 90% water across an ocean is poor value. On long supply lines, powder PAC and solid alum usually beat liquid on landed cost per kilogram of active metal, provided the site can make up solution safely.
Frequently asked questions
Do you supply chemicals to plants you did not build?
Yes, and it is most of the chemical business. The flotation cell, clarifier, lamella or filter press you are running does not change what the water needs. Send the current product specification, the current dose and a recent effluent analysis and we will quote against it.
What is the minimum order?
For liquids, one IBC of 1,000–1,250 kg is the practical minimum for sea freight, though drums ship as part of a mixed consignment. For powders and polymer, one pallet. Full-container and ISO-tank lots are where the landed cost per kilogram drops sharply, so on a steady dose it is usually worth sizing storage to take them.
Which coagulant should I use for my effluent?
Start from the dominant contaminant, not the industry label. Emulsified oil and protein respond to aluminium at slightly acid pH. Phosphorus and sulphide respond to iron. Fibre and mineral fines respond to almost anything with a high-molecular-weight anionic polymer behind it. The coagulants and jar testing guide sets out the reasoning, and the table above gives starting doses by industry.
How much coagulant will my plant use per month?
Multiply dose in mg/L by daily flow in m³/day, divide by 1,000, and you have kilograms per day of product as supplied. A 40 m³/h abattoir running 16 hours a day at 200 mg/L of PAC uses 640 m³/day × 200 ÷ 1,000 = 128 kg/day, or about 3.8 tonnes a month — roughly three IBCs. Storage for six to eight weeks of consumption is the normal target on an African supply line.
Can polymer be shipped as a liquid emulsion instead of powder?
It can, and emulsion is easier to make up automatically. But emulsion is 30–50% active against 88–92% for powder, so you pay to ship the balance as oil and water, and emulsion has a shorter shelf life in heat. On African supply lines powder is normally the better economics unless the site has no reliable make-up operator.
What shelf life should I plan for?
Liquid PAC, ACH and ferric products: 6–12 months in sealed original packaging out of direct sun. Powder PAC and alum: 12–24 months if kept dry — both are hygroscopic and will cake. Dry polyacrylamide: 12–24 months sealed, but made-up polymer solution degrades within 24–48 hours and should be prepared daily. Sodium hypochlorite is the exception: it loses roughly 2–5% of available chlorine per month at 25 °C and much faster above 30 °C, so it should be bought little and often.
Do you handle the import documentation?
We provide the commercial invoice, packing list, bill of lading, certificate of origin, batch certificate of analysis, safety data sheet and the HS code. Customs clearance in the destination country is normally handled by your own clearing agent, who will know the local permit position for the specific product better than we can.
Are any of these products restricted in African countries?
Some are controlled and it varies by country. Sulphuric acid and sodium hypochlorite attract precursor or dangerous-goods controls in several jurisdictions, and a few countries require an import permit for bulk acid regardless of end use. Tell us the destination country at enquiry stage and we will flag what we know, but the clearing agent’s reading of current local law takes precedence over ours.