Chemically enhanced primary
Dosing ahead of primary settling lifts TSS and BOD removal sharply and reduces load on the biological stage.
Application — wastewater
PAC for sewage and wastewater treatment
Used in STPs and industrial effluent plants across the UAE for suspended solids removal, COD reduction, phosphorus precipitation and improving sludge dewaterability.
Dosing points
Where PAC is dosed in a wastewater plant
Phosphorus precipitation
Aluminium precipitates phosphate as insoluble AlPO4 — the standard route to meeting tight discharge phosphorus limits.
Tertiary polishing
Post-biological dosing to catch residual solids and turbidity before final discharge or reuse.
Sludge conditioning
Improves dewaterability ahead of belt press, centrifuge or filter press, cutting cake volume and disposal cost.
Industrial effluent
Breaking emulsions and dropping COD in food, dairy, beverage, laundry, textile and metal-finishing streams.
Odour and H2S control
Reduces sulphide-driven odour in septic collection systems as a secondary benefit of solids removal.
Typical dose ranges by wastewater stream
| Stream | Typical PAC dose (as product) | Target |
|---|---|---|
| Municipal sewage — primary | 20–60 mg/L | TSS and BOD reduction ahead of biology |
| Phosphorus removal | 30–100 mg/L | Driven by influent P load and target discharge limit |
| Tertiary polishing | 5–20 mg/L | Residual turbidity and solids |
| Food and beverage effluent | 50–200 mg/L | COD, FOG and suspended solids |
| Laundry and textile effluent | 100–300 mg/L | Colour, surfactants and suspended solids |
| Sludge conditioning | 2–8 kg per tonne dry solids | Dewaterability and cake dryness |
Indicative ranges only, for planning a trial. Wastewater varies enormously between sites and across a single day. Establish your dose by jar test on representative samples at different times of the operating cycle.
Practical notes from STP operators
The most common mistake we see is dosing to a fixed setpoint against a variable influent. Sewage load in the UAE swings hard between morning peak, midday and night, and labour-accommodation plants swing harder still. A dose set for peak wastes chemical for eighteen hours a day; a dose set for average fails at peak.
The second is ignoring alkalinity. PAC consumes alkalinity, and where influent alkalinity is already marginal — common on plants receiving high-strength effluent — pH can drop far enough to inhibit the biological stage. Monitor it, and be prepared to supplement.
The third is under-valuing sludge. A coagulant producing 20% more sludge means 20% more tankering, and in the UAE sludge disposal is a real line item. Judge coagulant performance on total operating cost, sludge included, not on removal efficiency alone.
FAQ
Common questions
Typically 20 to 60 mg/L for primary treatment, higher where phosphorus removal is required. Actual dose depends on influent strength and your discharge limits, and should be set by jar test.
Yes. Aluminium in PAC precipitates phosphate as insoluble aluminium phosphate, which is then removed with the sludge. It is one of the most common routes to meeting tight phosphorus discharge limits.
It produces chemical sludge, but generally less than the equivalent alum dose, and PAC sludge dewaters better — which usually reduces net disposal cost.
In most cases yes, if you already have a coagulant dosing system. Confirm that pumps, lines and tanks are made from PAC-compatible materials — HDPE, PVC, FRP or rubber-lined steel.
Related
Continue reading
PAC for drinking water treatment
Polyaluminium chloride is the coagulant of choice for potable water clarification across the region — wider effective pH range, lower alkalinity…
PAC dosage calculation and jar testing
Getting the dose right is worth more than getting the price right. A plant over-dosing by 20% wastes more each year than most buyers ever negotiate…
PAC supplier in Dubai
We are based in Dubai, we ship through Jebel Ali, and we deliver polyaluminium chloride to sites across the emirate — usually within the same working…