In water treatment operations, Poly Aluminum Chloride (PAC) is one of the most commonly used coagulants. However, many facilities find that even with regular PAC dosing, the treatment results remain unsatisfactory. The root cause is often quite simple: a mismatch between the PAC grade and the specific water quality in question.
The active component of PAC is alumina (Al₂O₃), typically ranging from 26% to 32%, while the basicity varies between 40% and 95%. Alumina content directly determines coagulation activity and required dosage, while basicity affects floc formation speed and the clarity of settled water. PAC is manufactured using different processes – roller drying (lowest cost, higher insoluble residues, suitable for general wastewater), chamber press (higher alumina content, low insolubles, suitable for both wastewater and drinking water), and spray drying (highest purity, fastest solubility, ideal for drinking water and high‑standard treatment).
When the wrong PAC grade is chosen – for example, using a low‑content product for high‑turbidity wastewater – operators may need excessive dosage, leading to higher chemical costs and potential residual aluminum issues. Conversely, applying a high‑basicity PAC to low‑turbidity water can cause "over‑flocculation", producing tiny, hard‑to‑settle flocs that actually worsen effluent quality.
So how do you choose the right PAC for different types of water? Let's examine each scenario.
1. Drinking Water Treatment – Prioritize Safety with High‑Purity Products
Drinking water treatment imposes the strictest safety requirements. GB 15892-2020 (Poly Aluminum Chloride for Drinking Water) is the mandatory national standard in China. It specifies that solid PAC must contain at least 29.0% Al₂O₃, with a basicity range of 45%‑90%, and enforces tight limits on heavy metals such as arsenic, lead, cadmium, mercury, and chromium. For liquid PAC, the minimum Al₂O₃ content is 10%; for solid grades, it is 28%, with water insolubles ≤0.1%. Many water treatment facilities adopt even stricter internal specifications – requiring ≥29.2% Al₂O₃ and a basicity of 70%‑90% – to ensure safe, high‑quality drinking water.
Recommended choice for low‑turbidity, low‑color drinking water:
Select PAC with 28%‑30% Al₂O₃, medium basicity (60%‑70%), and produced via spray drying or a similarly high‑purity process to guarantee strict heavy metal control.
2. Industrial Wastewater – Tailor the Prescription to the Pollutant Profile
Industrial wastewater varies enormously across sectors. PAC selection must be adapted to the specific pollutant characteristics of each effluent type.
2.1 Textile, Paper, Electroplating and Similar Wastewaters
For textile, dyeing, paint, and tannery wastewater, typical PAC dosages range from 100 to 300 kg per 1,000 m³ of water. High‑turbidity, high‑suspended‑solids wastewater (e.g., textile, mineral processing) requires PAC with 30%‑32% Al₂O₃ and higher basicity (70%‑85%) to achieve fast flocculation and large, dense flocs. For electronic wastewater containing heavy metals, a modified PAC (basicity 70%‑85%) can achieve over 98% removal of nickel and chromium.
2.2 Mining, Coal Washing and Oilfield Wastewater
Coal washing and mining wastewater contain extremely high levels of silt and total suspended solids. Dosage ranges are wide: 200‑1,000 mg/L for coal washing and mining applications, and 50‑200 kg per 1,000 m³ for oilfield wastewater. For cost‑sensitive operations, a 27% Al₂O₃ roller‑dried PAC offers an economical solution – it flocculates quickly, forms dense flocs, and works well in primary treatment stages.
For very high turbidity, a 26% Al₂O₃ product provides the best cost‑effectiveness.
3. Municipal Wastewater – Balance Phosphorus Removal with Operating Cost
Chemical phosphorus removal is a key application of PAC in municipal wastewater treatment. PAC reacts with orthophosphate to form insoluble phosphate precipitates, which are then removed by solid‑liquid separation.
Research shows that in tertiary treatment, at a PAC dosage of 30‑80 mg/L and pH 6.5‑7.5, effluent total phosphorus can be consistently maintained below 0.3 mg/L, with SS removal reaching 90%‑95% – and 15%‑25% cost savings compared to traditional aluminum salts.
Typical dosage ranges:
Primary treatment: 50‑150 mg/L
Tertiary treatment: 20‑80 mg/L
Plant upgrade projects: 10‑50 mg/L
For municipal wastewater, 28% Al₂O₃ PAC is the "all‑rounder" that strikes an excellent balance between performance and cost. For projects requiring effluent quality to meet quasi‑Class IV standards or higher, 29% spray‑dried PAC (extremely low insolubles, highest coagulation efficiency, minimal sludge production) is the superior choice.
4. Extreme Water Conditions – High Turbidity & Low Temperature/Low Turbidity
Special water conditions put PAC performance to the test.
High turbidity: Choose PAC with higher basicity (70%‑90%) to rapidly form large, dense flocs and improve settling efficiency.
Low temperature and/or low turbidity (e.g., winter conditions or pH outside the 5‑9 range): Conventional PAC activity drops significantly. Specially formulated low‑temperature compound PAC can reduce dosage by 15%‑30% while maintaining stable flocculation. Moreover, for naturally low turbidity water, a high‑molecular‑weight, high‑charge‑density PAC provides more adsorption and bridging sites, effectively capturing micro‑impurities.
Quick Selection Reference Table
| Water Type | Recommended Al₂O₃ Content | Recommended Basicity | Typical Dosage | Preferred Manufacturing Process |
|---|---|---|---|---|
| Drinking water | 28%‑32% | 60%‑70% | 5‑20 mg/L | Spray drying |
| Municipal wastewater (P‑removal) | 28%‑29% | 40%‑90% | 30‑80 mg/L | Chamber press / spray drying |
| Textile / paper / tannery | 29%‑30% | 70%‑85% | 100‑300 kg/1,000 m³ | Chamber press |
| Electroplating / metallurgy | 28%‑29% | 70%‑85% | 20‑150 kg/1,000 m³ | Chamber press |
| Coal washing / mining | 26%‑27% | 70%‑90% | 200‑1,000 mg/L | Roller drying |
| Oilfield wastewater | 28%‑29% | Medium‑high | 50‑200 kg/1,000 m³ | Chamber press |
| Low‑temperature / low‑turbidity | ≥28% (compound) | 50%‑70% | 15%‑30% dosage reduction | Spray drying |
Always conduct jar tests using your actual water sample before full‑scale procurement. The jar test helps determine the most economical and effective dosage for your specific conditions.
Market Trends & Outlook
The PAC industry has seen steady growth. In 2025, domestic production reached approximately 2.31 million tons, with demand of 2.24 million tons, and a market size of around ¥3.70 billion. The average price was about ¥1,652 per ton. On a global scale, the PAC market was valued at US1.83 billion in 2025 and is projected to reach US 4.46 billion by 2035, representing a compound annual growth rate (CAGR) of approximately 9.5%. The Asia‑Pacific region is currently the largest market, while Latin America is the fastest‑growing.
The industry is moving toward intelligent, precise dosing – using online phosphate monitoring feedback control systems, and compound control strategies (flow‑proportional feed‑forward combined with phosphate feedback) are gradually replacing experience‑based manual dosing.
Driven by stricter environmental regulations, rising municipal wastewater treatment rates, tougher industrial discharge standards, and the expansion of rural safe drinking water projects, the demand for PAC is expected to continue its upward trend.
Keywords: Poly Aluminum Chloride, PAC Alumina Content, Drinking Water Grade PAC, Industrial Wastewater Treatment, Municipal Wastewater, PAC for Phosphorus Removal, Basicity, PAC Selection Guide, Water Treatment Cost, Flocculant, Coagulant
