FAQ – Water Treatment Chemicals

1. What is the most commonly used coagulant for water treatment?

Polyaluminium Chloride (PAC) is the most widely used coagulant globally. It outperforms traditional aluminum sulfate (alum) with faster floc formation, lower dosage requirements, wider pH range (5-9), and less sludge production. PAC accounts for over 70% of industrial water treatment coagulant usage worldwide.

2. What is the difference between PAC and aluminum sulfate (alum)?

PAC has 2-3x higher Al₂O₃ content (28-30% vs 14-16%), works across a broader pH range, produces less sludge, performs better in cold water, and requires lower dosage. Aluminum sulfate is cheaper per ton but usually costs more per treated volume. For most applications, PAC delivers better cost-effectiveness.

3. How do I calculate the correct PAC dosage for my water treatment system?

The optimal PAC dosage depends on raw water turbidity, pH, temperature, and target water quality. General guidelines: drinking water 10-30 mg/L, industrial wastewater 50-200 mg/L, municipal sewage 30-100 mg/L. We recommend jar testing to determine the exact dosage for your specific water chemistry. Contact our technical team for a free dosage calculation based on your water analysis report.

4. What types of Polyacrylamide (PAM) are available and which one should I choose?

Three main types: Anionic PAM (APAM, negative charge) — best for alkaline wastewater, mining, and mineral processing with inorganic coagulants like PAC. Cationic PAM (CPAM, positive charge) — best for sludge dewatering and organic-rich wastewater. Nonionic PAM (NPAM, neutral) — best for acidic conditions. The choice depends on your wastewater pH, solid charge characteristics, and treatment goals.

5. What is PAC basicity and why does it matter?

Basicity (B, %) measures the degree of polymerization in PAC — the ratio of hydroxyl to aluminum ions. Higher basicity (70-85%) means higher polymerization, better coagulation performance, and less pH impact on treated water. For drinking water, medium-to-high basicity (60-80%) is recommended. For industrial wastewater, high basicity (70-85%) typically performs best. Always ask your supplier for the basicity specification.

6. How should I store PAC and what is its shelf life?

Store PAC in a cool, dry, well-ventilated area away from direct sunlight and moisture. Keep containers tightly sealed. Liquid PAC should be stored in corrosion-resistant tanks (PE, FRP, or rubber-lined steel). Solid PAC powder has a shelf life of 12 months when stored properly. Liquid PAC should be used within 6 months. Avoid mixing with other chemicals during storage.

7. What is the difference between industrial grade and drinking water grade PAC?

Drinking water grade PAC meets stricter standards (e.g., NSF/ANSI 60, EN 883, GB 15892-2020) with lower heavy metal limits — Fe ≤ 0.01%, As ≤ 0.0002%, Pb ≤ 0.001%. Industrial grade PAC has slightly higher impurity tolerance and costs less. Never use industrial grade PAC for drinking water treatment. Always request certification documents from your supplier.

8. How do PAC and PAM work together in wastewater treatment?

PAC (coagulant) is added first to destabilize suspended particles and form micro-flocs. After 1-3 minutes of rapid mixing, PAM (flocculant) is added to bridge the micro-flocs into larger, settleable flocs with 2-5 minutes of slow mixing. The typical ratio is PAC 50-200 mg/L + PAM 1-5 mg/L. This combination can achieve 90-99% turbidity removal in most wastewater applications.

9. What are the shipping options and lead times for bulk chemical orders?

We ship globally from Chinese ports (Shanghai, Ningbo, Qingdao, Tianjin). Container options: 25kg PP/PE bags (20-28 MT per 20ft container), 500-1000kg bulk bags, or liquid in IBC totes. Typical lead time is 7-15 days after order confirmation. We handle all export documentation including MSDS, COA, Certificate of Origin, and SGS/BV inspection reports.

10. What quality certifications should I look for when sourcing water treatment chemicals from China?

Essential documents: ISO 9001 (quality management), MSDS (safety data sheet), COA (certificate of analysis) per batch, third-party test reports (SGS, BV, or Intertek). For drinking water grade: NSF/ANSI 60 certification is the gold standard for international markets. Also request heavy metal test reports and production process documentation. HydroChemix provides all these documents with every shipment.

11. What is the minimum order quantity (MOQ) for water treatment chemicals?

Our standard MOQ is 1 MT (metric ton) for most powdered products and 5 MT for liquid formulations. We offer sample quantities (1-5 kg) for testing and evaluation purposes — free of charge, customer only covers shipping. For trial orders, we support LCL (less than container load) shipments. Contact us for custom MOQ arrangements.

12. How do I test the quality of PAC before purchasing in bulk?

Key parameters to test: Al₂O₃ content (≥28% for premium grade), basicity (60-85%), water insoluble matter (≤0.5%), pH (3.5-5.0 at 1% solution), and heavy metal content. Request a pre-shipment sample and conduct jar tests with your actual water source. Perform accelerated stability tests. Third-party inspection (SGS/BV) before shipment is strongly recommended for large orders.

13. Which coagulant works best for textile/dyeing wastewater?

For textile wastewater with high color and COD, we recommend PAC (basicity 70-80%) combined with cationic PAM. The PAC neutralizes the negative charges on dye molecules, while CPAM bridges and settles the flocs. Typical dosage: PAC 200-500 mg/L + CPAM 2-5 mg/L. For reactive dyes, polyferric sulfate (PFS) can also be effective. Pre-treatment with our COD remover may be needed for very high-strength wastewater.

14. What are the payment terms for international orders?

We accept T/T (bank transfer) — 30% advance, 70% against B/L copy; L/C at sight for orders over $50,000; and Western Union for sample orders. Payment terms are negotiable based on order volume and customer relationship. All prices are FOB or CIF as per your preference. We work with all major international shipping lines for competitive freight rates.

15. How does water temperature affect coagulation performance?

Cold water (below 5°C) significantly reduces coagulation efficiency because water viscosity increases, particle movement slows, and floc formation takes longer. PAC performs better than alum in cold water due to its pre-polymerized structure. If treating cold water: increase coagulant dosage by 20-30%, extend mixing time, or use PAC with higher basicity (75-85%). Heating is rarely economical for large volumes.

16. What is COD Remover and when should I use it?

COD (Chemical Oxygen Demand) Remover is a specialized chemical blend that oxidizes and precipitates organic pollutants in wastewater. Use it when your wastewater COD is too high for conventional biological treatment or when you need rapid COD reduction. Typical dosage: 100-1000 mg/L depending on inlet COD. Our COD remover can achieve 60-85% COD reduction and works synergistically with PAC/PAM for complete treatment.

17. How do I switch from aluminum sulfate to PAC without disrupting my treatment process?

Start with a PAC dosage approximately 1/3 of your current alum dosage. Run jar tests first to confirm the optimal dose with your raw water. Gradually transition over 3-5 days: Day 1-2: 70% alum + 30% PAC; Day 3-4: 50/50; Day 5+: 100% PAC. Monitor effluent turbidity, pH, and sludge volume throughout. Most plants see improved performance within the first week of full conversion.

18. What is the function of activated carbon in water treatment?

Activated carbon removes organic contaminants, chlorine, taste, odor, and color from water through adsorption. It has an extremely high surface area (500-1500 m²/g) with millions of microscopic pores. Applications include drinking water purification, wastewater polishing, groundwater remediation, and industrial process water treatment. We supply coconut shell (higher hardness, better for drinking water) and coal-based (lower cost, good for industrial use) varieties.

19. How do I select the right filter media for my water treatment system?

The selection depends on your target contaminant: Quartz sand — general filtration, turbidity removal. Anthracite — dual-media filters with sand, removes organics. Manganese sand — iron and manganese removal from groundwater. Activated carbon — organics, chlorine, taste/odor removal. Key specifications: effective size (d10), uniformity coefficient (UC), specific gravity, and hardness. Contact us with your water analysis for a customized filter media recommendation.

20. What are the main export markets for Chinese water treatment chemicals?

Major export markets include Southeast Asia, Middle East, Africa, South America, and South Asia. Chinese water treatment chemicals are competitive due to mature manufacturing, abundant raw materials, and cost-effective production. In 2024-2025, the fastest growing markets are in Africa and Southeast Asia for municipal water projects, and the Middle East for oil & gas water treatment applications.

21. Do you provide technical support after purchase?

Yes. Every customer receives: pre-shipment application guidance, on-site dosage optimization support (remote or in-person for large projects), troubleshooting assistance, and regular follow-up on treatment performance. Our technical team has engineers with 10+ years of water treatment experience. Emergency support is available via WhatsApp/WeChat 24/7 for critical issues.

22. Can I get free samples for testing?

Yes, we provide free samples (1-5 kg) of all our products for evaluation. You only cover the shipping cost. Typical sample delivery time: 3-7 days via DHL/FedEx/UPS. We recommend testing at least 2-3 batches over different seasons to account for raw water quality variations before committing to bulk orders.

23. How does polyferric sulfate (PFS) compare to PAC?

PFS has a higher density floc that settles faster, works better at removing phosphorus, and is more effective in removing COD and color. However, it has a narrower pH range (6-9), higher corrosivity (requires acid-resistant equipment), and can leave residual iron color at high doses. PAC is more versatile and user-friendly. For phosphorus removal and high-color wastewater, PFS often outperforms PAC and can be used in combination.

24. What chemicals do I need for swimming pool water treatment?

Essential pool chemicals we supply: SDIC (sodium dichloroisocyanurate) or TCCA for chlorine disinfection (slow-dissolving tablets), Calcium hypochlorite for shock treatment, PAC or aluminum sulfate for coagulation/flocculation, pH adjusters (soda ash or sodium bisulfate), and algaecides. SDIC 60% granules are the most popular choice for daily pool chlorination due to stabilized chlorine with cyanuric acid protection from UV degradation.

25. Are your products compliant with international environmental regulations?

Yes. Our products comply with REACH (EU), TSCA (USA), and major international standards. We provide full safety documentation (MSDS/SDS in 16-section GHS format), environmental impact data, and regulatory compliance certificates. Our manufacturing facility is ISO 14001 certified for environmental management. All products are tested for restricted substances per international regulations.