Application of Anionic Polyacrylamide (NALCO 71661)

NALCO 71661 is a high-performance anionic polyacrylamide developed by Nalco Water (Ecolab), primarily used for solid–liquid separation, clarification, and sludge dewatering in industrial and municipal water treatment systems. This product is supplied either as a liquid emulsion or a dry polymer, depending on application needs, and it provides high efficiency in improving settling rates, filtration clarity, and water recovery.

Its molecular design — combining high molecular weight and moderate-to-high anionic charge density — allows NALCO 71661 to perform effectively in systems containing fine, negatively charged colloidal particles and organic or mineral solids.NALCO 7166

1. Product Overview

NALCO 71661 is part of Nalco’s anionic flocculant product line, often used where rapid clarification, efficient solids capture, and enhanced dewatering are required. Its typical indices are as follows:

• Polymer type: Anionic polyacrylamide

• Form: Liquid emulsion or dry powder (depending on product version)

• Charge density: Medium to high anionic charge (approx. 20–40%)

• Molecular weight: Very high (typically >10 million Daltons)

• Active content: ~35–45% (for emulsion); 100% (for dry powder)

• Solubility: Completely soluble in water after inversion or hydration

• pH range of use: 4.0–9.0

These properties make NALCO 71661 suitable for neutral to alkaline systems and effective across a wide range of industrial applications.NALCO 7166

2. Mechanism of Action

Anionic polyacrylamide such as NALCO 71661 works mainly through particle bridging and charge neutralization mechanisms.

• The negatively charged polymer chains adsorb onto the surface of fine, positively charged or neutral suspended solids.

• Through electrostatic attraction and long-chain bridging, the particles agglomerate into large, dense flocs.

• These flocs settle more rapidly in clarifiers and thickeners or can be easily dewatered through filtration or centrifugation.

This mechanism enhances the efficiency of solid–liquid separation processes and results in clear supernatant water and compact sludge.

3. Applications in Water and Wastewater Treatment

a. Raw Water Clarification

NALCO 71661 is widely used in raw water treatment, particularly for surface or river water with high turbidity or organic load.
When applied after inorganic coagulants such as alum, PAC (polyaluminum chloride), or ferric chloride, it enhances floc size, settling velocity, and filter performance. The result is reduced turbidity, improved clarity, and better throughput in sand filters or clarifiers.

b. Industrial Wastewater Treatment

In industrial wastewater, NALCO 71661 performs excellently for removing suspended solids and organic matter.
Industries such as chemical manufacturing, petrochemical refining, food and beverage, steel, and textile processing employ it for clarifier feed, dissolved air flotation (DAF), and sedimentation units.
It also helps reduce chemical oxygen demand (COD) and turbidity in treated effluent, enabling compliance with discharge or reuse standards.NALCO 7166

c. Sludge Thickening and Dewatering

In both municipal sewage treatment plants and industrial effluent treatment systems, NALCO 71661 is used to thicken and dewater sludge.
The flocculant enhances the formation of compact flocs that release water more readily, improving dewatering efficiency in belt presses, filter presses, or centrifuges.
Benefits include:

• Lower sludge moisture content.

• Reduced sludge volume and transport cost.

• Enhanced filtration rate and dry cake formation.
  Typical dosage ranges from 0.1–0.5 kg per ton of dry solids (DS) for thickening and 1–5 kg/t DS for dewatering.

4. Applications in Industrial Sectors

a. Mining and Mineral Processing

NALCO 71661 is extensively applied in mining operations for tailings dewatering, thickener optimization, and process water clarification.
It improves the settling of fine mineral particles in tailings ponds, accelerates thickener underflow consolidation, and produces clearer overflow water for reuse.
Applications include coal washing, iron ore beneficiation, bauxite (red mud) separation, phosphate, copper, and gold processing.

b. Power Generation

In thermal and coal-fired power plants, NALCO 71661 is used for ash water clarification, sludge treatment, and cooling water clarification.
It helps separate fly ash and bottom ash from process water, minimizing suspended solids in effluent and facilitating water recycling.

c. Pulp and Paper Industry

In the pulp and paper sector, NALCO 71661 serves as a retention aid and drainage improver. It increases fiber and filler retention on the paper machine wire section and accelerates dewatering.
Additionally, it is used for white water clarification and sludge dewatering in the wastewater system, reducing suspended solids discharge.

d. Oil and Gas IndustryNALCO 7166

In refinery wastewater treatment and produced water management, NALCO 71661 assists in removing suspended solids, fine oil droplets, and organic impurities.
It can also be used as a settling aid in desalters, oil–water separation units, and DAF systems to achieve clear water for reinjection or disposal.

5. Advantages of NALCO 71661

1. High Efficiency at Low Dosages:
   The polymer provides strong flocculation even at low concentrations, reducing chemical costs.

2. Improved Clarity:
   Produces clear supernatant suitable for reuse or discharge.

3. Operational Flexibility:
   Effective across a wide pH range (4–9) and compatible with most inorganic coagulants.

4. Enhanced Sludge Dewatering:
   Reduces cake moisture content and increases throughput of mechanical dewatering systems.

5. Environmental Safety:
   Non-toxic and non-corrosive; does not introduce harmful residues into treated water.

6. Easy Handling and Mixing:
   Available as liquid emulsion for automatic dosing systems or as dry polymer for economic long-term storage.

6. Method of Use

For best performance, NALCO 71661 should be prepared as a 0.1–0.5% polymer solution using clean water.

• For emulsions: invert the polymer using moderate agitation until fully dispersed.

• For powders: allow 30–60 minutes of hydration for complete dissolution.
  Feed the polymer continuously through a dosing pump into clarifiers, thickeners, or sludge lines.
  Dosage should be optimized based on jar tests or on-site pilot evaluation.

7. Safety and StorageNALCO 7166

• Store between 5°C and 35°C, away from direct sunlight.

• Avoid freezing or prolonged exposure to heat.

• Prevent contact with strong oxidizing agents.

• Use gloves and goggles when handling concentrated polymer solutions.

8. Summary

In conclusion, NALCO 71661 is a high-molecular-weight anionic polyacrylamide designed for effective solid–liquid separation across a broad spectrum of water treatment and industrial applications.
Its excellent flocculating properties make it suitable for raw water clarification, industrial effluent treatment, sludge dewatering, and mineral processing.
By producing robust, fast-settling flocs and improving sludge dryness, it significantly enhances plant efficiency, reduces water consumption, and lowers operating costs.

Through its combination of performance, versatility, and environmental compatibility, NALCO 71661 remains one of Nalco’s most reliable anionic flocculants for achieving superior water quality and sustainable wastewater management.