Selecting Polyacrylamide Flocculants: Avoiding 5 Major Pitfalls

In modern sewage treatment processes, polyacrylamide is an important flocculant. However, how to scientifically choose from the many types of polyacrylamide flocculant products and ensure precise dosing in practical applications while avoiding common pitfalls is an important issue faced by the sewage treatment industry.

How to Accurately Choose Polyacrylamide Flocculant Types in Sewage Treatment

Suspended solids(SS) and turbidity

For wastewater containing a large number of fine, hard-to-settle suspended particles, it is advisable to use high-molecular-weight, high-degree-of-hydrolyzed anionic polyacrylamide, as it has good bridging adsorption and net trapping effects, which can effectively coagulate and precipitate these particles.

pH value

If the wastewater is alkaline or acidic, the ionic type of polyacrylamide must be considered. Under acidic conditions, cationic polyacrylamide such as poly(dimethyl diallyl ammonium chloride) shows better flocculation effects; while in a slightly alkaline environment, anionic or nonionic polyacrylamide is more suitable.

Temperature factors

Different polyacrylamide products have different sensitivity to temperature. It is necessary to choose the appropriate temperature-resistant type polyacrylamide flocculant products based on the actual operating environment and temperature changes in the process.

Special pollutants

Wastewater from certain specific industries may contain special pollutants, such as heavy metal ions in mining and smelting wastewater, lignin in paper-making wastewater, etc. In this case, it is necessary to select polyacrylamide products that can specifically remove these pollutants based on experimental verification.

When choosing polyacrylamide flocculant in sewage treatment, it is essential to fully consider and analyze the various chemical and physical properties of the sewage. Laboratory small tests and on-site pilot tests should be conducted to determine the best flocculant type and dosage, thereby ensuring the efficient and stable operation of the sewage treatment process and achieving ideal purification effects.

5 Common Misconceptions in Choosing Polyacrylamide Flocculant

The higher the molecular weight, the better the effect

In fact, the best flocculation effect under different water quality conditions may correspond to a specific range of molecular weights, not necessarily the higher the better.

The higher the ionicity, the wider the applicability

The choice of ionicity should be based on the charge properties and organic content of the water to be treated. For example, for sewage treatment with a large amount of negatively charged sludge, cationic polyacrylamide with appropriate ionicity can provide good flocculation effect; while in some special cases, anionic or nonionic polyacrylamide may be more suitable.

The higher the preparation concentration, the more significant the effect

Too high a preparation concentration may not only cause difficulties in stirring and incomplete dissolution but also reduce flocculation speed and effect due to excessive solution viscosity. The correct preparation concentration is usually between 0.1%-0.5%, depending on the application scenario and the molecular weight of polyacrylamide.

Ignoring water quality changes

The quality of sewage varies with time and source. Therefore, one cannot rely on the results of a single test to consistently choose a specific type of polyacrylamide. Regular monitoring and adjustment of polyacrylamide flocculant type and dosage should be conducted to cope with changes in water quality.

Single-mindedly pursuing price advantages

When purchasing polyacrylamide, some users focus only on product price while ignoring product quality and performance. High-quality polyacrylamide may have a higher cost, but it can better match the sewage treatment needs, bring higher treatment efficiency, and lower operational costs.

In choosing polyacrylamide flocculant, one should fully consider the specific characteristics of the sewage, treatment goals, and polyacrylamide performance parameters, conduct comprehensive analysis and laboratory small test verification to ensure the selection of the most suitable flocculant product. Additionally, rational dosing methods and equipment are also very important elements.