How to deal with an accidental flocculant spill?

Coagulation and flocculation are two water treatment stages used together to separate solid particles suspended in cloudy water. Even if they have a complementary role, the coagulation and flocculation processes should not be confused because they do not involve the same chemicals or mechanisms.

Coagulation is carried out using metallic mineral salts, called coagulating agents, containing iron or aluminium such as ferric chloride FeCl3. Naturally, some suspended solid particles are electrically charged (+ or -) and therefore repel each other, they cannot agglomerate. Coagulation agents balance these charges and therefore allow solid particles to come together.

Flocculation is a physical-chemical phenomenon during which solids suspended in a liquid agglomerate to form flakes (also called flocs). These flakes then settle quickly or rise to the surface of the liquid, allowing them to be easily separated from the rest of the liquid. Flocculation is a natural phenomenon that can be accelerated by using chemicals called flocculants or flocculation agents.

There are several types of flocculants, which can be anionic (negatively charged), cationic (positively charged) or non-ionic (uncharged). The most common flocculants are based on a polymer, polyacrylamide. They can be marketed in solid, liquid or emulsion form, the main producers of flocculants in Europe are: Kemira, SNF Floerger, BASF, Solenis, Solvay….

In the industrial field, the water treatment sector uses the most flocculants. They are used in the treatment of sludge but also in drinking water clarification. As the paper industry is a water-intensive activity that produces sludge, flocculants are also frequently used.

Among consumers, flocculants are used to give clarity to cloudy pool water. When a flocculant is added, the solid particles are consolidated and then filtered.

Despite their very high effectiveness, flocculants suffer a major disadvantage: In the event of a spill or if residue sticks to the bottom of a shoe, the slightest contact with water can be disastrous. In contact with water, the flocculant dissolves and forms a viscous gel that is similar to hair gel. This gel then transforms the floor into a skating rink, which greatly increases the risk of falls.

Due to their role, flocculants should be added in small proportions to a large quantity of water (less than 0.1%). They are extremely effective even when highly diluted. Consequently, after cleaning, even the tiniest flocculant residue is enough to make the floor slippery again when water is added (e.g. when cleaning or if it rains).

→ For this reason, to avoid an accident it is very important to completely remove all flocculant residue.

In the event of a flocculant spill, washing with large amounts of water is absolutely not recommended ! This would make cleaning operations even more difficult.

POLYCAPTOR® absorbent is a synthetic powder specifically developed for its drying properties and its ability to clean up viscous liquid spills such as flocculants. This absorbent is composed of ultra-porous grains that absorb the liquid to the core through capillary action. The liquid can then be fully removed and leaves no residue. Even if water is added at a later date the risk of slipping is reduced, as the flocculant residue has been removed.

Bleach or sodium hypochlorite can be used to break down polyacrylamide-based flocculants. As bleach is a powerful oxidizer, it will cause the scission of certain polymer chains with a loss of consistency and consequently its viscous nature. On the other hand, this operation is quite dangerous because bleach can react with other polymer functions and form hazardous volatile chloramines: Chloramines are respiratory irritants and allergenic, they can also cause long-term respiratory problems. Bleach itself is a highly reactive, corrosive chemical and should only be handled by trained personnel with appropriate protective equipment.