Oily wastewater occurs when oil enters a body of water and becomes emulsified in the form of an oil-water emulsion. Waste oil emulsions can also form where water becomes emulsified in oil. In either case, these oil water emulsions require a customized separation treatment program. ChemTreat’s treatment programs include chemical, electrolytic, and physical methods.
ChemTreat’s chemical treatment programs offer a complete portfolio of emulsion flocculants. Emulsion flocculants are a suspension of minute beads of high molecular weight polymer in water, emulsified in an oil carrier. The minute beads are approximately 1 micron in diameter and contain concentrated polymer dissolved in water. These concentrated polymer beads, or “hydrogels”, are dispersed in a carrier fluid of high flashpoint mineral oil by means of a dispersing surfactant, that keeps the hydrogels from coalescing into larger droplets. Because the hydrogels are of greater density than the carrier oil, they are prone to settle over time, resulting in concentrated polymer solids on the bottom of the container with a layer of oil on the top. This separation can develop faster if the droplets are large, so keeping the droplets small and well dispersed is important in maintaining the product stability.
Emulsion flocculants are typically copolymers of acrylamide, a nonionic building block, along with a charge-bearing monomer. In the case of anionic flocculants, the anionic charge is produced by co-polymerizing acrylic acid with the acrylamide monomer. The ratio of acrylic acid to acrylamide determines the degree of charge on the molecule.
In the case of cationic flocculants, the cationic charge is provided by co-polymerizing AETAC, a methyl acrylate-derived cationic monomer with the acrylamide monomer. The ratio of AETAC to acrylamide determines the degree of charge on the molecule.
Because the hydrogels are made up of tightly-coiled polymer chains, mixing energy and time are required to ensure full contact of the hydrogels with the water and enable the polymer chains to uncoil fully. The polymer chains may be cationic, anionic, or nonionic with varying charge weights. The charge on the chain helps to uncoil the chain, so a higher-charged polymer will open faster than a low-charged or uncharged polymer.
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