Dewatering: Flocculants and Coagulants

Neo Solutions, Inc. supplies water soluble polymers for the dredging, hard rock mining, coal, and water treatment industries. Flocculants and coagulants are used in these industries in regards to solid – liquid separations, dewatering, sludge thickening, and solidification. In addition, we also provide specialty chemical products to control foam, dust, corrosion, and biological growth.

Flocculants and coagulants work on the principle of particle surface charge neutralization. As polymer is added and allowed to interact with the influent, it electrically bonds with particles. As each strand of polymer contains many electrically charged sites it binds with the solids forming a larger particle called a flock.

An extensive line of varied molecular weight cationic, anionic, and nonionic polymers for use as flocculants are available. These polymers are available in dry granular, high solids inverse emulsions, and dilute aqueous, ready-to-use forms.  These products are designed to meet the broad range of need for efficient, economical solid/liquid separation in industrial water treatment, mining, dredging applications. Many of these products are NSF/ANSI Standard 60 approved for use in potable and secondary water systems.

The addition of polymers can be extremely beneficial in the operation of mechanical dewatering methods. Such mechanical methods include but are not limited to; centrifuges, belt presses, and filter presses. Adding polymers to geotextile tubes can greatly increase their dewatering efficiency by preventing media blinding. If settling ponds of the dredging operation are to be utilized settling rates and effluent clarity can be adjusted to suit the foot print of the site and users requirements.

As inorganic and organic materials vary by location, bench scale testing is required to determine the proper product on an individual basis. Typically product selection and optimal dosing can be determined with a 5 gallon sample of the in-situ as dredged material.

Figure 1 shows a clarifier section operating with a dual polymer program instituted. Coagulant is introduced upstream to maximize mixing and dispersion. As the influent enters the center well, flocculent is added to bind up the microflocs created by the coagulant. The combination of the two products makes for extremely clear water with a high settling rate

Figure 2 shows well agitated slurries in 1L cylinders prepared for settling tests.

Figure 3 shows the same slurries as Figure 2 with addition of a coagulant and 10 inversions of the cylinders to disperse the product throughout. Time between pictures is ~60 seconds.

Figure 4 Shows the stacking of flocculated material being discharged from a centrifuge.

For more information on flocculants please contact Randy Stroop of Neo Solutions Inc. at 906-231-9301 or [email protected]

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