Wastewater Treatment Chemicals
There are a vast array of wastewater treatment chemicals used in an industrial setting to more effectively carry out contaminant/water separation. The following is a small primer on many of these chemicals used in the wastewater treatment field. Advanced Chemical Systems is a supplier of all chemicals listed below.
Before, after and even during the wastewater treatment chemical process, neutralization may be required to adjust the pH of effluent. Industrial facilities use the addition of acids, such as sulfuric or muriatic, to reduce pH, and caustic solutions, such as sodium hydroxide, to raise the pH value of waste streams. Adjustment may occur in the EQ tank, as to adjust pH before the chemical treatment process. It may also occur in the treat tank to assist in the chemical treatment process. Lastly, the pH value may need to be adjusted once treatment is complete to assure the discharge stream is between 6 and 9, thus complying with local regulations.
Precipitation is the chemical process of separating a solid substance from a solution. This is achieved either by changing the substance into an insoluble form, or by reducing the solubility of the substance. In an industrial environment, the wastewater treatment process often involves the addition of chemicals to a waste stream that precipitate heavy metals, allowing them to then be removed through sedimentation or filtration. Along with toxic metals, contaminants that may be removed through chemical precipitation include fats, oils, and greases along with certain inorganics, such as phosphorus. Once these contaminants have been chemically precipitated, water can be decanted, and then filtered, the resulting sludge leftover to be properly disposed of.
Once precipitation has occurred, it is often beneficial to add a clarifying agent to aid in the settling of colloids out of suspension. This results in reducing the amount of settling time needed during the wastewater treatment process and promotes stronger attraction between solids during flocculation. Slowly mixing the waste stream allows more and more particles to combine into larger, heavier, and more filterable solids. A coagulant and/or coagulant aid are often also added to aid in the chemical process.
During flocculation, a coagulant is added to destabilize wastewater particulate as to aggregate them during the chemical process. Through chemical coagulation, the charge of smaller solid particles is reduced, causing them to form larger particle groups. During flocculation, larger and larger groups of particles are formed, allowing them to settle out during sedimentation, and/or be filtered out using a press. Common coagulants include aluminum sulfate, ferric chloride, and ferric sulfite. Cationic polymers may also be used. When slow-settling flocculent is a concern the addition of a coagulation aid such as organic polymer is also popular in the wastewater treatment process.