What are coagulant chemicals used for?
In the treatment of municipal water, chemicals like aluminum sulfite and ferric chloride are used to help remove suspended solids from water. Your interviewer is looking to hear that you are familiar with the usage of these coagulants and what the goal of their use is with this question.
"I understand that coagulation treatment is vital in the treatment of water to help pull solids out of the water prior to the final filtration of it for usage. In an operation like yours, it sounds vital to pull out things like sand, clay, bacteria, and algae that may be present. I'm familiar with coagulants like aluminum sulfate and ferric chloride. Can you talk a bit about the coagulants you use here?"
As you fully research the water treatment processes that are used for public consumption, you'll find out that coagulation treatment is a very common step in the overall process that happens prior to sedimentation and filtration. The goal of the coagulation chemicals is to cause solids in the water to clump together and sink to the bottom for easier filtration. As you prepare to answer a question like this during your interview, be sure to touch on your familiarity of the different coagulants used in the treatment of water and their overall use.
