In this lab, we are conducting two experiments on natural surface water. The first experiment is to conduct jar tests to estimate an optimum dosage of iron salt to remove suspended solids. The seconds experiment is to observe the rate of floc formation nad sedimentation.
Coagulation and Flocculation:
Coagulation and flocculation are important part in water and wastewater treatment. Coagulation is the destabilization of particulate matter by physical or chemical processes. Flocculation is the formation of larger particles that will settle out of the solution. They are usually the first form of treatment of water and wastewater to remove suspended matter or color.
Jar tests are used as a control test for plant operations. Aluminum or iron salts can be used to for coagulation of particles and to form flocs that can settle out. Coagulation and flocculation tests provide the optimum dosages to remove turbidity and color, along with secondary effects such as adjusting pH. Jar tests also provide information on the amount of energy needed to provide the coagulation and flocculation treatments, as well as settleability of the flocs, and clarity of the water. They can also be used to study basic processes, for instance, kinetics of reactions and removal of constituents.
Determination of Optimum Coagulant Dosage
To determine the optimum coagulation dosage, a series of jar tests were conducted. First, 400 mL of clay and sodium bicarbonate amended DI water was measured and poured into a 500 mL Erlenmeyer flask using a graduated cylinder. The initial pH of that sample was then measured and recorded. The predetermined dose of coagulant was poured into a 100mL graduated cylinder and DI water was added to reach a total solution volume of 100 mL. A stir bar was added to the Erlenmeyer flask along with the coagulant dose. The flask was then...