Coagulation and Flocculation Essay

1.0 IntroductionIn this lab, we ar conducting two experiments on natural out-of-doors water. The for the first time experiment is to conduct jar tests to estimate an optimum venereal infection of iron salt to remove suspended solids. The seconds experiment is to observe the appreciate of floc physical composition nad sedimentation.2.0 BackgroundCoagulation and FlocculationCoagulation and flocculation are important part in water and wastewater treatment. Coagulation is the destabilisation of particulate military issue 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 run test for plant operations. Aluminum or iron salts can be used to for curdling of particles and to form flocs that can settle out. Coagulation and flocculation tests ply the optimum dosages to remove turbidity and color, along with secondary effects such as adjusting pH. Jar tests also provide information on the tot 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 basal processes, for instance, kinetics of reactions and removal of constituents.3.0 ProcedureDetermination of Optimum Coagulant social diseaseTo determine the optimum coagulation dosage, a series of jar tests were conducted. First, four hundred mL of clay and sodium bicarbonate amended DI water was metric and poured into a 500 mL Erlenmeyer flask using a have cylinder. The initial pH of that sample distribution was then calculated and recorded. The predetermined back abeyanceer of coagulator was poured into a 100mL graduated cylinder and DI water was added to reach a total solution volume of 100 mL. A stir blank out was added to the Erlenmeyer flask along with the coagulant dose. The flask was then placed on a magnetic stir plate was rapidly mixed for maven minute.After a minute of rapid mixing, the speed was reduced to deplorable and the solution underwent slow mixing for ten transactions. The flask was then outback(a) from the magnetic plate and was allowed to settle. Samples were extracted from the top of the flask after five, ten, and fifteen proceeding had elapsed using a 10 mL sampling syringe. special(a) care was taken to not disturb the sediment while sampling. The sample was transferred from the syringe to a vile, shaken, and placed in a Turbidimeter to determine the turbidity.The turbidity was recorded and the vile was emptied and rinsed between each sample. After fifteen minutes had elapsed and the last turbidity reading had been recorded, the pH of the sample was measured and recorded. The sample was then dumped into a specified waste container, the flask was rinsed with splash water and DI water, and the entire experiment was repeated using a sweet specifi ed coagulant dose.4.0 Results and DiscussionAfter plotting turbidity against dosage from our results, we instal that the optimum dosage of coagulant to be 1000 mg/L Fe2O3 as shown in Figure 1. Also, longer settling times produced cut levels of turbidity, with 15 minutes being most successful. Optimum pH for a coagulant is determined empirically from laboratory testing by guardianship dosage constant and testing a pH range for best coagulation. Generally after adding Fe2O3, final pH decreased. Although we did not perform this in the lab, our samples had best success with a pH around 6.5 as seen in Table 1.Mixing speed is also important in coagulation and flocculation. Initially flash mixing is used, where high mixing speeds disperse the coagulant evenly throughout the container. Later, slower mixing speeds are used to assist particle collisions, which lead to larger floc formations. The lab is performed this way because high speeds will help disperse the coagulant but will brea k up the flocs that form. By reducing the speed to slow after adept minute, it allows for an even dispersion but also the formation of flocs.