Question

To pH of 8.3	To pH of 4.5
0	320

Alkalinity.

Wastewater Problem.

Determine the alkalinity in mg/L CaCOs for DI water and tap water based on the number of digits (digits= mg/L CaCO3 in 100 ml) Assuming that 25mg/L of filter alum [Al2(SO4)3-14.3 H2O] with MW-600 was used for coagulation, determine the total amount of alkalinity consumed in mg/L CaCOs from coagulation and flocculation. Is the amount of alkalinity consumed from coagulation less than, equal to, or greater than the initial concentration of alkalinity that you measured in the tapwater?

Answer 1

Ca-hardness tap water 513 496 485 527 498 Total hardness tap water 801 772 751 737 796 Concentration of Mg DI water DI water Conc. mg 205.2 198.4 194 210.8 199.2 320.4 308.8 300.4 294.8 318.4 0.9 0.6 0.6 0.3 115.2 110.4 106.4 84 119.2 0.5 0.7 0.2 0.6 0.7 0.8 0.9 Mean Std. Dev Std. Err 95%conf. 0.16415672 0.003365 0.278461025 0.005017 0.345056 0.005201 201.52 5.8536826 0.12 2.61784644 0.053666 4.440684632 0.08 0.46 308.56 107.04 0.54 9.929672704 0.178885 12.30441 0.185472 5.502698 0.082946 Answer to first three questions are given in the table above 4. Moles of Ca2+ is 201.52/100.1 = 2.01 mmol and Mg = 1.27 mmol. Total moles 5. The concentration of Mg2+ is in acceptable level as it is below 250 mg/L 3.28 mmol.. Therefore, 3.28 mmol soda ash is necessary to soften the tap water, which is 347.7 mg