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HW-5 1. Find the MCLs for: haloacetic acids, arsenic, nitrate, glyphosate, and radium Hint: https://www.epa.gov/ground-water-and-drinking- water/national-primary-drinking-water-regulations 2. Determine the (a) lime and soda doses for the hardness removal unit of the Scaly Pipe City to achieve a final hardness of 85 mg/L as CaCO3. The water quality analysis is given below. The pH of the water is 7.8. (b) Report the total hardness, carbonate hardness and non-carbonate hardness (mg/L as CaCO3). (c) Calculate the split ratio, and the final hardness if the split treatment is utilized (mg/L as CaCO3), if split treatment was applied would the hardness removal goal reached? Compound Concentration (mg/L as CaCO3) 126.3 Ca2+ Mg2+ 92.7 Fe2+ 37.1 HCO3 194.3 SO42- Cl- 92.4 49.8 Hint: Go over the hardness removal example parts 1, 2 and 3. 3. If the settling velocity of a particle is 1.6 mm/s and the overflow rate of an upflow (circular) clarifier is 0.32 cm/s, what percent of the particles are removed? What would be your answer if the clarifier is a horizontal flow (rectangular) clarifier? 4. Determine the: (a) flowrate of water going through six dual- media filters (10 m by 15 m, each) if they are loaded at a velocity of 275 m/d, and (b) the loading rate if one filter is out of operation for backwashing.

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