Estimate the annual cost savings of Waterloo Region%u2019s recent decision to st

Question

Estimate the annual cost savings of Waterloo Region%u2019s recent decision to stop the addition of fluoride to its water.  The population of Waterloo Region is approximately 121,700 people with the average person using 329 L of water per day.  Hexafluorosilicic acid  (H2SiF6) was being used to fluoridate the water to the level of 0.7 ppm (0.7 g F/1,000,000 g water); a 30 mass% solution of hexafluorosilic acid can be purchased for $367/ton.  Water has a density of 1.00 g/mL.  

      Data: 1 ton = 2240 lbm, 1 year = 365 days

Explanation / Answer

for 365 days
amount of H2SiF6 being used = 365*number of people* 0.7* water in grams
= 365*121700*0.7*329*1000*10^-6
= 1.023*10^7 gm

for 30% mass solution
weight = wt*100/30

1 ton = 2240 lbm = 1,016 kg = 1,016*10^3 gm

given $367/ton
tons of H2SiF6 = 1.023*10^7/(1016*10^3)*10/3
=10.068 tons *10/3

annual cost saving = cost * weight used
= 367 * 10.068*10/3 = $12317.61

Related Questions

Navigate

• Browse (All)
• Browse E
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.