A municipal drinkign water service authority is adding softening to its water treatment. The facility is treating the water flow of 18,000 m3/d with the following hardness/alkalinity: Ca2 =347 mg/L; Mg2 =129 mg/L; HCO3-=1256 mg/L Softening chemicals are available at the follwing purity and cost: Lime: CaO: 67% purity at $82/1000 kg Soda-ash: Na2CO3: 98% purity at $105/1000 kg 

1) What is the annual cost ($/year) for lime and soda ash to be used as reagents in softening of the wter, assuming 100% removal of the hardness? 

2) What is the annual dry sludge mass (kg/year) generated from lime-soda ash softening of the water, assuming 100% removal of the hardness?