A water sample using FeSO4.7H20 as a coagulant at the rate of 139 ppm, gave the following results for raw water: Ca2+=320 ppm; Mg2+=120 ppm, CO2=88ppm; HCO3-=732 ppm. Calculate the lime and soda required for softening of 1000 litres of raw water.

To calculate the lime and soda required for softening of 1000 litres of raw water, we first need to understand that lime (Ca(OH)2) is used to remove the carbonate hardness, while soda (Na2CO3) is used to remove the non-carbonate hardness.

1. Calculate the carbonate hardness: Carbonate hardness is due to the presence of Ca2+ and Mg2+ ions in combination with CO2 and HCO3-. It is the smaller of total hardness and total alkalinity. In this case, total hardness is Ca2+ + Mg2+ = 320 ppm + 120 ppm = 440 ppm. Total alkalinity is due to CO2 and HCO3-, which is 88 ppm + 732 ppm = 820 ppm. Therefore, carbonate hardness is the smaller of 440 ppm and 820 ppm, which is 440 ppm.

2. Calculate the non-carbonate hardness: Non-carbonate hardness is the total hardness minus the carbonate hardness, which is 440 ppm - 440 ppm = 0 ppm.

3. Calculate the amount of lime required: The amount of lime required is equal to the carbonate hardness, which is 440 ppm. Therefore, for 1000 litres of water, the amount of lime required is 440 mg/L * 1000 L = 440 g.

4. Calculate the amount of soda required: The amount of soda required is equal to the non-carbonate hardness, which is 0 ppm. Therefore, for 1000 litres of water, the amount of soda required is 0 mg/L * 1000 L = 0 g.

So, 440 g of lime and 0 g of soda are required for softening of 1000 litres of raw water.