You have been tasked to set up a desalination plant to produce drinking water from seawater. A detailed analysis of the feedwater has found the average pH is 8 and an average temperature of 25C.

Cation	mg/L	Anion	mg/L
Na+	10556	Cl-	18980
K+	399	HCO3-	142
Ca2+	411	Br-	65
Mg2+	1272	SO42-	2649

The plant is to be equipped with a pump station that can supply 15 m³/h and will use RO membranes supplied by Toray Industries that have a salt rejection of 98%. Assuming a plant recovery of 70%, which of the following RO configurations will provide the highest possible volume of purified water. (i) One pass, (ii) two pass (iii) feed blend system? (25)