Question

You are assigned to operate a drinking water treatment plant which has a capacity of 280 ML per day. The source water is from a river that contains a high concentration of dissolved organic carbon (DOC), (13 mg L-1) and has a high colour (60 HU) but where the alkalinity changes seasonally. In summer to winter the alkalinity is high (> 100 mg L-1 as CaCO3) and in spring after snow has melted in the mountains and the water flows into the river, the alkalinity is very low (< 15 mg L-1 as CaCO3). You have a range of chemicals available with which to treat the water for drinking water supply including (1) Aluminium Chloro Hydrate, (2) Poly Aluminium Chloride, (3) Alum (Al2(SO4)3:18H20) (4) chlorine (5) sodium hydroxide (6) calcium carbonate (lime), and (6) the polymer floc aid: PolyDADMAC.

If the coagulant(s) you have selected need to be dosed into the raw water at 90 mg L calculate the mass of coagulant that needs to be dosed per day if the plant is operating at full capacity. If 5% of total raw water influent was used for filter backwashing without recycling and another 5% was lost due to sludge discharge and chlorine needs to be dosed is at 1 mg L-1 for the water after treatment, calculate the mass of chlorine that needs to be dosed each day at the treatment plant.

Answer 1

Ans: of the plant 280 ML 280 X 106 L coa gulant added to naa caatenat go Sa tatal mass of coagulant needed.. full capacity 25a00X106x Yo za52x1a5 waten lost fonfler backaashcng 280 X 10LX_5 t4x10 L water lost due to sludge deschange = 26२५10२ = 5% waten remained fo chlarine treatment 280 X106L 252 X106L chlotine doged at Ama Tatal amauntof chlorine needed 252 X1o Lx1Mg L 352 X10 353 X 106 252 X10q 252 Ka Sa above moas ochloncne needy to ho ES dogod ach day at tueatment. plant CamScanner