Question

QUESTION 6 [14 MARKS] A slow sand filter treats 4 MI/day at a rate of 0.1 m/hour. a. Determine the area and number of units required if the rate of must not exceed 0.18 m/hour when one filter is backwashed, and 0.25 m/hour when one filter is out of service and another is being backwashed. (10) b. Explain what would happen if the maximum rate of treatment is exceeded. (4)

Answer 1

9iven data & T4h 4x106itns/Day (a) Slow Cand Fit eatS =0.im/had 0.1 xlo00xLy Gereloay maximsn daily watei den and l.8xAverage deily dnd g01x hx31 Cl Ayea af Sleus Sad ilf mar dailywademand Rateof Fileatry 1.ex4 x106 O.18X 1000 x2 =1666.67m Areaaf Sand Filta SSun peens Stous Sand Filttes peqives backwashing ones-f 1-3men ths waee peluúrcel fis hack washing eo.2-05% amovne at Alot mention, at lese Petund in Jiven pablem haus many Unies are minticnaf stous sand Aees dimignsions, So ASSme -1o uniヒ$. Nlo. Filers 10 Afeaaf each Fiter 166.67m Sunfaa ee we Y noas Hyat Bedt 166.67 B 9.12 r L2B = 18.25m

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