KELOMPOK IX: Pramesti Ariandani (5213413072)

Nailu Sa’ada Turrohmah (5213413073)

Diyah Saras Wati (5213413074)

M. Khusni Annajib (5213413076)

Tugas: Utilitas ( Desain Rapid Sand Filter)

Soal !!!Buatlah desain rapid sand filter dengan kebutuhan 3 MLD. Dengan asumsi sebagai berikut:

Rate of filtration 5000/lit/hr/m2.

Dia. of perforation 13 mm.

Length =1.5 times the width.

The discharge of a rectangular flat bottom through is given by 1.376bd3/2. Where b = width and d = depth (u can add more assumption if needed)

Solution:

Asumsi: water required = 3MLD

Rate of filtration = 5000 lt/hr/ m2

Diameter of perforation = 13 mm

Length = 1,5 times the width -> L= 1,5 B

Discharge of rectangular flat bottom through = 1,376 bd3/2

Ammount of wash water = 0,2 -0,4 % -> we choose asumsi amount of wash water

= 0,3%

So, washing water = 0,009 MLD

Total amount of water needed = 3,009 MLD

Asumsi washing time dalam 1 hari adalah 40 menit (0,667 hr)

Filtration time = 23,33 hr

Ammount Q without washing time = 0,128 ML/hr

Area of filter bed = 25,6 m2

Asumsi jumlah unit yang digunakan = 1 unit

With area of filter bed is 25,6 m2 and know L=1,5B

So, we get width of filter bed (B) =4,13 m and length of filter bed (L)= 6,19 m

Design of laterals

With 0,2% of area filter we get total area of perforation = 0,051 m2

Asumsi c/c distance of laterals = 20 cm= 0,2 m

So, we get number of lateral = 30,95 -> 31 nos