Question

Wastewater from a small town is treated in a trickling filter which is preceeded by a screen, sand-removal and primary clarification. The maximum hydraulic capacity, or peak flow, of the treatment plant is 1,500 m3/h. The dry weather flow (Qdwf) amounts 7,500 m3/day, with a BOD concentration of 300 mg/l.
QUESTION 2C-1
After a while the screen gets clogged. The automated cleaning starts at a head loss of 10 cm. Calculate what percentage of the clean free space is clogged at this head loss. For the calculation: take the impact of clogging on the friction factor into account.

Calculate V in m/s.

QUESTION 2C-2
Calculate at which open screen area (m2) this velocity is reached.

Calculate what percentage of the clean free space is clogged at this head loss.

QUESTION 2D-2
Assume 4 channels. Take a W:L ratio of 1:15

Dimension the rectangular sand removal channels.

Length (m):


Width (m):


Maximum water height (m):


Allow a free waterboard of 15 cm and a maximum grit accumulation height of 20 cm. Give the total height in m of the grit channel.

Answer 1

Please help to get this answer ,Ham

Answer 2

8.6

Answer 3

QUESTION 2C-1: Calculate V in m/s is 1.22

QUESTION 2C-2: Calculate at which open screen area (m2) this velocity is reached - 0.34

Calculate what percentage of the clean free space is clogged ... 32

QUESTION 2D-1: Determine how many parallel channels 4

What is a common W:L ratio? 1:10

To prevent settling of organic matter a Vs should be > 0.03 m/s

Calculate Qdwf in m3/s.0.087

Calculate Qrwf in m3/s.0.42

QUESTION 2D-2: L-12, W-0.8, Max Water Height 0.44, grit Channel 0.8 m