Appendix C

DESIGN PARAMETERS AND CRITERIA

In general, the JKR Design Criteria and Standards for water Supply (1989) as adopted by the MWA Design Guidelines for Water Supply System (1994) form the basis for the design of the treatment work.

Treatment Plant

Process Unit Design Parameters/Criteria

1.1 Aerator

i) Type

ii) Total Overfall

iii) Surface Loading

iv) Diameter

1.2 Mixing Chamber

i) Type

ii) Retention Time

iii) Size

1.3 Flocculation Tank

i) Type

ii) No. of Units

iii) Retention Time

iv) Size

Multi tray

2m

40 m³/( m²/hr)

4.0m

Mixing of mechanical flush mixer

1 min

2.0m x 2.0m x 2.5m SWD

Mechanical Flocculator

3

25 min (all tanks working)

9.5m x 4.2m x 2.0m SWD

Appendix C

Treatment Plant

Process Unit Design Parameters/Criteria

1.4 Sedimentation

i) Type

ii) No. of Units

iii) Detention time

iv) Desludging

v) Size

1.5 Filtration

i) Type

ii) No. of Units

iii) Flow Control

iv) Max Filtration rate(two tanks out of service)

v) Tank Depth

vi) Backwashing

vii) Air source rate

Clarifier tank with tube settlers

3

1 Hour

Daily by timer – controlled electrically operated butterfly valves

10.1m x 4.2m x 4.5m SWD

Rapid gravity sand filter

3 (single bed)

Constant rate filter

7.5m/hr

4.5 m

Combined air water wash

6 cum/hr at 0.35 bar per sq.m for 6 minutes

Appendix C

Treatment Plant

Process Unit Design Parameters/Criteria

1.5 Filtration (continued)

viii) Combined wash water rate

ix) Rinsing wash water rate

x) Size

1.6 Backwash tank

i) No. of units

ii) Capacity

1.7 Chlorine Contact Tank/ Clear Water Tank

i) No. of tank

ii) Capacity

iii) Detention

ix) Size

8 cum/hr per sq.m for 6 minutes

20 cum/hr per sq.m for 9 minutes

9.0m x 6.0m

1 unit

270m³(sufficient for two filter bed washes and plant usage)

2

650m³

2 Hours

12.6m x 11.5m x 4.5m SWD