THIRD LILONGWE WATER BOARD SUPPLY PROJECT

The Lilongwe Water Board Supplies water to the City of Lilongwe. The source of water is from two reservoirs on the Lilongwe River. Water is released from these reservoirs at a controlled rate and this flow travels about 20km downstream to Lilongwe, where a small weir has been constructed to provide adequate water depth for the inlet structures to the two existing water treatment plants.

The original plant was constructed in 1966 and progressively extended to achieve a capacity of 35Mℓ/day. The second plant, constructed in 1991 has a nominal capacity of 27Mℓ/day with hydraulic overload capacity of 40Mℓ/day. This particular plant has been operated consistently at rates up to 33Mℓ/day, during periods of good raw water quality.

The water treatment plant extensions to augment the water supply from the Lilongwe Water Treatment Plant № 2, are sited adjacent to the existing plant. These extensions are provided with a branch from the existing intake pipeline.

The extensions, under this contract have a capacity of 27Mℓ/day of treated water with a hydraulic overload capacity of 40Mℓ/day. The plant has been designed to utilise the existing washing machinery.

The three work sites are the sites at the Water Treatment Plant, Chayamba and Kanengo Service Reservoirs, in and near Lilongwe the capital city of Malawi.

MAJOR ITEMS OF TREATMENT WORKS SUPPLIES

Clarification
Two PCI Flat Bed Clarifiers each measuring 22.5m x 10,66m with a surface area of 480m², having a nominal capacity of 625m³/hr at a rise rate of 3m/hr.

Filtration
Four Type “D” Filters, each measuring 4,19m x 8,1m with a filtering area of 159m² resulting in a nominal filtration a rate of 7,95m/hr at a flow of 30Mℓ/day.

Loss of Head Measurement
Electronic level sensors with audible alarms

Chemical Dosing
Primary Coagulant (Aluminium, Sulphate or Floccotan), Polyelectrolyte and Lime Dosing.

OSEC – (On site Electrolyte Chlorination Facilities).

Raw Water Metering
Measurements of the flow of Raw Water via an Electromagnetic Flow Meter.