Treatment plant & Main Pump House


Contract Cost: YEN MILLION 3,037
Start Date: 03rd March 2015
Finish Date: 02nd December 2018


The contract package number 01, involves the design and construction of the wastewater treatment plant, the main sewage pumping station, treated effluent disposal system and a sludge drying bed facility as well as the procurement and delivery of specialized sewer maintenance vehicles and operating equipment.

Domestic wastewater will be collected (under contract package number 02) and will be delivered by gravity at the main pump station at William Gopallawa Mawatha, where it will be pumped across the river to the inlet of the treatment works.

The treatment plant will have a capacity of 14,000 m3/day. This can serve for a population of 55,000 by the design year 2030. The treatment plant will remove carbonaceous BOD and Nitrogen using the oxidation ditch process. The treatment plant will also treat wastewater and septage collected from septic tanks. Excess activated sludge is thickened and transferred to the sludge dewatering area by pumps, where it is dosed with polymer and fed through dewatering machines to reduce it to sludge with a solid content of between 15% and 20%. The pressed sludge is then transferred off-site to a new sludge drying bed facility at Gohagoda where the sludge is dried to approximately 60% solids content. An air-conditioned administration building and a workshop will also be built including a fully equipped process laboratory. Operator training will be done during testing and commissioning.

Treatment Plant Layout