Regional Sewage Treatment Plant (Co-treatment of fecal sludge) at Kuala Sawah, Malaysia

Site visit done by: Sumit Kumar Gautam, Naveen Kumar, Ridhima Gupta
Date of visit: 8 August, 2017

Scale of service: Seremban City (320,000 PE for fecal sludge), Catchment area: 106 km2
Inlet: Sewage + Fecal Sludge
Operational since: 2009
Treatment capacity: 59,000 m3/ day sewage + 260 m3/ day fecal sludge

Outlet/end products: Treated water in river + dried sludge in trenching site
Opex of the plant: 1,000,000 RM per annum (INR 16,026,863)
Sludge treatment time (approx.): 24 hrs


RSTP Kuala Sawah 2 is located about 20 km from Seremban town in Kuala Sawah, Negeri Sembilan, Malaysia. It is designed for a capacity of 360,000 PE to treat sewage from catchment area of 97 hectares. The plant employs Oxidation Ditch system for sewage treatment process and screw press thickener for drying the sludge to at least 20% dried sludge. It has been in operation since 28th Feb 2009. The plant has been operated and maintained by Indah Water Konsortium (IWK, owned by the Ministry of Finance incorporated). The STP co-treats the tankered sludge (fecal sludge from OSS) along with thickened sludge from clarifiers into a screw press dewatering unit.


Sewage conveyed through 11 km long underground drain, is passed and treated through grit chamber – oxidation ditch- clarifier and finally disinfected before discharging into river. Two manual coarse screen (50mm opening) and two mechanical drum screens with 7mm opening screen the tankered sludge. A scum collection tank equipped with baffles removes oil, grease and other floating materials, which are pumped to a sand bed. Screen sludge is temporarily stored in sludge receiving tank. Then, the screened sludge is pumped into screw press dewatering machines via sludge thickener.

Chemical condition by polymer and coagulant are used to increase solid content. A screw conveyor transfers dewatered sludge cake from screw press direct to sludge cake yard (designed to store 14 days sludge). Finally, the sludge cakes are disposed of in trenching/landfill site.

Ref.:Regional Sewage Treatment Plant (Rstp) Kuala Sawah - Sen330 (Od), IWK (shared through personal communication)





Incoming Quality

Design target

Incoming quality

Design Target


220 mg/L

10 mg/L

5,500 mg/L


Not available

Suspended Solids

270 mg/ L

20 mg/L

25,000 mg/L

Total Nitrogen

40 mg/L

10 mg/L

600 mg/L

Ref.:Regional Sewage Treatment Plant (Rstp) Kuala Sawah - Sen330 (Od), IWK (shared through personal communication)


Mr. James Oliver Warren
Indah Water Konsortium (IWK), Malaysia
+60 12 295 4401
Seremban Unit Office No 29, Jalan Dataran Kemuning 2 Dataran Kemuning, Senawang 70450 Seremban Negeri Sembilan, Tel: 06-678 9050, Fax: 06-678 9052