Performance of Waste Stabilization Ponds: Experience from Cold Climatic Conditions of Bhutan

S. Phuntsho, H.K. Shon, S. Vigneswaran, H.H. Ngo, J. Kandasamy, P. Dorji



Like any other developing countries, Bhutan too is facing the challenges of rapid urbanisation and the need to improve wastewater treatment and management. Waste stabilization pond (WSP) of capacity 1,750 m3 per day capacity with 12,500 population equivalent was constructed at Thimphu in 1996 to treat the domestic wastewater. This paper reports the study conducted in 2010 based on the available data of the wastewater effluent quality between 2006 and 2007. After 11 years of commissioning, the performance of the Thimphu SWP was observed to be very promising. The effluent quality meets the National Environment Commission (NEC) industrial effluent standards, and the performance of anaerobic pond in removing BOD of up to 70% was also particularly significant. The flow record indicates that the sewage treatment plant (STP) is yet to be loaded to its full designed capacity, although the flow measuring techniques need to be improved preferably by automatic flow recording device. The study of various influent and effluent qualities have concluded that the WSP is an efficient and suitable technology for removing organic and microbiological pollutants from wastewater in Bhutan with climatic conditions similar to that of Thimphu.