Constructed Wetland Wastewater Treatment Facilities

This paper presents the planning, design and first year of operating experience for the award-winning Manila CSD Wastewater Treatment Facilities. The facilities were constructed to replace a failed community leachfield system. The influent is septic tank effluent from a STEP system operated by the District. Treatment of the septic tank effluent at the wastewater treatment plant occurs via two Surface Aerated Facultative (SAF) lagoons followed by three Free Water Surface (FWS) wetland cells. Disposal is through rapid infiltration basins which discharge to groundwater. With the exception of the first few months when the wetland vegetation was becoming established and the biota were developing in the lagoons, the plant performed well. Although peak flows exceeded the expected design flow rates due to exceptionally heavy winter storms, the plant provided effective treatment and disposal at all times.