2 Decades Constructed Wetland Experience in Treating Municipal Effluent for Power Plant Cooling at the Shand Power Station, SaskPower Part III: Annual TreatmentPerformance on PO43--P, TP, Volatile and Total Suspended Solids, Inorganic Constituents, and Bacteria

Emmanuel K. Quagraine, Bruce Duncan, Minghui Chi, Austin Lothian



This paper is third in series of publicationson 20-year periodconstructed wetland (CW) operational experience at SaskPower’sShand Power Station and highlights the yearly performance of the wetland on PO43-, total phosphorous, volatile suspended solid (VSS), total suspended solids (TSS), bacteria, major inorganic constituents and trace elements.Moderately good phosphorous and VSS removalswere realized in the initial two years when the inflow to the CW was a facultative effluent(56-60% and ~ 69 ± 27%, respectively). These howeverdeclined to only 1.2-7.4% and 35± 33% for the remainingyears when the inflow to the CW was an upgrade to conventional secondary treated quality. TSS removal was more efficient in latter 18-year period of operation, but the efficiency was quite erratic (47±43%). The CWgenerally was ineffective in removing major inorganic species and trace elements although K+(31 ± 5%) and Mn (50± 22%)removal wererealized in the early 2-years of operation. Effective reduction of both total coliform (56% average) and faecal coliform (98% average) was demonstrated in the early two years of the CW. Yet, whereas total coliform removal was sustainedor improved till a flood incidence in 2011 (77% average reduction), faecal coliform removal became erratic, showing some large net exports which is attributed to different warm-blooded animals that inhibit or frequent the CW including duck population in the storage pond (the CW outlet).