Full Description

The use of spiral wound membranes for treatment of brackish groundwater sources has gainedwidespread acceptance. This technology, however, is not without operational difficulties, one ofwhich is membrane fouling. Groundwater supplies in the province of Saskatchewan, Canadaare typically very hard, laden with iron, manganese, and often organic carbon and ammonium.Fouling through scaling can be controlled with antiscalant chemicals and recovery but typicallysome form of pretreatment is required to reduce the constituents that cause colloidal andbiological fouling.Biological filtration prior to membranes has been implemented in some small First Nations watertreatment systems in Saskatchewan. The stepwise filtration process targets iron, arsenic,ammonium and organic carbon to reduce these constituents as they can be used as an energysource for bacteria that may populate and foul the membrane elements. This process alsoreduces the potential for colloidal fouling by oxidized iron and manganese as chemical oxidantsare not used. The water produced by the membranes exhibits a very low chlorine demand dueto the removal of readily oxidized species. By limiting reliance and demand on chemicals fortreatment of the water to only low dosages of membrane antiscalant and chlorine, the FirstNation communities have gained a consistent, sustainable, and environmentally friendly methodof treating their drinking water, with reduced costs and complications of utilizing chemicals tooxidize and remove potential foulants.The initial installation of this process at the Yellow Quill First Nation was a green-fieldconstruction using a water source previously thought unfeasible to treat economically. Buildingon the success of the Yellow Quill project, an existing manganese greensand process at thePasqua First Nation was retrofitted to provide biological iron, arsenic, and ammonium reductionfollowed by membrane treatment to provide higher quality water to the First Nation residentsthere. The process capacity was similar to the Yellow Quill process but was provided as a plantretrofit within the existing building footprint at Pasqua, at a fraction of the construction cost of theYellow Quill process. The paper describes the development of the process, types of water it issuitable for, issues encountered, retrofit considerations and the logistics surrounding theprocess conversion. Cost implications of these processes are also described. Includes 12 references, tables, figures.

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Edition: Vol. - No. Published: 06/01/2007 Number of Pages: 47File Size: 1 file , 8.8 MB