AWWA ACE65615

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 greenfieldconstruction using a water source previously thought untreatable. Building on the success ofthe Yellow Quill project, an existing manganese greensand process at the Pasqua First Nationwas retrofitted to provide biological iron, arsenic, and ammonium reduction followed bymembrane treatment to provide higher quality water to the First Nation residents. This paper describes the source water conditions and the process and the benefits of using biological filtration topre-condition the water upstream of the reverse osmosis membrane filters. Includes 9 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

06/01/2007

Number of Pages:

52

File Size:

1 file , 6.8 MB