Full Description

The City of Los Angeles (City) operates the Advanced Wastewater Treatment Facility (AWTF) at theTerminal Island Water Reclamation Plant (TIWRP), which has a capacity of producing up to 5 milliongallons per day (MGD) of high quality reclaimed water for injection into the Los Angeles CountyDepartment of Public Works' Dominguez Gap Seawater Intrusion Barrier. TIWRP's tertiary filtereffluent serves as the influent to the AWTF, which includes microfiltration (MF), reverse osmosis(RO), lime stabilization, and chlorination. Bench-testing was designed to identify the most appropriate treatment technique for the stabilization ofthe AWTF RO permeate. Particulate addition through chemical addition will negatively impact pumpoperation and injection well performance, so minimization of particulate addition was also a criterionduring chemical testing and selection. Specifically, the main objectives of the bench-scale study were to:test three chemicals for their effectiveness in stabilizing the RO permeate, the reclaimedwater quality requirements as established by Los Angeles County areModified Fouling Index (MFI) monthly average 1, andMFI maximum 2 during less than one week of one month period;Turbidity daily average 0.2 NTU;Turbidity maximum 0.5 NTU during less than 5% of 24-hour period;the criteria for stabilization of the permeate would be6.5 less than/equal to pH less than/equal to 8.5;alkalinity minimum of 15 mg/L;Langelier Saturation Index (LSI) minimum of -0.5;to identify the appropriate dose of each chemical needed to achieve the desired permeatestability; and,to investigate the effect of other process parameters (e.g. aeration) in stabilizing the ROpermeate.The three chemicals that were tested for the stabilization of the RO permeate include:liquid caustic and liquid calcium chloride;lime slurry - MicroCal HF calcium hydroxide; and,saturated lime solution.Lime stabilization tests were carried out in two phases: the chemical stabilization tests; and, themembrane fouling index (MFI) tests. The chemical stabilization tests were performed to determine theappropriate dose required for stabilization of the permeate. The MFI tests were performed on thestabilized solutions to estimate membrane fouling potential of suspended solids. Includes 3 references, tables, figures.

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Edition: Vol. - No. Published: 11/01/2008 Number of Pages: 12File Size: 1 file , 820 KB