• AWWA ACE63020

AWWA ACE63020

Characteristics of Waste Streams Generated by Anion Exchangers

American Water Works Association , 06/01/2006

Publisher: AWWA

File Format: PDF

$12.00$24.00


The use of anion exchange technology by water utilities and industries for water purification has many applications including removal of organic carbon, nitrates, sulfides, sulfates, and other anions. Typically, anion exchangers are operated in a forward-flow mode until the resin becomes saturated and breakthrough occurs. The majority of weakbase anion exchanges are operated by exchanging chloride for anions in the water source. To regenerate anion exchange systems, the resin is equilibrated with a brine solution. Resin regeneration consists of five phases: backwash, draindown, addition of brine solution, slow rinse, and fast rinse. The waste streams generated by regeneration include the backwash water and the brine. These waste streams share different characteristics that make each one unique. One unique characteristic that differentiates the two streams is the amount of chlorides present. Chloride levels in backwash water reflect the chloride concentration of the water source and are typically below 50 mg/L. Chloride concentrations in the brine can exceed 15,000 mg/L. Discharge of brine solutions to wastewater treatment facilities may impact treatment effectiveness. In addition, the additional chloride loading may impact reclaimed water characteristics. There are reasons waste streams could affect the wastewater treatment process. It is proven through research that chloride levels over 20 mg/L in wastewater can cause the growth rate of bacteria in the activated sludge process to reduce. With the high chloride levels in the brine, slow rinse, and fast rinse, the activated sludge process could be altered depending on how high the chloride levels are in each waste stream generated. These high chloride levels along with high sodium levels are caused by salt that is present in the brine solution. The brine causes a loading of chlorides and sodium that can change the chemical characteristics of the waste stream. The real impact that the waste streams will have on the wastewater is the volume generated by each waste stream during regeneration. The larger volumes of waste stream for the brine, slow rinse, and fast rinsed coupled along with the high chloride and sodium levels could be harmful to the wastewater treatment process and also could affect the reclaimed water as well as irrigation. Includes 5 references, table, figures.

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