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.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 260 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 13 |
| Published : | 06/01/2006 |
