Arsenic Removal
Arsenic can be found in groundwater, surface water supplies and in industrial wastewater. There are a number of treatment approaches that have been found to be effective. Among them are:
Coagulation and Filtration
Adsorptive Media
Greensand
The approach best suited to a particular application depends on the amount of arsenic present, whether the arsenic is present as AsIII (arsenite) or AsV (arsenate), the pH of the water, its alkalinity, and other ions in the water. Other considerations include the volume of water to be treated daily and the willingness or ability to use coagulants or chemicals in the treatment process. A brief overview of arsenic removal strategies is provided below. Arsenic can be removed via chemical coagulation followed by filtration. The coagulants used typically include:
Aluminum Sulfate
Ferric Chloride
Ferric Sulfate
Jar tests using samples of the water to be treated are needed in order to determine which coagulant, dosage level and pH will produce the required arsenic removal. In instances where there is a high concentration of flocs formed, a settling step may be needed prior to filtration. pH adjustment may also be needed. In most cases multi-media filters are used to remove the suspended solids formed through coagulation. However, where the volume of water to be treated is low, consideration can be given to the use of backwashable cartridge filters.