Wis. Admin. Code Department of Natural Resources NR 811.46

Current through September 30, 2024

Section NR 811.46 - Arsenic removal

The following minimum requirements shall be met when the following treatment methods are employed for arsenic removal:

(1) PILOT TESTING. All process designs shall be based on information from a pilot study unless waived by the department based upon previous demonstration that the process design will effectively remove arsenic based upon the water quality to be treated. Documentation shall be submitted to the department to support any pilot test waiver.

(2) OXIDATION AND FILTRATION. Arsenic III shall be oxidized by chemical or physical processes or both to arsenic V and then filtered out.

(a) Adequate detention time shall be provided if necessary to complete the conversion to arsenic V before filtration.

(b) Ferric chloride or ferric sulfate shall be added to the water supply for water with less than a 20 to 1 ratio of iron to arsenic if necessary in order to provide adequate arsenic removal efficiency.

(3) ADSORPTIVE MEDIA. Metal oxide coated adsorptive media may be used as the sole means of removing arsenic or in cooperation with or as a polishing unit after oxidation and filtration of arsenic.

(a) The adsorptive media shall be NSF/ANSI Standard 61 approved in accordance with s. NR 810.09(5).

(b) The pilot study and final design shall address the following issues:

1. Pre- and post-filtration adjustment of pH to enhance the arsenic removal rate and reduce water corrosivity.

2. Conversion of the arsenic III to arsenic V prior to filtration.

3. Oxidation and filtration of iron and manganese to prevent fouling of the media.

4. Concentrations of sulfate and dissolved solids in the source water and the need to remove or reduce the concentrations in order to maintain treatment efficiency and minimize media fouling.

(4) OTHER ACCEPTABLE TREATMENT METHODS. Coagulation and filtration, anion exchange, electrodialysis, membrane filtration, and lime softening are treatment methods that may also be used to remove arsenic. The pilot study and final design shall address the following issues, if applicable:

(a) Pre- and post-treatment adjustment of pH to enhance the arsenic removal rate, prevent scaling, or fouling of the treatment equipment, and reduce water corrosivity.

(b) Conversion of the arsenic III to arsenic V prior to removal.

(c) Oxidation and filtration of iron and manganese to prevent fouling of the treatment equipment.

(d) The use of ferric chloride, ferric sulfate, alum, or a polymer as coagulant aids.

(e) Concentrations of sulfate and dissolved solids in the source water and the need to remove or reduce the concentrations in order to maintain treatment efficiency and minimize treatment equipment fouling.

Wis. Admin. Code Department of Natural Resources NR 811.46

CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.