National Secondary Drinking Water Regulations - by Nelsen Corporation
Recognized Treatment Techniques for Meeting the national Secondary Drinking Water regulations with the application of Point-Of Use Systems
National Secondary Drinking Water Regulations (NSDWRs or secondary standards) are non-enforceable guidelines for contaminants that may cause cosmetic effects (such as skin or tooth discolouration) or aesthetic effect (such as taste, odour or colour) in drinking water. EPA recommends secondary standards to water systems but does not require systems to comply. However, states may choose to adopt them as enforceable standards.
Note: This document addresses the United States Environmental Protection Agency National Primary Drinking Water Regulations in effect at its time of publication. These regulations are continually being reviewed and updated at the federal level. Accordingly, this list of recognized treatment technologies will be reviewed and amended periodically.
Copyright © 2011 by Water Quality Association
| Contaminant | SML, MG/I + | Treatment Methods | |
|---|---|---|---|
| Alkalinity (measured as calcium carbonate, CaCo) | No federal limit Low alkalinity - < 30mg/L High alkalinity - > 300 mg/L | Raise alkalinity by feeding 1.5 mg/L of soda as for each on mg/L of alkalinity needed or calcite filtration. Lower alkalinity by feeding white vinegar carbon dioxide; ion exchange dealkalization; reverse osmosis; distillation or electrodialysis |
|
| Aluminium (AI +³) on case-by-case | 0.05 to 0.2 depending Reverse Osmosis circumstances | Cation Exchange Ultrafiltration Distillation | Electrodialysis Deionization |
| Chloride (C1 -¹) | 250 | Reverse Osmosis Anion Exchange Deinization | Electrodialysis Deionization |
| Colour | 15 color units | Anion Exchange Activated Carbon Filtration Chlorination | Reverse Osmosis Distillation Ozonation |
| Note: Color units are based on the APHA recommended standard of 1 color unit being equal to 1 mg/L of platinum or chloroplatinate ion. | |||
| Copper (Cu +²) | 1.0 | Reverse Osmosis Cation Exchange (20%-90%) | Corrosion Control Distillation |
| Corrosivity | Non-corrosive | Calcite or Calcite/Magnesium Oxide (Magnesia) (5 to 1) Filter to raise pH Soda Ash Chemical Feed Polyphosphate Feed Sodium Silicate Feed Remove all hydrogen peroxide Reduce TDS via Reverse Osmosis (partial, split stream treatment) Coatings Insulating Unions with Ground straps around all insulating breaks in metal pip |
|
| Fluoride (FI -¹) | 2.0 | Activated Alumina Reverse Osmosis | Electrodialysis Distillation |
| Foaming agents (MBAS) | 0.5 | Chlorination Activated Carbon Ozonation | Reverse Osmosis Distillation |
| Hard Water (measured as calcium carbonate CaCo3) | No federal limit Soft - < 17.1 to 60 Moderate - 60 to 120 Hard - 120 to 180 Very hard - > 180 | Remove all calcium and magnesium ions with a cation exchange water softener (general limit is 1710 mg/L total hardness. Above 70 grains per gallon, install two softeners in a series. | |
| Iron | 0.3 (total iron) | ||
| Hard Water (measured as calcium carbonate CaCo3) | No federal limit Soft - < 17.1 to 60 Moderate - 60 to 120 Hard - 120 to 180 Very hard - > 180 | Remove all calcium and magnesium ions with a cation exchange water softener (general limit is 1710 mg/L total hardness. Above 70 grains per gallon, install two softeners in a series. | |
| Iron | 0.3 (total iron) | ||
| Ferrous Iron (Fe +²) | Filtration (oxidizing filters) Electrodialysis Pressure Aeration/ Filtration Oxidation/Precipation/ Filtration | Distillation Cation Exchange Reverse Osmosis |
|
| Ferric Iron (Fe +³) | 0.3 (total iron) | Filtration Greensand Calcite (also raise pH to 7.2) | Sand Cartridges |
| Sequestered Iron Iron Bacteria | Strong oxidation and/or fine (10 micron or < ) filtration Disinfection and Retention followed by activated carbon filtration for dechlorination | ||
| Colloidal Iron | Coagulation/Filtration | Submicron Filtration | |
| *Manganese must be maintained in the soluble manganous (Mn +²) state to avoid fouling and interference with effective reverse osmosis membrane rejection. | |||
| Methyl Tertiary Butyl Ether (MTBE) | No federal limit | Activated Carbon (similar to chloroform and TTHMs, except the treatment life of the activated carbon may be one-half or less of that for chloroform when MTBE will begin to break through). For MBTE concentrations greater than 0.1 mg/L, pre-treat with high air-to-water ratio air stripping prior to activated carbon filtration. |
|
| Odor | 3 threshold odor number | Activated Carbon | Air Stripping |
| Oxidation followed by retention and filtration Disinfection for sulfate-reducing bacteria If H2S is in the hot water only, remove the hot water anode rod or replace it with an aluminium anode rod. |
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| Note: Chlorine and hydrogen sulfide are examples of odors that may be reduced by the treatment methods suggested. | |||
| pH | 6.5 - 8.5 | Neutralizing filter (calcite or calcite plus magnesia oxide). pH may be increased by alkalies and may be decreased by acids. Chemical feed of soda ash to raise pH or white vinegar to lower pH. | |
| Silver (Ag +¹) | 0.1 | Coagulation/Filtration Submicron Filtration/ | Distillation Reverse Osmosis |
| Activated Carbon Ion Exchange (Anion or Cation depending on complexed Ion Species) | |||
| Sulfate (SO4-2) | 250 | Reverse Osmosis Anion Exchange | Distillation Electrodialysis |
| Total dissolved solids (TDS) | 500 | Deionization by Ion Exchange (Cation/Anion in two bed or mixed bed | |
| Zinc (Zn+2) | 5 | Reverse Osmosis Cation Exchange | Distillation Electrodialysis |
| (P)* = Proposed Standard SMCL (mg/L+) = Secondary Maximum Contaminant Level expressed in milligrams per liter (unless otherwise specified). |
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Contact:
George Hogg
WTC
Email:
info@waterbygeorge.ca
Cell:
780 871 9283
Phone:
780 809 2256
Postal Address:
PO Box 12699
Lloydminster, AB T9V 0Y4