Secondary (Aesthetic) Contaminants


Secondary (Aesthetic) Contaminants
Contaminant	SMC, mg/L *	Treatment Methods
Aluminium (Al+3)	0.05 to 0.2 depending on case-by-case circumstances	Cation Exchange Reverse Osmosis Distillation Electrodialysis

Chloride (Cl-1)	250	Reverse Osmosis Distillation Anion Exchange Electrodialysis

Color	15 color units	Anion Exchange Reverse Osmosis Activated Carbon Distillation Filtration Ozonation Chlorination Activated Alumina
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 Distillation Cation Exchange (20%-90%) Electrodialysis

Corrosivity	Noncorrosive	Calcite or Calcite/Magnesium Oxide (Magnesia) (5 to 1) Filter to raise pH Soda Ash Chemical Feed Polyphosphate Feed Sodium Silicate Feed Reduce TDS via Reverse Osmosis (partial, split stream treatment) Coatings Insulating Unions

Fluoride (Fl-1)	2.0	Activated Alumina Bone Char Reverse Osmosis Distillation Electrodialysis

Foaming agents (MBAS) (methylene blue active substances	0.5	Chlorination Reverse Osmosis Activated Carbon Distillation Ozonation

Iron (Fe+2) (ferrous ion)	0.3 (Total Iron)	Filtration (oxidizing filters) Distillation Electrodialysis Cation Exchange* Reverse Osmosis* Pressure Aeration/Filtration Chlorination-Precipitation/Filtration

Iron (Fe+3) (ferric ion)		Filtration
* Ferrous Iron (clean water ion) is readily converted to ferric iron (red water iron) in the presence of any air or oxidizing material; precipitating ferric iron must be prevented to avoid fouling and interference with effective reverse osmosis membrane rejection, and also the most effective removal by cation exchange.

Manganese (Mn+2)	0.05 (Total Manganese)	Filtration (Oxidizing Filters) Cation Exchange* Reverse osmosis* Distillation Chlorination-Precipitation/Filtration Presure Aeration/Filtration Electrodialysis

Manganese (Mn+4) oxidized		Filtration
* Manganese must be maintained in the soluble manganous (Mn+2) state to avoid fouling and interference with effective reverse osmosis membrane rejection, and also the most effective removal by cation exchange.

Odor	3 threshold odor number	Activated Carbon Aeration Oxidation
Note: Chlorine and hydrogen sulfide (rotten egg) are examples of odors that may be reduced by the treatment methods suggested.

pH	6.5-8.5	pH may be increased by alkaliesand maby be decreased by acids Ion Exchange Neutralizing Filter (Calcite, Magnesia)

Silver (A+1)	0.1	Coagulation/Filtration Submicron Filtration/Activated Carbon Ion Exchange (Anion or Cation depending on the complexed Ion Species)

Sulfate (SO4 -2)	250	Reverse Osmosis Distillation Anion Exchange Electrodialysis

Total dissolved solids (TDS)	500	Reverse Osmosis Distillation Deionization by Ion Exchange (Cation/Anion in two bed or mixed be) Electrodialysis

Zinc(Zn+2)	5	Reverse Osmosis Distillation Cation Exchange Electrodialysis
(P)* = Proposed Standard SMCL (mg/L*) = Secondary Maximum Contaminant Level espresses in milligrams per liter (unless otherwise specified).