Contaminants are predominately mineral salts. In some circumstances ground water contamination may also create organic chemical issues. Excessive levels of iron may also be the prime concern. In many cases biological pathogens are low however this should be confirmed by laboratory testing.
Treatment solutions for mineral salts may include coarse filtration, 5 micron filtration, desalination by reverse osmosis, pH adjustment and disinfection.
Iron presents a special challenge. Ground water iron is usually clear until exposed to air. Oxidation through contact with air over several hours will cause the clear ferrous iron to change to red/brown ferric iron. The ferric iron coagulates into small particles that foul most water treatment systems.
Treatment for iron usually involves accelerated oxidation followed by settling or media filtration.
Typically applied technologies include:
Oxidation - aeration, chlorine, chlorine dioxide - only when iron is present
Coarse filtration - backwashing multimedia filtration plus bag filter or cartridge filter
Fine filtration - 1 micron cartridge filter
Mineral salt reduction - reverse osmosis @ 15 to 25 Bar
pH adjustment - sodium hydroxide injection or calcite filter
Disinfection - chlorine, ozone, ultraviolet irradiation