Copper is a divalent cation similar to cadmium, lead, and calcium. It is therefore removed very well by membrane process. A typical RO membrane should give 97-99% rejection of copper. Well waters or surface waters may contain very low levels of Copper, generally less than 0.001 mg/L. [....]
Conductivity is a measurement of the ability of water to transmit electricity due to the presence of dissolved ions. Absolute pure water with no ions will not conduct an electrical current. Conductivity is measured by a conductivity meter and is reported as micromhos/cm or microSiemens/cm. Conductivity is a convenient method of determining the level of ions in a water [....]
Color is a non-specific test that measures the relative level of organic compounds in water based on their contribution to adding color and is reported in APHA units relative to the platinum standard. [....]
COD is a non-specific test that measures the quantity of both bio-degradable and non-biodegradable organic matter and is reported as "ppm as oxygen". The test measures the ability of a hot chromic acid solution to oxidize organic matter. [....]
A monovalent anion. The solubility of chloride salts is high and does not create a RO scaling problem. Chloride, in seawater, is the prevalent anion. Chloride is the anion used to automatically balance a RO feed water analysis. The recommended upper limit for chloride in potable water by the US EPA and WHO is 250 ppm based on taste [....]
Cations are ions with a positive valence state (they are willing to accept electrons) and have the ability to react with anions which are ions with a negative valence state (they have extra electrons to share). The sharing of electrons creates electroneutrality. For example, the calcium ion is a divalent cation and will combine with two monovalent chloride ions [....]