Cations and Anions

                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 [....]

Carbonate (CO3)

                 A divalent anion. The solubility of calcium carbonate is low and can cause a RO scaling problem in the back-end of a RO. Calcium carbonate solubility is measured using LSI (Langlier Saturation Index) for brackish waters or SDSI (Stiff-Davis Index) for seawaters and is lower with increasing temperature and increasing pH. Carbonate is one component of alkalinity and its [....]

Carbon Dioxide (CO2)

              Carbon dioxide is a gas that when dissolved in water reacts with the water to form weak carbonic acid (H2CO3). If a pure water was completely saturated with carbon dioxide, its concentration would be about 1600 ppm and the pH would be about 4.0. A typical source for carbon dioxide in natural waters is the result of a balance [....]

Calcium (Ca)

                 A divalent cation. Calcium, along with magnesium, is a major component of hardness in brackish water. The solubility of calcium sulfate (CaSO4)(gypsum) is typically limited to 230% with the use of an antiscalant. The solubility of calcium carbonate is typically limited to a LSI (Langlier Saturation Index) value of positive 1.8 to 2.5. [....]

Brackish Water

              Brackish water, in one sense, is defined as a fresh low TDS water source that experiences a large increase in normal TDS due to seawater intrusion. In the RO field, brackish water can be defined as feed water with low to medium TDS levels (up to 10,000 to 15,000 ppm) that can be treated with a "brackish RO [....]

Boron (B)

             Boron can be found in seawater at levels up to 5 ppm and at lower levels in brackish waters where inland seas once existed. Boron is not a foulant. The removal of boron to ppb levels is an important issue in the electronics industry as it adversely affects the process in some applications. The removal of boron is important [....]