External Requirements
		Standard Seawater: Seawater with TDS of 35,000 mg/l (ppm) is considered as "standard seawater" since this constitutes by far the largest amount of water worldwide. The composition is nearly the same all over the world (see table 1)
				TABLE 1: "Standard Seawater" Composition Calcium 410 mg/l Silica 0.04 - 8.0 mg/l Magnesium 1,310 mg/l Chloride 19,700 mg/l Sodium 1,900 mg/l Sulphate 2,740 mg/l Potassium 390 mg/l Fluoride 1.4 mg/l Barium 0.05 mg/l Bromide 65 mg/l Strontium 13 mg/l Nitrate < 0.7 mg/l Iron < 0.02 mg/l Bicarbonate 152 mg/l Manganese < 0.01 mg/l TDS = 35,000 mg/l pH = 8.1
			The actual TDS content may, however, vary within wide limits from e.g. the Baltic Sea with 7,000 ppm to the Red Sea with up to 45,000 ppm. The actual composition can be proportionally estimated from the "standard seawater" composition. Be aware that seashore wells depending on the soil, influx from island, etc. can often have salinity and composition quite different from that of a sample taken from the sea itself. In seawater treatment the limiting factor is of a physical nature, i.e. the osmotic pressure caused by the high TDS.