A significant number of humans have no access to potable water.
“The freshwater crisis is the most urgent and serious problem to our planet.” Dr Klaus Töpfer, Director UNEP
Raw water for the production of drinking water is seldom of a sufficiently high quality to be used without treatment. Raw water sources which include groundwater, lakes, rivers and reservoirs are affected by both people and nature. The more people are concentrated in towns and municipalities, the greater the impact they have on the water source, and the greater the pollution.
In order to protect human health, all water from lakes and rivers has to be purified against pathogens before being used for human consumption. In order to be palatable and enjoyable, drinking water should be colourless. Coagulation with aluminium and iron salts is the most commonly used technique for removing particles, clay colour, algae, bacteria, virus and other pathogens.
During the coagulation process the impurities form aggregates, ie. form flocs. The choice of precipitation chemical is important for creating optimal flocculation and separation conditions.
Did you know?
Utilising chemical precipitation to purify water is not a new technlogy. In the Old Testament we can read about the prophet Elisha who, outside the walls of Jericho, found that the town was beautiful but that the water was undrinkable. He took up some water in a bowl, added salt which he had dug from the ground, and stirred it. The water was then drinkable and tasted good! What Elisha had done was to chemically purify the water using a naturally occurring mineral containing potassium aluminium sulphate, better known as potash alum. This salt is closely related to aluminium sulphate.
