Recovery of Alum from Synthetic Sludge

Abstract

Being in 21st century we can see the rapid growth of world, which is very quick. With increase in population, the demand for water is also increasing. We know very well that 70% of water on Earth is not potable. To make is consumable, we must purify water. Alum is widely used as coagulant in water purification process. In this process, alum is wasted in more amount than it is used. About 15-20% of the alum used is recovered. Rest of it is simply dissolved in water and thus goes waste. There are four ways to recover the alum used for water purification. They are – Acidic Method, Alkaline Method, Membrane Separation and Ion Exchange. Among these methods, Membrane Separation and Ion Exchange are quite expensive. Using these methods to recover large quantity of alum proves to be very costly and thus is impractical. These methods can’t be used in places where money is short (for example – developing Nations). This is where acidic and alkaline methods come handy! These methods of alum recovery are inexpensive and very efficient. About 84% (maximum) of alum is recovered using these methods. It is an impressive amount! Recovered alum can be reused for water purification. Thanks to alum recovery, the sludge, which is in liquid state, gets converted into solid state. Due to this, levels of pollution is reduced greatly.