What is Antiscalant? How Antiscalant Improves Quality Of Water Purifier?
Antiscalant — An Introduction
Antiscalants are pre treatment balls/chemicals that are used in Reverse Osmosis water purificarion process to prevent the Reverse Osmosis Membrane from scaling. It plays a very important role in maintaining the quality and life of Reverse Osmosis Membrane.
Antiscalants ( also known as scale inhibitor agent ) are used to minimize the potential of the scale that deposits on the surface of a RO Membrane. Scale formation on the surface of membrane can be prevented by adding antiscalant to the feed water.
It is widely used to avoid scaling by salts like silica, iron, barium sulphate, calcium carbonate, gypsum etc.
What is Scale?
Scale are those mineral compounds or salts that deposit on the surface of Reverse Osmosis Membrane and reduces its flow rate. We all know the importance of membrane in water purification. A membrane reduces the high TDS level of water.
The concentration of these mineral compounds in water depends on the source of feed water. Below we are mentioning mineral scalants as per their scaling ability :
(i) High Capacity :
(a) Calcium Carbonate (CaCO3)
(b) Calcium Sulphate (CaSO4)
© Strontium Sulphate (SrSO4)
(d) Barium Sulphate (BaSO4)
(ii) Low Capacity :
(a) Calcium Phosphate [ Ca3(PO4)2 ]
(b) Calcium Fluoride ( CaF2 )
(iii) Non Harmful
Silica ( SiO2 )
Methods Of Controlling Scale
There are mainly three methods used to control scaling :
(i) Acid Addition : This is one of the oldest and simple method. In this process, some amount of acid is added to the feed water. Acid reduces the pH of water and scale forming salts and salts get dissolved. Thus, they lose their ability to form scale on the surface of Reverse Osmosis Membrane and membrane remains safe from scaling.
(ii) Installation of Softener : Water Softeners are used to convert hard water into soft water. Hard minerals like calcium, magnesium and other scale forming salts are removed by the softener and membrane remains safe from scaling. Resin seeds are used in water softener to remove hardness of water.
(iii) Antiscalant Addition : This is the widely used method to prevent scale formation on the surface of Reverse Osmosis Membrane. Anitscalant is added to feed water before it enter the membrane. There are Two Forms of Antiscalant :
(a) Solid Form ( Balls ) : Balls are used in domestic water purifiers. These balls are kept in the pre sediment filter housing.
(b) Liquid Form ( Chemical ) : This is used in Industrial Reverse Osmosis System. Industrial Reverse Osmosis System purifies thousands of liters of water in day. Therefore we need to add Anitiscalant chemical in the feed water through a dosing pump at an appropriate dosing rate. Balls are not used in Industrial RO System because it will need to be changed 20–30 times a day which is inconvenient.
