Wastewater coming out from industries need to be treated by physical and chemical methods to remove the toxic and harmful chemicals. As per the environmental regulation standards, the effluent such as urea, ammonia and carbon dioxide can be treated by hydrolysis and desorption technique. By this technique, the treated water reused as boiler feed water. Cooling water mixed with this treated water to maintain water balance in the process industry.
Urea and ammonia hydrolysed in a reactor where high-pressure steam is feed from the bottom and leave out from the top of the reactor section. The nitrogen and carbon compounds dissolved in the wastewater stripped out. High-pressure steam will carry the wastewater chemical components to the low-pressure column. Water condensed at low-pressure section and urea, ammonia and carbon dioxide removed as vapours from the top of the low-pressure column. Treated water contains no traces of ammonia, carbon dioxide or urea. This type of system is preferred in ammonia and urea production industries.
Another technique follows a countercurrent flow system in hydrolysis. Thermal application of hydrolysis will make ammonia and urea removal more effective but consumes high energy. However, by use of pervaporation technique added to thermal hydrolysis system large amount heat distributed without loss. The condensers used in condensing the vapours of treated water, vapours that contain the impurities avoided, and the heat duty is taken care by the pervaporation system.
