Recovery of Nutrients from Drain Channel of CAN and NP Plants

Abstract

This project is aimed at recovering the nutrients, namely nitrates and phosphates, that are being lost in the drain channels of the calcium ammonium nitrate (CAN) and nitrophosphate (NP) plants at Pak-Arab Fertilizers, Multan. In the current operating conditions, the plant is losing water at a rate of 15 m3/hr with a total dissolved solid (TDS) content of approximately 23,000. The water has to be treated in the effluent treatment plant (ETP) to bring the effluents to environmental standards. A scheme to recover the water along with the nutrients has been devised, bringing the plant to zero liquid discharge (ZLD) standards. The prominent processes that are put into practice are reverse osmosis (RO), electrodialysis (ED), crystallization and filtration. The effluent streams are combined and then sent through the suggested schemes. After the effluent streams have been processed, the recovered water is valued at over 12 tons per hour and the recoverable solids amount to 404.87 kg per hour, out of which 189.28 kg are retrieved in usable form and 215.59 kg are recycled.