ZERO LIQUID DISCHARGE (ZLD) PROJECT FOR THE WASTEWATER STREAMS OF ATTOCK REFINERY LIMITED (ARL), RAWALPINDI

Abstract

Zero Liquid Discharge (ZLD) is an innovative approach that ensures no liquid waste is discharged from the plant. This sustainable approach reduces water consumption, conserves precious resources, and helps industries and municipalities meet stringent regulatory standards. Despite requiring initial investment, ZLD offers significant long-term benefits by promoting water conservation and minimizing pollution. Attock refinery limited (ARL) has daily water requirements of 12 lacs gal/day and waste is almost 500,000 gal/day. The objective of this project is to implement a Zero Liquid Discharge (ZLD) technique for the 500,000 gal/day of wastewater streams at the plant. The technology’s multi-layered approach such as conventional biological treatment processes with membrane filtration in single membrane bioreactor (MBR), reverse osmosis (RO) membranes, and advanced multimechanical vapor recompression evaporators resulting in complete recovery of two types of water e.g. demineralized water (for cooling towers) and boiler feed water (for steam production). The implemented technique recovers 99% of high-quality water for cooling towers and boilers that significantly reduce blowdown and corrosion at the plant