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
