Performance and Environmental Assessment of a Designed Water Recycling Pretreatment Unit for MLD in the Acid Liquefaction Industry

Abstract

Abstract With growing water scarcity worldwide, water recycling is now a vital component to save water and ensure sustainable water management. Boilers are extensively used in various industries to generate steam for industrial processes and heating. Boiler operation results in polluted wastewater, which has to be specially treated before it can be released into the environment. Effective treatment of boiler wastewater is indispensable to ensure environmental protection as well as regulatory compliance. In this study, a specially designed pre-treatment facility was used for treating boiler wastewater from a hydrochloric acid factory. The wastewater was mixed with reverse osmosis (RO) unit effluents that supplied the production line, followed by reusing the treated water in Hydraulic acid liquefaction process. As an inexpensive pretreatment technique, effective removal of inorganic contaminants, 20%—30% diminution in the level of sulfate, and the levels of phosphate also diminished, whereas metals (zinc and iron) were reduced to the extent of approximately 70%–80%. The Water Quality Index (WQI) indicates fair quality and demonstrates that the system was effective in improving water quality. Life Cycle Assessment (LCA) further revealed that integrating economic and environmental strategies is essential for sustainability. Consequently, 80% of the plant’s wastewater was successfully recovered and reused in a neighboring sulfuric acid production line, achieving a Minimal Liquid Discharge (MLD) outcome.