Zero Liquid Discharge of Petrochemical industry Wastewaters via Environmentally Friendly Technologies: An overview

Half of the world's population, or 90% of the developing countries, may be affected by water scarcity, which is predicted to quadruple in size over the next 25 years. Petrochemical industries, which are linked to water-intensive industrial processes, are concerned with such “water-intensive” scenario. Water is primarily used in these industries in different aspects including: cooling towers, high-pressure boilers, process water, firefighting water, and municipal activities including potable water, with cooling towers being the largest water consumers. Accordingly, industries have to consider the alternatives eco-friendly solutions concerning safe reuse water. Therefore, it is crucial to implement steps towards wastewater reuse technology. In this respect, the current conventional treatment systems are unable to remove the high level of salts present in such wastewaters. This prevents water reuse in the industrial process. Due to the release of these industries; as toxic effluent streams; into the environment, the expansion of petrochemical industry is frequently linked to significant negative environmental impact. Therefore, the petro-chemical wastewaters are; then; classified as having extremely high concentration of variable organic pollutants that are mostly highly resistant to the bio-degradation treatment. The present review article presents the most important integrated technologies dealing with the treatment of petrochemical discharged wastewater. The main aim include: safe discharge, and / or adequate/ safe reused. On the other hand, it is recommended to adapt the current eco-friendly techniques for treatment of various wastewaters so that the treated effluent can be recovered, reused, and / or safely reclaimed. In this review, the approaches for zero liquid discharge (ZLD) around the world are thoroughly reviewed, along with their applicability in petrochemical industry.