Zero-to-minimal liquid discharge as waste water management approach

Zero liquid discharge (ZLD) process is a waste water management approach where all industrial waste streams can be reused after recycling without any discharge into natural water bodies. This concept is also extended to municipal waste waters. Strict environmental regulatory norms, water scarcity and growing awareness of environmental issues are the major drivers for adoption of zero liquid discharge (ZLD) technology in industries. Water was always considered an underpriced resource, but with the implementation of zero-to-minimal liquid discharge, there is a shift in focus where industrial polluters need to devise methods to achieve least environmental impact. Complete recycling is a complex chemical and thermodynamic factor that seems virtually impossible; hence industries and small-sector enterprises have adopted minimal liquid discharge (MLD) techniques. The global estimates reveal that total market potential of zero-to-minimal discharge techniques may reach 210 billion by 2020. This article presents concept of zero-to-minimal liquid discharge, processes involved and case study of existing MLD/ZLD treatment plants in textile and electroplating industries in India, challenges, opportunities in application-specific industrial setting.