Case Study: Zero Liquid Discharge for Metallurgical Wastewater at Bayannur Zijin 

【Project Overview】

The metallurgical industry faces increasingly stringent environmental pressures and cost challenges, making "Zero Liquid Discharge" for high-salinity wastewater a mandatory requirement for sustainable enterprise development. However, traditional treatment methods are often plagued by high operating costs, poor system stability, and difficulties in resource recovery. This is especially true for wastewater with TDS exceeding 30,000 mg/L and complex compositions, where conventional membrane processes are prone to scaling and fouling, while direct evaporation/crystallization entails massive energy consumption, leaving many enterprises trapped in an "unaffordable treatment" dilemma.

This project involved the construction of a deep treatment and resource recovery unit for a specific metallurgical enterprise, targeting its high-salinity wastewater flow of 18-19 m³/h with a TDS as high as 33,000 mg/L (composed primarily of a 1:1 ratio of sodium chloride to sodium sulfate). The project aimed to precisely solve these industry pains, ensuring not only compliant wastewater treatment but also, more crucially, achieving the dual resource recovery of water and inorganic salts. It successfully produces 13.8-14.2 m³/h of high-quality reuse water (TDS ≤ 10,000 mg/L) and 4.2-4.5 m³/h of standardized brine with a TDS of ~160,000 mg/L, transforming the environmental compliance "cost center" into a resource regeneration "profit center." This pioneers a new, green, economical, and sustainable pathway for high-salinity wastewater management in the metallurgical industry.

【Project Highlights】

• conventional membrane processes under extreme salinity, ensuring long-term, stable operation.
  Precision "Salt-Splitting" Pretreatment: Targeting the scaling risk posed by the 1:1 ratio of sodium chloride and sodium sulfate, the process employs precise softening and advanced oxidation pretreatment, clearing obstacles for subsequent efficient concentration and salt resource recovery, overcoming a common industry technical bottleneck.
• Resource Circulation: Transforming an "Environmental Burden" into "Economic Benefit"
  Conserving Resources & Cutting Costs: Reduces freshwater consumption and discharge fees. Creating Revenue Streams: The produced high-concentration sodium sulfate and sodium chloride brine provides the basis for producing.
• industrial-grade anhydrous sodium sulfate and refined salt, generating additional revenue. 
  Cost-Effectiveness: Optimizing Lifecycle Cost Energy Saving & Consumption Reduction: Optimized system design and energy recovery reduce energy consumption per ton of water treated by over 20% compared to traditional "Membrane Process + Evaporation/Crystallization" routes.High Return on Investment: The highly integrated system has a small footprint. Resource recovery revenues enable a reasonable investment payback period, achieving a win-win for both environmental protection and cost reduction.