How BASF Achieved Zero Liquid Discharge at Its China Verbund Site: Wastewater Compliance Case Study

BASF’s integrated Verbund site in Zhanjiang, Guangdong Province, represents one of the most ambitious chemical manufacturing investments by a foreign company in China. Announced in 2018 with a total investment of approximately €10 billion, the Zhanjiang Verbund site is BASF’s largest single investment worldwide and its third-largest Verbund site globally. From the outset, BASF committed to achieving Zero Liquid Discharge (ZLD)—a wastewater management approach that eliminates any liquid effluent leaving the facility—at this site. This commitment places BASF at the forefront of industrial wastewater management in China and offers a powerful case study for foreign chemical companies navigating the country’s increasingly stringent water pollution regulations.

This case study examines how BASF designed, implemented, and operates its ZLD system at the Zhanjiang site, the regulatory drivers that shaped the approach, the technologies deployed, and the lessons that other foreign chemical manufacturers can apply to their China operations.

Regulatory Context: China’s Evolving Water Pollution Framework

The decision to pursue ZLD at Zhanjiang was driven primarily by China’s progressively tightening water pollution regulations, which have evolved significantly over the past decade:

• Water Pollution Prevention and Control Action Plan (《水污染防治行动计划》, known as “Water Ten Plan,” 2015): This landmark policy set ambitious targets for reducing water pollution across all industrial sectors and established stricter discharge standards for key industries including chemicals, textiles, and pharmaceuticals.
• Yangtze River Protection Law (《长江保护法》, 2021): Zhanjiang sits on the coast of Guangdong, not directly on the Yangtze. However, the law’s strict liability provisions and enhanced penalties for water pollution violations set a new nationwide benchmark for enforcement rigor. BASF anticipated that similar standards would eventually apply to all major waterways.
• Guangdong Province Water Pollution Prevention Regulations (2023 revision): Guangdong Province, where Zhanjiang is located, has been among the most aggressive provinces in implementing water pollution controls. The 2023 revision of provincial regulations introduced stricter effluent limits for chemical plants and mandated continuous online monitoring for all major industrial discharges.
• China’s “Dual Carbon” Goals: While primarily focused on carbon emissions, the 2030/2060 goals have cascading effects on water management, as comprehensive ZLD systems require energy-intensive processes like evaporation and crystallization.

BASF recognized early that these regulatory trends pointed toward increasingly stringent water discharge standards across China. Rather than building a conventional wastewater treatment system that would require costly upgrades as regulations tightened, the company opted for a ZLD approach that would not only ensure compliance through multiple regulatory cycles but also reduce long-term operational risk.

The Zero Liquid Discharge System: Technical Architecture

BASF’s ZLD system at the Zhanjiang Verbund site is a multi-stage treatment train designed to recover and reuse over 99% of process water while producing only solid salt byproducts suitable for beneficial reuse or safe disposal.

Stage 1: Primary Treatment and Equalization

All process wastewater from the various chemical production units within the Verbund site flows to a central equalization basin. This basin—with a capacity of approximately 25,000 cubic meters—serves to homogenize flow and composition, damping the variations that occur from different production campaigns. Primary treatment includes pH adjustment, oil-water separation, and removal of coarse solids through screening and sedimentation. The equalization stage is critical for ZLD system reliability: by providing consistent feed quality to downstream treatment processes, it prevents the shock loading that can disrupt membrane and thermal systems.

Stage 2: Membrane Bioreactor (MBR)

Following primary treatment, wastewater enters a membrane bioreactor system that combines biological treatment with membrane filtration. The MBR system uses submerged ultrafiltration membranes to separate treated water from the biological sludge, producing a high-quality permeate while maintaining a concentrated biomass for effective organic degradation.

The MBR system at Zhanjiang is designed to handle the complex and variable organic loads typical of a multi-product chemical site. BASF’s German engineers worked closely with Chinese technology partners to select membrane materials and operating parameters appropriate for the local wastewater characteristics. The system achieves over 95% removal of biochemical oxygen demand (BOD) and chemical oxygen demand (COD), producing permeate suitable for reverse osmosis feed.

Stage 3: Reverse Osmosis and Brine Concentration

The MBR permeate is further treated through a two-stage reverse osmosis (RO) system. The first stage operates at conventional pressure (10–15 bar) and recovers approximately 75% of the water as high-quality permeate suitable for reuse in cooling towers and process applications. The RO concentrate from the first stage feeds a second-stage high-pressure RO system operating at up to 70 bar, which recovers an additional 10–15% of water.

The combined RO recovery rate of approximately 85–90% means that the volume of brine requiring final treatment is reduced to only 10–15% of the original wastewater volume. This brine stream has a total dissolved solids (TDS) concentration of 30,000–60,000 mg/L, making it suitable for thermal concentration.

Stage 4: Thermal Evaporation and Crystallization

The final stage of the ZLD system uses mechanical vapor recompression (MVR) evaporators followed by forced-circulation crystallizers to convert the brine stream into solid salts and distilled water. The MVR evaporators use compressor-driven vapor recirculation to minimize energy consumption—approximately 20–30 kWh per cubic meter of distillate produced, significantly less than conventional single-effect evaporation.

The crystallizers produce solid salt crystals that are separated, washed, and either (a) sold for industrial use (primarily sodium chloride and sodium sulfate), (b) used as raw material in other Verbund processes, or (c) disposed of as non-hazardous solid waste at licensed landfills. BASF reports that over 80% of the salt byproduct is beneficially reused, with less than 20% requiring landfill disposal. The distilled water from the evaporators—of extremely high purity (< 10 μS/cm conductivity)—is returned to the site's demineralized water system for reuse in high-grade process applications.

Cost-Benefit Analysis: Investment vs. Long-Term Savings

BASF’s ZLD system represents a significant capital investment. The company has not publicly disclosed the exact cost of the wastewater treatment infrastructure at Zhanjiang, but industry estimates for a ZLD system serving a large chemical Verbund site range from $80–150 million, depending on flow rates, wastewater composition, and the level of automation.

However, the cost-benefit analysis shifts substantially when viewed over the site’s 40+ year expected operational life:

While the 20-year total cost of the ZLD system is higher, the differential narrows significantly when factoring in regulatory certainty. BASF’s decision effectively insulates the Zhanjiang site from future water discharge standard tightening—a significant competitive advantage as China continues to strengthen industrial wastewater regulations across all provinces.

Regulatory and Community Benefits

Beyond the operational and financial considerations, BASF’s ZLD commitment has generated substantial intangible benefits:

• Regulatory goodwill: The ZLD approach positions BASF as a technology leader in environmental management, earning favorable treatment from Guangdong’s environmental authorities in permit processing and inspection scheduling.
• Community acceptance: In a region where water quality is a sensitive issue, the zero-discharge commitment has been a powerful tool for building community trust and securing the social license to operate.
• Workforce attraction: BASF reports that its environmental commitments—including ZLD—are a significant factor in attracting and retaining qualified Chinese engineers and environmental professionals who want to work for a sustainability leader.
• Brand reputation: The Zhanjiang ZLD system has been featured in multiple Chinese government publications as a model for green chemical manufacturing, enhancing BASF’s brand position among Chinese customers, partners, and regulators.

Lessons for Foreign Chemical Companies in China

BASF’s experience offers several strategic lessons for foreign chemical companies operating or planning operations in China:

1. Anticipate regulatory trajectories, not just current requirements. BASF’s decision to implement ZLD was based not on what Chinese law required at the time but on the direction of regulatory change. Companies that plan for future standards rather than current minimums will avoid costly retrofits and operational disruptions.
2. Integrate environmental and production design. The ZLD system at Zhanjiang was designed as an integral part of the Verbund site, not as an afterthought. This integration allowed for optimal siting, shared utilities, and process synergies that would not have been achievable with a retrofit approach.
3. Partner with local technology providers. BASF worked with Chinese membrane manufacturers, evaporator suppliers, and engineering firms to design and build the ZLD system. This not only reduced costs but also ensured that the system met Chinese regulatory standards for equipment and construction.
4. Plan for solid waste management. ZLD eliminates liquid discharge but produces solid salt byproducts. Companies must have a plan for salt reuse or disposal that complies with China’s Solid Waste Law and does not simply shift the environmental burden from water to land.
5. Document the business case comprehensively. BASF’s corporate headquarters required a thorough cost-benefit analysis that accounted for regulatory risk, brand value, and long-term competitiveness—not just immediate capital costs.

Conclusion

BASF’s ZLD system at the Zhanjiang Verbund site represents a benchmark for industrial wastewater management in China’s chemical sector. By investing in a comprehensive, multi-stage treatment system that eliminates liquid discharge entirely, BASF has not only ensured compliance with current and anticipated regulations but also created operational, reputational, and strategic advantages that will compound over the site’s decades-long operational life. For foreign chemical companies evaluating their China wastewater strategy, the BASF Zhanjiang model demonstrates that ZLD—while capital-intensive—can be a sound long-term investment when viewed in the context of China’s tightening regulatory environment, growing community expectations, and the strategic value of environmental leadership.

Last updated: July 2026. Information in this case study is based on publicly available sources including BASF corporate publications, Chinese regulatory announcements, and industry analyses. For specific implementation guidance, consult qualified environmental engineering and legal professionals.