🌊 1️⃣. GENERAL INTRODUCTION TO THE ELECTROPLATING WASTEWATER EVAPORATION TECHNOLOGY PROJECT

In the electroplating and metal processing industry, wastewater contains very high concentrations of salts, heavy metals, and COD. These characteristics often exceed the treatment capacity of conventional biological or physicochemical processes.

To comply with the latest discharge regulation QCVN 40:2011/BTNMT – Column B, reduce operating costs, and move toward a Zero Liquid Discharge (ZLD) model, TVTS researched and implemented Heat Pump Vacuum Evaporation (HPVE) technology combined with STRO membrane filtration at an electroplating plant with a capacity of 100 m³/day.

💧 2️⃣. INFLUENT WASTEWATER CHARACTERISTICS

2.1 Flow Rate

• Wastewater flow rate: 0.1 m³/hour (~2 m³/day)

• Operating time: 20 hours/day

• Planned expansion: 0.3 m³/hour (~6 m³/day) in the next phase

2.2 Influent Wastewater Composition

2.3 Effluent Requirements (QCVN 40:2011 – Column B)

🔬 3️⃣. HPVE TECHNOLOGY COMBINED WITH STRO MEMBRANE SOLUTION

3.1 Operating Principle

When the level sensor in the feed tank detects a full condition, the system automatically starts the vacuum pump and creates a pressure of approximately 33 mbar inside the evaporation chamber.

Under this condition, wastewater boils at a very low temperature (30–40°C), which reduces energy consumption and limits organic compound degradation.

During the electroplating wastewater evaporation process:

• The compressor compresses refrigerant gas to 60–70°C at 16–20 bar,

• The hot refrigerant transfers heat to the wastewater inside the evaporation chamber,

• The generated vapor flows to the condenser and forms clean condensate water.

The system stores condensate in the condensate tank and then circulates it through the STRO RO membrane to ensure reuse water quality.

Average power consumption: 140–150 W per liter of influent wastewater.

3.2 Concentration Performance

• Concentration factor: 8–10 times

• Clean water recovery rate: 95%

• Evaporation temperature: 35–40°C

• Operating vacuum: 33 mbar

• No cooling tower or auxiliary boiler required

When the wastewater reaches the designed concentration level, the discharge valve opens automatically and transfers the concentrate to the hazardous waste storage tank. The condensate passes through the STRO membrane system and is reused for cooling towers or metal surface rinsing.

⚙️ 4️⃣. PERFORMANCE & OPERATING COST

⚡ The system reduces treatment costs by approximately 70% compared to conventional physicochemical treatment (typically 1.6–1.8 million VND/m³).

Payback period (ROI): ~1.3 years.

🧩 5️⃣. RESULTS AND PRACTICAL APPLICATION

• Water evaporation and separation efficiency >95%

• Treated water can be reused internally

• Concentrate volume decreases by >90%, significantly reducing hazardous waste disposal costs

🌱 6️⃣. ADVANTAGES OF THE HPVE + STRO SOLUTION

• No steam, boiler, or cooling tower required

• Lowest electricity consumption among concentration systems

• PLC–SCADA automation, easy operation, simple maintenance

• Titanium / Duplex materials resistant to Cl⁻ and Ni²⁺ corrosion

• Complies with QCVN 40:2011 standards and supplies water to cooling towers

• Supports Zero Liquid Discharge (ZLD) – no wastewater discharge to the environment

🏁 7️⃣. CONCLUSION

The successful application of electroplating wastewater evaporation technology using HPVE combined with STRO membrane filtration demonstrates high efficiency:

• Reduces operating costs by more than 70%

• Recovers 95% clean water

• Reduces hazardous solid waste by >90%

• Meets environmental discharge standards and supports circular economy and ZLD strategies

TVTS – Thinh Vuong Technical Services JSC
Pioneer in designing and manufacturing evaporation, crystallization, and ZLD systems in Vietnam.