Choosing a Zero Liquid Discharge (ZLD) system is a major capital decision. This guide compares the two main evaporation technologies to help you make an informed choice.
Two Main Evaporation Technologies
1. Thermal Evaporation
Uses heat to vaporize water. Includes:
- MVR (Mechanical Vapor Recompression) - Recovers vapor heat
- MED (Multiple Effect Distillation) - Multiple stages of evaporation
- Thermal Vapor Compression - Combines heat sources
2. Non-Thermal Evaporation
Uses mechanical atomization + natural evaporation:
- Atomizing Spray - Fine water droplets
- Forced Draft - Air circulation
- Natural Evaporation - Solar/ambient
Cost Comparison Table
| Parameter | Thermal (MVR) | Non-Thermal |
|---|---|---|
| CAPEX | ₹2-10 crore | ₹50 lakh - 2 crore |
| Power Consumption | 80-150 kWh/m³ | 15-30 kWh/m³ |
| Operating Cost | ₹80-150/m³ | ₹15-35/m³ |
| Steam Required | Yes | No |
| Maintenance | High (compressors) | Low (pumps, fans) |
| Footprint | Compact | Large |
| Startup Time | 30-60 min | 5-10 min |
5-Year Total Cost of Ownership
For a typical 100 m³/day system:
| Cost Component | Thermal (MVR) | Non-Thermal |
|---|---|---|
| CAPEX | ₹5 crore | ₹1 crore |
| 5-Year OPEX | ₹1.5 crore | ₹0.4 crore |
| 5-Year Maintenance | ₹50 lakh | ₹15 lakh |
| Total 5-Year Cost | ₹7 crore | ₹1.55 crore |
Savings with Non-Thermal: 78% lower total cost!
When to Choose Thermal
- Limited space (compact required)
- Very high volumes (>500 m³/day)
- 24/7 continuous operation
- Availability of cheap steam/heat
When to Choose Non-Thermal
- Budget constraints
- Lower volumes (<200 m³/day)
- Intermittent operation
- Want fastest ROI
- No steam availability
Real-World Example: Chemical Industry, Gujarat
Client: Specialty chemicals manufacturer, Vatwa
Volume: 50 m³/day RO reject, TDS 12,000
| Thermal MVR | Non-Thermal | |
|---|---|---|
| System Cost | ₹3.5 crore | ₹75 lakh |
| Annual Operating | ₹45 lakh | ₹12 lakh |
| ROI Period | 5 years | 1.5 years |
Client chose: Non-thermal (Asiatic Engineers system)
Result: 18-month payback, ₹33 lakh annual savings
Conclusion
For most Indian industries, non-thermal evaporation offers superior economics. The 60-70% lower operating costs translate to faster ROI and lower total cost of ownership. Thermal systems make sense only in specific high-volume, continuous-operation scenarios.
Get a cost estimate for your facility: Contact Asiatic Engineers +91 98240 54002