Feed chemistry
Silica, hardness, sulphate, organics and antiscalant compatibility can determine recovery limits.
Industrial water treatment
Zero Liquid Discharge (ZLD) Plant
Advanced recovery trains for industrial sites seeking high water recovery and minimal or zero liquid discharge.
Engineering approach
Start with a mass balance
A ZLD design should be built from wastewater flow, TDS, scaling species, organics, silica, temperature, recovery targets and available energy. Concentration and crystallisation stages must be evaluated against the chemistry and economics of the specific site.
Process flow
Typical ZLD process train
1Pretreatment
2RO / membrane recovery
3Concentrate management
4Evaporation / concentration
5Crystallisation or solids handling
6Water recovery & reuse
Design & operating considerations
Mass balance
Every stream—feed, permeate, reject, condensate and solids—should close in the overall water and salt balance.
Energy
Thermal and electrical energy requirements can dominate operating cost at high recovery.
Solids
Crystalliser and salt-handling requirements should be planned before selecting the final process.
Applications
- High-TDS industrial effluent
- Chemical and process industries
- Textile wastewater
- Water-scarce manufacturing sites
- High-recovery reuse projects
Support
Aqua Chem Labs can support water analysis, process selection, pilot or jar testing where appropriate, equipment integration and operational troubleshooting.
Final equipment configuration, chemical dosing and operating targets should be based on actual water analysis, plant load and applicable discharge/process requirements.
Technical resource
Detailed engineering guide
Use the expanded ZLD engineering guide for treatment stages, chemistry, mass balance and practical considerations.
Open technical guideFrequently asked questions
Is ZLD suitable for every wastewater?
Not necessarily. A feasibility study should examine wastewater chemistry, recovery goals, energy, concentrate characteristics and economics.
Does ZLD always use an evaporator?
High-recovery ZLD trains often include thermal concentration, but the exact process depends on the wastewater and recovery target.
What data is needed before a ZLD design?
Flow, TDS, ionic composition, hardness, silica, COD/organics, temperature and the required reuse/discharge target are common starting data.