Zero Liquid Discharge (ZLD)
Zero Liquid Discharge (ZLD) is an industrial process which does not
release any wastewater. This target is commonly achieved by separating
streams into evaporation or crystallization paths. During these
processes, contaminated elements are discharged as solid waste whilst
the condensate is recovered. Typically, the effluent is a salty solution
and the thermal separation is the final step of ZLD, after being
exposed to pre-treatments, ultrafiltration and reverse osmosis units.
ZLD technology has characteristic advantages on wastewater concentrations:
- No wastewater discharge leaves the plant. Only solid wastes are produced and they are disposed of appropriately
reduction of the effluent can be maximized with a water content of up
to 1-3% of water content. This results in low disposal costs
- The condensate, otherwise known as distillate, can be recycled as process water.
evaporation and crystallization systems commonly operate under vacuum
and can be designed for single-duty or multi-purpose operation. They
optimally combine the following technologies:
Falling Film Evaporators
technology is particularly suited for energy-saving, multiple-effect
evaporation and mechanical vapor re-compression processes. It only
requires a very small operating temperature and thus allows it to be
easily controlled and fast to start up and shut down due to a minimal
liquid hold-up. Falling film technology is the right solution for
streams which are viscous in nature and contain small concentrations of
suspended solids. A falling film evaporator can be used as a
pre-concentrator in a combined multiple-effect plant. It has the
capacity to treat streams with small to large flow rates.Thin Film Evaporators/Dryers
devices are mostly used when strong sludge dewatering or drying is
required. They can be used to achieve a water content of less than 5%.
Like the falling film evaporators, this technology is easy to control
and fast to start up and shut down due to a very low liquid hold-up.
Thin film technology is the right solution for scaling products and for
highly viscous fluids. A thin film evaporator can be used as a
high-concentrator in a combined multiple-effect plant. It has the
capacity to treat streams with small to medium flow rates.
Forced Circulation Evaporators
to the high circulation flow-rate and evaporation external to the heat
exchanger, forced circulation technology is the right solution for
highly viscous streams containing a large concentration of suspended
solids, fouling products. A forced circulation evaporator can be used as
a high-concentrator in a combined multiple-effect plant with a
mechanical vapor recompression arrangement. It has the capacity to treat
streams with medium to large flow rates.
3V Tech always tries to apply techniques which minimize energy
consumption for its evaporation plants. Some of the methodologies we
- Multiple effect arrangement (ME)
- Thermal vapor recompression (TVR)
- Mechanical vapor recompression (MVR)
- Usage of waste energy
Our ZLD plants can be supplied as a skid-mounted unit or are suitable for on-site installation.