Zero liquid discharge
zero dischargezero-discharge
Zero Liquid Discharge (ZLD) is a treatment process designed to remove all the liquid waste from a system.wikipedia


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Evaporator
Evaporatorsevaporator coilevaporating unit
The conventional way to reach ZLD is with thermal technologies such as evaporators (multi stage flash (MSF), multi effect distillation (MED) and mechanical vapor compression (MCV)) and crystallizers and recover their condensate.
In the case of desalination of sea water or in Zero Liquid Discharge plants, the reverse purpose applies; evaporation removes the desirable drinking water from the undesired solute/product, salt.




Wastewater
waste watermunicipal wastewaterwastewater treatment facility
The focus of ZLD is to reduce wastewater economically and produce clean water that is suitable for reuse (e.g. irrigation), thereby saving money and being beneficial to the environment.


Reclaimed water
recycled waterwater reclamationwater recycling
Also ZLD technologies help plants meet discharge and water reuse requirements, enabling businesses to:



Multi-stage flash distillation
Multi-Stage Flashmulti stage flashmultistage flash distillation
The conventional way to reach ZLD is with thermal technologies such as evaporators (multi stage flash (MSF), multi effect distillation (MED) and mechanical vapor compression (MCV)) and crystallizers and recover their condensate.

Distillation
distillerydistilleddistilling
The conventional way to reach ZLD is with thermal technologies such as evaporators (multi stage flash (MSF), multi effect distillation (MED) and mechanical vapor compression (MCV)) and crystallizers and recover their condensate.









Crystallization
crystallizecrystallisationcrystallized
The conventional way to reach ZLD is with thermal technologies such as evaporators (multi stage flash (MSF), multi effect distillation (MED) and mechanical vapor compression (MCV)) and crystallizers and recover their condensate.









Condensation
condensecondensedcondenses
The conventional way to reach ZLD is with thermal technologies such as evaporators (multi stage flash (MSF), multi effect distillation (MED) and mechanical vapor compression (MCV)) and crystallizers and recover their condensate.



Municipal solid waste
solid wastemunicipal wastehousehold waste
Thus, ZLD plants produce solid waste.


Sodium sulfate
Glauber's saltsodium sulphateNa 2 SO 4

Gypsum
gypsiferouscalcium sulfate dihydrategypseous









Evaporation
evaporateevaporatedevaporates
ZLD technology includes pre-treatment and evaporation of the industrial effluent until the dissolved solids precipitate as crystals.

Industrial wastewater treatment
industrial wastewaterindustrial effluentwastewater treatment plant
ZLD technology includes pre-treatment and evaporation of the industrial effluent until the dissolved solids precipitate as crystals.





Filter press
filterfilter pressesPressure filtration
These crystals are removed and dewatered with a filter press or a centrifuge.


Centrifuge
centrifugescentrifugalcentrifuging
These crystals are removed and dewatered with a filter press or a centrifuge.








Electrodialysis
This has led to processes like electrodialysis (ED/EDR), forward osmosis (FO) and membrane distillation (MD).

Forward osmosis
This has led to processes like electrodialysis (ED/EDR), forward osmosis (FO) and membrane distillation (MD).








Membrane distillation
vacuum multi-effect membrane distillation system
This has led to processes like electrodialysis (ED/EDR), forward osmosis (FO) and membrane distillation (MD).





Effluent guidelines
effluent guideline processEffluent limitation guidelineseffluent limitations guidelines
Diane Wilson
In 1994 she won "zero discharge" agreements (meaning no liquid effluent discharge into the environment) from Formosa and Alcoa.
Noyyal River
NoyyalNoyyal river canalRiver Noyyal
After several petitions from 2003 to 2011, dying and bleaching units were ordered closed on the river until zero liquid discharge status was achieved.


Hyderabad Pharma City
The Park will comply as a zero liquid discharge (ZLD) facility and with presence of common effluent treatment plants with a total capacity of 66 MLD.