ZERO LIQUID DISCHARGE: Balancing industry and environment

ZERO LIQUID DISCHARGE: Balancing industry and environment

Subject: Economy

Context: The Centre is examining various options of moving forward on the country’s Zero Liquid Discharge (ZLD) policy to ensure that investment in emerging sectors such as semiconductors is not hampered while environment continues to be protected.

Concept:

• The Department for Policy on Investments and Internal Trade (DPIIT) has been getting suggestions for removing regulatory compliances such as Zero Liquid Discharge to encourage investments in sectors like semiconductors.
• The DPIIT has held discussions with stakeholders such as Ministry of Environment, Forest and Climate Change (MoEFCC), Ministry of Electronics and Information Technology, Central Pollution Control Board (CPCB) and the State governments of Gujarat, Haryana and Tamil Nadu, on what the policy for zero level discharge will be going ahead, the official said

Zero Liquid Discharge

• ZLD is a water treatment process to recirculate all the water back to the process with zero liquid waste. Government regulations demand fool-proof operations of the wastewater treatment plants for the purpose.
• 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.
• ZLD systems employ advanced wastewater/desalination treatment technologies to purify and recycle virtually all of the wastewater produced.
• Also ZLD technologies help plants meet discharge and water reuse requirements, enabling businesses to:
• Meet stringent government discharge regulations
• Reach higher water recovery (%)
• Treat and recover valuable materials from the wastewater streams, such as potassium sulfate, caustic soda, sodium sulfate, lithium and gypsum
• 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. Thus, ZLD plants produce solid waste