Zero Liquid Discharge Ecology

In news: The Aqua Rejuvenation Pilot Plant (ARP) installed at CSIR-CMERI recently can help to reach towards a Zero Liquid Discharge Ecology

The Aqua Rejuvenation Pilot Plant (ARP) of CSIR

• To remove the water contaminants & to purify the sewage water ,CSIR-CMERI developed innovative  technology in combination with chemical & physical processes  such as
  • Mechanical segregation & filtration
  • Coagulation-flocculation techniques and 
  • Chemical/physical adsorption.
• It comprehensively treats WasteWater, based upon diverse purification parameters. 
• The approx. 24,000 litres of Water that can be rejuvenated using ARP, will be sufficient for almost 4 acres of Agricultural Land (barring seasonal variations in water requirements). 
• It is capable of removing all pollutants from sewage (below W.H.O recommended level) and based upon geographical variations they may be modified. 
• The filter media is also locally source-able so as to ensure that there would not be any stress in the supply chain for scaled-up manufacturing of ARP.

How does it purify sewage water?

The methods of purification applied by CSIR-CMERI in this technology are 

• Sedimentation (settlement of flocculated or coagulated particles)
• Filtration (process of removing solids from Liquid) and 
• Aeration (Oxidation and Hydration).  

Key benefits

• The technology will help in solving two problems at one go:
  • In one hand it converts sewage water to potable water which may be used for agricultural purposes thereby conserving the fresh water resources
  • On the other hand it helps to reduce the burden of pollutant enriched grey water converting it into potable one.
• An integrated mechanical and physico-chemical treatment processes based water purification system for effective removal of sewage water contaminants.
• The technology is economical in terms of maintenance and affordable in terms of operation.
• Sustainability towards healthy livelihood generation
• Selective backwash without dismantling any part of the plant; less cumbersome approach.

Significance of the technology

• ARP has maximum capacity to treat 40,000 litres/day in its scaled-up version. With this technology, CSIR-CMERI will incrementally reach towards a Zero Liquid Discharge Ecology. 
• The treated water processed from the ARP is preferable for agricultural purposes and with enhanced settling time it can be used for drinking purposes. 
• This treated water will help to improve the environment by fixation of carbon dioxide and will also provide food security.

What is a Zero Liquid DischargeZLD)?

• It refers to a treatment process in which the plant discharges no liquid effluent into surface waters, in effect completely eliminating the environmental pollution associated with treatment.
• It is a combination of technologies that work together to minimize wastewater as much as technically and economically practical, often resulting in a concentrated solid product and high-quality clean water for re-use or environmental discharge.
• It is achieved by treating wastewater through recycling and then recovery and reuse for industrial purposes.

Components of ZLD

A systematic ZLD is made up of the following components:

• pretreatment (physicochemical and Biological)
• RO (membrane processes)
• evaporator and crystallizer (thermal processes)

How does it work?

 ZLD systems employ advanced wastewater/desalination treatment technologies to purify and recycle virtually all of the wastewater produced

Benefits of ZLD

Following are the benefits of ZLD system

• Wastewater discharge is avoided by recycling.
• Recovery of water and salt aids in reducing the cost of operation of ZLD.
• It promotes the sustainability of the industry and the environment at large.
• There is less use of water by the textile industry, which means water is available for other purposes such as irrigation (agriculture) and domestic utilities.
• ZLD helps recover the environment.
• The sludge can be effectively used by the cement industry.