Zero Liquid Discharge

Regulatory norms are becoming stringent concerning the limits of liquid discharge & Wastewater treatment. To reduce impact on the environment, increasing number of industries are going in for Zero Liquid Discharge (ZLD). A ZLD system implies that practically no liquid waste goes outside the boundary of the manufacturing facility.

Praj offers various combinations like Recycle & Reuse, Evaporation & Crystallization in designing Zero Liquid Discharge Systems in accordance with the unique requirement of the customer.

Solvent Recovery & Scrubbing

ECOFINE

ECOFINE Distillation systems are designed to have minimum moisture content in product and better separation of low boiling impurities to meet the required standards.

Praj offers highly efficient column internals like bubble cap trays and hyper stat grid trays for more effective separation of impurities along with reduced scaling and down-time.
Praj offers solvent recovery plants based on :

• Azeotropic distillation
• Extractive distillation
• Liquid-liquid separation technologies
• Adsorption technologies
• Complete solvent recovery
• Advantages :
• Multiproduct distillation system to products as per stipulated standards
• Energy conservation through multi-pressure distillation
• Maximization of production by using multi-pressure distillation techniques
• Plant automation based on SCADA/PLC
• Consistency in product quality
• 
  

  Scrubbing

  Scrubbing is absorption of gases from the Wastewater. Industrial and municipal Wastewater contains hazardous gases like ammonia, hydrogen sulphide etc.
  Praj Offers :
• Ammonia (NH3) Scrubbers.
• Hydrogen Sulphide (H2S) Scrubbers
• Carbon dioxide (Co2) Scrubbers
• 
  Advantages :
• Low operating cost
• High efficiency & reliable
• Low maintenance.

Evaporation

Evaporation is the process of vaporization of solvent from solution in order to increase the concentration of the solute. Evaporation is extensively energy intensive unit operation. 

ECOVAP*ECOVAP* is the environment friendly, energy efficient range of evaporators.
Praj offers a range of solutions which includes :

• Falling Film Evaporators
• Forced Circulation Evaporators
• Special Falling Film Evaporators
• Thin Film Evaporators
• Patented Fluidized Bed Evaporators
  Combination of Evaporation :

  Multi Effect Evaporation Plant :

  Multiple Effect Evaporator is an apparatus for efficiently using the heat from steam to evaporate water to concentrate dissolved salts in the water. 
  
  In Multiple effects Evaporator, water is boiled in sequence of vessels, each held at lower pressure than the last. As boiling of water decreases with pressure, Vapor produced in one vessel can be used to heat the next vessel.
  
  Only first vessel requires the source of external heat.
  Advantages :
• Ease of operation
• Most proven system for Evaporation
•  

  Multi effect Evaporation Using Thermal Vapor Recompression (TVR):

• Steam Jet Ejector is used to raise the temperature and pressure of generated vapors from respectice effect of evaporator.
• The motive steam mixes with the part of vapors generated from respective effect of evaporator.
• Resultant vapors (motive steam + part of vapors from respective Effect) are utilized for effect of condensation.
• It increases overall energy efficiency of multiple effects Evaporation Plant.
• 
  Advantage Praj :
• Highly Energy Efficient System.
•  

  Evaporation with Mechanical Vapor Recompression :

  It is the most energy efficient System for Evaporation. This system requires theoretically zero Steam and Cooling Water during steady operation.
  
  Mechanical Vapor Recompression system can work with any kind of evaporator like Falling Film Evaporator, Forced Circulation Evaporator or Plastic Evaporator.
  
  Advantages :
• Low Energy Consumption
• Higher Performance Coefficient
• Reduced load on cooling tower
• Simplicity of Process, Operation and Maintenance
•  

  Typical MVR Evaporator :

• Falling Film Evaporator
•  

Praj offers dryers and crystallization which is a key part Zero Liquid Discharge Solutions. Crystallizers are thermal evaporators that can be driven by either steam or mechanical vapor compression.

Praj offers :

Forced Circulation Crystallizers.
Chilling Crystallizers.

Forced Circulation Crystallizers :

Last effect of Multieffect evaporator acts as a crystallizer, in which effluent is concentrated above the solubility of salt (super saturation) and then supersaturated salt solution is fed to the thickener or settling tank. Low rpm agitator is provided to ensure suspension of salt in the tank.

This mother liquor and crystals are fed to continuous type pusher centrifuge, after pusher centrifuge dry salts are collected and mother liquor is recycled back to Multieffect evaporation system for further concentration. Distillate recovered from the process is suitable for reuse depending on the feed properties.

Chilling Crystallizers :

This is a selective type of crystallizer in which liquid effluent is concentrated up to certain required concentration and then fed to thickener. This thickener is equipped with jacketed chilling system, as solubility of salt decreases with decrease in temperature. As temperature decreases, salt crystallizes.


Advantages :

Continuous operation
Best suitable for mixture of crystalline salts
lower operating cost

Agitated Thin Film Dryer

Agitated thin film dryers are used for continuous drying of heat sensitive products with total solvent recovery. This is ideal for drying pharmaceuticals, bulk drugs and intermediates, organic and inorganic salts. 

Agitated Thin Film Dryer (ATFD) is the final stage equipment in Zero Liquid Discharge plant. Concentrated liquid is spread over the wall of jacket vessel to form thin film. Due to film technology high heat transfer coefficient is achieved and liquid gets evaporated. Powered product is collected from the bottom of the ATFD.

Scrapping blades are provided to scrap the powder from wall of jacket to keep surface area ready for new film evaporation. Evaporated vapors are condensed in separate condenser for solvent recovery.

Spray Dryer

Spray drying is a method of producing a dry powder from a liquid or slurry by rapidly drying with a hot gas. This is the preferred method of drying of many thermally-sensitive materials such as foods and pharmaceuticals. Spray Dryer takes a liquid stream and separates the solute or suspension as a solid and the solvent into a vapor. The solid is usually collected in a drum or cyclone. The liquid input stream is sprayed through a nozzle into a hot vapor stream and vaporized. 

Solids form as moisture quickly leaves the droplets. A nozzle is usually used to make the droplets as small as possible.

Applications of Spray Dryers

• Food and Beverages: Production of milk powder, coffee, tea.
• Pharmaceutical: Antibiotics, medical Ingredients.
• Industrial : paints, ceramic materials

Advantage :

• Effective for viscous, fibrous and crystalline products
• High heat transfer rates due to film boiling
• Compact design
• Complete solvent recovery
• Easy for maintenance
• Final product in complete dried form

Recycle & Reuse

Praj is helping to meet the demand with the basket of proven technologies, innovations and years of experience in treating most difficult effluent.

Praj’s Recycle and Reuse solutions integrate physico-chemical, biological and membrane separation process for efficient Recycle and Reuse. Solutions include advanced effluent treatment processes like Micro filtration, Ultra filtration, Nano filtration, Reverse Osmosis systems and Membrane Bioreactors. 

ECOBRANE-SB/XT

• ECOBRANE is membrane Bioreactor with submerged and external configurations.

Advantages :

• Higher Mix Liquor Suspended Solids (MLSS) up to 25 g/L is maintained.
• Higher organic removal efficiencies
• 66-75% reduction in footprint as compared to conventional systems.
• Safe, Easy and Economical Cleaning
• Low membrane fouling and less waste sludge production.
• Modular in design and construction
• Minimum Civil Work 
•  

Waste To Energy

Waste-to-energy or energy-from-waste is the process of creating energy in the form of electricity or heat from the incineration of waste source such as effluent with higher COD and BOD. Praj has developed various Waste - to - Energy conversion processes and can offer customized solutions.

Advantage Praj :

• ECOMET-XT/SB gives high Biogas yield from wastewater.
• Biogas is cleaned for reduction in content with advanced biochemical scrubber and elemental sulphur is recovered as a byproduct.
• High energy efficient Biogas engine generates 1.8-2.2 KWH electricity per m3 of Biogas fed.