1. Rinse water Recovery System-METAPure for recovery and reuse of electroplating rinse water.
Pure Tech India,
A-5, Trec step, Thuvakudi, Trichy
Telephone: ; Telefax:
website:

2. Electroplating processes and various chemicals used:
S. No
Plating process
Major chemicals used 1
Cadmium plating
Cadmium Oxide, Sodium Cyanide,
Sodium Hydroxide 2
Zinc plating
Zinc Oxide, Sodium Cyanide, Sodium Hydroxide 3
Copper plating
Copper Cyanide, Sodium Cyanide, Sodium Hydroxide 4
Nickel plating
Nickel Sulphate, Nickel Chloride, Boric Acid 5
Chromium plating
High speed self regulating salt (Chromium sulphate, Chromic Acid)

3. Important Contributors in a Electroplating Effluent Generation:
Component
Function
Effluent Contribution/Remarks
Plating Bath
Main component primarily responsible for plating. Contains bath chemicals.
Bath is not drained at all except for some unavoidable circumstances generally not seen.
Plating Rinse
Removes excess coating material.
Major contributor of effluent. Contains primarily bath chemicals with some environmental contaminants.
Acid Bath and Rinse
To clean materials of rust.
Bath and rinse becomes unusable after a particular period of operation. Main contaminants include rust material with some dust particles.
Alkali Bath and Rinse
To clean materials of rust preventive solutions, oil and grease for better plating efficiency.
Bath and rinse becomes unusable after a particular period of operation. Main contaminants include oil and grease, rust preventive solution.
Floor Washings
Spillovers from plating, rinse, acid and alkali tanks.
All effluents listed above in small quantities with water used for floor washing.

4. Treatment processes available:
Chemical treatment using
Sulphuric Acid (pH reduction for chromium conversion)
Sodium Bisulphite (used for converting hexavalent to trivalent Chromium)
Sodium Hypo (Cyanide Oxidation)
Lime/ Caustic (neutralization)
Polyelectrolyte (flocculation)
Clarification (solid- liquid separation) and
Solid sludge separation.
Membrane based physical/physiochemical processes.

5. Conventional Treatment:
Electroplating Effluent
Oxidation/ Reduction/ Neutralization *
Neutralization
Precipitation
Flocculation (Polyelectrolyte)
Waste water discharge
Clarification
Sludge Storage
* : NOTE
Cyanide waste: Oxidation
Chromium Waste: Reduction
Acid/Alkali Waste: Neutralization
Dewatering
Disposal

6. Membrane Systems
An Overview

7. Filtration: Types and Comparison
Normal Filtration Cross- flow Filtration
Normal Filtration: Water with contaminants pass in direction perpendicular to filter media. The contaminants will choke the pores of the filter media.
Cross- flow Filtration: Water with contaminants pass in direction parallel to the filter media. The Outlet from this filtration will have two streams coming out. The concentrate stream will carry along with it the contaminants. The filtered water will come out of a separate outlet. The frequency of filter media getting choked is very low when compared to normal filtration.

8. Cross- flow Membrane Processes:
Macromolecules
Sugar, DV Salts, DA
MV Salts, UA MF UF NF RO
Water
KEY:
SS Suspended solids
DV Salts - Divalent salts
DA Dissociated acids
MV Salts - Monovalent salts
UA Undissociated acids
Reject portion
Permeate portion
MF – Micro filtration
UF - Ultra filtration
NF – Nano Filtration
RO – Reverse Osmosis

9. Specific advantages of membrane based treatment systems:
Compact and less space occupying.
Marginal chemical consumption (needed in case of pH correction).
Skid mounted systems.
Very low sludge generation.
Very low electricity consumption.
Requires little/ no civil construction.
Separated water is ideally suitable for high quality rinse and bath top up.

10. Finest form of filtration
Reverse Osmosis:
Finest form of filtration

11. Osmosis - Reverse Osmosis Illustration:
Pressure P
Concentrate
Dilute
Concentrate
Dilute
Semi- Permeable Membrane
Semi- Permeable membrane is one which will allow only water molecules to pass and not salts.
In the Left diagram, under normal circumstances, water molecules from dilute solution side will permeate towards concentrate side to form an equilibrium.This is Osmosis and the pressure present is Osmostic pressure.
In the right diagram, when a pressure P is applied in excess to the normal pressure , water alone is squeezed into the dilute solution side from the concentrate solution side. This is Reverse- Osmosis.

12. Typical Reverse Osmosis Membranes:

13. Reverse Osmosis Process flow diagram:

14. RO membrane structure:

15. Separated components applications:
Permeate flow (usable/product water flow)
Rinse
Bath top up
Concentrate flow (Reject flow):-
Bath (if the concentrate contains only salts used in the electroplating bath with permissible contaminants)

16. Reverse Osmosis Membranes Rejection Rates:
Solute
Symbol
Molecular weight
Rejection (%)
Sodium Fluoride
NaF 42 99
Sodium Cyanide
NaCN (pH 11) 49 97
Sodium Chloride
NaCl 58
Silica
SiO2 (50 ppm) 60 98
Sodium Bi- Carbonate
NaHCo3 84
Sodium Nitrate
NaNo3 85
Magnesium Chloride
MgCl2 95
Calcium Chloride
CaCl2
111
Magnesium Sulphate
MgSo4
120
>99
Nickel Sulphate
NiSo4
155
Copper Sulphate
CuSo4
160

17. Membrane based Rinse water recovery systems

18. Major contaminants and their removal:
S .No
Contaminant
Removal Process 1.
pH Correction
Acid/ Alkali addition 2.
Suspended Solids
Stainless Steel Filter Strainer
Stainless Steel Bag Filter 3.
Microscopic oil particles
Activated Carbon Filter 4.
Coating Materials
IONICS unit using Reverse Osmosis
membranes

19. Process Flow Diagram RO based IONICS Unit Effluent from Filtration
electroplating
process
Filtration
System
Prep Tank
Pump
Acid/ Alkali
addition
Permeate tank
to process
RO based IONICS
Unit
High pressure
pump
Reject back
to bath/ treatment

20. Low flow membrane systems:

21. High flow membrane systems:

22. A Typical application in electroplating process:
Flow of parts
Stage 1
Stage 2
Stage 3
Stage 4
Spray-Dip-Spray
City Water Rinse
High Pressure Rinse
Chemical Cleaner
Phosphate Dip
Flow of parts
Stage 5
Stage 6
Stage 7
Stage 8
Stage 9
DI water
Spray-Dip-Spray
City Water Rinse
Spray-Dip-Spray
Water Rinse
Spray Water Rinse
Chromate Dip
Spray Rinse RO
TO WASTE TREATMENT

23. RO Process in Nickel Plating
evaporation
PLATE
RINSE # 1
RINSE # 2
parts
parts
feed RO
permeate
concentrate
95%
recovery
Make-up
(Pure water)

24. Benefits:
70% of rinse water can be recovered and reused for Bath Top up and as Rinse water.
Pollution Problem solved
The cost of treatment is got back to by way of water which can be reused for rinsing process.
Customers:
Silver Crown Electroplaters: 100 and 200 LPH
Divya Engineering : 10 LPH
Sundaram Fasteners Limited, Chennai: 200 LPH

25. Other Electroplating Process related Products:
Desorber: Oil water separator for Degreasing Baths.
OleoSepa: Desorber, Ultrafiltration System for complete oil removal and reuse of Degreasing solutions.
Bag Filtration System: For filtering suspended solids upto 1 microns for your plating baths. Filter media can be offered in Stainless Steel, Polypropylene and HDPE wire cloths. Complete unit can be fabricated in the above materials.
RO Plant: For removing Total Dissolved Solids in water used for bath and rinse for better efficiency of plating.

26. Thank You For Queries, Please contact:
E- Mail:
(Photographs shown are taken from our supplied equipments and there are feature additions taking place in each new equipment manufactured)