Rinse water Recovery System-METAPure for recovery and reuse of electroplating rinse water. Pure Tech India, A-5, Trec step, Thuvakudi, Trichy -620 015 Telephone:00 91-431 320 6753; Telefax: 00 91-431 250 1100 E-Mail: contact@puretechindia.com; website: www.puretechindia.com

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)

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.

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.

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

Membrane Systems An Overview

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.

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

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.

Finest form of filtration Reverse Osmosis: Finest form of filtration

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.

Typical Reverse Osmosis Membranes:

Reverse Osmosis Process flow diagram:

RO membrane structure:

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)

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

Membrane based Rinse water recovery systems

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

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

Low flow membrane systems:

High flow membrane systems:

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

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

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

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.

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