1. Submitted To ASLIHAN KERÇ ENVE 420

4.  Galvanized steel has gone through a chemical process to keep it from corroding  The principal method of making steel resist corrosion is by alloying it with another metal . For countless outdoor, marine, or industrial applications, galvanized steel is an essential fabrication component

5. Any or all of the substances used in plating, can be found in ww either via rinsing of the prodeuctor from pillage and pumping of process baths. o Acidic solutions o Toxic metals o Solvents o Cynanides etc  Effluent contains a large number of metals, including chromium, copper, nickel, zinc,manganese and lead

6.  The term heavy metal refers to any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations.  Heayvy metals cannot be degraded or destroyed. As trace elements, some heavy metals (e.g. Copper,selenium,zinc)are essential to maintain the metabolism of the human body.  @higher concentrations they can lead to poisoning  Heavy metals are dangerous because they are taken up in a biological organism and stored faster than they are broken down

9. This industrial estate contains many plating industries: o Metal or plastic plating&galvanizing industries o Chemical preparation industries for plating industries. Different plating materials are used: o Nickel o Zinc o Copper etc.

10. o ARSAL METAL KAPLAMA SANAY İ nickel, chrominum, silver, gold plating o BAK-TAM METAL KAPLAMA SAN. ve T İ C. zinc galvanizing o AYTAŞ K İ MYA SAN. ve T İ C.LTD.ŞT İ. metal plating raw material sale – laboratory & technical information services

11. The galvanizing process consists of three elements: 1.Surface Preparation 2.Galvanizing 3.Inspection

12.  Surface preparation is the most important step in the application of any coating  In most cases where a coating fails before the expected service life, it is due to incorrect or inadequate surface preparation

13. Degreasing(Caustic Cleaning): Materials are sinked in a hot caustic solution to remove oil, grease, dirt, paints. Rinsing: The material is then rinsed in water. Acid Pickling Materials are sinked in dilute Hydrochloric acid (HCI) solution to remove rust and any other surface contaminants. Rinsing The materials are rinsed in water to remove excess acid and iron salts.

14. Fluxing The materials are then sinked in zinc-ammonium chloride solution. This step is performed to remove any remaining impurities, moisture or oxides from the steel and to obtain the metal's surface is chemically clean and ready for galvanizing. Drying Deck After the material is removed from the flux solution, the work is hot-dried before entering the molten zinc.

15.  The material is then sinked in high grad pure molten zinc here it will react to form a series of zinc-iron alloy layers

16.  The material is sinked in a quenching solution. It is performed to minimize the formation of dark, gray coatings by stopping the galvanizing reaction  The material is then dipped in a Sodium Dichromate solution to prevent the formation of white rust QuenchingPassivation

17. The two properties are controlled after galvanizing: coating thickness and coating appearance. Finishing o Materials are weighed, the coating thickness, uniformity and adherence are tested for compliance with standards, and the surface quality of the material is visually inspected. If necessary, the material is cleaned to remove excess zinc drips. Shipping o The material is identified and checked off against the customer's paperwork and then prepared and packaged. So,the products are galvanized according to required standards

20.  Wastewater comes from several plating industries to collection system of wastewater treatment plant with PVC pipes by gravity  Wastewater is collected in a distribution chamber and pumped to neutralization tank by rotary pump

21.  pH control is done by a pH sensor, if needed, H 2 SO 4 is added automatically to reduce the pH about 2.5 Acidic range of pH is needed for conversion: Cr 6+ + Fe 2+ + H +  Cr 3+ + Fe 3+  After pH adjustment, water flows to 3 serial circular aeration tanks: o Volume of each tanks is 180 m 3 o Air is supplied by the nozzles o Cr +6 is reduced to Cr +3, at this time aeration is stopped and precipitation occurs  This sludge is pumped to a tank where the lime addition is done for pH adjustment, and the sludge flows to the sludge disposal unit.

24.  Water flows to a “control tank”,sodium metabisulfite(Na 2 S 2 O 7 ) is added 2K 2 Cr 2 O 7 + 3Na 2 S 2 O 7 + 5H 2 SO 4  2K 2 SO 4 + 2Na 2 SO 4 + 2Cr 2 (SO 4 ) 3 + 5H 2 SO 4  Water flows to the “process tank” from the control tanks. In the process tank pH adjustment is done by the addition of lime. pH 6.5 – 7 is needed to produce sodium salts

25. In process tank, polyelectrolyte is added. So, the precipitation occurs.  Supernatant of the solution is sent o chemical treatment by gravity  Precipitaed sludge is pumped to sludge treatment unit

26.  For the removing of the CN -, NaOCl is added in to chemical tank CN - + NaOCI  CNO - + NaCl  Since an alkaline solution (pH 11.0) of sodium hypochlorite is used to treat dilute cyanide wastewater, lime is added if needed.There are pH sensors in this  Finally, polyelectrolyte is added again.

28.  In filter press, the sludge cake is dewatered up to 35-40%  While heating up 1200 oC, sludge gets rid of toxic materials and becomes inert  Output material is collected and collected by ISTAÇ  The only problem in output material is sulfate

30.  Separation of the mass from the gaseous phase to liquid phase (absorption)  There are absorptive material  inside of the scrubber  Washing solution  spread upward  Polluted gas  spread downward  Reaction between them and absorption is made

33. Total chrominum NickelIronCopperSulfateChlorine Ion Zinc 150 mg/L200mg/L300mg/L150mg/L3.5 g/L4 g/L250g/L Table -1

34. Table -3  Treatment of inffluent parameters are mostly achieved  Since problem occurs in copper and nickel, these parameters are contolled at every two hour by laboratory experiments  Table- 2 indicates results of laboratory experiments of 30/12/2009  Effluent parameters are suitable to İ SK İ ’s dicharge standards galvano teknik effluents CopperNickel 0.9 mg/L1.61mg/L İ SK İ ’s dicharge standards CopperNickel 2 mg/L5mg/L Table -2

36.  Chemical Precipitation  Filtration conventional(mono or multi-media) filtration or membrane filtration (microfiltration and ultrafiltration).  Fixed Bed Adsorption  Fluidized Bed Adsorption  Adsorption on a Continously Regenerated Active Surface;

37.  A mixed plating rinse wastewater containing zinc, hexavalent chromium, trivalent chromium, and cyanide with total dissolved solids of 424 mg/1 was treated by a model consisting of a sand filter and ion exchange columns.  A strongly acidic cation resin in hydrogen form and a strongly basic anion resin in hydroxide form were used in the columns as cationic and anionic exchangers, respectively.

38.  A 100% removal of zinc, total chromium, hexavalent chromium and trivalent chromium was achieved  Very high removal of total dissolved solids, cyanide and hardness level was achieved at 98.9%, 99.9% and 96.5%, respectively  The case study has shown that treatment systems using cationic and anionic resin were able to treat a mixed plating bath effluent to comply with the standard discharge

40.  Heavy metals are non-renewable resources. Therefore, effective recovery of heavy metals is as important as removal of them from waste streams.  Also reuse is an important issue since metal plating is highly water consuming process.

41.  Altough effluent parameters of wastewater from Galvona Teknik Industrial estate is suitable to ISKI’s wastewater discharge standards, some other tecniques could be used  Recovery of heavy metals in an important issue in plating industry  Using treated ww in rinsing process also can be useful

42.  Sludge treatment in Galvano Teknik Industrial Estate is an advanced process  But nowadays sulfate amount is detected high in solid product and studies in this issue continues  After decreasing the sulfate amount, product also can be reused

43. C inf of Ni = 200 mg/L C eff of Ni = 1.61 mg/L Flowrate = 50 m 3 /hr = 0.014 m 3 /sec (200 mg/L) * (0.014 m 3 /sec) = 2.7 gr/sec (loading rate for Ni) Ni 2+ + Ca(OH) 2 Ni(OH) 2 + Ca 2+ Lime Consumption Rate; (2.7gr Ni / sec) * (74 gr Ca(OH) 2 / 28 gr Ni) = 7.14 gr Ca(OH) 2 /sec Sludge Production Rate; (2.7gr Ni / sec) * (62 gr Ni(OH) 2 / 28 gr Ni) = 5.97 ≈ 6 gr Ni(OH) 2 /sec