Investigation On Treatment And Recycling Of Nickel Plating Rinse Wastewater

In this paper the technology of ion exchange was used for the treatment and recycling of nickel plating rinse wastewater. This study includes three parts: removing the organic contaminations in rinse wastewater by oxidation processes, studying some factors influencing the ion exchange process, researching the treatment and recycling project of nickel plating rinse wastewater.The experimental results of wastewater pretreatment showed that: hi the ozone oxidization experiment, the COD removal efficiency increased with higher pH, more added ozone, and higher temperature, while it declined with the increasing initial COD. According to the mechanism analysis, the degradation of organic contamination was partly resulted by highly active oxidants which were the product of nickel catalytic decomposition of ozone. In the hydrogen peroxide oxidization experiment, the COD removal efficiency increased with more added hydrogen peroxide and oxygen mixing, but the COD removal efficiency was low. hi the O3/H2O2 oxidization experiment, the COD removal efficiency was affected by initial COD, as well as the wastage of ozone and hydrogen peroxide. The ozone oxidization and O3/H2O2 oxidization process could get high COD removal efficiency for nickel plating rinse wastewater of different COD, and O3/H2O2 oxidization process was the best.The experimental results of rinse wastewater treatment with ion exchange showed that: It was necessary to find proper method of ion exchange resin pretreatment to ensure the quality of recycling water. The operating exchange capability of cation ion resin and the quality of treated water were affected by pH value, Ni2+ concentration, flow velocity and hardness of the rinse water. The proper operational parameter were unadjusted pH, Ni2+ concentration lower than 300mg/L, flow velocity lower than 20m/h and using soft water as rinse water. The operating exchange capability of anion resin increased with higher SO₄²- concentration and lower flow velocity, while it declined with higher concentration of carbon dioxide in rinse wastewater and was affected by organic contamination in the rinse wastewater. More wastage of regeneration reagent and lower flow velocity was good for resin regeneration, In the continuous experiment using real nickel plating rinse wastewater, the treated wastewater reaching desalted water level could be reused as rinse water, and the regenerated nickel sulfate could also be recycled somewhere. The operating exchange capabilities of the resins were declined but steady after some times of regeneration.The research of real project showed that: 90% of rinse wastewater could be reused through ion exchange process. Through continuous water quality detecting, it was sure that the treated wastewater could be recycled to the nickel-plating plant. The main problems during the project running were that some calcium sulfate formed while the D001 cation resin was regenerated and part of D201 anion resin was polluted by organic contamination in the rinse wastewater of nickel plating, so some effective action should be taken to solve those problems.