Flat-sheet Ceramic UF Membrane Process For Removal Of Heavy Metal Contaminants From Electro-Plating Wastewater

The removal efficiency of heavy metal contaminants from electroplating wastewater using flat-sheet ceramic membrane ultrafiltration process was studied in this thesis.Three kinds of salt ions and two additives were tested to evaluate the removal impact on five heavy metal ions in lab tested.The degradation parametaers regarding EDTA and critic acid complexes with heavy metal ions were optimized with Fenton Oxidation Process.In the pilot scale test,the stability and reliability of the ceramic membrane treatment were further verified so as to determine the best process parameters.The operation issues related with ceramic membrane ultrafiltration in Baifeng electroplating wastewater project were investigated in detail.Finally,a preliminary design was finished for an electroplating wastewater treatment project in Hansheng auto parts manufactory.It was found that the flux of ceramic membrane tested for the removal of Ni²⁺was80 L/?m²?h?under pH=10.5.While the removal efficiency with ceramic membrane ultrafiltration was slightly influenced by wastewater conductivity and salt ions like Ca²⁺,SO₄^2-,Cl^-,as well as additives like saccharin sodium,and SDS.Fenton Oxidation Process was very effective in breaking down EDTA and citric acid complexes to free heavy metal ions.The ceramic membrane is also effective in removing the mixed heavy metal ions including Ni²⁺?Cu²⁺?Zn²⁺?Cr³⁺and Cd²⁺,related membrane flux was 80 L/?m²?h?under pH=11.It was noticeable that the normalized TMP??TMP?increased by 30.1 kPa during 14 days ultrafiltration,which was caused by reversible fouling instead of irreversible fouling.The pilot scale test demonstrated that ceramic membrane flux was 40 L/?m²?h?with alkaline agent?NaOH?under pH=9.5,related flocs ranged from 2?m to 5?m.The turbidity of the effluent was below 0.1 NTU.The ceramic membrane could integrate process untis as mixing,sedimentation and filtration together into one untis without use of coagulant and flucculant chemicals in Baifeng electroplating wastewater project.Herein,the integrated process could provide better performance compared with the conventional process units.However,it was found that the ceramic membrane was not applicable under strong alkaline conditions.The research achievements in this thesis were applied to an upgrading project for the electroplating wastewater treatment in Hansheng Company.The capacity was400 m³/d,with 130 m³/d being reused and 270 m³/d being discharged.It is of great economic and environmental significance,ralted investment of the project was3,338,500 yuan,and the cost of sewage treatment was 14.06 yuan per tonne.