Advanced Treatment Of Secondary Effluent Of Cephalosporin Synthesis Wastewater By Electrochemical Oxidation

In this study, advanced treatment of secondary effluent of cephalosporin synthesisprocessing by electrochemical oxidation was studied. The electrochemical properties ofgraphite electrode and DSA electrode electrochemical were emphasized on to determinethe optimum anode and process control parameters. On this basis, the electrochemicalperformance with self-control C/PTFE electrode, graphite felt electrode and modifygraphite felt electrode combination were investigated, to determine the optimum electrodecomposition and process control parameters. The results of this study will providetechnical support for cephalosporin wastewater treatment. The main conclusions of thisstudy were as following:(1) The graphite electrode and two kinds of DSA electrode (ruthenium-coatedtitanium electrode and titanium-coated iridium ruthenium electrode) were selected asanode, and the graphite electrode was selected as cathode in this electrochemical oxidationtest. The results showed that it was best to choose the titanium-coated iridium rutheniumelectrode as anode. When current density was0.1A/cm2, electrodes span was2cm,concentration of electrolyte (Na2SO4) was0.4mol/L and the initial pH of the wastewaterwas no changing, the COD concentration of the influent was reduced from259.49mg/L to119.25mg/L by electrochemical oxidized for60min. In this case, the current efficiencywas18.79%, the energy was233.67kWh/kgCOD. And the index of the final effluent canmeet the standards of “Water Pollutants for Pharmaceutical Industry Chemical SynthesisProducts Category”(GB21904-2008). The electrochemical oxidation degradation processof COD was approximate complied with the first-order kinetics equation: ln(c0/ct)=0.0147t-0.0462(R2=0.9931).(2) Electrochemical oxidation of secondary effluent of cephalosporin wastewater wasinvestigated in this study using the titanium-coated iridium ruthenium electrode as anode,the self-control C/PTFE electrode and the graphite felt electrode as cathode. The resultsshow that the graphite felt electrode is better than the self-control C/PTFE electrode.When the combination of the titanium-coated iridium ruthenium anode and graphite feltcathode were selected current density was0.06A/cm2, electrodes span was3cm, theconcentration of electrolyte (Na2SO4) was0.3mol/L and the initial pH of the wastewaterwas no changing, the COD concentration of the influent was reduced from263.15mg/L to 117.91mg/L by electrochemical oxidized for60min. In this case, the COD removal ratewas over55%, the current efficiency was over32%, and the energy was72.29kWh/kgCOD. The effluent can meet the emission standard. The electrochemical oxidationdegradation process of COD was approximate complied with the first-order kineticsequation: ln(c0/ct)=0.0171t-0.0462(R2=0.9854).(3) Electrochemical oxidation of secondary effluent of cephalosporin wastewater wasinvestigated in this study using the titanium-coated iridium ruthenium electrode as anode.The graphite felt electrode was modified with anthraquinone and2-ethyl anthraquinone.The results showed that the electrochemical oxidation effect of2-ethyl anthraquinonemodified electrodes was better than that with anthraquinone modified electrodes andgraphite felt electrodes. When current density was0.06A/cm2, electrodes span was4cm,concentration of electrolyte (Na2SO4) was0.2mol/L and the initial pH of the wastewaterwas no changing, the COD concentration of the influent was reduced from263.152mg/Lto117.62mg/L by electrochemical oxidized for60min. In this case, the COD removal ratewas over55%, the current efficiency was over32%, and the energy was51.54kWh/kgCOD. The effluent can meet the emission standard. The electrochemicaloxidation degradation process of COD was approximate complied with the first-orderkinetics equation: ln(c0/ct)=0.0166t-0.1284(R2=0.9769).(4) By comparing the electrochemical properties of different electrode combinations,and referring to the standard (COD<120mg/L), the titanium-coated iridium rutheniumanode and the graphite felt cathode modified by2-ethyl anthraquinone was identified asthe best electrode combination. The current efficiency had no significantly improved,while the energy consumption was greatly reduced, which was only51.54kWh/kgCOD.The cost is about5.15RMB/m3.