Study On Three-stage Combined Treatment Of Pharmaceutical Wastewater By Catalytic Wet Air Oxidation-photocatalysis-adsorption

This paper takes cephalosporin antibiotic production wastewater of Yancheng Kaiyuan Pharmaceutical Chemical Co.,Ltd.as the research object,and studies a set of three-stage combined treatment process based on catalytic wet air oxidation technology,photocatalysis technology and adsorption technology.Firstly,this study prepared a Mo-Na catalyst with good catalytic activity and confirmed its catalytic wet oxidation effect.Secondly,this study prepared a magnetic,easily separated BiVO₄@MS photocatalyst and confirmed its photocatalytic activity.Thirdly,in this study,the phosphorus-adsorbing material AC@FA,which is easy to settle,was prepared and its adsorption process for phosphorus was studied.Finally,based on the Mo-Na catalytic wet air oxidation catalyst,BiVO₄@MS photocatalyst and AC@FA phosphorus adsorption material,the three stages of"catalytic wet air oxidation-photocatalysis-adsorption"that can effectively treat actual cephalosporin antibiotic production wastewater.With the combined treatment process,the water quality index after wastewater treatment can stably reach the takeover standard of the local chemical park.In view of the fact that the COD and TOC of cephalosporin antibiotic production wastewater are up to about 8000 mg/L,a Mo-Na catalyst material with obvious catalytic wet oxidation activity was prepared.The results of material characterization show that the Mo-Na composite catalyst has a large specific surface area.The micro-morphology of the catalyst presents a crystalline rod-like morphology,the micro-length is about 0.5-1.0?m,and the micro-width and thickness is about 0.1?m.The catalyst material is mainly composed of Na₄Mo₈O₂₆·12H₂O and Na_0.9Mo O₃H_0.85 mineral phases.The catalyst has good thermal stability.The preliminary catalytic wet oxidation experiment results show that:when the dosage of Mo-Na composite catalyst is 3g/L,the reaction temperature is 190?,the oxygen partial pressure is 1.6 Mpa,and the reaction time is1.8 h,the catalytic wet oxidation of wastewater TOC and The residual rate of COD removal can reach 11.97%and 16.99%.Due to the problem that the COD and TOC in the wastewater after the catalytic wet air oxidation effluent still cannot meet the takeover standard,the BiVO₄@MS photocatalyst materials with good photocatalytic performance and magnetic properties were prepared.The results of material characterization show that the mineral phase of BiVO₄@MS material is mainly composed of monoclinic scheelite BiVO₄ and hematite,and contains a small amount of quartz and mullite.The microscopic morphology of BiVO₄@MS material is spherical particles of about 50?m.The surface of the particles is wrapped by BiVO₄ particles.The BiVO₄ particles wrapped on the magnetic beads are about 100?500nm.BiVO₄@MS material has good magnetic properties and light absorption.The photocatalytic degradation test of methylene blue simulated wastewater shows that BiVO₄@MS photocatalyst material has good photocatalytic performance,and its photodegradation process can be used to meet the first-order kinetic degradation equation.Aiming at the problem that the phosphorus element in the photocatalyst effluent water still exceeds the standard,AC@FA phosphorus adsorption material that is easy to settle is prepared.The material characterization results show that the AC@FA material has a micro-morphology with irregular structure and micro-amorphous morphology,and its surface has a rich porous activated carbon channel structure.The specific surface area of AC@FA material is large,the mass loss at high temperature is small,and the thermal stability is good.The simulated phosphorus solution adsorption results show that:AC@FA material has good sedimentation performance,and its saturated adsorption capacity of phosphorus element can reach 8.38 mg/g.Lower temperature?about 20??and lower solution p H?3?7?are beneficial to the adsorption process.The adsorption process of phosphorus on AC@FA is more in line with the quasi-second-order kinetic equation and Langmuir isotherm model.Based on the Mo-Na catalytic wet oxidation catalyst,BiVO₄@MS photocatalyst and AC@FA phosphorus adsorption material,a three-stage combined treatment process"catalytic wet air oxidation-photocatalysis-adsorption"that can effectively treat the actual cephalosporin antibiotic production wastewater has been developed.The results of the catalytic wet air oxidation process show that the increase in reaction temperature,the increase in reaction time and the amount of catalyst added are beneficial to the degradation of wastewater COD and TOC.The degradation process of wastewater COD and TOC is more in line with the quasi-second order kinetic equation.The minimum residual rate of TOC and COD can reach 10.39%and 13.71%?reaction temperature190?,catalyst amount 1.5 g/L,reaction time 3 h?and the effect of catalyst reuse is not significantly reduced.The results of the photocatalytic process research show that:through the photocatalytic reaction process,COD,TOC and chroma in the wastewater can be further reduced.When the photocatalytic reaction reaches 60 minutes,the residual COD?459 mg/L?in the wastewater can be Reaching the takeover standard for wastewater discharge from local industrial parks,the degradation process can be fitted with a second-order kinetic equation.The research results of the phosphorus adsorption process show that the use of AC@FA material for static phosphorus adsorption operation can effectively reduce the phosphorus element content in the photocatalytic effluent.The dosage of AC@FC is 6 g/L,and the adsorption time should be 20 minutes.After treatment,the phosphorus element in the wastewater can be reduced to less than1mg/L.In short,based on suitable catalytic materials and adsorption materials,through the optimization of various process parameters,the"catalytic wet oxidation-photocatalysis-adsorption"three-stage combined treatment process can effectively treat cephalosporin antibiotic production wastewater.