Advanced Treatment Of Compound Glutinous Sauce-flavor Liquor Wastewater By Microbubble Ozone Heterogeneous Catalytic Oxidation Process

The wastewater from compound glutinous sauce-flavor liquor production is different from the conventional brewing wastewater.It contains a large number of lignin decomposition products,tannins,humic acids and other refractory complex pollutants.After traditional"anaerobic+aerobic"biological treatment,the COD and chromaticity cannot meet the standards,so we must carry out the deep treatment.Microbubble ozone heterogeneous catalytic oxidation technology has received extensive attention and research in the field of advanced wastewater treatment due to its efficient mass transfer and good catalytic activity.In this study,the microbubble ozone heterogeneous catalytic oxidation process was used to conduct advanced treatment experiments on the biochemical effluent of compound glutinous sauce-flavor liquor wastewater.Preparation and screening of supported catalysts with good performance and exploring the best conditions of ozone oxidation for the treatment of wastewater from compound glutinous flavor liquor production by ozone catalyst.The stability of the microbubble ozone heterogeneous catalytic oxidation process was further investigated through continuous experiments.The main conclusions of this study are as follows:（1）The preparation and performance of supported catalysts were studied:using spherical activated carbon（AC）as a carrier,supported catalysts containing Fe,Mn,Zn,Co,Cu,Ce different transition metal elements were prepared.The results showed that activated carbon supported copper（Cu/AC）had the best catalytic removal effect,and the removal rates of COD and UV₂₅₄ were increased by 20.92%and 4.39%,respectively,compared with ozone alone under the same conditions.The stability analysis of Cu/AC catalyst shows that Cu/AC has relatively good stability and good practical value.The performance of Cu/AC was characterized by BET,SEM,XRD,EDS,XPS and FTIR,and the physicochemical properties such as specific surface area,surface morphology,crystal phase structure,element composition and surface functional groups of the supported Cu/AC catalyst were determined.（2）The operating conditions of microbubble O₃+Cu/AC process were studied:the influencing factors of microbubble O₃+Cu/AC were studied.It was found that the removal rates of COD and UV₂₅₄ first increased and then tended to be flat with the increase of Cu/AC dosage,reaction time and ozone dosage.With the increase of the initial p H,it first increased and then decreased slightly,and the ozone concentration had little effect on it.The response surface analysis showed that the significant order of the influence of each factor on the microbubble O₃+Cu/AC process was Cu/AC dosage>ozone dosage>initial p H>reaction time.The optimal process conditions for calculating the COD removal rate by the regression model were as follows:the dosage of Cu/AC was 24 g/L,the initial p H was 7.9,the dosage of ozone was 900 mg/L,and the reaction time was 80 min.（3）The continuous operation performance of the microbubble O₃+Cu/AC process was studied:under the optimal conditions,the microbubble O₃+Cu/AC process continued to operate,the average concentration of COD and UV₂₅₄ in the influent was190 mg/L and 2.3 cm^-1,the average concentration of COD and UV₂₅₄ in the effluent was 45 mg/L and 0.19 cm^-1,and the average removal rate was 76%and 92%,and the effluent chromaticity is≤10 times,the removal rate is over 95%.Through the detection of other conventional pollution indicators,the TN of the inlet and outlet water has little change,the NH₄⁺-N has decreased,and the p H of the effluent water has increased.After oxidation,the redox potential ORP increased significantly,and the reactor presented an oxidizing environment.The characterization analysis of Cu/AC before and after use showed that the main elements composition of the catalyst did not change after use,part of the copper element was lost,and the oxygen element was increased compared with the previous one.The prepared Cu/AC catalyst had higher stability and impact resistance.（4）The analysis of the water quality of the influent and effluent under stable conditions shows that the biochemical effluent of compound glutinous sauce-flavor liquor wastewater contains macromolecular refractory organics such as humic acids and polycyclic aromatic hydrocarbons,and the biodegradability is poor.Microbubble O₃+Cu/AC treatment can destroy Stable Structures of humic acids and polycyclic aromatic hydrocarbons compounds,most organic matter and chromogenic groups are effectively removed,and the biodegradability of wastewater is significantly improved.Subsequent use of ozone and biochemical technology can be used for further treatment.When the hydroxyl radical quencher tert-butanol was added to the heterogeneous ozone catalytic system,the removal of COD was first unchanged and then significantly inhibited.The oxidation ability of microbubble O₃+Cu/AC came from the direct oxidation of O₃ and the indirect oxidation of·OH.