Experimental Study On Treatment Of Phenol Wastewater By Electrolysis-A/O-DMBR

Phenol-containing wastewater mainly from coking plants,gas plants,oil refineries,printing and dyeing industry,pharmaceutical and chemical enterprises,among which typical pollutants are quinoline,indole,phenol and phenol homologues,this kind of wastewater becomes emphasis and difficulty in the study of wastewater treatment technology because of high toxic and difficult to deal with by biochemical means.At present,China is in the period of rapid economic development,and the problems of industrial wastewater pollution are becoming more and more serious.Therefore,it is urgent to put forward practical treatment methods for such wastewater.As a kind of high advanced oxidation technology,electrolysis has many characteristics,such as high efficiency,low pollution,strong oxidation,simple operation,small footprint,no secondary pollution,etc,which has an important position in the field of wastewater treatment;dynamic membrane bioreactor?DMBR?,as a new type of urban sewage treatment technology,not only has the advantages of traditional membrane bioreactor?MBR?,good treatment effect,low sludge production rate,but also has high filtration flux and backwashing more convenient,which makes it become a potential substitute for the traditional technology.In this paper,the electrolysis-A/O-DMBR coupling process is used to treat the phenol-containing wastewater,mainly to explore the effect of the coupling process on the pollution removal effect and internal relationships between the characteristics of the sludge mixture and the membrane pollution,which to find a kind of wastewater treatment method of high efficiency,low pollution,with a view to the field of toxic and hazardous wastewater treatment to provide a scientific basis and theoretical basis.In this study,the research object is artificial disposition of phenol wastewater,The ultimate tolerance concentration of influent phenol and the optimum process parameters were main investigated in the A/O-DMBR process,hydraulic retention time?HRT?,reflux ratio?R?and dissolved oxygen?DO?were selected as exploratory factors.The results showed that the ultimate tolerance concentration of A/O-DMBR system to phenol was110mg/L;and the optimum technological parameters were as follows:hydraulic retention time was 24h,reflux ratio was 200%,and dissolved oxygen was 3mg/L.Referring to a large number of literatures about phenol-containing wastewater treatment,the electrolysis method is regarded as the pretreatment method of wastewater.Using the single factor experiment investigate the initial pH,voltage,electrode spacing,electrolyte concentration and initial concentration of phenol and other factors on the influence of the pretreatment effect;on this basis,using response surface analysis method?RSM?to optimize the factors and determine the degree of influence of relative size;under the optimum process parameter on the basis of further exploration of different water dynamics the concentration of phenol degradation model.The experimental results showed that the contribution of electrolytic factors to phenol removal rate was:voltage>electrolyte concentration>plate spacing>initial pH>initial concentration;voltage and initial concentration,electrolyte concentration and the initial concentration was highly significant for phenol removal?P<0.01?.Optimum electrolytic parameters was:the initial pH is 6.56,the voltage is 24.93V,the plate spacing is 20.05mm,the concentration of electrolyte is 2.46g/L and the initial concentration is 368.87mg/L,the effluent phenol concentration is 10.84mg/L,and experimental verification value is 17.89mg/L.Under the optimum parameters,the concentrations of 100mg/L,200mg/L,300mg/L,400mg/L and500mg/L phenol were respectively treated by electrolysis,the results showed that the electrolysis process with five concentration gradients met the first order reaction kinetic model.Under the optimum technological conditions,studying electrolytic-A/O-DMBR coupling process on the pollution removal effect and internal relationships between sludge mixing characteristics and membrane fouling resistance.The results show that the coupling process has good effects on the treatment of phenol,COD,TP,ammonia nitrogen and total nitrogen.The removal rates are 100%,98%,89%,92.5%and 86%respectively.Through correlation analysis found that there are relationships between the sludge concentration?MLSS?,sludge viscosity,relative hydrophobicity?RH?,soluble microbial products?SMP?and membrane fouling resistance?R_f?,various influencing factors on the contribution rate of R_f order is:MLSS>SMP>viscosity=RH.Among them,MLSS has a strong correlation with sludge viscosity?r_p=0.788?.Experiments show that controlling MLSS within 6g/L can not only reduce sludge viscosity,but also delay the operation cycle of the process.By using three-dimensional fluorescence spectroscopy?EEM?technique,it was found that SMP components were mainly composed of humic acid,fulvic acid and protein,it could be seen that most of the proteins are entrapped in the membrane pool as macromolecules compared with SMP fraction in the membrane tank and effluent,and the correlation coefficient between protein content and R_f is 0.723,it could further proof that:protein is one of the important reasons of membrane fouling.By measuring the content of polysaccharide in SMP,it was found that polysaccharide,as the main provider of hydrophilic group,is closely related to RH,and two of them are important reasons for the decrease of membrane flux.The model of membrane fouling resistance was obtained by multiple linear regression analysis:R_f(×10¹¹)=0.855+0.244MLSS+0.588 Viscosity-0.004RH+0.008SMP...