| With the rapid development of the pharmaceutical industry,environmental pollution caused by the wastewater discharged in it's process of production has increasingly drawn people's attention.According to the environmental protection department of China,pharmaceutical industry is one of the 12 industries which are needed to be treated seriously,due to characteristics of pharmaceutical wastewater,such as low biodegradability,strong toxicity,and high pollutant concentration.Traditional biological treatment process has been unable to meet the requirements of the new standard"Standard for Discharge of Water Pollutants from Pharmaceutical Industry"which was promulgated by Chinese government in 2008.Based on the comprehensive analysis of vitamin C production process and its pollution node,a combinedprocessof“Fe/Cmicro-electrolysis/flocculation-ABR/MBR-Photocatalysis/MF”was choosed to deal with wastewater of vitamin C production in this paper,for realizing the standard emission and reuse of it,which has great significance.Spectrophotometric method based on theory of complementary color has been raised to mensurate chromaticity of industrial wastewater,and has compensated the shortcomings of dilution method.Spectrophotometric method does not need the expensive chromaticity standard solution,and partly removes effects of human factors on result of chromaticity mensuration.It shows same results as Dilution method but more repeatability and stability.Against the influence of high concentration of chloride ion in wastewater of vitamin C on COD determination,Ag2SO4 replaced by MnSO4 as a catalyst,a novel COD determination method was presented for wastewater with high chloride ion by method of Cl-COD standard curve,in which a sealed digestion method was used,and no using of heavy metal such as Ag and Hg.After validation,using vitamin C wastewater as a sample,there is no significant difference between this method and the national standard method.So the method can be used to determine COD of industrial wastewater with high chloride and low COD.Vitamin C wastewater was pretreated ferric-carbon micro-electrolysis flocculation method,and the influence of time,pH,ferric-carbon ratio,aeration amount,so1lid-liquid ratio and other factors on removal of COD of wastewater were investigated;On the basis of single factor experiment,the mathematical model of the ferric-carbon micro-electrolysis process was established,aiming at the COD removal rate by response surface method.The main effects and interaction effects of the reaction time,pH,ferric-carbon ratio,aeration amount,solid-liquid ratio and other factors on the objective function of the model were determined,through variance analysis and significance test and model pictorial diagram.Based on response surface model,the optimized conditions in the ferric-carbon micro-electrolysis process were obtained as follows:reaction time 96.6 min,pH3.12,solid-liquid ratio 0.57,iron/carbon ratio 1.27and aeration rates 63.18 L/h.Under these conditions,the predicted values of removal rate of the system to COD were separately 34.58%and 58.34%before and after flocculation,which were consistent with the experimental values?33.67%and 59.14%?.After ferric-carbon micro-electrolysis treatment,BOD5/COD=0.37,which indicate the biochemical ability of wastewater have improved greatly.Flocculation played an important role in treating of the wastewater of vitamin C by ferric-carbon micro-electrolysis method,COD removal rate caused by the flocculation accounted for 43.1%of the total.ABR-MBR process was used to make biological treatment for the effluent pretreated by ferric-carbon micro-electrolysis,in which a ceramic membrane was used.After five stages of the anaerobic cultivation and domestication of sludge in 80 d,the ABR reactor was started successfully,and the optimum HRT of ABR obtained was 24h.After a 30d aerobic cultivation and domestication of sludge,the MBR reactor was started successfully,HRT had great impact on the removal rate of the system to COD and ammonium of MBR,but small effect on TN,and the optimum HRT of MBR obtained was 12h.The kinetic analyses of the wastewater treatment by MBR using Monod model were discussed and the relevant kinetic parameters were determined as follow:Y=0.366 gVSS/gCOD,Kd=0.0169 d-1,Vmax=0.766 gCOD/?gVSS·d?,Ks=266.09 mgCOD/L.The result of kinetic analysis showed that MBR was suitable for treating high substrate concentration wastewater of vitamin C.By ABR-MBR experiment,the influence of reflux ratio on the system operation process was investigated.After the treatment by ABR-MBR,the effluent COD 84.07 mg/L and TN22.75 mg/L were all reached the national discharge standards.But the effluent color was still high,which did not meet the emissions standards.No significant membrane fouling phenomenon occurred during operation,the transmembrane pressure was maintained at about 34 KPa,which indicated ceramic membrane has a strong anti-pollution ability.The combination technique of photocatalysis/MF was used for advanced treatment of the effluent after biological treatment,the effects of reaction time,catalyst amount,aeration amount,pH and other factors on treatment efficiency had been investigated;In a certain range,chrominance and COD removal rate increased with the increase of reaction time and catalyst dosage respectively;Aeration had less effect on the treatment efficiency,treatment effect under acidic condition was better than that under alkaline condition.The results of orthogonal experiment showed that the reaction time and the amount of catalyst were the main influence factors,pH and aeration rate of have less effect on chrominance and COD removal rate.The adsorption of TiO2 on pollutant accords with Langmuir adsorption isotherm,but the adsorption capacity is small,the qmax=16.75 mg/g,the adsorption equilibrium constant KL=0.022,the adsorption process played an important role on the reaction rate.The photocatalytic reaction accorded with the apparent second order reaction,through the analysis of L-H model,the COD value had less effect on the initial reaction rate.Continuous experiment result showed that the integrated photocatalysis-MF combination process had pretty good decolorizing effect,the effluent of biological treatment after deep treatment reached discharge standard and water recycling requirements?GB/T 19923-2005?. |
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