农药废水生物处理过程中溶解性有机物特性及荧光强度与COD的关系

摘要

Three-dimensional fluorescence spectrum was used to investigate fluorescence spectral characteristics of dis-solved organic matter(DOM)in organic pesticides wastewater under treatment,in an attempt to establish correlation be-tween DOM fluorescence intensity and COD concentration.The analysis shows that there are three fluorescence peaks in the three-dimensional fluorescence spectrum.They are Peak A in the visible light zone reflecting the existence of fulvic acid,Peak B in the UV light zone reflecting the existence of fulvic acid and Peak C in the high excitation wavelength zone reflecting the existence of tryptophan.The fulvic acid with fluorescence in the visible light and UV light zones was degraded into more biodegradable tryptophan with fluorescence in the high excitation wavelength zone after the wastewater went through the air floatation tank,hydrolysis acidification tank and anaerobic fluidized bed.After going through the contact ox-idation tank,the 3 types of DOM in the wastewater declined in fluorescence intensity as a result of biodegradation.Among the three,tryptophan degraded more quickly than fulvic acid.Of the four indices of DOM,fluorescence index(IF)and bi-ogenesis index(XBI)reflect that the DOM in the wastewater comes mainly from extraneous sources,and fluorescence in-tensity ratio of fulvic acid in ultraviolet and visible region(rB/A)and humification index(XHI)reveal that the DOM has the properties of humus.With the treatment going on,both the fluorescence intensity of fulvic acid and the concentration of COD decreased with COD dropping from 3 311.0 to 169.6 mg·L-1.The fulvic acid in the visible light zone dropped from 4 065.2 to 903.1 in fluorescence intensity,and the fulvic acid in the UV light zone did from 4 023.1 to 178.6.A good correlation between COD concentration and fluorescence intensities of the fulvic acid in the visible light and UV light zones has been discovered,with correlation coefficients being 0.978 1 and 0.981 3,respectively,which indicates that the tech-nique of 3-D fluorescence spectrometry can be used to monitor real-time changes in COD concentration in organic pesti-cides wastewater under treatment.%采用三维荧光光谱技术对有机农药废水处理过程中溶解性有机物(DOM)的荧光光谱特性进行分析,并建立DOM荧光强度和COD的相关关系.三维荧光光谱分析表明,废水中DOM主要有可见光区富里酸(峰A)、紫外光区富里酸(峰B)和高激发波长色氨酸(峰C)3种物质.可见光区富里酸和紫外光区富里酸经气浮池、水解酸化池和厌氧流化床处理后,转化为更易被微生物降解的高激发波长色氨酸.经过接触氧化池处理后,3种DOM的荧光强度均因微生物降解而逐渐降低,其中高激发波长色氨酸比富里酸易降解.荧光指数(IF)、生物源指数(XBI)、紫外光区富里酸与可见光区富里酸荧光强度比值(rB/A)和腐殖化指数(XHI)分析表明:IF和XBI反映DOM来源以外源输入为主;rB/A和XHI反映DOM属于腐殖质特征.废水处理过程中COD和富里酸荧光强度均逐渐降低,COD从3311.0降至169.6 mg·L-1;可见光区富里酸荧光强度由4065.2降低至903.1,紫外光区富里酸荧光强度由4023.1降至178.6.研究表明,可见光区富里酸和紫外光区富里酸的荧光强度与COD均具有良好的相关性,R2分别为0.9781和0.9813,说明可通过三维荧光光谱技术快速监测有机农药废水处理过程中的COD.