基于FTIR分析猪场废水有机物分解过程中组成结构变化

摘要

More and more attentions were paid on the environmental pollutions of wastewater discharged from scale pig farms, and it could provide scientific bases for formulating reasonable pollution control measures to study the structural changes of organic matter composition in piggery wastewater.In the present study,a laboratory-scale incubation experiment was carried out with piggery wastewater collected from different scale pig farms,and a continuous sampling was conducted at a certain interval during the process of incubation experiment.The main purpose of this study was to elucidate the change of structural composi-tion of dissolved organic matter (DOM)in piggery wastewater during the process of organic degradation.All dried and solid DOM samples were achieved using filtration and freeze-drying methods.Spectral analysis of all DOM samples was completed with the application of Fourier transform infrared (FTIR)spectrometer.Results of spectral analysis showed a similar DOM structural composition was observed in the wastewater derived from different scale pig farms,and was mainly comprised of lip-ids,proteins,fulvic acids,polysaccharides,and phenolic compounds.With the increase in the incubation days,the percent of functional groups,related to proteins,phenolic acids,and lipids,decreased gradually and kept stable eventually,while these functional groups,linked with fulvic acids and polysaccharides,showed a significant increase and leveled off at the end.Com-pared with primary samples,fulvic acids and polysaccharides were the predominant fractions of DOM at 20 days after organic degradation,indicating a higher aromatic degree of DOM.Meanwhile,the degradation rate of OH bonded by intermolecular H-bond of cellulose was faster than OH bonded by intra-molecular H-bond of cellulose,whereas the latter was more sensitive to microbial degradation.The degradation rate of phenolic hydroxyl C—O was the fastest,followed by aromatic COOH,carbohy-drate C—O,and amide C—O.Furthermore,the carbohydrate C—O was apt to be utilized preferentially by microorganisms.In sum,the structural change of various DOM in piggery wastewater was different during the process of organic degradation.%猪场废水排放的环境污染问题日益受到重视，研究废水中有机物的组成结构变化将可为制订合理的污染防治措施提供科学依据。本研究通过设置不同规模化猪场废水的室内培养试验，在培养过程中定期采样，采用抽滤、冷冻干燥等方法获得可溶性有机物(DOM)固体样品；运用FTIR光谱仪采集样品的红外谱图，研究废水中DOM组成结构在有机分解过程中的变化。结果表明，不同猪场来源的废水中 DOM具有类似的组成结构，且主要由蛋白质、脂质类、腐殖酸、多糖类和酚类等有机物组成。随着培养天数的增加，与脂质类、蛋白质和酚类等相关的官能团含量逐渐降低并趋于稳定，而与腐殖酸和多糖类相关的官能团显著增加直至平稳。与初始样品相比，培养20天后样品中DOM组成结构以腐殖酸和多糖类为主，表明DOM的腐殖化程度有所提高。此外，与纤维素分子内氢键缔合的羟基(OH)相比，纤维素分子间氢键缔合的羟基降解速率相对更快，而以前者对微生物的降解更为敏感。废水中 DOM以酚羟基 C—O 的降解速率更快，随后是芳香族COOH、糖类C—O和酰胺羰基 C—O ，而糖类C—O倾向于优先被微生物所利用。综上所述，废水中不同的DOM组成结构在有机降解过程中的变化存在一定差异。