悬移质泥沙影响下水体中DBP的降解

The degradation of di-n-butyl phthalate in suspended particulate matter contained waters

为探究含悬移质泥沙(SPM)影响下水体中邻苯二甲酸二正丁酯(DBP)的去除过程,采集了三峡库区一级支流御临河中的原位水样和SPM,以DBP为供试试剂,在室内构建实验体系,设置4组实验:原水(对照)、原水-Na N3、原水-SPM-Na N3和原水-SPM,研究了扰动水体中DBP的光解、吸附和生物降解过程.研究发现:水相中的DBP可通过直接吸收光电子诱导有机分子降解或在有色溶解性腐殖质(包括富里酸和类胡敏酸等)中的发色团(苯环、羧基等)吸收电子产生活性中间体而诱导DBP发生光催化降解;在原水-Na N3实验组中,在2种光解反应的作用下,24d后水相中DBP浓度降低了82.86%;SPM的吸附作用对DBP的去除效果不佳(0.63%),可能是由于DBP光降解产物及原位水中的溶解性有机质会与DBP竞争SPM上的表面吸附位点;SPM附着生物膜对DBP的吸附-生物降解,导致水相中89.81%的DBP被去除.虽然24d内,各处理组DBP的去除率接近(82%~89%),但原水-SPM组中总溶解性有机碳去除率显著高于(P<0.05)其他组,表明在原水-SPM组中实现了DBP的降解.

A microcosm scale study was established to explore the adsorption, photodegradation and biodegradation of di-n-butyl phthalate(DBP) in suspended particulate matter(SPM) contained waters. The water and SPM samples were collected from the Yulin River, a tributary of the Three Gorges Reservoir. Twelve columns containing the same amount of water were prepared, and were divided into 4 treatments. 1) containing water and 5 mg/L DBP, which were used as controls;2) containing water, 5 mg/L DBP, and NaN3;3) containing water, 5 mg/L DBP, and SPM_(2.5) 4) containing water, 5 mg/L DBP, SPM and NaN3. The water volume, SPM and NaN3 concentration was equivalent for the 4 treatments. The results showed that the DBP in the water phase can directly absorb photoelectrons or the chromophore(benzene ring, carboxyl group, etc.) in the colored soluble humus(including fulvic acid and humic acid-like, etc.) could absorb electrons to generate active intermediates, which induced the photocatalytic degradation of DBP.In the raw water-NaN3 experimental group, photocatalytic degradation was responsible for 82.86% degradation of DBP in the water after 24 days. The adsorption of DBP by the SPM was insignificant and triggered 0.63% reduction of DBP in the water, this may be due to the competition of adsorption sites between DBP photodegradation products, soluble organic matter and DBP. The joint effect of adsorption and biofilm degradation by the SPM attached biofilm effectively degraded 89.81% DBP in the water. Although the overall removal efficiency of DBP in the four treatments displayed slight difference(in the range of 82%~89%), the concentration of dissolved organic carbon in the SPM added group but without the addition of NaN3 was significantly higher(P<0.05) than others,indicating the degradation of DBP from the water.