生物炭对径流雨水中溶解性有机物的去除研究

Research on the removal of dissolved organic matter in runoff stormwater by biochar

径流雨水中的大量溶解性有机物(DOM)可通过城市雨水系统进入自然水体,导致水体出现富营养化和黑臭现象,并可能在后续水处理消毒工艺中与消毒剂反应生成具有三致特性的消毒副产物(DBPs)。研究选用生物炭为吸附剂,并通过酸碱改性,探究其对径流雨水中DOM的吸附效能。结果表明,竹子类生物炭对水样中的DOM具有优良的吸附去除效果,经KOH改性后的竹子生物炭吸附性能大大提升;其对溶解性有机碳(DOC)和溶解性有机氮(DON)的去除率分别为63.1%和79.9%,对DBPs前体物的去除率高达63.2%。荧光光谱分析结果表明,与未落地雨水成分不同,径流雨水的DOM荧光成分较为复杂,荧光响应强度依次为腐殖酸类、富里酸类、可溶性微生物产物类、芳香性类蛋白Ⅱ和芳香性类蛋白Ⅰ物质。经竹子类生物炭吸附处理后,腐殖酸类和芳香性类蛋白物质的响应值大大下降,是削减DBPs前体物的关键。改性增加了生物炭的比表面积、孔结构和官能团,推测吸附机理有空隙填充作用、氢键作用、疏水相互作用和π-π相互作用。总之,竹子类生物炭在快速削减城市径流雨水污染负荷方面具有低成本和高效率的优点。

Amounts of dissolved organic matter(DOM)in stormwater would enter natural wa-ter through urban stormwater drainage systems.Excessive DOM can cause aesthetic concerns such as black and stink water with unpleasant colors and odors,water eutrophication,and it can act as the precursors of hazardous disinfection byproducts(DBPs).In this study,biochar was used as absorbent to investigate the adsorption effect on DOM in stormwater.The results revealed that bam-boo biochar showed excellent adsorption effects on DOM.Moreover,KZC,modified by KOH,had the best adsorption performance,and the removal efficiencies of dissolved organic carbon(DOC)and dissolved organic nitrogen(DON)were 63.1%and 79.9%respectively,and the removal efficiency of total DBP FPs was up to 63.2%.Additionally,the results of EEM showed that the DOM components of runoff rainwater were complex,and the intensity of humic acid-like,fulvic acidlike,soluble microbial product-like substances,and aromatic proteins were very high.Particularly,after the bamboo biochar adsorption treatment,the intensity of aromatic proteins and humic acid-like decreased significantly,which was the key to reduce DBPs precursors.The adsorption mechanism of modified biochar included pore filling,hydrogen bonding,hydrophobic interaction andπ-πinteraction.In general,bamboo biochar has considerable application potential in rapidly controlling runoff stormwater pollution.