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在我国城市河流中,长期的外源污染输入和水生生物残渣的沉积,导致河流水质恶化并产生黑臭现象。水体黑臭是一种生物化学现象,水体中有机污染物含量过高时,有机物在好氧条件下进行生物分解时耗氧较大,远远超出水体复氧量,造成水体缺氧,致使有机物降解不完全、速度减缓。厌氧生物降解过程生成氨、硫化氢、有机胺、硫醇和有机酸等发臭物质,同时形成FeS、MnS等黑色物质,使水体发生黑臭。在形成城市黑臭水体的许多因素中,有机物污染是直接原因[1]。微生物原位修复技术作为一种低成本、实地操作性强、生态节能的方法,被广泛应用于各个领域[2-3]。目前,微生物原位修复技术主要包括曝气、投加菌剂、生物促生剂等[4-6]。近年来,利用微生物法净化黑臭水体在我国部分地区的实际应用中已取得了一定的效果,但对有机物净化效果尚不理想,这是因为有机物的去除效果往往只是采用传统的表观有机物指标如COD、BOD等进行评价,这些指标很难反映微生物法处理黑臭水过程中各类溶解有机物(DOM)组成和含量的变化特征。
由于DOM中存在发色团和荧光团,光谱技术可以揭示其特征和结构组成。三维荧光激发发射光谱矩阵(EEM)已被证明是表征DOM的有用技术[7-9]。其具有快速、灵敏和不使用化学试剂等优点,有利于识别各种水系统中DOM的位置、强度和区域比例。CHEN等[10]根据模型化合物、DOM组分和海水或淡水的荧光特征,将EEMs划分为5个区域:类富里酸物质、类腐殖酸物质、类色氨酸物质、类酪氨酸物质和微生物腐殖质类物质。近年来,三维荧光光谱与平行因子分析(PARAFAC)相结合的方法得到广泛应用,它通过整合每个区域的体积,对DOM的荧光响应部分进行定量分析[11]。EEM-FRI技术已被广泛用于不同的领域,包括对河流和废水样品[11]、废水污泥样品[12]等的检测,通过该方法鉴定光谱组分,可以进一步了解不同废水处理过程中有机物的动态。因此,利用三维荧光技术对不同微生物法处理废水过程中的溶解性有机物检测对水污染控制具有重要意义。
本研究以重度黑臭水(劣V类水)为研究对象,分别对曝气、菌剂+曝气、生物促生剂+曝气和菌剂+生物促生剂+曝气4种微生物处理方式进出水中的DOM特征和来源进行了探讨,采用三维荧光光谱法对各处理方式中DOM的荧光特性进行了测定和分析,结合平行因子(PARAFAC)分析方法,提取有效的荧光光谱特征,分析了黑臭水体DOM的主要组成成分、来源以及不同处理方式下水体中DOM的降解过程,阐明不同生物处理方式对黑臭水体中DOM特征变化的影响,为进一步高效治理黑臭水体提供参考。
基于三维荧光光谱技术解析不同微生物法净化黑臭水体的效果
Effect of different microbial methods on purifying black-odor water based on three-dimensional fluorescence spectroscopy
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摘要: 应用曝气、菌剂+曝气、生物促生剂+曝气、菌剂+生物促生剂+曝气4种微生物技术净化黑臭水体,分别考察了进水中溶解性有机物(DOM)的特征和来源及出水中DOM的特征和效果,采用三维荧光(EEM)光谱技术与平行因子(PARAFAC)模型相结合的方式对进出水DOM进行了分析。结果表明,不同处理方式下进出水DOM的不同组分荧光峰强度变化存在较明显的差异,经过菌剂和生物促生剂联合处理之后,对类腐殖质等难降解物质削减效果最好。FI、HIX和BIX指数分析表明各处理水样中的DOM整体处于较强的自生源特征。利用主成分分析法(PCA)对影响黑臭水体DOM的主要因素及其贡献量研究发现:第1主成分表现为陆源类腐殖质和生物源类腐殖质共存的现象,对水体中DOM的贡献率为54.98%;第2主成分反映了以微生物代谢过程为代表的内源污染,对水体中DOM的贡献率为26.56%。因此,利用三维荧光分析能够较好的反映水中DOM的去除情况,易于实时在线监测,对黑臭水治理具有重要意义。Abstract: Excitation-emission matrix (EEM) fluorescence spectroscopy combined with parallel factor analysis (PARAFAC) were employed to analyze the characteristics and source of dissolved organic matter (DOM) in influent and the characteristics and effect of DOM in effluent when four microbial technologies: aeration, microbial inoculum+aeration, biostimulant+aeration, microbial inoculum+biostimulant+aeration, were used to purifying black-odor water. The results showed that the fluorescence peak intensity of different components of DOM was significantly different under different treatments. The combined treatment with microbial inoculum and biostimulant had the best reduction effect on non-biodegradable substances such as humus. The FI, HIX and BIX index analysis showed that the DOM in effluent was in a strong autogenous source. Principal component analysis (PCA) was used to study the main factors affecting the DOM of black-odor water and their contributions. The results indicated that the first principal component was characterized by the coexistence of terrestrial humus and biogenic humus, contributing 54.98% to the DOM in water. The second principal component reflected the endogenous pollution represented by microbial metabolism, accounting for 26.56% of the DOM in water. Therefore, the use of three-dimensional fluorescence analysis can better reflect the removal of DOM in water, and is easy to realize real-time on-line monitoring, which is of great significance for black-odor water treatment.
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表 1 黑臭水体背景值
Table 1. Black-odor water background values
mg·L−1 标准和背景值 TN TP COD NH3-N 溶解氧 地表V类水标准 2 0.4 40 2 2 黑臭水体背景值 590.47 3.45 370 94.88 0.35 表 2 实验分组情况
Table 2. Experimental group numbers
序号 曝气 促生剂 菌剂 处理组 1 × × × 空白对照组 2 √ × × 曝气组 3 √ × √ 菌剂+曝气组 4 √ √ × 生物促生剂+曝气组 5 √ √ √ 菌剂+生物促生剂+曝气组 注:√表示添加,×表示不添加。 表 3 荧光光谱分区及其对应物质
Table 3. Fluorescence spectral partition and its corresponding substances
区域 激发波长/nm 发射波长/nm 物质类型 I 220~250 280~330 酪氨酸类蛋白质 II 220~250 330~380 色氨酸类蛋白质 III 220~250 380~480 富里酸类腐殖质 IV 250~360 280~380 含苯环蛋白质、溶解性
微生物代谢物V 250~420 380~520 腐殖酸类腐殖质 表 4 不同处理方式下进出水DOM三维荧光光谱参数
Table 4. Three-dimensional fluorescence spectral parameters of DOM in influent and effluent under different treatment modes
实验组 FI HIX BIX 进水 出水 进水 出水 进水 出水 空白组 2.37 2.79 1.13 1.85 1.07 0.60 曝气组 2.07 2.81 1.21 1.88 1.12 0.77 菌剂+曝气组 2.22 2.51 1.16 1.95 1.05 0.90 生物促生剂+曝气组 2.38 2.60 0.74 2.15 1.11 1.08 菌剂+生物促生剂+曝气组 2.35 2.08 0.75 1.85 1.09 1.08 -
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