A Simplified DOC Fractionation SPE Method Without Recovering Sorbed Compounds

This research aims to advance the understanding of dissolved organic carbon (DOC) fractions in water treatment processes. Current fractionation methods, such as Solid Phase Extraction (SPE), primarily focus on recovering sorbed compounds and assume that treatment impacts only the quantity, not the characteristics, of DOC fractions. Additionally, varying recovery rates and inconsistent fractionation pH definitions complicate cross-study comparisons of hydrophilic (HPI) and hydrophobic (HPO) DOC composition. This study addresses these gaps by investigating the impact of different pH approaches (pH 3, pH 7, and sequential adjustment) on DOC fractionation focused on organic compounds in the SPE filtrate, as well as the effects of coagulation, softening, and filtration on DOC composition and characteristics.
We introduced a novel fractionation method using Bond Elut ENV cartridges at two pH levels—pH 3 and pH 7—to estimate major DOC fractions: hydrophilic neutral (HPIN), total acidic (TA), and hydrophobic neutral (HPON). This approach eliminates the need to recover sorbed DOC fractions, simplifying the process and enabling more consistent cross-study comparisons. Applying this method in a conventional coagulation/softening plant revealed HPON decreased while the relative amounts of HPI and TA increased after the treatment. However, the treated water HPI exhibited significantly higher STHMFP and contained approximately twice the proportion of low-molecular-weight compounds than raw water HPI, highlighting significant changes in both the content and properties of DOC fractions after the treatment process. Our study indicates the contribution of HPI DOC fraction to SUVA and THM formation potential (THMFP) in treated water is greater than that of HPO DOC.
The data collected, including DOC concentrations, UV254 absorbance, THMFP, and molecular weight distribution using high-performance size exclusion chromatography (HPSEC) across different water samples and in SPE filtrates at various fractionation pH values and SPE types (Bond Elit C18, C18-EWP, and ENV). Also, we conducted a thorough literature review on DOC fractions isolated using bulk resin or SPE methods in drinking water applications. The data provides a comprehensive view of DOC behavior in conventional water treatment processes. This dataset can help practitioners design more efficient processes by considering changes in DOC composition throughout treatment. Researchers can apply these findings to understand better the influence of pH-based fractionation, DOC aromaticity, and the roles of specific DOC fractions in THM formation.

本研究旨在推进对水处理过程中溶解有机碳（DOC）组分理解。现有的分组方法，如固相萃取（SPE），主要集中于回收吸附化合物，并假设处理仅影响DOC组分的数量，而非其特性。此外，不同的回收率以及不统一的分组pH值定义使得水溶性（HPI）和疏水性（HPO）DOC组成的跨研究比较复杂。本研究通过探究不同pH值方法（pH 3、pH 7以及连续调整）对DOC分组的影响，重点关注SPE滤液中的有机化合物，以及絮凝、软化及过滤对DOC组成及特性的作用，旨在弥补这些不足。我们引入了一种新型的分组方法，即采用Bond Elut ENV小柱在两种pH值——pH 3和pH 7——下进行分组，以估算主要的DOC组分：亲水性中性（HPIN）、总酸性（TA）和疏水性中性（HPON）。该方法消除了回收吸附DOC组分的必要性，简化了过程，并使得跨研究的比较更加一致。将此方法应用于传统的絮凝/软化工厂，发现HPON含量降低，而相对的HPI和TA含量增加，经过处理后，处理水的HPI表现出显著更高的STHMFP，并且其低分子量化合物的比例约为原水的两倍，突显了DOC组分在内容和性质上的显著变化。我们的研究指出，HPI DOC组分对处理水中的SUVA和三卤甲烷（THM）形成潜力（THMFP）的贡献大于HPO DOC。收集的数据包括DOC浓度、UV254吸光度、THMFP以及使用高性能尺寸排阻色谱（HPSEC）在不同水样和SPE滤液中不同分组pH值及SPE类型（Bond Elit C18、C18-EWP和ENV）下的分子量分布。此外，我们还对使用整体树脂或SPE方法在饮用水应用中分离的DOC组分进行了广泛的文献综述。这些数据为DOC在传统水处理过程中的行为提供了全面的视角。此数据集有助于从业者通过考虑整个处理过程中DOC组成的改变来设计更有效的流程。研究人员可以将这些发现应用于更好地理解基于pH值的分组、DOC的芳香性以及特定DOC组分在THM形成中的作用。