Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, United States.
Department of Chemical and Environmental Engineering, University of California at Riverside, Riverside, CA 92521, United States.
Sci Total Environ. 2015 Apr 1;511:47-53. doi: 10.1016/j.scitotenv.2014.11.005. Epub 2014 Dec 18.
There is still a great knowledge gap in the understanding of characteristics and bioavailability of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) in wastewater effluents, which surmise implications related to both discharge regulation and treatment practice. In this study, we simultaneously investigated the characteristics and bioavailability of both DON and DOP, with separated hydrophilic versus hydrophobic fractions, in highly-treated wastewater effluents for the first time. The tertiary effluents from two wastewater treatment plants were separated into two fractions by XAD-8 resin coupled with anion exchange resin based on the hydrophobicity. Results showed that the majority of DON was present in hydrophilic forms while more DOP existed in hydrophobic forms. Hydrophilic DON contributed to 64.0%-72.2% of whole DON, while hydrophobic DOP accounted for 61.4%-80.7% of total DOP for the two plants evaluated. The effluents and their fractions were then subject to bioavailability assay based on 14-day algae growth. The results indicated that majority (~73-75%) of the effluent DOP, particularly the hydrophobic fraction with lower C/P ratio was more likely to be bioavailable for algal growth. The bioavailable fraction of DON varied widely (28%-61%) for the two plants studied and the hydrophilic fraction with lower C/N ratio seemed to exhibit higher bioavailability than the hydrophobic portion. The differences in bioavailable DON and DOP distributions of effluents from those two plants could be attributed to different receiving effluent compositions and wastewater treatment processes. In addition, fluorescence excitation-emission matrices (EEMs) combined with parallel factor analysis (PARAFAC) were used to characterize the dissolved organic matter (DOM) in wastewater effluent, which provided insights into the nature of organic matter in wastewater samples with different characteristics and originating sources.
目前，人们对废水处理厂出水中溶解有机氮（DON）和溶解有机磷（DOP）的特性和生物可利用性仍缺乏了解，这可能会对排放控制和处理实践产生影响。本研究首次同时研究了高度处理的废水处理厂出水中，DON 和 DOP 的特性和生物可利用性，并且对其亲水和疏水部分进行了分离。采用 XAD-8 树脂和阴离子交换树脂，将两座污水处理厂的三级出水按疏水性分为两部分。结果表明，大多数 DON 以亲水形式存在，而更多的 DOP 则以疏水形式存在。亲水 DON 占两厂总 DON 的 64.0%-72.2%，而疏水 DOP 占总 DOP 的 61.4%-80.7%。然后，对出水及其各部分进行基于 14 天藻类生长的生物可利用性测定。结果表明，大部分（约 73-75%）的废水 DOP，特别是 C/P 比值较低的疏水部分更有可能被藻类生长利用。两个研究工厂的 DON 生物可利用部分差异很大（28%-61%），C/N 比值较低的亲水部分似乎比疏水部分具有更高的生物可利用性。这两个工厂的出水可利用 DON 和 DOP 分布的差异可能归因于不同的进水组成和废水处理工艺。此外，采用荧光激发-发射矩阵（EEMs）结合平行因子分析（PARAFAC）对废水处理厂出水中的溶解有机物（DOM）进行了表征，为不同特性和来源的废水样品中有机物的性质提供了深入了解。
