Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19711, USA.
Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19711, USA.
Sci Total Environ. 2018 Jun 1;625:1321-1329. doi: 10.1016/j.scitotenv.2017.12.326. Epub 2018 Jan 12.
The present research attempted to assess the seasonal variation of engineered nanoparticles (ENPs) in a major municipal wastewater treatment system. A monthly survey over a 12-month period was conducted to monitor the concentration of TiO and ZnO nanoparticles throughout the treatment process. Results showed inflow concentrations in the range of 21.6±5.0-391.0±43.0μg/L and 20.0±12.0-212.0±53.0μg/L for TiO and ZnO, respectively. Seasonal pattern of the inflow ENPs concentration showed elevated value in the summer and winter periods for both TiO and ZnO. Based on the concentration profile, the hydraulic flow rate, and the concentration of mixed liquid suspended solid (MLSS), the daily mass loading (DML) or mass flow rate of nanoparticles and the mass ratio of engineered nanoparticle to MLSS were calculated. DML provided a real-time estimate of temporal distribution of ENPs in the treatment processes. Results indicated a daily mass loading of 50.1±12.7 and 44.7±14.1kg/day (yearly average) for TiO and ZnO, respectively. The amount of ENPs captured by sludge particulates were, yearly average, of 7.1kg-ZnO/d and 39.8kg-TiO/d, and 8.9kg-ZnO/d and 25.1kg-TiO/d, by the primary and the secondary sludge particulates, respectively. ENPs to MLSS mass ratio also showed a seasonal patter similar to the inflow ENPs concentration, where summer and winter periods showed elevated values. Additionally, loss of ENPs throughout the treatment plant that was not accounted for, also can be estimated from the daily mass loading rate and the mass ratio of ENPs to MLSS. Based on the seasonal distribution of ENPs in wastewater treatment systems, especially the daily mass loading rate, it is possible to estimate the uses of nanoparticle-related commercial and personal care products in the urban areas and enable decision-making on the strategy of sludge disposal management.
本研究旨在评估主要城市污水处理系统中工程纳米颗粒（ENPs）的季节性变化。在 12 个月的时间内进行了每月调查，以监测整个处理过程中 TiO 和 ZnO 纳米颗粒的浓度。结果表明，流入浓度分别在 21.6±5.0-391.0±43.0μg/L 和 20.0±12.0-212.0±53.0μg/L 范围内。TiO 和 ZnO 的流入 ENPs 浓度的季节性模式显示在夏季和冬季期间均呈升高趋势。根据浓度分布、水力流速和混合液悬浮固体（MLSS）浓度，计算了纳米颗粒的日质量负荷（DML）或质量流量以及工程纳米颗粒与 MLSS 的质量比。DML 提供了处理过程中 ENPs 时间分布的实时估计。结果表明，TiO 和 ZnO 的日质量负荷分别为 50.1±12.7kg/d 和 44.7±14.1kg/d（年平均值）。每年通过污泥颗粒捕获的 ENPs 量分别为 7.1kg-ZnO/d 和 39.8kg-TiO/d，以及 8.9kg-ZnO/d 和 25.1kg-TiO/d，分别由初级和二级污泥颗粒捕获。ENPs 与 MLSS 的质量比也表现出与流入 ENPs 浓度相似的季节性模式，其中夏季和冬季期间呈升高趋势。此外，通过处理厂流失的无法解释的 ENPs 量也可以根据日质量负荷率和 ENPs 与 MLSS 的质量比进行估算。基于废水处理系统中 ENPs 的季节性分布，特别是日质量负荷率，可以估算城市地区纳米颗粒相关商业和个人护理产品的使用情况，并为污泥处置管理策略的决策提供依据。
