Direct potable reuse requires stringent water quality assurance to protect public health. This study developed an online analytical technique—high-performance liquid chromatography followed by photochemical reaction and chemiluminescence detection (HPLC-PR-CL)—for determination of the concentration of N-nitrosodimethylamine (NDMA) and three other N-nitrosamines. Its feasibility for near real-time analysis was evaluated by analyzing an ultrafiltration (UF)-treated wastewater before and after a pilot-scale reverse osmosis (RO) treatment system. The online instrument with a method detection limit of 0.3–2.7 ng/L requires a direct injection (i.e., no sample pre-concentration) of only 20–200 µL sample volume for the determination of N-nitrosamine concentrations every 20 min. NDMA concentrations in UF-treated wastewater were successfully monitored in a range of 50–200 ng/L over the course of 24 h. Likewise, NDMA concentrations in RO permeate ranged from 25–80 ng/L over the course of 48 h. The online monitor was capable of recording variations in N-nitrosamine concentration in RO permeate that occurred following changes in feedwater concentration and temperature. This study demonstrates the potential for online water quality assurance that directly measures trace levels of organic contaminants, which is highly relevant to the implementation of potable reuse.

中文翻译：

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在线高效液相色谱-光化学反应-化学发光法对饮用水回用中的N-亚硝基二甲胺进行近实时监测

直接的饮用水回用需要严格的水质保证，以保护公众健康。这项研究开发了一种在线分析技术-高效液相色谱，然后进行光化学反应和化学发光检测（HPLC-PR-CL）-用于确定N-亚硝基二甲胺（NDMA）和其他三种N-亚硝胺的浓度。通过在中试规模的反渗透（RO）处理系统之前和之后分析超滤（UF）处理的废水，评估了其近实时分析的可行性。方法检出限为0.3–2.7 ng / L的在线仪器需要每20分钟直接进样（即不进行样品预浓缩）仅20–200 µL样品体积才能测定N-亚硝胺浓度。在24小时内，用UF处理的废水中的NDMA浓度已成功监测到50-200 ng / L。同样，RO渗透液中NDMA的浓度在48小时内范围为25–80 ng / L。在线监控器能够记录由于给水浓度和温度变化而导致的RO渗透物中N-亚硝胺浓度的变化。这项研究证明了在线水质保证直接测量痕量有机污染物水平的潜力，这与饮用水回用的实施高度相关。在线监控器能够记录由于给水浓度和温度变化而导致的RO渗透物中N-亚硝胺浓度的变化。这项研究证明了在线水质保证直接测量痕量有机污染物水平的潜力，这与饮用水回用的实施高度相关。在线监控器能够记录由于给水浓度和温度变化而导致的RO渗透物中N-亚硝胺浓度的变化。这项研究证明了在线水质保证直接测量痕量有机污染物水平的潜力，这与饮用水回用的实施高度相关。