Civil and Environmental Engineering Department, Virginia Tech, Blacksburg, VA, USA.
Hampton Roads Sanitation District (HRSD), Virginia Beach, VA, USA.
Water Environ Res. 2021 Aug;93(8):1157-1172. doi: 10.1002/wer.1525. Epub 2021 Feb 17.
The Sustainable Water Initiative for Tomorrow (SWIFT) program is the effort of the Hampton Roads Sanitation District to implement indirect potable reuse to recharge the depleted Potomac Aquifer. This initiative is being demonstrated at the 1-MGD SWIFT Research Center with a treatment train including coagulation/flocculation/sedimentation (floc/sed), ozonation, biofiltration (BAF), granular activated carbon (GAC) adsorption, and UV disinfection, followed by managed aquifer recharge. Bulk total organic carbon (TOC) removal occurred via multiple treatment barriers including, floc/sed (26% removal), ozone/BAF (30% removal), and adsorption by GAC. BAF acclimation was observed during the first months of plant operation which coincided with the establishment of biological nitrification and dissolved metal removal. Bromate formation during ozonation was efficiently controlled below 10 µg/L using preformed monochloramine and preoxidation with free chlorine. N-nitrosodimethylamine (NDMA) was formed at an average concentration of 53 ng/L post-ozonation and was removed >70% by the BAFs after several months of operation. Contaminants of emerging concern were removed by multiple treatment barriers including oxidation, biological degradation, and adsorption. The breakthrough of these contaminants and bulk TOC will likely determine the replacement interval of GAC. The ozone/BAC/GAC treatment process was shown to meet all defined treatment goals for managed aquifer recharge. PRACTITIONER POINTS: Floc/sed, biofiltration, and GAC adsorption provide important barriers in carbon-based treatment trains for bulk TOC and trace organic contaminant removal. Biofilter acclimation was observed during the first three months of operation in each operating period as evidenced by the establishment of nitrification. Bromate was effectively controlled during ozonation of a high bromide water with monochloramine doses of 3-5 mg/L. NDMA was formed at an average concentration of 53 ng/L by ozonation and complete removal was achieved by BAFs after several months of biological acclimation. An average 25% removal of 1,4-dioxane was achieved via oxidation by hydroxyl radicals during ozonation.
明天可持续水倡议 (SWIFT) 计划是汉普顿路污水处理区努力实施间接饮用水再利用，以补充枯竭的波托马克含水层。该倡议正在 1 百万加仑/天的 SWIFT 研究中心进行示范，处理过程包括混凝/絮凝/沉淀 (floc/sed)、臭氧氧化、生物过滤 (BAF)、颗粒活性炭 (GAC) 吸附和紫外线消毒，然后进行管理型含水层补给。总有机碳 (TOC) 的大量去除是通过多个处理屏障实现的，包括 floc/sed（去除 26%）、臭氧/BAF（去除 30%）和 GAC 吸附。在工厂运行的最初几个月中观察到 BAF 的驯化，这与生物硝化和溶解金属去除的建立同时发生。使用预形成的一氯胺和自由氯预氧化，有效地将臭氧化过程中的溴酸盐形成控制在 10μg/L 以下。臭氧氧化后形成的 N-亚硝基二甲胺 (NDMA) 的平均浓度为 53ng/L，经过几个月的运行，BAFs 的去除率超过 70%。通过多个处理屏障去除新兴关注的污染物，包括氧化、生物降解和吸附。这些污染物和总 TOC 的突破可能决定 GAC 的更换间隔。臭氧/BAF/GAC 处理工艺被证明满足管理型含水层补给的所有定义处理目标。从业者要点：floc/sed、生物过滤和 GAC 吸附为基于碳的处理工艺提供了重要的屏障，用于去除总 TOC 和痕量有机污染物。在每个运行期的前三个月观察到生物滤池的驯化，这表明硝化作用的建立。在高溴化物水中使用 3-5mg/L 的一氯胺剂量进行臭氧氧化时，有效地控制了溴酸盐的形成。臭氧氧化后形成的 NDMA 的平均浓度为 53ng/L，经过几个月的生物驯化，BAFs 完全去除。臭氧氧化过程中通过羟基自由基氧化，1,4-二恶烷的平均去除率为 25%。
