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.

As populations around the world continue to grow and communities appreciate the difficulty in securing new water supplies, water reuse is expected to expand in the coming years. Other factors, such as localized drought severity and increased community and regulatory pressure may also increase the application of water reuse. The level of treatment provided in water reuse projects varies significantly throughout the world depending on numerous factors, such as regulations, water quality, end uses of the treated water, and public influence. Selecting the appropriate treatment technology and level of treatment can be a complex decision. Recent experiences within the water reuse industry have demonstrated that governmental and nongovernmental organizations and advocacy groups can influence selection of a higher or more costly level of treatment than is fit for the water purpose. This is partially because of a failure to consider the full financial, environmental, and social elements of the triple bottom line (TBL). The focus of this report was to develop and apply a TBL framework to help guide sound selection of the treatment process. The objective is to match the treatment to the intended use without expending unnecessary funds or energy or emitting excess greenhouse gas (GHG) and other air emissions, while minimizing other environmental and social costs. Although the present research addresses water reuse only, the TBL approach is equally applicable toward evaluating the full suite of water supply and demand alternatives.Environ. Sci.: Water Res. Technol. This journal is More communities than ever are investigating the feasibility of implementing potable reuse projects to increase their water supply and protect against periods of drought. The complexity of this task is compounded by the variety of reuse treatment technologies, which can differ in terms of benefit to the end user as well as in the true cost of implementation. This paper examines the benefits and costs of various levels of treatment for potable reuse applications. A triple bottom line (TBL) analysis was performed that includes financial, environmental, and social elements to help ensure that the right treatment process is applied for the intended use without expending unnecessary funds, energy, greenhouse gases, and other social and environmental costs.

An upflow floc blanket reactor installed upstream of ultrafiltration membranes assists adsorption of dissolved organic carbon. The hybrid process resulting from adding powdered activated carbon (PAC) to ultrafiltration (UF) reactors is being used to remove organic compounds in full‐scale drinking water treatment plants. One way to increase the adsorption efficiency of PAC is to add it to continuously stirred tank reactors (CSTRs) or to plug flow reactors installed upstream of the membranes. Additionally, the PAC that is recovered from the membrane backwash can be recycled to a floc blanket reactor (FBR) installed upstream of the PAC/CSTR–UF process. This study developed an adsorption model that predicts the removal of dissolved organic carbon (DOC) in the FBR–PAC/CSTR–UF system. The model was verified experimentally using two commercially available PACs in a laboratory‐scale pilot unit. Removal of DOC by coagulation with aluminum salts and adsorption on the recycled PAC in the FBR substantially reduced carbon use. The model was used to assess the effect of various operating parameters on DOC adsorption efficiency and to determine optimal operating conditions.

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