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E474 Anumol et al. | http://dx.doi.org/10.5942/jawwa.2015.107.0129 Peer-Reviewed Point-of-Use Devices for Attenuation of Trace Organic Compounds in Water TARUN ANUMOL,1, 2 BRADLEY O. CLARKE,1, 3 SYLVAIN MEREL,1, 4 AND SHANE A. SNYDER1, 5 1Department of Chemical and Environmental Engineering, University of Arizona, Tucson Technologies, Wilmington, Del. 3RMIT University, School of Applied Sciences, Melbourne, Australia 4Department of Geosciences, University of Tübingen, Tübingen, Germany 5National University of Singapore Environmental Research Institute, Singapore 2Agilent Trace organic compounds (TOrCs) continue to be detected in drinking water, and their recalcitrance makes them difficult to attenuate without installing expensive advanced treatment processes. Because human consumption is a small portion of net household water use, point-of-use (POU) devices may provide additional security against drinking water contaminants. This research evaluated three pitcher and two refrigerator POU devices using two waters. Refrigerator POU devices removed more TOrCs over the manufacturer’s expected lifetime in terms of total mass than the pitcher POU devices. Average removal through all filters for nonionic, hydrophobic compounds was higher than for hydrophilic compounds in both waters. Removal of ionic compounds was enhanced by cation/anion exchange resins present in pitcher POU devices. Results indicated that POU devices are capable of removing significant amounts of organic contaminants in water. However, removal of a specific compound depends on its molecular properties, treatment technology implemented, and water quality and lifetime of the cartridge. Keywords: perfluoroalkyl substance, pharmaceutical, point of use, POU, water treatment More than 1.1 billion people are unable to access safe drinking water (Sobsey et al. 2008). Even when clean water supply is available, compromised public pipes, old distribution systems, and introduction of anthropogenic contaminants can lead to unsafe water at the tap. Research suggests that improving water quality at the point of use (POU) is more effective than upgrades at source treatment plants in achieving a significant decrease in waterborne disease (Clasen et al. 2007, Esrey et al. 1991). Because of a lack of infrastructure to provide potable water, consumers in the developing world must find alternate strategies to ensure safe drinking water in the household (Greenstone & Hanna 2011). Although regulations for conventional contaminants exist and are more stringent in the developed world, a growing percentage of the population is suspicious of emerging contaminants and quality of tap water provided by crumbling distribution systems that are several decades old (Gelt 1996). For these reasons, over the years POU devices have been used in developing and developed countries to provide better finished water quality from both a health and aesthetic perspective. BACKGROUND In 1999 the primary drinking water sources for 67% of US residents were bottled water, POU devices, or both (WQA 1999), and today nearly 40% of all US consumers use a water purification device (Mintel 2011). Several states allow for communities to meet regulated water quality compliance through the use of JOURNAL AWWA POU devices (if proved to be effective) instead of centralized treatment (NSF International 2010). For instance, Arizona and Texas have permitted POU devices as a means for compliance for arsenic and radionuclides (ADEQ 2005). In Washington, D.C., thousands of POU devices were distributed to treat high levels of lead in drinking water (Edwards et al. 2009). Removal of radioactive elements using POU devices can be applied during emergencies and disaster zones (Sato et al. 2011) and was suggested in Japan after the disaster at the Fukushima nuclear facility. In developing countries, applications of POU devices in urban and rural areas have shown dramatic reduction in microbial contaminants and metals, resulting in better water quality (Luoto et al. 2011, Albert et al. 2010, Ngai et al. 2007). A POU treatment device is any unit that is designed to improve water quality by providing a barrier against both microbial and chemical contaminants in water within a home (Mintel 2011, Miles et al. 2009, Sobsey et al. 2008, Esrey et al. 1991). Several configurations of POU devices are commercially available, and technologies within a POU type device can be configured for a particular water quality. Thus, POU devices offer a high degree of flexibility, depending on the water quality to be treated and the desired produced water quality. Activated carbon-based POU devices are a viable option for removal of both organic compounds, such as pesticides, certain disinfection by-products, and some industrial chemicals (Smith & El Komos 2009, Ahmedna et al. 2004a) and 2015 © American Water Works Association SEPTEMBER 2015 | 107:9 E475 Anumol et al. | http://dx.doi.org/10.5942/jawwa.2015.107.0129 Peer-Reviewed metals such as arsenic, copper, lead, and manganese (Carriere et al. 2011, Deshomes et al. 2010, Moller et al. 2009, Ahmedna et al. 2004b, Lin et al. 2002). Although the ability of these devices to attenuate microbial and conventional chemical contaminants has been shown, studies on their feasibility to treat emerging organic contaminants are lacking. With increased anthropogenic influence on source waters because of a burgeoning population and limited availability of pristine water sources, contaminants not previously expected in waters are being detected. Contaminants such as pharmaceuticals and hormones are being detected in tap waters throughout the world (Félix-Cañedo et al. 2013, Mak et al. 2009, Heberer 2002) and pose an unknown health risk to a significant portion of the global population through chronic exposure via drinking water. Trace organic compounds (TOrCs). TOrCs are ubiquitous in the aquatic environment through wastewater discharge, surface runoff, and other point and nonpoint source inputs (Benotti et al. 2009, Focazio et al. 2008, Kolpin et al. 2002). Also known as contaminants of emerging concern, this group of compounds includes pharmaceuticals, personal care products, endocrine disruptors, and industrial compounds such as perfluoroalkyl substances. Humans are often exposed to low concentrations of TOrCs through drinking water because traditional treatment processes generally are unable to ensure complete removal of these substances (Benotti et al. 2009, Westerhoff et al. 2005). While some TOrCs are known to affect wildlife at concentrations occurring in wastewater discharge (Sanderson et al. 2004, Bevans 1995), the detection of most TOrCs at low ng/L concentrations in potable water is not expected to pose an immediate threat to public health (Bruce et al. 2010). However, synergistic and additive effects, long-term exposures, and low-dose impacts of individual and mixtures of TOrCs are largely unknown (Kim et al. 2009, Daughton & Ternes 1999). Beyond those compounds currently monitored, additional substances are certain to be detected as analytical technologies continue to improve. In addition, new compounds are constantly introduced into commerce, and others are formed through transformation within natural and engineered systems. Within the United States, regulatory actions to determine acceptable concentrations of TOrCs in water are generally slow and often controversial (Novak et al. 2011), and most countries currently do not have regulations in place for these compounds. For this reason, many consumers have decided to use bottled water and/or POU devices in hopes of gaining improved water quality and security, from both health and aesthetic standpoints. Treatment processes to attenuate TOrCs. Currently only advanced water treatment processes such as advanced oxidation processes, activated carbon, and desalting membranes such as reverse osmosis/nanofiltration are able to effectively attenuate most TOrCs’ resilience to conventional treatment such as coagulation and chlorination (Anumol et al. 2015, Rosario-Ortiz et al. 2010, Kimura et al. 2004). Advanced treatment approaches are rarely applied, however, because they are often prohibitively expensive and energy-intensive (Høibye et al. 2008, Jones et al. 2007). Furthermore, they require significant capital investment and upgrade of existing infrastructure that is often unaffordable in developing JOURNAL AWWA countries (Roccaro et al. 2013). This is especially true for small and isolated communities, some of which rely on small networks of wells that are not always interconnected. Desalting membrane processes such as reverse osmosis and nanofiltration are not only energy-intensive but also generally result in a loss of water through the creation of a waste stream from the consequential brine. Activated carbon requires large amounts of thermal energy to produce and regenerate and must be transported to and from locations repeatedly. Advanced oxidation is particularly attractive but can lead to formation of toxic and uncharacterized by-products (Heringa et al. 2011, Andrzejewski et al. 2008, Von Gunten & Holgne 1994). Moreover, even the highest purity of produced drinking water can be compromised in the distribution system through cross-connections, infrastructure failure, or intentional perturbations (Cleland 2010). Less than 1% of potable water generated in the United States is used for drinking and cooking (Cotruvo 2003), which means that most potable water is used as “service water” for nonpotable purposes. Advanced water treatment to reduce emerging contaminants incurs significant costs, both financial and environmental. Given these realities, future safe drinking water paradigms may shift toward providing the right quality of water for the intended application; in other words, the highest quality water is used for consumption and high-exposure use (i.e., bathing), and the remaining water for nonpotable applications is treated to a lesser standard to save energy, chemical, and infrastructure costs. The aim of the current study was to determine the effectiveness of five commercially available POU devices in removing a representative group of indicator TOrCs from two differing waters. The TOrCs were selected as model compounds, representing a larger class of organic compounds with diverse chemical structures and physical properties that may be present in drinking water. The application of POU devices in attenuating these TOrCs would be viable in both developed and developing countries to ensure safe drinking water at the point of use. MATERIALS AND METHODS Selection of POU devices. This research tested three commercially available pitcher POU (P-POU) devices—the Brita® Riviera eight-cup filter, 1 PUR™ CR-6000 seven-cup filter, 2 and ZeroWater® eight-cup filter3—and two refrigerator-fitted POU (R-POU) devices—the GE ® MSWF 4 and Whirlpool ® W10295370 filter.5 R-POU and P-POU devices were selected for testing because in the United States, nearly 40% of POU users have an R-POU device and 38% own a P-POU device (Mintel 2011). These POU devices are in use because they are small, easy to install, and easy to transport to rural and hardto-reach regions. The individual POU brands were selected on the basis of sales data provided by the Good Housekeeping Research Institute in New York, N.Y. (Genovese 2011). The P-POU devices all used activated carbon plus cation exchange resins, with the ZeroWater also containing an anion exchange resin (Brita 2015, Kaz USA 2013, Kellam 2012). While the exact amount of activated carbon and ion exchange (IX) resin in each filter is proprietary business information, a report found that 60% of the Brita filter consisted of activated carbon, 2015 © American Water Works Association SEPTEMBER 2015 | 107:9 E476 Anumol et al. | http://dx.doi.org/10.5942/jawwa.2015.107.0129 Peer-Reviewed and the remaining was filled with a cation exchange resin (Dean et al. 2010). The R-POU devices operated with solid block activated carbon (SBAC) technology and no IX resin. Each filter had an exhaustion time specified by the manufacturer either as volume of water passed through the filter or time of service; this was termed the manufacturer’s expected lifetime (MEL). In terms of volume of water, the MELs of the R-POU devices (GE MSWF = 1,136 L, Whirlpool = 757 L) were an order of magnitude greater than those of the P-POU devices (Brita = 151 L, PUR = 151 L, ZeroWater = 85 L). Each filter was tested in duplicate or triplicate in accordance with NSF/ANSI Standard 53 guidelines (NSF International/ANSI 2007). Selection of target compounds. The current research considered 16 indicator TOrCs selected on the basis of multiple criteria, including their resistance to conventional drinking water treatment, frequency of detection in finished water, and ease of analytical detection, as well as the representation of different chemical properties and class of compounds. Eight of the compounds chosen for the study have since been added to NSF/ ANSI Standard 401 to test emerging contaminant removal by POU/point-of-entry devices (NSF International/ANSI 2014). Table 1 lists the TOrCs analyzed in this study and shows their relevant chemical properties. Selection of test waters. Two waters were included in this study. The first, a potable water taken directly from the tap and originating from groundwater in the city of Tucson, Ariz. (Tucson GW). The second was a surface water from Colorado River water from the Central Arizona Project (CAP) canal in Arva Valley, Ariz. (CAP water). Experimental setup. Test waters were passed sequentially through 10-, 5-, and 1-µm cartridge filters to remove any large particles and then stored in a 2,000-L high-density polyethylene tank and held at room temperature (25ºC) for the duration of testing. The tank was mixed and aerated for 5 h to remove free chlorine, which was measured for both waters by the DPD method using a pocket colorimeter6 to ensure there was no free chlorine in the tank. Prior to beginning the experiment, each POU device was preconditioned with the test water as recommended by the manufacturer. The general conditions for testing POU devices for organics removal as stated in the NSF/ANSI Standard 53 were followed (NSF International/ANSI 2007). Water was fed to the three P-POU devices in 1-L increments followed by an equilibration time of 15 to 30 s before the subsequent 1-L addition. The R-POU devices were connected to a centrifugal pump that passed water through the devices at a fixed pressure of 35 to 40 psi. A calibrated flowmeter7 was used to monitor the volume of water passed through each POU device, and the flow rates for each were monitored at regular intervals. The test was discontinued after 150% of the MEL or if the flow rate of a device fell below 20% of its initial flow. Devices were operated for 10 h/d followed by a rest period of 14 h, during which the devices were stored at 4ºC. Water samples of 1 L were collected in silanized amber glass bottles for each POU device when the percentage of water passed through was equivalent to 0, 25, 50, 75, 100, 125, and 150% of the MEL in accordance with NSF/ANSI Standard 53 guidelines (NSF International/ANSI 2007). These guidelines state that filters with a performance indication JOURNAL AWWA device must be operated to 120% MEL and those without a performance indicator to 200% MEL; as a compromise and to maintain consistency, all tests in the current research were stopped at 150% MEL. The MEL at 0% was considered to be after the preconditioning of the POU device with test water. Control samples from the tank were collected at the same time to verify that no degradation of the TOrCs had occurred during the experiment. The average influent concentration of each TOrC after spiking for all experiments was between 140 and 1,300 ng/L. Samples were stored at 4°C immediately after collection. Analytical methods. All samples were extracted using a solidphase extraction (SPE) technique previously published (Anumol et al. 2013). Briefly, a 1-L sample was spiked with surrogate standards at 100 ng/L and extracted using a 200-mg hydrophilic–lipophilic balance cartridge8 using an automated SPE device.9 SPE cartridges were sequentially conditioned with 5 mL each of methyl-tert-butyl-ether (MTBE), methanol, and ultrapure water and then loaded with the samples at 15 mL/min. Cartridges were dried for 30 min using nitrogen and then eluted with 5 mL of methanol followed by 5 mL of 90:10 (volume per volume) MTBE-to-methanol, followed by concentration to 500 µL and reconstitution to 1,000 µL in methanol for analysis. Four different analytical methods were used to analyze the TOrCs in the current study. All compounds were analyzed with liquid chromatography using a binary pump10 while using two separate detectors. A triple quadrupole mass spectrometer11 was used to analyze all pharmaceuticals and personal care products, details of which are described elsewhere (Anumol et al. 2013). Estrone and bisphenol A were analyzed using liquid chromatography–mass spectrometry/mass spectrometry in negative electrospray ionization mode, and a fluorescence detector was used to quantify the two alkylphenols—nonylphenol (NP) and octylphenol (OP). RESULTS AND DISCUSSION TOrC breakthrough in P-POU filters. The P-POU devices were effective in removal of TOrCs, but their performance and removal efficiency depended on the brand of device, volume of water treated, water quality, and chemical properties of the individual TOrC. All P-POU devices were able to pass water at an acceptable flow rate to the MEL for Tucson GW but only the Brita filter managed to run until the experimental goal of 150% MEL; the PUR (125% MEL) and ZeroWater (110% MEL) filters had drop in flow rate of greater than 80%, which resulted in cessation of the test. In the CAP water, with a higher TOC of 3.7 mg/L, all three P-POU devices had lower average flow rates, but the Brita filter was able to reach the 150% MEL whereas the ZeroWater filter ceased at its MEL. The PUR filter suffered severe flow rate loss at 25% MEL in the CAP water, and the experiments were stopped prematurely. The higher TOC in the CAP water may also have affected the flow rates of the filters. The ZeroWater filter flow was, on an average, 28% faster in the Tucson GW (91 mL/min) compared with CAP water (65 mL/min), and flow for the Brita filter was more than 40% faster in the Tucson GW (332 mL/min) than in the CAP 2015 © American Water Works Association SEPTEMBER 2015 | 107:9 E477 Anumol et al. | http://dx.doi.org/10.5942/jawwa.2015.107.0129 Peer-Reviewed TABLE 1 Chemical properties and molecular structure of TOrCs studied Compound Use pKa Log Kow Log Dow (pH = 7.8) Log Dow (pH = 8.2) Atrazine Herbicide 1.7 2.3 2.3 2.3 Bisphenol Aa Plasticizer 10.1 4.1 4.1 4.1 Carbamazepinea Anti-seizure medication 13.9 2.8 2.6 2.6 DEETa Insect repellant 0.7 2.5 2.5 2.5 Estronea Steroid 10.4 4.3 4.3 4.3 Fluoxetine Antidepressant 9.5 4.2 2.0 3.2 Ibuprofena Analgesic 4.9 3.8 1.3 0.6 4-n-Nonylphenola Surfactant degradate 10.7 5.7 5.7 5.7 4-n-Octylphenol Surfactant degradate 10.4 5.3 5.3 5.3 JOURNAL AWWA 2015 © American Water Works Association Structure SEPTEMBER 2015 | 107:9 E478 Anumol et al. | http://dx.doi.org/10.5942/jawwa.2015.107.0129 Peer-Reviewed TABLE 1 Chemical properties and molecular structure of TOrCs studied (continued) Use pKa Log Kow Log Dow (pH = 7.8) Log Dow (pH = 8.2) PFOA Fluorosurfactant 2.8 5.1 1.8 1.8 PFOS Fluorosurfactant NA 5.4 3.1 3.1 Primidone Anticonvulsant 11.6 1.1 1.1 1.1 Sucralose Artificial sweetener NA –0.4 –0.3 –0.3 Sulfamethoxazole Antibiotic 6.0 0.8 0.5 0 TCEPa Flame retardant NA –1.2 –8.9 –9.7 Trimethoprima Antibiotic 7.1 1.3 1.0 1.3 Compound Structure DEET—N,N-diethyl-meta-toluamide, NA—not available, PFOA—perfluorooctanoic acid, PFOS—perfluorooctane sulfonate, TCEP—tris(2-carboxyethyl)phosphine, TOrC—trace organic compound aCompounds are listed for testing in NSF/ANSI Standard 401 (NSF International/ANSI, 2014); pKa and log D values were calculated from ChemAxon (www.chemicalize.com). water (181 ml/min). The average flow rate of the PUR filters was also slower in the CAP water (104 mL/min) compared with the Tucson GW (247 ml/min). Because the filters varied in terms of lifetime and performance, the authors used four criteria to compare and contrast the efficacy of the different POU devices in attenuating TOrCs: JOURNAL AWWA •• The individual removal efficiency (IRE) is defined as the removal of a specific TOrC at a given sampling point. •• The lifetime individual removal efficiency (LIRE) is defined as the average removal of a specific TOrC throughout the MEL (0–100% MEL). 2015 © American Water Works Association SEPTEMBER 2015 | 107:9 E479 Anumol et al. | http://dx.doi.org/10.5942/jawwa.2015.107.0129 Peer-Reviewed •• The overall removal efficiency (ORE) is defined as the average removal of all contaminants (∑TOrCs) at each sampling point by each filter. •• The lifetime overall removal efficiency (LORE) is defined as the mean percent removal of all contaminants throughout the MEL (0–100% MEL) of the filter. The ORE and LORE for each filter in the two waters are shown in Figure 1. At the 0% MEL sample in Tucson GW, the Brita filter achieved >85% removal of ∑TOrCs whereas the PUR and ZeroWater filters had nearly complete removal (>98%). At 100% of the MEL, the filters’ removal of all TOrCs in the Tucson GW decreased in the following order: ZeroWater (93.2%) > PUR (83.6%) > Brita (50.2%). In the CAP water, the OREs for all three filters were similar as in the Tucson GW (Brita = 91.6%, PUR = 98.5%, ZeroWater = 99.6%) at the initial sample point (0% MEL); at 100% MEL, and the ORE for the Brita filter was 51%, whereas ZeroWater removals were 87.9%. The PUR filter had greater than 98% ORE for the two sampling points (0 and 25% MEL) in the CAP water. Compared with the Tucson GW, the LORE in the CAP water decreased by an average of 11% in the Brita filter (70.7% versus 63.4%) and 4% in the ZeroWater filter (94.9% versus 91.6%). Because the PUR filter clogged and FIGURE 1 Overall removal efficiency of TOrCs by all POU devices in both water qualities Tucson GW Cap (SW) Brita Filter 100 40 80 Removal—% 60 60 40 20 20 25 50 75 100 125 150 LORE MEL—% 0 25 50 75 100 125 150 LORE MEL—% 40 80 80 60 40 20 0 0 25 50 75 100 125 150 LORE MEL—% Whirlpool Filter 100 Removal—% Removal—% GE Filter 100 0 60 20 0 0 ZeroWater Filter 100 80 Removal—% Removal—% PUR Filter 100 80 0 was unable to pass water at 25% of its MEL, no removal was assumed for the rest of its expected MEL in the CAP water, and this resulted in a LORE of 38.9% (compared with 90.6% in Tucson GW). The removal of all TOrCs in both the Tucson GW and CAP water was measured, and reduction of nine representative TOrCs showing different behaviors is shown in Figure 2. NP, OP, estrone, sucralose, and tris(2-carboxyethyl)phosphine (TCEP). The three P-POU devices have two principal attenuation strategies: adsorption by activated carbon and ion exchange by IX resins. The pH-corrected log KOW known as the distribution coefficient (log DOW) is generally used for assessing the adsorption of charged species at environmental pH. The high-log Dow compounds such as NP (5.7), OP (5.3), and estrone (4.3) were well removed by all P-POU devices throughout their life-spans, in contrast to hydrophilic compounds such as sucralose (–0.3) and TCEP (–1.2). For instance, in the Tucson GW, the LIRE of the Brita filter for OP, NP, and estrone was 97.8, 91.9, and 89.5%, respectively. In contrast, the Brita filter removed on average only 48.7% of sucralose and 69.3% of TCEP in Tucson GW throughout its lifetime. Similar to the ∑TOrC removal, individual contaminant removal was also negatively affected by the higher-TOC CAP water. This 60 40 20 0 25 50 75 100 125 150 LORE 0 0 25 50 MEL—% 75 100 125 150 LORE MEL—% CAP—Central Arizona Project, GW—groundwater, LORE—lifetime overall removal efficiency, MEL—manufacturer’s expected lifetime, POU—point-of-use, SW—surface water, TOrCs—trace organic compounds JOURNAL AWWA 2015 © American Water Works Association SEPTEMBER 2015 | 107:9 E480 Anumol et al. | http://dx.doi.org/10.5942/jawwa.2015.107.0129 Peer-Reviewed FIGURE 2 Removal of nine representative TOrCs by all five POU devices Trimethoprim Sucralose PFOA PFOS Carbamazepine Fluoxetine Octylphenol Nonylphenol Primidone Brita GE CAP (SW) Tucson GW 100 80 80 80 80 60 40 0 60 40 20 0 25 0 50 75 100 125 150 MEL—% Removal—% 100 Removal—% 100 20 60 40 20 0 25 25 50 80 80 100 50 75 100 125 150 MEL—% 96 94 40 92 0 0 75 100 125 150 90 0 100 25 MEL—% 25 50 50 75 100 125 150 MEL—% 80 99 60 98 97 40 96 20 0 0 CAP (SW) 100 80 Removal—% 60 20 50 100 98 20 25 25 Tucson GW Removal—% 100 Removal—% 100 0 0 Whirlpool CAP (SW) 40 40 0 75 100 125 150 MEL—% PUR 60 60 20 0 0 50 75 100 125 150 MEL—% Tucson GW Removal—% CAP (SW) 100 Removal—% Removal—% Tucson GW 95 0 100 99 60 98 97 40 96 20 0 25 50 75 100125 150 25 50 75 100 125 150 0 95 0 25 0 50 MEL—% 25 50 75 100 125 150 MEL—% ZeroWater Tucson GW 100 80 100 Removal—% Removal—% 80 60 90 40 80 20 60 40 20 70 0 CAP (SW) 100 0 25 0 25 50 75 100 125 50 75 100 125 150 MEL—% 0 0 25 50 75 100 125 150 MEL—% CAP—Central Arizona Project, GW—groundwater, LORE—lifetime overall removal efficiency, MEL—manufacturer’s expected lifetime, PFOA—perfluorooctanoic acid, PFOS—perfluorooctane sulfonate, POU—point-of-use, SW—surface water, TOrCs—trace organic compounds For the sake of clarity, insets have been added to some graphs to provide a better scale for showing slight variations in TOrC removals. GE filter results for all nine compounds in Tucson GW are shown at the top of the graph, but individual results cannot be discerned because they were virtually identical. Similarly, for GE filter results in CAP water, some compounds were completely removed (100% removal) and are grouped so closely at the top of the graph that individual results cannot be discerned. JOURNAL AWWA 2015 © American Water Works Association SEPTEMBER 2015 | 107:9 E481 Anumol et al. | http://dx.doi.org/10.5942/jawwa.2015.107.0129 Peer-Reviewed could be attributed to increased competition for pore sites on the activated carbon between TOrCs and natural organic matter (de Ridder et al. 2011). In the CAP water, the Brita filter LIREs for OP and estrone dropped to 95.1 and 72.5%, respectively, and the LIREs for sucralose and TCEP dropped to 36.7 and 55.4%, respectively. The ZeroWater filter showed similar trends, but compared with the Brita filter demonstrated higher IREs at each MEL in both waters. The LIREs of the ZeroWater filter for estrone, sucralose, and TCEP were 100, 85, and 92.4%, respectively, in Tucson GW and 98.5, 67.7, and 78.9%, respectively, in CAP water. OP was completely removed throughout the experiment in both waters by the ZeroWater filter. The lifetime removal of NP by the ZeroWater and Brita filters increased slightly in CAP water to 100 and 93%, respectively, compared with 93.2 and 92%, respectively, in the Tucson GW; this increase may be attributable to the high sorption capacity of NP to dissolved organic matter (Düring et al. 2002), which allowed for marginally better removal by the filter. In the Tucson GW, the PUR filter had LIREs of 98.8, 94.8, 100, 81.3, and 90.9% for OP, NP, estrone, sucralose, and TCEP, respectively. Because of the early stoppage of the PUR filter in the CAP water, it was difficult to make any significant observations, but the filter removed greater than 94% of all five compounds at both sampling points (0 and 25% MEL). Fluoxetine, atrazine, perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA). The cation exchange resins present in the three pour-through P-POU devices enhanced the removal of charged species in both test waters. Fluoxetine (pKa = 10.4, log Dow = 2.0) was primarily in cationic form in the Tucson GW (pH = 7.8), and its removal by all three P-POU devices was higher than removal of the neutral atrazine (pKa = 1.7) with a similar log Dow of 2.3. In the Tucson GW, the LIREs of fluoxetine for the Brita, PUR, and ZeroWater filters were 83.9, 97.8, and 99.6%, respectively, whereas atrazine removals for the three filters were 63.3, 89, and 93.6%, respectively. Removal of fluoxetine and atrazine by the three P-POU devices followed a similar trend in the CAP water (pH = 8.2). The LIREs of the two perfluoroalkyl substances—PFOS and PFOA—were lower than most other compounds for the Brita filter (57 and 52%, respectively) and PUR filter (84.8 and 79.4%, respectively), but PFOS and PFOA were well removed by the ZeroWater filter (96.7 and 97.5%, respectively). PFOS and PFOA are dominantly present in their anionic form in the environment (Kissa 1994). The presence of an anionic exchange resin in the ZeroWater P-POU device allowed greater removal of PFOS and PFOA, compared with the Brita and PUR P-POU devices in the two waters. As these cases illustrate, the octanol–water partition coefficient may be a good indicator for removal of nonionic species, but information on individual compound pKa values as well as the solution pH is essential to understand actual removal in activated carbon-based POU devices that also incorporate IX resins. TOrC breakthrough in R-POU filters. In line with the manufacturer’s specifications, the two refrigerator filters in this study were operated at much higher flow rates and treated greater volumes than the P-POU filters. In the Tucson GW, both R-POU filters, operated at constant pressure, maintained flow rates in excess of 1.4 L/min throughout the experiment, with an average flow rate JOURNAL AWWA of >1.6 L/min for the GE filter and 1.5 L/min for the Whirlpool filter. Similar to the P-POU devices, the flow rate of both R-POU devices was negatively affected by the CAP water. Although the GE filter reached the experimental goal of 150% MEL in both waters, its average flow rate was 1.3 L/min in the CAP water (~20% reduction compared with the Tucson GW). Similar to the PUR P-POU filter, the flow rate of the Whirlpool R-POU device in the CAP water was significantly reduced from 1.6 L/min to below 0.4 L/min, resulting in termination of the experiment just before 50% MEL (48%). The two R-POU devices were very effective (>96%) at removing TOrCs in the Tucson GW at each sampling point throughout the experiment. The GE filter had OREs between 96.9 and 99.6% throughout the experiment in the Tucson GW with a LORE of 98.4%. The Whirlpool filter had OREs between 96.8 and 99.7% and average removal of 99% throughout its MEL. On the basis of this testing, both R-POU devices would pass the requirements for the NSF/ANSI Standard 401 testing for emerging contaminant removal in the Tucson GW (NSF International/ANSI 2014). TOrC removal efficiency of both R-POU devices was negatively affected by the constituents of the CAP water; for the GE filter in the CAP water, OREs were between 83.3 and 99.9% throughout the MEL, with a LORE of 90.1%. Removal efficiency declined steadily with volume of water passed through the GE filter, resulting in a 17% reduction in removal efficiency of TOrCs from 0% through to 100% MEL in the CAP water. There was continued gradual decline in performance past the MEL with an ORE of 74% at the end of the experiment (150% MEL). The ORE of the Whirlpool filter in the CAP water from start to exhaustion (48% MEL) was 97.1 to 99.9% at the three sampling points. However, the Whirlpool filter was unable to reach even half its expected MEL in this water quality because of flow rate decline; therefore, the LORE was 59.3% because no removal was assumed from 50 to 100% MEL for this filter. Although specific information on average particle size and distribution of the carbons was not available, both R-POU devices use SBAC, which is packed with much smaller particle sizes of carbon than the loosely packed carbon in P-POU devices. Hence, the R-POU devices have larger surface areas, allowing for greater physical adsorption of organic contaminants. Both the GE and Whirlpool R-POU devices are listed as NSF certified Class I particulate-reduction devices by the manufacturers, meaning that according to NSF/ANSI Standard 42, these POU devices are certified to reduce at least 85% of particles from 0.5 to <1 µm in size (NSF International/ANSI 2012). The smaller carbon particle sizes could result in higher carbon surface area, which provides more binding capacity for TOrCs than does the loosely packed carbon in the P-POU devices. Additionally, the source of carbon used to make the two types of POU devices may be different and could be a contributing factor to TOrC removal. NP, OP, estrone, sucralose, primidone, PFOS, PFOA, ibuprofen, and sulfamethoxazole. Both R-POU devices had LIREs of >89% for all contaminants tested in the Tucson GW. The hydrophobic alkylphenols (NP, OP) were completely removed by the GE filter in both waters and by the Whirlpool filter in the Tucson GW throughout the experiment (150% MEL). The Whirlpool filter also 2015 © American Water Works Association SEPTEMBER 2015 | 107:9 E482 Anumol et al. | http://dx.doi.org/10.5942/jawwa.2015.107.0129 Peer-Reviewed JOURNAL AWWA half the mass rejection (0.27 mg) compared with the other two. The MLR of all P-POU devices was lower in the CAP water, indicating a loss of performance in higher TOC water. MLR = (∑TOrC Cin × LIRE) × Vol (up to 100% MEL) (1) in which MLR is the mass loading rejection (mg), Cin is the influent concentration (mg/L), and Vol is the volume of water treated (L). The refrigerator filters were more effective than the pitcher (pour-through) filters in terms of both TOrC attenuation at each percent MEL and overall mass rejection. The LOREs of the GE and Whirlpool filters in the Tucson GW were 98.7 and 99.2%, respectively, compared with 70.7, 90.6, and 94.9% for the Brita, PUR, and ZeroWater P-POU devices, respectively. The GE R-POU filter was able to treat approximately 10 times the volume of the P-POU filters, and the Whirlpool filter treated five times as much in the Tucson GW and twice as much in the CAP water. In terms of MLR, the GE filter was able to remove 7.56 mg of TOrCs in the Tucson GW, which was greater than seven, 10, and 12 times more than the PUR, Brita, and ZeroWater filters, respectively. The Whirlpool R-POU filter had a slightly greater LORE than the GE filter in the Tucson GW but treated only 67% of the volume of water and had an MLR of 5.06 mg. Like the P-POU devices, both R-POU devices were negatively affected by the CAP water, with 6.81 and 2.43 mg of MLR achieved by the GE and Whirlpool R-POU devices, respectively. Cost comparison of POU treatments. Eventually, the use of POU devices to provide additional attenuation of contaminants in water will be determined by their economic feasibility in comparison with use of bottled water and other newer water treatment technologies on the market. With this in mind, a cost comparison of the different FIGURE 3 10 Mass load rejection (mg) of all five POU devices in both water qualities Tucson GW CAP (SW) 7.58 8 6 MLR—mg removed >98% of these two contaminants in the CAP water at all three sampling points. In the CAP water, the GE R-POU device had LIREs that were higher for the hydrophobic compounds such as NP (100%), OP (100%), and estrone (99.8%) and lower for nonionic hydrophilic compounds such as sucralose (63.1%) and primidone (91%). This reduction in removal efficacy was greater at later MELs (especially after the 100% MEL), with average removals of only 24.5 and 62% observed for sucralose and primidone, respectively. The Whirlpool filter had higher IREs of sucralose compared with the GE filter in the CAP water at corresponding MELs but was not able to reach even half the MEL because of poor flow rate. The absence of IX resins in the R-POU devices may have hindered the LIREs of ionized TOrCs, especially in the CAP water. The lifetime removals of fully or partly ionic species such as PFOS (49.3%), PFOA (66.6%), ibuprofen (84%), and sulfamethoxazole (73.4%) by the GE POU device in the CAP water were significantly lower than for uncharged TOrCs. The removal efficiency for ionic species seemed to follow a pattern based on proportion of compound present in ionic form. On the basis of pKa values, less than 20% of sulfamethoxazole and ibuprofen were present in their charged form in the CAP water, whereas PFOA and PFOS were entirely in their anionic form. Therefore, better removal of sulfamethoxazole and ibuprofen compared with PFOS and PFOA may be attributable to the adsorption of the neutral form of these compounds by the SBAC even though their log Dow values are smaller. Although the R-POU devices did not have any IX resins, electrokinetic adsorption may have accounted for some anionic species removal whereas physical/mechanical adsorption because of enhanced surface area and more uniform size distribution of carbon in SBAC POU devices may also have assisted in removal of these contaminants. Summary of POU device efficacy. All POU devices were shown to be effective in attenuating a wide variety of TOrCs in the test waters. The range of removal efficacy depended on the type of POU device, the water quality, the volume treated, and the chemical properties of the specific trace contaminant. The ZeroWater P-POU device was the best-performing pitcher filter in terms of LORE, with >92% in the Tucson GW and >87% in the CAP water throughout the experiment. However, the ZeroWater P-POU filter was rated to treat only about 58% of the Brita and PUR filters; a comparison of overall average removals on a volume-treated basis showed that the PUR and ZeroWater filters had very similar removals (94.6%) in the Tucson GW, whereas the Brita filter had >80% removal at the same volume. Removals by both the Brita and ZeroWater filters were reduced in the CAP water, and the PUR filter was able to pass water at an acceptable flow rate to only 25% of its MEL. To account for the different volume of water treated by each filter, mass load rejection (MLR) was calculated for each POU device as shown in Eq 1 and presented in Figure 3. The MLR can be defined as the total mass of contaminants rejected by the filter during its specified lifetime (0–100% MEL). The MLR of the three P-POU devices in Tucson GW showed that the PUR filter had highest mass rejection (0.99 mg) followed by the Brita (0.74 mg) and ZeroWater (0.59 mg). However, in the CAP water, the Brita filter had the greatest mass rejection (0.66 mg) closely followed by the ZeroWater (0.56 mg), whereas the PUR filters’ early stoppage resulted in less than 5.06 4 2 1.0 0.8 0.99 0.74 0.59 0.6 0.4 0.66 0.2 6.81 2.42 GE Whirlpool 0.56 0.27 0.0 Brita PUR ZeroWater MEL—% CAP—Central Arizona Project, GW—groundwater, MLR—mass load rejection, POU—point-of-use, SW—surface water 2015 © American Water Works Association SEPTEMBER 2015 | 107:9 E483 Anumol et al. | http://dx.doi.org/10.5942/jawwa.2015.107.0129 Peer-Reviewed TABLE 2 Cost comparison of five POU devices Brita Riviera PUR CR-6000 ZeroWater Eight-Cup Filter GE MSWF Whirlpool W10295370 32.99 21.99 33.99 700–3,000 410–2,500 8 7 8 NA NA Replacement filter cost—$ 7.99 10.99 14.99 41.99 39.99 Filter lifetime—L 757 Parameter Estimated capital costa—$ Capacity—cups 151 151 85 1136 Recommended filter replacement—months 2 2 2 6 6 Average filter lifetimeb—days 19 19 11 142 95 Annual cost of ownershipc—$ 153 211 498 109 154 0.05 0.07 0.17 0.04 0.05 Annual cost per liter treatedb—$/L NA—not applicable, POU—point-of-use aCost of purchasing either the pitcher filter or a compatible refrigerator (data from manufacturer’s website) a family of four consuming 2 L/d each cost of ownership does not consider the capital cost of the refrigerator bAssuming cAnnual POU devices was conducted with respect to capital required, cost of replacement filters and annual cost of ownership (Table 2). The annual cost of ownership was calculated on the basis of the cost of a replacement filter (with the assumption that the filter will run for its MEL and will be used by a family of four, each consuming 2 L/d of water). Because of the high variability in the cost of purchasing a refrigerator or other similar device to operate the R-POU units, the annual cost of ownership did not consider the capital cost (though estimated capital cost is included in Table 2). Furthermore, the consumer may already own a refrigerator, the cost of which will be offset by the other ancillary benefits it provides. The GE R-POU device had the lowest annual cost at $109, followed closely by the Brita P-POU filter ($153) and Whirlpool R-POU device ($154). The ZeroWater P-POU filter ($498) had the highest annual cost, primarily because of its lower expected lifetime in terms of volume of water treated, which would necessitate more frequent replacement of the filter. When costs per liter of water treated were compared, all of the POU devices had annual costs below $0.20/L. While a basic cost analysis is provided here, it is not in the scope of this article to provide a detailed assessment of the economic suitability and environmental sustainability of these devices. The authors encourage further study into a cradle-to-grave analysis of POU technologies, including detailed life cycle assessment of these devices and cost comparisons with bottled water and other advanced treatment technologies for providing high quality water. CONCLUSION This study demonstrated that POU devices have the ability to reduce the concentration of a diversity of emerging organic chemical contaminants in potable water, complementing the removal of metals, inorganics, and microbes researched by others (Sato et al. 2011, Deshomes et al. 2010, Miles et al. 2009). Furthermore, these devices provide an additional barrier to accidental or intentional contamination that may occur in the distribution system, such as cross-connections, loss of pressure, or acts of terrorism (Zhong et al. 2012). The results presented here indicate that POU devices can be considered as an alternative to full-scale treatment JOURNAL AWWA processes as a means of attenuating trace organic compounds in regions that have poor infrastructure and are in need of clean drinking water. The application of POU devices may also be considered an additional final barrier in water treatment to provide the highest-quality drinking water to concerned consumers and to increase public confidence, especially when impaired source waters are used, such as in potable water reuse applications. Certainly any benefits are conditional on the proper maintenance and timely replacement of POU components as specified by the manufacturer. Previous studies have shown the cost-effectiveness of POU devices compared with installation of a centralized unit process to achieve a particular water quality (Quintana et al. 2010). However, further cost–benefit analysis is required to understand the life-cycle costs and benefits of a POU system. In light of global water sustainability challenges of water quality and quantity, POU devices could lead to a paradigm shift that allows for more appropriate use of the highest-quality water versus service water. ACKNOWLEDGMENT This study was funded in part by the Good Housekeeping Research Institute in New York, N.Y. The authors thank Armando Durazo, Colin Richards, and Amanda Veitch from the University of Arizona (Tucson) for assistance with solid-phase extraction of the samples. The authors also acknowledge Jeffrey Bliznick and Gaylen Bennett at the Environmental Research Laboratory of the University of Arizona for help in setting up the experiments. The authors are grateful to Agilent Technologies (Santa Clara, Calif.) and especially Joe Weitzel for providing instrumentation and technical support used in this work. ABOUT THE AUTHORS 2015 © American Water Works Association Tarun Anumol is a liquid chromatography/ mass spectrometry applications scientist at Agilent Technologies in Wilmington, Del. At the time of this study, he was a PhD student in the Department of Chemical and Environmental Engineering at the University of Arizona from which he graduated in SEPTEMBER 2015 | 107:9 E484 Anumol et al. | http://dx.doi.org/10.5942/jawwa.2015.107.0129 Peer-Reviewed August 2014. In addition to holding a doctorate, Anumol holds a master of science degree in civil and environmental engineering from Carnegie Mellon University in Pittsburgh, Pa., and a bachelor of technology degree in chemical engineering from Anna University in Chennai, India. Bradley O. Clarke is a senior lecturer at RMIT University in Melbourne, Australia. Sylvain Merel is a research professor at the University of Tübingen in Germany. Shane A. Snyder (to whom correspondence may be addressed) is a professor in the Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721 USA; [email protected]. Brita, 2015. See What We Filter Out of Your Tap. www.brita.com/why-brita/whatwe-filter/ (accessed June 15, 2015). Bruce, G.M.; Pleus, R.C.; & Snyder, S.A., 2010. Toxicological Relevance of Pharmaceuticals in Drinking Water. Environmental Science & Technology, 44:14:5619. http://dx.doi.org/10.1021/es1004895. Carriere, A.; Brouillon, M.; Sauve, S.; Bouchard, M.F.; & Barbeau, B., 2011. Performance of Point-of-Use Devices to Remove Manganese From Drinking Water. Journal of Environmental Science and Health Part A: Toxic/ Hazardous Substances and Environmental Engineering, 46:6:601. http://dx. doi.org/10.1080/10934529.2011.562852. 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