Journal of Environmental Science and Health, Part A (2013) 48, 753–759 C Taylor & Francis Group, LLC Copyright  ISSN: 1093-4529 (Print); 1532-4117 (Online) DOI: 10.1080/10934529.2013.744616 Assessing an intermittently operated household scale slow sand filter paired with household bleach for the removal of endocrine disrupting compounds TIMOTHY J. KENNEDY1, TODD A. ANDERSON2, E. ANNETTE HERNANDEZ1 and AUDRA N. MORSE1 1 Department of Civil and Environmental Engineering, Texas Tech University, Lubbock, Texas, USA The Institute for Environmental and Human Health (TIEHH), Department of Environmental Toxicology, Texas Tech University, Lubbock, Texas, USA Downloaded by [Erzincan Universitesi ] at 06:45 31 July 2015 2 Endocrine disrupting compounds (EDCs) are a contaminant of emerging concern throughout the world, including developing countries where centralized water and wastewater treatment plants are not common. In developing countries, household scale water treatment technologies such as the biosand filter (BSF) are used to improve drinking water quality. No studies currently exist on the ability of the BSF to remove EDCs. In this experiment, the BSF was evaluated for the removal of three EDCs, estrone (E1), estriol (E3), and 17α-ethinyl estradiol (EE2). Removal results were compared to the slow sand filter (SSF) from the literature, which is similar to the BSF in principal but comparisons have revealed differences in removal of other water quality parameters between SSF and BSF. In general, the BSF minimally removed the compounds from spiked lake water as removal was less than 15% for all three compounds, though mass removal much higher than other studies in which the SSF was used. Household bleach was added to the rate was BSF effluent as suggested in order to achieve different Cl- concentrations (0.67, 2.0, 5.0, and 10.0 mg/L) and subsequent removal of EDCs by oxidation was examined. Concentrations were reduced > 98% for all compounds when the Cl- concentration was greater than 5 mg/L. Removal efficiency was > 50% at the 0.67 mg/L Cl- concentration, while almost 70% removal was observed for all compounds at the 2.0 mg/L Cl- concentration. Keywords: Endocrine disrupting compounds (EDCs), developing world, biosand filter (BSF), estrogen, slow sand filtration (SSF). Introduction A new concern has developed in the past decade in aquatic systems treatment. Endocrine disrupting compounds (EDCs) and pharmaceuticals and personal care products (PPCPs) have been found in both ground and surface waters as well as in the influent to wastewater and drinking water treatment plants.[1–8] EDCs and PPCPs reach soil and aquatic environments through agricultural runoff, wastewater treatment plant discharge, the spreading of manure, and application of treated wastewater to land.[4–6,9] Concentrations of these compounds have typically been reported in rivers and wastewater effluents at µg/L to ng/L levels. Research has shown that at these concentrations, EDCs and PPCPs may be biologically active and could be considered a risk to human and wildlife health.[10–12] Sex hormones such as estrogens are secreted Address correspondence to Audra N. Morse, Department of Civil and Environmental Engineering, Texas Tech University, Lubbock, TX 79409-1023, USA; E-mail: audra.n.morse@ttu.edu Received May 2, 2012. naturally by both men and women and are EDCs of concern.[5,12,13] Estrogens can bioaccumulate in body fat until eventually reaching a significant dose.[13] These chemicals can then be released from body fat during starvation, pregnancy, and through colostrums/milk.[13] After an extensive literature search, only a few studies could be located documenting the occurrence and fate of PPCPs or EDCs in the developing world. Therefore, three EDCS of potential concern in the developing world were examined; two natural steroids (estrone (E1) and estriol (E3)) and one synthetic steroid used in contraceptives (17αethinyl estradiol (EE2)). E1 and E3 were chosen as they are produced naturally by humans and animals, and are present everywhere in the world, thus are potentially a worldwide problem in recycled water.[14–16] While birth control is not as common in the developing world when compared to the developed world, usage has seen an increase over the last few years and is projected to have continued growth,[17] thus EE2 could be used as an indicator of a common EDC found in the developing world. Current water and wastewater treatment plants are not designed specifically for the removal of EDCs, though many studies have shown promising removal rates. Wastewater Downloaded by [Erzincan Universitesi ] at 06:45 31 July 2015 754 treatment plants using activated sludge systems can remove E1 from 25% to greater than 99%.[1,18,19] The activated sludge process in wastewater treatment plants (WWTP) is known to remove E3 and EE2 at efficiencies of 18% to greater than 99%, and 34% to greater than 99%, respectively.[1,18,19] Removal in activated sludge plants is achieved through either sorption or biodegradation.[5,18,20–22] Studies involving advanced oxidation processes used in both water and wastewater treatment plants have shown varying reduction efficiency depending on the oxidizer used. E1 has shown reduction efficiencies of 66% to greater than 99% when ozone is used as the oxidizer. E3 and EE2 reductions were similar when ozone was used, with reductions of 56% to greater than 99%, and 70% to greater than 99%, respectively.[1,18,23–25] A more common oxidizer, frequently used as a disinfectant, chlorine, reduced E1, EE2, and E3 from 70% to greater than 99% in multiple studies.[6,23,24] Although many studies have been conducted in developed countries that employ tertiary treatment technologies previously mentioned (ozone, granular activated carbon, UV), few studies have been conducted in the developing world or using smaller scale technologies commonly used in these countries. The lack of attention in the developing world has occurred in spite of the probability of exposure to EDCs being higher as treatment facilities (both water and wastewater) are not as frequent.[14] Little data are available on the concentrations of EDCs and PPCPs in these countries. The lack of data is likely due to the fact that developing countries are dealing with more immediate problems,[14] such as the presence of bacteria, parasites, and viruses in water. While centralized water treatment plants do exist in large cities, a large portion of the population in developing countries live in urban areas where drinking water is obtained wherever possible.[26] In the urban cases, water comes from both surface and groundwater sources that are often contaminated.[26,27] To help solve the problem of decentralized drinking water treatment, point of use treatments (POUs) have been employed. A POU that has been employed worldwide is the biosand filter (BSF).[28] The BSF was developed by Dr. David Manz at the University of Calvary.[29] Similar to a slow sand filter, the BSF treats water by pouring raw (potentially contaminated) water through a volume of sand. Over time, like slow sand filtration, the BSF naturally builds up a biological layer, or schmutzdeke, in the top layer of sand that aids in the treatment of contaminated water. Once water passes through the schmutzdeke, the mechanisms of inactivation (predation or degradation), physical straining, and attachment to sand particles are employed for removal of pathogens in the raw water. To increase bacterial reduction it is suggested that household bleach (NaOCl) is added after filtration has been completed.[30] Although there has been little concern shown in developing countries due to more immediate water problems such as bacteria, parasites, and virus treatment, this issue Kennedy et al. is one that is facing the developing world and should not be overlooked. Although most water in the United States is treated by a wastewater treatment plant, in the developing world effluents may be disposed of in the same surface water that drinking water is drawn from with little to no further treatment. The purpose of this experiment was to evaluate the ability of the BSF to remove E1, E3, and EE2 independently, as well as the effectiveness of the addition of household bleach (5.25% NaClO) at concentrations of 0.67, 2.0, 5.0, and 10.0 mg/L Cl− at removing the target compounds. Materials and methods BSF experimental setup R A plastic Hydraid BSF was obtained from Triple Quest (Grand Rapids, MI). The filter was assembled as shown in Fig. 1, in accordance with Triple Quest guidelines,[30] at Texas Tech University (TTU), in Lubbock, TX. The BSF received 20 L of lake water from Canyon Lake # 2 (Lubbock, TX) daily for 3 weeks prior to the beginning of the experiment to ensure the biofilm in the filter was mature. Experimental design Twenty liters of lake water (Canyon Lake #2 Lubbock, TX) was spiked with 100 mL of a 1000 mg/L estrogen solution to a concentration of 5 mg/L. The estrogen solution (E1, E3, 17α-ethinyl estradiol) was prepared in acetonitrile (HPLC grade) to a concentration of 1000 mg/L. A stock Fig. 1. Circular cross-section of the hydraid (R) biosand filter used in the experiment. 755 Downloaded by [Erzincan Universitesi ] at 06:45 31 July 2015 Using household bleach for the removal of endocrine-disrupting compounds solution of the estrogen mixture was made fresh each day. The BSF was challenged with the spiked lake water once daily for 7 days. Following the initial 7-day experiment, filters were cleaned according to the manufacturers guidelines [30] and the experiment was repeated. The high concentration (5 mg/L) of estrogen compounds was used to determine the BSFs ability to retain and/or degrade the PPCPs and EDCs without intense sample preparation, similar to previous studies.[31–33] Samples were collected 3 times during the week from the standing water above the sand in the BSF (Fig. 1) before spiked lake water was filtered and after the filter run was complete to ensure degradation was not occurring overnight. Effluent samples were collected 3x weekly in 40-mL amber vials from the spout of the BSF after 1, 5, and 20 L had been filtered. Sample points were chosen to represent water that had been allowed overnight degradation (1 and 5 L) and water in which no “pause” time was allowed (20 L). After filtering was complete, 4 grab samples (80 mL each) were obtained from the BSF effluent bucket. Household R bleach (Clorox ) was then added in the amount suggested in the Hydraid handbook[30] at 20 drops (1 mL) per 20 L (0.67 mg/L Cl−) to simulate current standard operating procedures. Household bleach was then added to the three remaining effluent grab samples at predetermined concentrations (2, 5, and 10 mg/L Cl−). Each sample was transferred into a 2-mL amber glass HPLC auto-sampler vial, sealed with PTFE/rubber septa, and stored at 4◦ C until analysis (< 24 h). Test chemicals Estrogen compounds E1 (purity > 99%), E3 (purity > 99%), and EE2 (purity > 98%) were obtained from Sigma Aldrich (St. Louis, MO, USA). A detailed description of the physical properties as well as sorption/desorption behavior of these compounds can be found in the methods described by Karnjanapiboonwong et al.[9] Ultra-pure water (>18M) was provided by a Millipore system. A combined stock solution containing E1, E3, and EE2 was prepared at 100 ppm in 100% HPLC grade acetonitrile obtained from BDH (West Chester, PA, USA) and diluted for analytical standards. Spiking solutions were prepared in 100% HPLC-grade acetonitrile at 1000 mg/L. Chemical analysis Concentrations of samples and standards were determined by reverse phase high performance liquid chromatography (HPLC) with a Grace Econosphere C-18 column (250 × 4.6 mm, 5 µm, Deerfield, IL, USA), and Chemstation analytical software (HP series 1100, Hewlett-Packard, Avondale, PA, USA). The sample injection volume was 50 µL for each sample, while the eluent flow was set at 0.8 mL/min Table 1. Summary of concentrations (mg/L ± RSD) of estrogens during the experiment. Influent (n = 33) BSF 1 L (n = 21) BSF 5 L (n = 21) BSF 25 L (n = 21) BSF Effluent Grab Sample (n = 12) E1 (mg/L) EE2 (mg/L) E3 (mg/L) 3.97 ± 10% 3.23 ± 9% 3.21 ± 9% 3.62 ± 9% 3.36 ± 11% 4.77 ± 8% 4.16 ± 11% 4.30 ± 9% 4.82 ± 8% 4.20 ± 10% 3.92 ± 13% 3.10 ± 12% 3.34 ± 12% 3.26 ± 8% 3.25 ± 10% using an acetonitrile-water ratio of 60:40. Detection wavelength was 200 nm for E1, E3, and EE2. Results and discussion Average effluent concentrations after BSF filtration, along with spiked influent concentrations of target compounds are presented in Table 1 as well as relative standard deviations. Loss of the target compounds has been interpreted to be due to the filtering process and chemical oxidant, as the samples taken above the sand before adding the daily 20 L charge were similar to those taken from the standing water the previous day after filtration was complete. Removal of compounds by BSF A comparison of spiked lake water influent and BSF effluent average concentrations of target compounds is shown in. As seen in the figure, removal efficiency was low for E1, EE2, and E3 in the BSF. Average removal efficiency was greatest for E3 (15.6 ± 12%), while E1 was only slightly lower (14.4 ± 12%). Average removal efficiency for EE2 (11.4 ± 11%) was less than E1 and E3. Overall, the average removal efficiencies of estrogen compounds by the BSF are similar to studies previously performed at water and wastewater treatment plants in which slow sand filtration was employed.[1,34,35] Average concentrations of target compounds at different filtered volumes, as well as relative standard deviations are presented in Fig. 2. Removal in the BSF is likely due to sorption to sand and biomass, as well as biodegradation by the microorganisms living throughout the BSF. In theory, removal of EE2 should be the greatest if removed by sorption, as EE2 has the highest octanol-water partition coefficient (logKow ), and thus is the most hydrophobic of the target compounds. While the results indicated the opposite of theory, previous studies have shown that among the estrogens commonly studied, E3 has shown the highest sorption affinity, not EE2.[18] Sorption likely contributed to the removal of the estrogen compounds, but overall it is likely that it was not the greatest contributor to removal. Sand is the primary media in the BSF, and has a low organic carbon content, thus is not an optimal media for adsorption of the estrogens 756 Kennedy et al. 6 Influent Effluent Concentration (mg/L) 5 4 3 2 0 E1 EE2 E3 Fig. 2. Influent and effluent concentrations of (A) E1; (B) EE2; and (C) E3 during labratory study of the BSF error bars represent standard deviation. to occur. Khanal et al.[19] determined that pure sand had an adsorption capacity coefficient (Kf ) for free estrogen of 4, while media with high organic carbon content, such as LaDelle-silt Loam had a Kf of 667. Biodegradation in the filter by the microbial population also contributed to the removal of the estrogen compounds. Higher removal efficiency of the target compounds that occurred in the 1 and 5 L samples compared to the 25 L sample is likely due to biodegradation. Samples taken at 1 and 5 L remained in the BSF for 24 hours following completion of a filtration run, while the 25 L sample point represents water only treated by the BSF with no time allowed for biodegradation. Microorganisms throughout the BSF use organic matter that is trapped as substrate, thus explaining the slight increase in removal of the estrogen compounds observed in the 1 and 5 L samples. Studies have shown that natural estrogens (E1 and E3) are generally readily biodegradable by bacteria such as E. coli,[19,36] while EE2 is not as easily biodegradable as natural estrogens due to the ethinyl group, which can sterically hinder substratereceptor binding and enzyme expression.[18] The microorganisms in the BSF were capable of degrading the estrogens as shown by the mass removal rate, but increased mass removal could be observed if the 120 100 Removal Efficiency Downloaded by [Erzincan Universitesi ] at 06:45 31 July 2015 1 0.67 mg/L Cl2 mg/L Cl5 mg/L Cl10 mg/L Cl- 80 60 40 20 0 E1 EE2 E3 Fig. 3. Removal efficiencies of estrogen compounds after treatment of BSF effluent with different Cl− doses. Error bars represent one standard deviation of the mean (n = 6 for 2, 5, and 10 mg/L Cl−, while n = 5 for 0.67 mg/L Cl− concentration). 757 Downloaded by [Erzincan Universitesi ] at 06:45 31 July 2015 Using household bleach for the removal of endocrine-disrupting compounds microorganisms were given adequate time to adapt to the occurrence of the estrogens.[37] Previous studies indicate that the organisms in slow sand filters that degraded the target compound grew to a larger population and were acclimated to the compounds at day 150, at which point removal rates increased from negligible to 96 ± 10% for E1 and 41 ± 21% EE2.[35] It is likely that if the experiment were to continue, increased mass removal rates by the microorganisms would occur as the current study only lasted 14 days and the population had not fully acclimated or reached its growth potential. Studies involving SSFs were used for comparison as no other studies involving the BSF were available. Although the SSF and BSF are similar in design, previous studies involving the BSF have shown that removal of various water quality parameters in the BSF vary from the SSF.[38,39] More studies are needed to further examine removal mechanisms in the BSF. Removal of compounds by chlorination After filtration, the addition of household bleach is suggested as a final disinfection process in the developing world. Increased removal efficiency of estrone (E1) was seen as the concentration of chlorine was increased (Fig. 3). At 10 mg/L Cl−, concentrations of estrone were not detected, while at 5 mg/ L the concentrations were only above the limit of detection for 6 of the 48 samples analyzed, with an average removal efficiency of 99 ± 2%. Average removal efficiency of E1 at 2.0 and 0.67 mg/L Cl− were 64 ± 7% and 56 ± 14%. As expected due to similar chemical structures, removal efficiency of 17α-ethinyl estradiol (EE2) and estriol (E3) were similar to the removal of E1 for all of the concentrations. For the 10 mg/L Cl− dose, EE2 and E3 were not below the limit of detection, while at 5 mg/L Cl−, 98 ± 2% and 99 ± 2% removal occurred for EE2 and E3, respectively. The current standard operating procedure dose (0.67 mg/L Cl−) removed 58 ± 15% and 52 ± 17% of EE2 and E3, respectively, while the 2 mg/L Cl− dose removed 66 ± 6% for both compounds. Previous experimental studies have shown removal efficiencies of greater than 70% for all three target compounds when chlorine is used as an oxidizer.[6,20,24,40,41] The previous studies examined removal in water treatment when Cl− concentrations were greater than 2 mg/L, hence the reason the current suggested dose was not as effective at removing the compounds as previous studies. The halflives of the three target compounds at slightly lower and higher concentrations than the current suggested dose are presented in Table 2.[40] The removal efficiency observed at the 0.67 mg/L Cl− dose was consistent with the previously calculated half-lives. Our results indicate that under the current standards of practice the dose is only high enough to remove about half of the target compound, while if the Table 2. Half-lives of estrogens at various chlorine concentrations. Table adapted from Deborde et al., 2004.[40] t1/2 (min) Compound 17α-Ethinylestradiol Estrone Estriol Chlorine Concentration 0.5 mg/L Chlorine Concentration 1.0 mg/L 14.6 12.5 14.4 7.3 6.3 7.2 dose is increased to 5 mg/L Cl− removal greater than 98% of the target compounds are removed. Conclusion Endocrine disrupting compounds (EDCs) are an increasing worldwide concern as they affect human health and ecological systems. While many studies have examined treatment of aquatic systems in the developed world, few have examined those used in the developing world, thus little knowledge is available to determine the effects of EDCs on people or ecosystems in the developing world. Not only do few studies exist documenting occurrence of EDCs, even fewer exist documenting effectiveness of the current treatment technologies to remove emerging contaminants. Water and wastewater treatment technologies used in the developing world differ from those in the developed world. Because many people live in remote rural areas, centralized water and wastewater treatment technologies are not an option. Thus, the population must use point of use (POU) water treatment technologies to improve water quality. In this study, the efficiency of a POU technology, the BSF used in conjunction with household bleach at different doses to remove the hormones E1, EE2, and E3 was investigated. The results indicated that estrogen percent removal efficiency in the BSF alone is low, but similar in comparison to previous studies on a similar technology, the slow sand filter (SSF). No comparison could be made to other BSF studies as this study is the first involving the BSF. While SSFs are similar to the BSF in that the BSF is a household scale SSF, performance is not equivalent in the BSF. Studies have tested chemical, microbial, and physical contaminants and observed that the reduction of the water quality parameter is different in the BSF than in the SSF.[38,39] Therefore, the BSF cannot be treated as a SSF and more studies are needed in addition to the current one to assess the BSFs ability to remove EDCs. The addition of household bleach to water treated by the BSF removed about half of the effluent filtered concentration when the current suggested dose (0.67 mg/L Cl−) was added, while percent removal increased to greater than 98% when the dose was increased to 5 mg/L Cl−. Future experiments should focus the ability of the BSF to remove a larger 758 group of EDCs at environmental concentrations. Furthermore, other treatment procedures should also be examined to gain further insight into the efficiency of water treatment technologies in the developing world. Kennedy et al. [15] [16] Acknowledgments [17] The authors would like to acknowledge Triple Quest, the producer of the Hydraid filter. [18] Downloaded by [Erzincan Universitesi ] at 06:45 31 July 2015 References [1] Nakada, N.; Shinohara, H.; Murata, A.; Kiri, K.; Managaki, S.; Sato, N.; Takada, H. Removal of selected pharmaceuticals and personal care products (PPCPs) and endocrine-disrupting chemicals (EDCs) during sand filtration and ozonation at a municipal sewage treatment plant. Water Res. 2007, 41, 4373– 4382. [2] Karnjanapiboonwong, A.; Suski, J.; Shah, A.; Cai, Q.; Morse, A.; Anderson, T. 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