Research Stimulatory Drugs of Abuse in Surface Waters and Their Removal in a Conventional Drinking Water Treatment Plant M A R I A H U E R T A - F O N T E L A , †,‡ MARIA TERESA GALCERAN,‡ AND F R A N C E S C V E N T U R A * ,† AGBAR, Av. Diagonal 211, 08018-Barcelona, Spain and Department of Analytical Chemistry, University of Barcelona, Av. Diagonal 647, 08028-Barcelona, Spain
Received March 18, 2008. Revised manuscript received June 16, 2008. Accepted June 20, 2008.
The presence of psychoactive stimulatory drugs in raw waters used for drinking water production and in finished drinking water was evaluated in a Spanish drinking water treatment plant (DWTP). Contamination of the river basin which provides raw water to this DWTP was also studied. In surface waters, illicit drugs such as cocaine, benzoylecgonine (cocaine metabolite), amphetamine, methamphetamine, MDMA(ecstasy),andMDAweredetectedatmeanconcentrations ranging from 4 to 350 ng/L. Nicotine, caffeine, and their metabolites were also found at the µg/L level. The elimination of these compounds during drinking water treatment was investigated in a real waterworks. Amphetamine-type stimulants (exceptMDMA)werecompletelyremovedduringprechlorination, flocculation, and sand filtration steps, yielding concentrations lower than their limits of detection (LODs). Further, ozone treatment was shown to be effective in partially eliminating caffeine (76%), while subsequent granulated activated carbon (GAC) filtration removed cocaine (100%), MDMA (88%), benzoylecgonine (72%), and cotinine (63%). Postchlorination achieved the complete elimination of cocaine and nicotine and only one parent compound (caffeine) and two metabolites (cotinine and benzoylecgonine) persisted throughout treatment, although reductions of 90% for caffeine and benzoylecgonine and 74% for cotinine were obtained.
Introduction It has been widely demonstrated that human habits and activities impact the environment in many ways, one of which is water contamination. Recently, several studies have revealed the presence of human source contaminants such as pharmaceuticals, hormones, and personal care products in wastewater effluents that discharge to rivers, lakes, and seas (reviewed in ref 1). Since some of these waters may be used as raw sources for drinking water production, the presence of such organic contaminants might have a negative impact on the quality of drinking water. To date, few studies have evaluated the removal of these * Corresponding author phone: +34 93 342 2715; fax: +34 93 342 2666; e-mail:
[email protected]. † AGBAR. ‡ University of Barcelona. 10.1021/es800768h CCC: $40.75
Published on Web 08/06/2008
2008 American Chemical Society
compounds through conventional drinking water treatments, or considered their presence in finished drinking water (reviewed in ref 2). Adsorption on activated carbon (3, 4), ozone oxidation (5), and chlorine or chlorine dioxide reactions (6) have been shown to be effective in removing several organic compounds such as pesticides, pharmaceuticals, and odor and taste compounds. As regards illicit drugs, these have already been detected in wastewaters and surface waters from the United States (7), Italy (8–10), Germany (11), Ireland (12) and Spain (13–15). It has also been demonstrated that some of these compounds are not quantitatively eliminated by wastewater treatments and, moreover, that they can survive natural attenuation processes in surface waters. For instance, Zuccato et al. (10) reported concentrations higher than the LOQ for cocaine (44 ng/L) and MDMA (ecstasy; above 1.7 ng/L) in the Olona River (Italy), while cocaine was also detected in two rivers from Ireland at concentrations ranging from 25 to 33 ng/L (12). The present study aimed to evaluate the removal of several controlled and noncontrolled drugs in a drinking water treatment plant (DWTP). The most representative stimulatory psychoactive drugs of abuse, such as cocaine, its metabolite benzoylecgonine (BE), amphetamine-type-stimulants (ATS), ketamine, phencyclidine (PCP), lysergic acid (LSD), and fentanyl were selected (Table S1 in the Supporting Information). Stimulatory noncontrolled drugs such as nicotine and caffeine were also included in this study due to their high and widespread consumption. The presence of these drugs was also studied in the raw water of the Llobregat River (NE Spain), which is used for drinking water production in the abovementioned DWTP. This river receives effluents from several WWTPs already studied in a previous report (15). Daily and seasonal variations were also assessed by collecting water from this river over seven consecutive days and a full year, respectively. To evaluate the efficiency of the conventional drinking water treatment process (chlorination, coagulation/flocculation, sand filtration, ozonation, and GAC filtration) in removing these compounds, treated waters from each step were analyzed and removal efficiencies were calculated. To the best of our knowledge, this is the first study to report the removal of psychoactive illicit drugs in a conventional drinking water treatment system.
2. Materials and methods Sample Collection. Samples were collected and stored in glass bottles below 4 °C. Surface raw waters were filtered through glass microfiber GF/A filters (Whatman, UK), and ascorbic acid was added to treated waters in order to prevent further degradation with chlorine. (a) Surface Water Monitoring. River water samples were collected from the Llobregat River (NE Spain), from its two main tributaries (Cardener River and Anoia River), and from one additional creek (Rubi) (Figure 1) during three different campaigns conducted in January, March, and May 2007: each sample was analyzed in triplicate. Sampling points were selected in order to evaluate the effects of population and industries along the river. Llobregat River sampling points 1 and 2 were located before and after a reservoir and have no major external contributions from WWTPs. Sampling point 3 was situated downstream of a heavily populated area where more than 30% of the Llobregat River water is diverted for irrigation and drinking water purposes. Sampling point 4 was located downstream, where a decrease in flow rates arises due to the abovementioned diverted flow. Important inputs VOL. 42, NO. 18, 2008 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
9
6809
FIGURE 1. Map of surface sampling points in the Llobregat River (NE-Spain).
FIGURE 2. Treatment scheme of the DWTP and locations of sampling points. from large WWTPs cause a general deterioration in quality between this point and sampling point 7. Sampling points 4 and 5 were located up- and downstream of the mouth of the Cardener River into the Llobregat River while points 6 and 7 were situated up- and downstream of the mouth of the Anoia River to the Llobregat River. Sampling points 8 and 9 did not receive any external contribution except for partial and sporadic contributions from the Rubi creek (sampling point 16) which is fully diverted for irrigation purposes and receives several wastewater effluents from both important WWTPs and a densely populated area. Cardener River sampling points 10 and 11 were located before and after a mining zone, while the water of the point 12 was affected by urban contributions and by the remainder of the 30% diverted from the Llobregat River. Sampling points 13, 14, and 15 (Anoia River) were selected in order to evaluate the effect of two densely populated areas. It should also be noted that only 10% of this river discharges into the main river because of its high level of pollution and the remaining portion is diverted. (b) Seasonal and Daily Variations. To assess the quality of raw water used for drinking water production and to evaluate potential daily and seasonal variations due to different patterns of use, samples were collected at the intake of a DWTP located in the Llobregat river basin. Daily 6810
9
ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 42, NO. 18, 2008
variations were evaluated by collecting three samples over 7 consecutive days (n ) 7 × 3) at the same time (10 a.m.) from Monday to Sunday (December 2006). Seasonal variations were also studied by performing a survey during one complete year (May 2006-April 2007). Samples were collected once a week (n ) 48) and always on the same day (Monday) and at the same time (10 a.m.). (c) Drinking Water Monitoring. The DWTP selected for this study treats about 300 million liters per day and supplies a population of over 1 million people. The raw water used for drinking water production consists of surface water from the Llobregat River. Some properties of the river water measured during the study period (from January to June 2007) are summarized in Table S2. The characteristics of the treatment performed in the selected DWTP are displayed in Figure 2. The first step consists of a preoxidation by adding chlorine until breakpoint is achieved. In this step several alum-coagulants such as aluminum sulfate (Al2(SO4)3), aluminum polychloride (AlxCl3), aluminum oxide (Al2O3), and flocculants (polyDADMAC) are also added. Clarified water passes through sand filters (0.60 m height; 15-30 min) and at this point dilution with groundwater is performed at variable percentages to improve the water quality. The water is then pumped to ozone treatment facilities. Ozone is generated in situ and
water is treated inside four ozone chambers (5 mg/L for nominal flow), yielding a residual concentration of 0.2 mg/ L. This treatment lasts around 15-20 min depending on the treated water volume. The water is then passed through GAC filters (10 m/h) for at least 15 min at a water flow rate of 6 m3/s. Finally, a postchlorination step is performed in order to maintain a chlorine residual concentration of about 0.8-1.2 mg/L through the distribution system. To assess the efficiency of the different steps of the treatment, samples were collected before and after each process, taking into account the hydraulic retention times (HRTs). The total HRT can range from 5 to more than 10 h depending on the amount of treated water, the groundwater dilution, the impulsion flow rates, and the number of operative ozone generators. The sampling survey was first performed in January 2007 (n ) 3) and removal efficiencies were calculated. The survey was then extended from January 2007 to June 2007 (four samples per month; n ) 24). Analytical Methods. The analytical method for the selected compounds (Table S3) has been described in a previous report (13). Water samples were enriched by solidphase extraction (SPE). The SPE extracts were injected into an ultraperformance liquid chromatography (UPLC) system (Waters, USA) coupled to a Quattro Micro triple quadrupole mass spectrometer (Micromass, Waters, USA) with electrospray ionization working in positive mode. Acquisition was performed in selected reaction monitoring (SRM) mode and two transitions (quantification, confirmation) were obtained for each compound. ESI-MS/MS parameters and a detailed description of the calibration and the quality parameters validation are described elsewhere (13). Isotope dilution was used for quantitation by adding labeled standards to samples prior to extraction. To assess potential contamination during the analysis, blanks were included with each set of 12 samples. Quality parameters of the method such as run-to-run and day-to-day precisions, LODs, and LOQs of the target compounds were established in both ultrapure water and surface water (see Table S3). Loads Calculation. The Llobregat is a Mediterranean River with a torrential regime and shows important fluctuations in flow rates (from 1000 to 22,700 L/s in 2006) depending on the season. Moreover, important variations in flow rates are also registered throughout the river basin. For instance, the flow rates measured in January ranged from 50 (sampling point 13) to 4000 L/s (sampling point 5), while in March they ranged from 90 (sampling point 13) to 7000 L/s (sampling point 5). To minimize the effect of these fluctuations and normalize the concentration values obtained, loads were calculated by multiplying concentrations by the flow rates measured when collecting the samples and were then expressed as g/day. These values should be considered as estimations since errors associated with the flow rates are ∼20% for river basin survey and
