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Carbamazepine removal in three pilot-scale hybrid wetlands planted with ornamental species
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Carbamazepine removal in three pilot-scale hybrid wetlands planted with ornamental species Allan Tejeda, Ángeles X. Torres-Bojorges, Florentina Zurita ∗ Quality Environmental Laboratory, Centro Universitario de la Ciénega, University of Guadalajara, Av. Universidad 1115, Ocotlán, Jalisco, Mexico
a r t i c l e
i n f o
Article history: Received 15 January 2016 Received in revised form 30 March 2016 Accepted 28 April 2016 Available online xxx Keywords: Hybrid constructed wetlands Pharmaceuticals I. sibirica Z. aethiopica Subtropical climate Reductive conditions
a b s t r a c t The aims of this one-year study, were to evaluate the removal of carbamazepine (CBZ) in three pilotscale two-stage hybrid constructed wetlands as well as to evaluate the performance of three emergent species (Thypha latifolia, Iris sibirica and Zantedeschia aethiopica) planted as a polyculture. The systems included horizontal subsurface flow wetlands (HSSF-CW), vertical subsurface flow wetlands (VSSF-CW) and stabilization ponds (SP). The three different configurations were: HSSF-CWs followed by SPs, HSSFCWs followed by VSSF-CWs and VSSF-CWs followed by HSSF-CWs, which were identified as system I (SI), system II (SII) and system III (SIII) respectively. In addition, measurements of DO, Eh and pH, were taken in situ in order to know the internal system conditions. Out of the three hybrid systems, two were equally effective (SI and SII) and superior to SIII (p > 0.05). In these two systems (HSSF-CWs- SPs and HSSF-CWsVSSF-CWs) the average mass removals were 62.5 ± 4.5% and 59.0 ± 4.5%, respectively. CBZ removal was more effective under reductive environment (∼−60 to +50 mV) and near-anoxic conditions (<1.5 mg/L of DO). In addition, the two ornamental plants exhibited a better capacity to tolerate and take up CBZ in comparison to T. latifolia. These results demonstrate that it is possible to obtain higher CBZ removal efficiencies in CWs than those reported so far, under subtropical climate by using hybrid systems planted with a polyculture that include ornamental species and using a ground local filter material. © 2016 Elsevier B.V. All rights reserved.
1. Introduction During the last two decades, pharmaceuticals have been receiving increasing attention because of their widespread uses and continuous release to the aquatic environment (Zhang et al., 2014). Pharmaceuticals are potential bioactive chemicals which reach the aquatic environment mainly through the effluent of wastewater treatment plants (WTPs) (Li et al., 2014; Rivera-Utrilla et al., 2013) or through the discharges of untreated wastewater, mostly in developing countries (Zurita et al., 2012). The pharmaceuticals frequently found in both untreated and treated wastewater, as well as in environmental water bodies around the world, include antibiotics (trimethoprim, metronidazole, ciprofloxacin, sulfamethoxazole, tetracycline,), analgesic/anti-inflammatory drugs (ketoprofen, naproxen, ibuprofen, diclofenac and salicylic acid), an antiepileptic drug (carbamazepine), lipid regulators (clofibric acid), a diuretic drug (furosemide), antacids (ranitidine), beta-blockers (metropolol, sotalol, atenolol), lipid-lowering drugs (bezafibrate, clofibrate, gemfibrozil), and stimulants (caffeine) (Hijosa-Valsero
∗ Corresponding author. E-mail address: [email protected] (F. Zurita).
et al., 2010a; Al-Khateeb et al., 2014; Li et al., 2014; Rivera-Utrilla et al., 2013; Zhang et al., 2014). Although, the ecotoxicological effects of these compounds as well as their impact on human health due to a continuous exposition are mostly unknown, there are evidences of their hazardousness. Studies with animals have demonstrated that some pharmaceuticals can be either carcinogenic and teratogenic agents or hormonal system disruptors (Rosal et al., 2010). Carbamazepine, an antiepilectic drug, is one of the pharmaceuticals most frequently detected in aquatic environment owing to its poor removal in conventional biological treatments (Hai et al., 2011). In activated sludge treatment systems, the removal of CBZ is generally lower than 10% (Zhang et al., 2008). Currently, constructed wetlands are attracting increasing attention as an alternative secondary wastewater treatment system or a wastewater polishing treatment system, for the removal of pharmaceuticals from wastewater (Ávila et al., 2010; Li et al., 2014). The great potential of this low-cost technology of being used for the removal of pharmaceuticals has been proved by different researchers. It is well-known that pollutant removal in constructed wetlands takes place by means of complex physicochemical and microbiological interactions during the slow flow of wastewater across the soil matrix, which includes rhizomes and roots of emergent vegetation. In the particular case of pharmaceuticals,
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the specific mechanisms responsible for their removal are microbial degradation, plant uptake, bed adsorption and volatilization (Kadlec and Knight, 1996; Matamoros et al., 2008). It has been reported that plants play a very important role in the removal of pharmaceuticals not only through the direct uptake, assimilation, translocation and degradation in its tissues, but also in promoting the development of microbial communities capable of degrading such pollutants. Plants release oxygen through their roots, produce exudates that catalyze the degradation processes and provide their roots for biofilm formation (Li et al., 2014; Zhang et al., 2014). The crucial role of macrophytes in drug removal in constructed wetlands, as well as the fact that specific macrophytes could influence the removal efficiencies of pharmaceuticals, underscore the need of the evaluation of a large variety of them (Zhang et al., 2014). So far, mainly three species, namely Phragmites australis, Thypha latifolia and Typha angustifolia has been broadly used when evaluating CWs for drug removal (Carvalho et al., 2012; Li et al., 2014). On the other hand, in general, the pharmaceutical removal efficiencies in constructed wetlands have been found to be higher than the efficiencies reported in conventional wastewater treatment plants (Zhang et al., 2011). Moreover, the efficiencies of elimination for some pharmaceuticals have reached values superior to 70% (Zhang et al., 2014). However, for carbamazepine, which is considered as one of the most recalcitrant pharmaceuticals (HijosaValsero et al., 2010b; Zhang et al., 2011) the removal efficiencies
has been certainly low. For example, Zhang et al. (2012) found CBZ removal efficiencies in a range of 24–28% in HSSF-CWs planted with Typha angustifolia; while Matamoros et al. (2007) found a removal less than 20% in HSSF-CW and a removal of 26% in VSSF-CWs both planted with Phragmites. Furthermore, Li et al. (2014) report an average removal of CBZ less than 30% in both HSSF-CWs and VSSFCWs. In addition, there are a limited number of studies in which the removal of CBZ have been assessed in hybrid wetland systems. Therefore, the aims of this study were to evaluate and compare the removal of carbamazepine in three hybrid wetlands with two stages of treatment, using a polyculture of three macrophytes that includes ornamental plants as emergent vegetation, as well as to study the performance of the plants in HSSF-CWs. 2. Materials and methods 2.1. Description of the experiment This study was carried out at Ocotlán, Jalisco, Mexico; located at 1530 m above sea level and a latitude of 20◦ 21 00 , with a humid subtropical climate and an annual average temperature of 21 ◦ C. The study was conducted during one year, from June 2013 to May 2014 in three duplicated pilot-scale hybrid wetlands (Fig. 1) located inside the Centro Universitario de la Ciénega, a campus of the University of Guadalajara. The systems were in operation since
Fig. 1. The three hybrid wetland systems showing the measurement points for the parameters in situ. System I: HSSF-CW—SPs; System II: HSSF-CWs—VSSF-CWs; System III: VSSF-CWs—HSSF-CWs.
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September 2009 and have been fed with a portion of the wastewater generated in the campus (Zurita and White, 2014; Zurita and Carreón-Álvarez, 2015). For this study, the primary effluent was pumped to a 400 L-feeding tank where it was spiked with carbamazepine (99% purity, Sigma-Aldrich) for a final concentration of 25 g/L. The systems are fully described in Zurita and White (2014). Briefly, system I consisted of a HSSF-CW followed by a SP. The horizontal flow CWs were continuously fed with a theoretical hydraulic retention time (THRT) of 3 days. The effluent from the HSSF-CWs flowed by gravity to the SPs (THRT of 8.9 d). System II was also configured with a HSSF-CW (THRT of 3 d) as a first stage which was then followed by a VSSF-CW as a second stage. The HSSF-CW operated in the same way as in the system I, but the effluent was collected in a tank and pumped intermittently every 2 h on to the substrate of the VSSF-CW (HLR of 118 mm/d). System III was configured with a VSSF-CW (HLR of 146 mm/d) followed by a HSSF-CW (THRT of 3 d). The vertical flow CW was intermittently fed by a pump programmed to discharge 2.8 L every 2 h on to the surface. The effluent discharged directly on to the HSSF-CW. The HSSF-CWs were originally planted with Canna indica, but for this study this species was removed totally and the systems were replanted with a polyculture of three macrophyte species, each species had three plants randomly distributed on the wetland surface. The three macrophytes were Zantedeschia aethiopica, Iris sibirica, and Typha latifolia. The use of a polyculture was to promote the growth of a higher variety of microorganisms (Karathanasis et al., 2003; Vacca et al., 2005; Zurita et al., 2009) and thus probably promote the carbamazepine biodegradation. In contrast, the VSSF-CWs were planted originally with only one plant species, Strelitzia reginae and were not modified for this study. Ground tezontle with d10 of 0.645 mm and d60 of 2.3 mm, as well as a uniformity coefficient of 3.6, was used as substrate in both types of wetlands. 2.2. Carbamazepine quantification in aqueous samples The systems were fed with wastewater since the beginning of the study, but without the addition of CBZ for three months. In this way the systems were provided a stabilization period in order to give the emergent plants the opportunity to be adapted to the environmental conditions before the exposition to CBZ. In addition, presumably internal chemical and microbiological processes became more stable along this period. Quantification of CBZ was started after the 3-month period of stabilization. Samples were taken in a weekly basis at the general inlet and outlets of each system, resulting in 13 total samples. In triplicate, 100 mL of each sample was filtered through filter paper (Whatman 41) to remove suspended solids and then it was subjected to a three successive extraction with 100 mL of methylene chloride (1:1 ratio). The organic phase was concentrated to dryness with a rotary evaporator (IKA HB 10) at 40 ◦ C, and nitrogen gas. Then the extracts were reconstituted by using 1 mL of methanol. Each resuspension was filtered through a 0.20 m PTFE filter. The recovery rate was 96.5 ± 1.5%. Finally, quantitation of carbamazepine was performed on a reverse-phase Waters HPLC comprising a binary pump (Waters 1525) and a UV–vis detector with diode array (Waters 2998). For analytical purposes the – c´ et al. techniques described by Dordio et al. (2010) and Ðordevi (2009) were modified. A Waters column (Symmetry C18), 75 mm long, 4.6 mm internal diameter and 3.5 m in particle size was used. The mobile phase was a mixture of acetonitrile, water and orthophosphoric acid (55:45: 0.1), the flow rate was 1 mL/min and carbamazepine was detected at 285 nm, at a retention time between 3.37 and 3.41 min. Duplicate injections were made for each sample and the injection volume was 20 L into a loop of 100 L. For each set of triplicate samples, calibration curves were obtained with carbamazepine (99% purity, Sigma-Aldrich)
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The curve fitting was verified with the coefficient of determination (r2) which was always greater than 0.999. The limit of detection and quantification was 0.47 ± 0.00 g/L. 2.3. Influent water quality parameters and parameters in situ Organic-N, Ammonia, Nitrate, total N, BOD, COD, TSS and total P, were measured at the influent of the three systems in order to better characterize the wastewater under evaluation. Chemical and biological water quality parameters were determined as described in the Standard Methods for the examination of Water and Wastewater (APHA, 2005). Additionally, measurements of dissolved oxygen, redox potential and pH, in each system were performed in situ in order to know the systems environmental conditions. An HQ40d series portable Hach meter with Intellical sensors was used for these three parameters. The measurements were performed in four different points (internal and external) in the hybrid systems (Fig. 1). Perforated pipes were installed at inlets and outlets zones inside the HSSF CWs in order to insert the measuring devices. With respect to SPs, such measurements were performed inside the ponds as well as in the deposit of the final effluent collection. Meanwhile, in VSSF CWs the parameter readings were taken at the influent and effluent (Fig. 1). 2.4. Calculation of carbamazepine mass removal efficiencies The mass removal efficiency is the more reliable calculation method to assess constructed wetland efficiency, because this method includes water gains and losses, in addition to influent and effluent concentrations (Hijosa-Valsero et al., 2010b). Therefore, this leads to more realistic removal results, in comparison to the results obtained only by pollutant concentration decrease (Kadlec and Wallace, 2009). The mass removal efficiency calculation (MRE) is expressed as follows: MRE (%) =
Mr C Q − Ce Q e × 100 = i i × 100 Mi Ci Qi
(1)
where Mr (mg/d) is the mass of the pollutant removed in the wetland, Mi (mg/d) is the pollutant mass which enters in the wetland, Ci (mg/L) is the influent pollutant concentration, Qi (L/d) is the influent flow rate, Ce (mg/L) is the effluent pollutant concentration and Qe (L/d) is the effluent flow. 2.5. Performance of the three macrophytes in HSSFC-CWs At the end of the study, the standing live biomass (both aboveground and belowground biomass) as well as the capacity of each macrophyte to assimilate CBZ and the total assimilation of CBZ by each species were estimated in the HSSF-CWs. Briefly, after 9 months of exposition to CBZ, the plants were removed from the HSSF-CWs, classified in species and washed with abundant tap water. Then, each plant was separated in aerial and underground part and rinsed three times with distilled water, dried with paper towels and weighed for the evaluation of standing live biomass. Thereafter, both the aerial and underground parts were cut in small pieces with stainless steel scissors and dried at 40 ◦ C for 120 h. Finally, the plants were ground with a coffee grinder, and mortar and pestle and weighed again. The samples were kept in a desiccator until their analysis for CBZ concentration. The extraction by sonication and solid phase extraction methods employed for carbamazepine in plant tissues were based on the method of Wu et al. (2012). Briefly, around 1 g of the dried and ground sample was transferred to a 50 mL-propylene tube and sonicated two times for 20 min, first with 15 mL of methanol and then with 15 mL of acetone. After each sonication, the supernatant was filtered through a 1.6 m GF/A Whatman fiber glass filter. Each plant sample was
Please cite this article in press as: Tejeda, A., et al., Carbamazepine removal in three pilot-scale hybrid wetlands planted with ornamental species. Ecol. Eng. (2016), http://dx.doi.org/10.1016/j.ecoleng.2016.04.012
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processed in triplicate. After the filtration, the extracts were collected and concentrated to 5 mL by means of a rotary evaporator (IKA 210) and finally, diluted with deionized water to 100 mL. The SPE was performed using Strata-X cartridges (200 mg/6 cc, Phenomenex). The cartridges were conditioned with 5 mL of methanol and 5 mL of deionized water at a flow rate of 5 mL/min. Then, the extracts were passed through the cartridge with a flow rate of 2 mL/min. In order to remove any interference, the cartridges were washed with 5 mL of deionized water and then dried under vacuum for 60 min. The elution of the compound was performed by adding 5 mL of methanol. Thereafter, 1 mL of the eluate was filtered through a 0.20 m PTFE filter. The WATERS liquid chromatograph described previously, was used for CBZ quantification in plant tissues. The same column and mobile phase were used. Gradient elution employed was based on the method of Matilla and Kumpulainen (2002). The detection and quantification limits were 0.43 g/L and 1.31 g/mL, respectively.
3. Results and discussion The mean characteristics of the wastewater used in the study is reported in Table 1. According to the COD and BOD, this wastewater could be classified as a weak one, although the ammonium concentration is higher in comparison to that concentration normally found in common domestic wastewater. 3.1. Parameter measured in situ 3.1.1. Dissolved oxygen behavior System I showed the lowest concentration of DO along the treatment (Fig. 2A). In the first stage this was due to the presence of HSSF-CWs in which anoxic conditions prevails due to the saturated water matrix that prevents the oxygen diffusion from the surface (Saeed and Sun, 2012).With regard to the low concentration of DO in the SPs, this was due to a low algae production (which means low photosynthetic activity) because of the indirect exposure of the systems to sunlight. With respect to the system II, the HSSF CWs in the first stage had a similar behavior to their parallels HSSF treatments in the system I. In contrast, in the second stage (VSSF-CWs) there was an increase in the DO concentration because of the intermittent feeding of this type of CW (Fig. 2A). Finally, in the system III, the DO increased noticeable in the VSSF treatment as the first stage. In this case, the direct discharge of DO-high concentration effluent amended the internal conditions of the HSSF CWs used as second stage. Although there was a DO concentration decrease, the average value was maintained above to 2 mg/L, indicating aerobic conditions inside the HSSF-CWs in contrast with their parallels in systems I and II (Fig. 2A).
2.6. Approximate CBZ mass balance calculation in HSSF-CWs At the end of the study, a CBZ mass balance was performed in each HSSF-CWs by taking into account the total CBZ-mass input, the total CBZ-mass output and the total CB retained in the plant biomass; the remaining loss of CBZ from the mass balance was considered the CBZ removal by other mechanisms (adsorption, biodegradation, biotransformation, etc.). The biomass dried and removed from the systems along the study was not considered for the balance. The total CBZ-mass input and output in each HSSF-CW was calculated from the cumulative total CBZ-mass inflow and outflow along the whole period of operation of 280 days. The CBZ mass balance was represented by the following equation:
3.1.2. Redox potential behavior Redox potential (Eh) is a quantitative measurement of either the pollutant’s oxidation or reduction trend within the system and similar to DO, indicates the microbial processes occurring inside the wetland (Kadlec and Wallace, 2009). The results regarding this parameter, were consistent with the DO results. System I showed negative Eh values at the first stage (HSSF-CWs), indicating, as expected, reductive conditions. However, the average value showed a slight increase at the outlet zone in comparison to the inlet zone (Fig. 2B). This could be explained by the BOD decrease as the wastewater passes through the treatment (Kadlec and Wallace, 2009), as well as the macrophyte’s constant oxygen supply into the matrix soil (Brix, 1997). Inside the SPs, the Eh showed again a new increase, reaching a small positive value. With respect to the SII, the behavior of Eh in the first stage (HSSF CWs) was similar to the results in its parallel in the SI. In contrast, in the second stage an increase in Eh was observed in the effluent, as a result of the wastewater oxygenation during its pass through the VSSF-CWs. The system III showed the most oxidative conditions throughout the treatment, with Eh values near and over 100 mV (Fig. 2B). These
CBZ-massin = CBZ-massoutintheeffluent + CBZinplants + CBZmassremovalbyothermechanisms.
2.7. Statistical analysis A randomized block design was used to analyze the mass removal efficiencies along the time in this study. Multifactor analysis of variance (ANOVA) was carried out using the Statgraphics Centurion XV.II software package to check differences amongst treatments (stage 1 and stage 2 in each individual hybrid system or total removal in each of the three systems). A significance level of p = 0.05 was used for all statistical tests, and values reported are the mean (average) ± standard error of the mean. When a significant difference was observed between treatments in the ANOVA procedure, multiple comparisons were made using the Least Significant Difference (LSD) test for differences between means.
Table 1 Characteristics of the wastewater in the three systems, along the period of evaluation (Average ± SD). Influent
SYSTEM I: HF-SP
Parameter (mg/L) Chemical Oxygen Demand Biochemical Oxygen Demand Phosphorus Organic N Ammonium Nitrate Total N Total suspended solids
1st stage HF-CW 170.9 130.8 6.9 4.3 68.6 4.2 77.1 30.4
± ± ± ± ± ± ± ±
149.3 52.5 5.3 2.0 47.9 1.4 47.9 18.4
85.5 23.8 7.8 2.9 58.0 2.0 62.9 17.7
± ± ± ± ± ± ± ±
78.3 8.2 5.0 1.4 41.0 1.4 41.0 18.0
SYSTEM II: HF-VF 2nd stage SP 115.7 79.7 6.8 3.6 33.1 21.6 58.3 60.5
± ± ± ± ± ± ± ±
100.7 26.2 2.6 2.5 21.8 11.3 29.3 53.6
1st stage HF-CW 48.6 20.4 6.3 1.9 61.8 0.7 64.4 9.5
± ± ± ± ± ± ± ±
32.8 5.7 3.6 0.9 35.7 0.5 36.0 6.9
SYSTEM III: VF-HF 2nd stage VF-CW 35.6 6.1 6.8 1.3 9.3 65.6 76.2 12.8
± ± ± ± ± ± ± ±
26.9 3.7 2.7 1.2 7.9 38.2 41.9 9.7
1st stage VF-CW 63.8 13.6 6.7 2.7 25.4 50.0 77.0 17.3
± ± ± ± ± ± ± ±
31.4 5.6 3.8 1.4 22.9 33.1 44.3 19.1
2nd stage HF-CW 44.8 3.7 6.3 1.4 15.9 50.6 68.0 10.7
± ± ± ± ± ± ± ±
59.3 2.0 3.5 0.7 17.2 25.2.2 39.5 6.0
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pH decreased at the first stage outlet (VSSF-CW) due to the common nitrification process in such wetlands. Then this value was kept along the second stage (HSSF-CW) due to its buffer capacity mentioned previously.
3.2. Carbamazepine removal
Fig. 2. Parameters in situ along the hybrid wetland systems (n = 47) Average ± SD. A. Dissolved oxygen; B. Redox potential; C. pH.
conditions remained even throughout the second stage, which supports the DO results. 3.1.3. pH behavior pH plays a very important role in pollutant removal in constructed wetlands by directly affecting the substrate sorption capacity (Li et al., 2014) and microbial processes (Meng et al., 2014). System I behavior was remarkably stable along the two stages, with pH values near 8 (Fig. 2C). This performance is the result of the buffer capacity of the HSSF-CWs and the low variability in pH in the stabilization ponds, likely because of the low algae production (Kadlec and Wallace, 2009). System II also showed a stable pH in its first stage, with very similar values at inlet and outlet zones. However, as expected, in the second stage (VSSF CW) a pH decrease was registered at the outlet as a consequence of the nitrification process that takes place inside vertical wetlands and leads to H+ ion generation (Vymazal and Kropfelová, 2008). In contrast, the system III performance was quite different in comparison to SI and SII, showing pH values close to 7 along the treatment (Fig. 2C). The
The final concentration of CBZ reached in each of the three hybrid CWs along the period of evaluation, is shown in Table 2. When analyzing the performance of the systems individually, it was found that in SI, the mean removal efficiency was 48.3 ± 7.4% in the HSSF-CWs and increased by 14.1 ± 9.5% in the SPs (p < 0.05). In a similar way, in SII, the removal efficiency was 49% in the HSSF-CWs and increased by 10% in the VSSF-CWs (p < 0.05). In contrast, in SIII, the removal efficiency was 38% in the VSSF-CWs and did not increase significantly in the HSSF CWs (p > 0.05), despite an apparent additional removal of 6%. With regard to the total removal efficiencies, it was found that SI and SII were the most efficient systems and statistically equal; while the least effective was SIII (p < 0.05). The average efficiencies were 62.5 ± 4.5%, 59.0 ± 4.5% and 44.2 ± 4.5% for SI, SII and SIII, respectively. According to these results, the HSSF-CWs (as a first stage) were mainly the responsible for the higher efficiencies in SI and II. This suggests that CBZ removal is favored by anoxic conditions which predominated in this type of CWs along the study, instead of the aerobic conditions in the VSSF-CWs. In SI, these conditions prevailed even in the SPs as was discussed previously. These outcomes are in agreement to those reported by other authors who found that CBZ was biologically degraded under anoxic conditions (Park et al., 2009). Hai et al. (2011), reached a removal of 68 ± 10% under near anoxic conditions (DO = 0.5 mg/L) in comparison to aerobic conditions (DO > 2 mg/L) in membrane bioreactors (MBR). Moreover, the removal efficiency of CBZ obtained in the HSSF-CWs as a first stage, was higher than the efficiencies reported by different researchers (Matamoros et al., 2008; Park et al., 2009; Hijosa-Valsero et al., 2010b; Zhang et al., 2011, 2012; Li et al., 2014). The better results in this study, were probably due to a greater biodegradation as a result of the presence of a more diverse microbial populations promoted by the polyculture of three macrophytes in comparison to monoculture systems (Karathanasis et al., 2003; Vacca et al., 2005; Zurita et al., 2009). In general, the presence of macrophytes stimulate the diversity of rhizosphere-inhabiting microorganisms (Healy et al., 2007) and has been recently found by Zhang et al. (2016) that enhance the specific taxonomic groups in HSSF-CWs receiving pharmaceuticalenriched wastewater. With a high diversity of microorganisms, the biodegradation of this type of compounds is more probable by means of fortuitous metabolism and co-metabolism (the recalcitrant compound is biodegraded by enzymes produced during the biodegradation of another primary pollutant). By these mechanisms, continual biodegradation of xenobiotic compounds is through the use of additional carbon and energy sources supplied from the action of other organisms in a mixed microbial community (Grady, 1985). In addition to the probable biodegradation, CBZ uptake by the different plants used was also important, as will be discussed later. In contrast, in the HSSF-CWs as second stage in SIII, the removal of CBZ was very low, probably owing to the aforementioned more aerobic conditions resulting from the direct discharge of the VSSF CWs effluent. On the other hand, the removal efficiency of 34% in VSSF CWs as first stage was also higher than the average 26% reported by Matamoros et al. (2007) who evaluated a range of HLR from 13 to 160 mm/d. Once again, these better result could be due to the presence of the ornamental species S. reginae, whose roots reached almost 1 m length at the end of the study.
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3.3. Standing live biomass and carbamazepine assimilation by tissues The species with the lowest standing biomass was T. latifolia (Fig. 3A) in comparison to the two ornamental species (p < 0.05) (Fig. 3B and C). This result was expected because T. latifolia was clearly the species that exhibited more signs of stress when being exposed to CBZ, in comparison to the two ornamental plants. After ∼5 weeks of feeding CBZ into the systems, chlorosis began to be observed in T. latifolia. This species continued desiccating throughout the study until its complete desiccation from three out of six cells. This result is opposite to those reported by other authors, with respect to the good tolerance of cattails to the exposure to CBZ even in higher concentrations (Dordio et al., 2010, 2011). However, many of these studies have been conducted only in hydroponic assays (Dordio et al., 2011) or in batch operation systems with periods of evaluation in days (Dordio et al., 2010). The most similar study to the present one is that carried out by Zhang et al. (2011) who evalu-
ated CWs planted with T. angustifolia, fed by synthetic wastewater with a concentration of 25 g/L of CBZ in two-month study. So, to the best of our knowledge this is the first time that this species was exposed to CBZ in such concentration under more realistic conditions in a long period of evaluation. With regard to CBZ uptake, the species with the lowest capacity was once more T. latifolia while the species with the highest capacity was I. sibirica, mainly in its roots (p > 0.05) (Fig. 4A–C). In the HSSF-CWs of the SI and SII, the uptake in I. sibirica roots varied from 14.6 to 35.9 g/g dw, and decreased in HSSF-CWs of the SIII, to a range of 7.0 a 10.3 g/g dw, likely because of the lower concentration of CBZ after the VSSF-CWs. Furthermore, the calculation of the total CBZ assimilated in the standing live biomass by each species (Fig. 5A–C.) showed once again, that T. latifolia was the species that assimilated the least quantity of CBZ in its tissues in comparison to the ornamental plants, as a result of a low standing biomass and poor uptake capacity. With regard to the I. sibirica, the species with the higher total CBZ assimilation, most of the CBZ
Fig. 3. Standing live biomass in the HSSF-CWs after one year of experimentation. A. T. latifolia; B. Z. aethiopica; C. I. sibirica.
Fig. 4. CBZ uptake by the three emergent plants in HSSF-CWs. A. T. latifolia; B. Z. aethiopica; C. I. sibirica.
Table 2 CBZ concentration in the three systems, along the period of evaluation (Average ± standard error of the mean). Influent
CBZ concentration (g/L)
25.0 ± 0.01
SYSTEM I: HF-SP
SYSTEM II: HF-VF
SYSTEM III: VF-HF
1st stage HF-CW
2nd stage SP
1st stage HF-CW
2nd stage VF-CW
1st stage VF-CW
2nd stage HF-CW
13.13 ± 0.05
9.32 ± 0.05
12.87 ± 0.04
10.12 ± 0.04
13.30 ± 0.05
12.76 ± 0.06
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Fig. 6. CBZ mass balance performed in HSSF-CWs after the whole period of experimentation.
increase of 20.6% in the removal of ibuprofen in HSSF-CWs planted with Thypha angustifolia. Additionally, the plants can metabolize pharmaceuticals to other products so the real uptake could be underestimated. Zhang et al. (2013), found in a 21-day hydroponic study, that the direct CBZ uptake by S. validus was much less than the total CBZ elimination, suggesting that CBZ must have been transformed to other products by catabolism. In addition, Dordio et al. (2011), observed in another hydroponic study, a decrease in the CBZ amount in the leaves of Thypa spp. between 14 and 21 days of exposition and found that this was because the plant was capable of translocating and metabolizing CBZ, which was evident with the detection of the metabolite 10,11-dihidro-10,11epoxycarbamazepine. 4. Conclusions
Fig. 5. Total CBZ assimilation in the standing biomass by each species in HSSF-CWs. A. T. latifolia; B. Z. aethiopica; C. I. sibirica.
was accumulated in its roots. In the system III, the proportion of CBZ in root/stem was almost 20 (Fig. 5C). In this way, apparently, Z. aethiopica exhibited a better ability to translocate CBZ in comparison to I. sibirica. Although, these species were evaluated as a polyculture and the competition amongst them could have been an additional stress source, these results suggest that the performance of macrophytes when being exposed to CBZ vary according to the species and more research is required in order to, probably, select the more appropriate species. 3.4. CBZ mass balance in HSSF-CWs According to the CBZ mass balance (Fig. 6), the percentage of CBZ accumulated directly in the plant biomass was only ∼2% in the HSSF-CWs in SI and II (as a first stage) and ∼4% in HSSF-CWs in SII (as a second stage). While the removal by other mechanisms, was ∼45% and ∼6%, respectively. However, the plants could have also contributed to these “other mechanisms” by modifying the environmental conditions and microbial communities as has been demonstrated in recent studies with planted and unplanted systems; such as that performed by Zhang et al. (2016) who found an
In this study we demonstrated that it is possible to obtain higher removal efficiency of the known recalcitrant CBZ in constructed wetlands by using hybrid systems in comparison to single-stage systems. This was possible under subtropical climate through the use of a ground local volcanic rock as filter material, a polyculture of three species in HSSF-CWs and an ornamental species in VSSF-CWs. Out of the three hybrid systems, two were equally effective (SI and SII). In these two systems (HSSF-CW- SP and HSF-CW-VSSF-CW) the average mass removals were 62% and 59%, respectively during the period of evaluation. Such results indicate that CBZ removal is more effective under reductive environment (∼ −60 to +50 mV) and near-anoxic conditions (<1.5 mg/L of DO). Moreover, HSSF-CWs were more effective than VSSF-CW, when comparing them as a first stage for the same reasons. Furthermore, under subtropical and tropical climate, it is possible to use ornamental species in HSSF-CWs such as I. sibirica and Z. aetiopica for CBZ removal. These species contributed to the treatment by assimilating CBZ in their roots, leaves and stems and probably transformed it to other products (as has been observed in other species), playing in this way, a crucial role in the elimination of CBZ from the systems. Additionally, out of the three macrophytes, apparently, the most recomendable species would be I. sibirica which showed the highest total assimilation capacity due to a combination of a high production biomass and a good ability to assimilate this pharmaceutical. However, further research is needed in order to better understand the metabolism of CBZ by these ornamental species and to achieve more conclusive results with regard to their performance when being exposed to CBZ.
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Acknowledgements The work was funded by a grant from the Ministry of Education through the Programa para el Desarrollo Profesional Docente (PRODEP) in the call 2013 “Fortalecimiento de Cuerpos Académicos”. The authors would like to thank Zaira López for technical assistance and to the many undergraduate students of the Centro Universitario de la Ciénega for supervising the proper operation of the systems. References Ávila, C., Pedescoll, A., Matamoros, V., Bayona, J.M., García, J., 2010. Capacity of horizontal subsurface flow constructed wetland system for removal of emerging pollutants: an injection experiment. Chemosphere 81, 1137–1142. – c, ´ S., Kilibarda, V., Stojanovic, ´ T., 2009. Determination of carbamazepine in Ðordevi serum and saliva samples by high performance liquid chromatography with ultraviolet detection. Vojnosanit. Pregl. 66 (5), 347–352. APHA, AWWA, WEF, 2005. Standard Methods for the Examination of Water and Wastewater. APHA (American Public Health Association), Washington DC. Al-Khateeb, L.A., Almotiry, S., Salam, M.A., 2014. Adsorption of pharmaceutical pollutants onto graphene nanoplatelets. Chem. Eng. J. 248, 191–199. Brix, H., 1997. Do macrophytes play a role in constructed treatment wetlands? Water Sci. Technol. 35 (5), 11–17. Carvalho, P.N., Basto, M.Cl.P., Almeida, C.M.R., 2012. Potential of Phragmites australis for the removal of veterinary pharmaceuticals from aquatic media. Bioresour. Technol. 116, 497–501. Dordio, A., Carvalho, A.J.P., Teixeira, D.M., Dias, C.B., Pinto, A.P., 2010. Removal of pharmaceuticals in microcosm constructed wetlands using Typha spp. and LECA. Bioresour. Technol. 101, 886–892. Dordio, A.V., Belo, M., Teixeira, D.M., Carvalho, A.J.P., Dias, C.M.B., Picó, Y., Pinto, A.P., 2011. Evaluation of carbamazepine uptake and metabolization by Typha spp.: a plant with potential use in phytotreatment. Bioresour. Technol. 102, 7827–7834. Grady, C.P., 1985. Biodegradation: its measurement and microbiological basis. Biotechnol. Bioeng. 27 (5), 660–674. Hai, F.I., Li, X., Price, W.E., Nghiem, L.D., 2011. Removal of carbamazepine and sulfamethoxazole by MBR under anoxic and aerobic conditions. Bioresour. Technol. 102, 10386–10390. Healy, M.G., Rodgers, M., Mulqueen, J., 2007. Treatment of dairy wastewater using constructed wetlands and intermittent sand filters. Bioresour. Technol. 98, 2268–2281. Hijosa-Valsero, M., Matamoros, V., Martin-Villacorta, J., Bécares, E., Bayona, J.M., 2010a. Assessment of full-scale natural systems for the removal of PPCPs from wastewater in small communities. Water Res. 44, 1429–1439. Hijosa-Valsero, M., Matamoros, V., Sidrach-Cardona, R., Martin-Villacorta, J., Bécares, E., Bayona, J.M., 2010b. Comprehensive assessment of the design configuration of constructed wetlands for the removal pharmaceuticals and personal care products from urban wastewaters. Water Res. 44, 3669–3678. Kadlec, R.H., Knight, R.L., 1996. Treatment Wetlands. CRC Press, Lewis Publishers, Boca Raton, FL. Kadlec, R.H., Wallace, S.D., 2009. Treatment Wetlands, 2nd ed. CRC Press, Boca Raton, New York. Karathanasis, A.D., Potter, C.L., Coyne, M.S., 2003. Vegetation effects on fecal bacteria, BOD, and suspended solid removal in constructed wetlands treating domestic wastewater. Ecol. Eng. 20, 157–169. Li, Y., Zhu, G., Jern, W., Keat, S., 2014. A review on removing pharmaceutical contaminants from wastewater by constructed wetlands: design, performance and mechanism. Sci. Total Environ. 468–469, 908–932. Matamoros, V., Arias, C., Brix, H., Bayona, J.M., 2007. Removal of pharmaceuticals and personal care products (PPCPs) from urban wastewater in a pilot vertical flow constructed wetland and a sand filter. Environ. Sci. Technol. 41, 8171–8177.
Matamoros, V., Caselles-Osorio, A., Garcia, J., Bayona, J.M., 2008. Behavior of pharmaceutical products and biodegradation intermediates in horizontal subsurface flow constructed wetland: a microcosm experiment. Sci. Total Environ. 394, 171–176. Matilla, P., Kumpulainen, J., 2002. Determination of free and total phenolic acids in plant-derived foods by HPLC with diode array detection. J. Agric. Food Chem. 50, 3660–3667. Meng, P., Pei, H., Hu, W., Shao, Y., Li, Z., 2014. How to increase microbial degradation in constructed wetlands: influencing factors and improvements measures. Bioresour. Technol. 157, 316–326. Park, N., Vanderford, B.J., Snyder, S.A., Sarp, S., Kim, S.D., Cho, J., 2009. Effective controls of micropollutants included in wastewater effluent using constructed wetlands under anoxic condition. Ecol. Eng. 35, 418–423. Rivera-Utrilla, J., Sánchez-Polo, M., Ferro-García, M.A., Prados-Joya, G., Ocampo-Pérez, R., 2013. Pharmaceuticals as emerging contaminants and their removal from water. A review. Chemosphere 93, 1268–1287. Rosal, R., Rodriguez, A., Perdigon-Melon, J.A., Petre, A., Garcia-Calvo, E., Gomez, M.J., Aguera, A., Fernandez-Alba, A.R., 2010. Occurrence of emerging pollutants in urban wastewater and their removal through biological treatment followed by ozonation. Water Res. 44, 578–588. Saeed, T., Sun, G., 2012. A review on nitrogen and organics removal mechanisms in subsurface flow constructed wetlands: dependency on environmental parameters, operating conditions and supporting media. J. Environ. Manag. 112, 429–448. Vacca, G., Wand, H., Nikolausz, M., Kuschk, P., Kästner, M., 2005. Effect of plants and filter materials on bacteria removal pilot-scale constructed wetlands. Water Res. 39, 1361–1373. Vymazal, J., Kropfelová, L., 2008. Wastewater Treatment in Constructed Wetlands with Horizontal Sub-surface Flow, 1st ed. Springer, Dordrecht, The Netherlands. Wu, X., Conkle, J.L., Gan, J., 2012. Multi-residue determination of pharmaceutical and personal care products in vegetables. J. Chromatogr. A 1257, 78–86. Zhang, Y., Geißen, S.-U., Gal, C., 2008. Carbamazepine and diclofenac: removal in wastewater treatment plants and occurrence in water bodies. Chemosphere 73, 1151–1161. Zhang, D.Q., Keat, S., Gersberg, R.M., Sadreddini, S., Zhu, J., Anh Tuan, N., 2011. Removal of pharmaceutical compounds in tropical constructed wetlands. Ecol. Eng. 37, 460–464. Zhang, D.Q., Gersberg, R.M., Hua, T., Zhu, J., Anh Tuan, N., Keat, S., 2012. Pharmaceutical removal in tropical subsurface flow constructed wetlands at varying hydraulic loading rates. Chemosphere 87, 273–277. Zhang, D.Q., Hua, T., Gersberg, R.M., Zhu, J., Ng, W.J., Tan, S.K., 2013. Carbamazepine and naproxen: fate in wetland mesocosms planted with Scirpus validus. Chemosphere 91, 14–21. Zhang, D.Q., Gersberg, R.M., Ng, W.J., Tan, S.K., 2014. Removal of pharmaceuticals and personal care products in aquatic plant-based systems: a review. Environ. Pollut. 184, 620–639. Zhang, D., Lou, J., Lee, Z.M.P., Maspolim, Y., Gersberg, R.M., Liu, Y., Tan, S.K., Ng, W.J., 2016. Characterization of bacterial communities in wetland mesocosms receiving pharmaceutical-enriched wastewater. Ecol. Eng. 90, 215–224. Zurita, F., Carreón-Álvarez, A., 2015. Performance of three pilot-scale hybrid constructed wetlands for total coliforms and Escherichia coli removal from primary effluent—a 2-year study in a subtropical climate. J. Water Health 13 (2), 446–458. Zurita, F., White, J.R., 2014. Comparative study of three two-stage hybrid ecological wastewater treatment systems for producing high nutrient, reclaimed water for irrigation reuse in developing countries. Water 6, 213–228. Zurita, F., De Anda, J., Belmont, M.A., 2009. Treatment of domestic wastewater and production of commercial flowers in vertical and horizontal subsurface-flow constructed wetlands. Ecol. Eng. 35, 861–869. Zurita, F., Roy, E.D., White, J.R., 2012. Municipal wastewater treatment in Mexico: current status and opportunities for employing ecological treatment systems. Environ. Technol. 33 (10), 1151–1158.
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Carbamazepine removal in three pilot-scale hybrid wetlands planted with ornamental species Allan Tejeda, Ángeles X. Torres-Bojorges, Florentina Zurita ∗ Quality Environmental Laboratory, Centro Universitario de la Ciénega, University of Guadalajara, Av. Universidad 1115, Ocotlán, Jalisco, Mexico
a r t i c l e
i n f o
Article history: Received 15 January 2016 Received in revised form 30 March 2016 Accepted 28 April 2016 Available online xxx Keywords: Hybrid constructed wetlands Pharmaceuticals I. sibirica Z. aethiopica Subtropical climate Reductive conditions
a b s t r a c t The aims of this one-year study, were to evaluate the removal of carbamazepine (CBZ) in three pilotscale two-stage hybrid constructed wetlands as well as to evaluate the performance of three emergent species (Thypha latifolia, Iris sibirica and Zantedeschia aethiopica) planted as a polyculture. The systems included horizontal subsurface flow wetlands (HSSF-CW), vertical subsurface flow wetlands (VSSF-CW) and stabilization ponds (SP). The three different configurations were: HSSF-CWs followed by SPs, HSSFCWs followed by VSSF-CWs and VSSF-CWs followed by HSSF-CWs, which were identified as system I (SI), system II (SII) and system III (SIII) respectively. In addition, measurements of DO, Eh and pH, were taken in situ in order to know the internal system conditions. Out of the three hybrid systems, two were equally effective (SI and SII) and superior to SIII (p > 0.05). In these two systems (HSSF-CWs- SPs and HSSF-CWsVSSF-CWs) the average mass removals were 62.5 ± 4.5% and 59.0 ± 4.5%, respectively. CBZ removal was more effective under reductive environment (∼−60 to +50 mV) and near-anoxic conditions (<1.5 mg/L of DO). In addition, the two ornamental plants exhibited a better capacity to tolerate and take up CBZ in comparison to T. latifolia. These results demonstrate that it is possible to obtain higher CBZ removal efficiencies in CWs than those reported so far, under subtropical climate by using hybrid systems planted with a polyculture that include ornamental species and using a ground local filter material. © 2016 Elsevier B.V. All rights reserved.
1. Introduction During the last two decades, pharmaceuticals have been receiving increasing attention because of their widespread uses and continuous release to the aquatic environment (Zhang et al., 2014). Pharmaceuticals are potential bioactive chemicals which reach the aquatic environment mainly through the effluent of wastewater treatment plants (WTPs) (Li et al., 2014; Rivera-Utrilla et al., 2013) or through the discharges of untreated wastewater, mostly in developing countries (Zurita et al., 2012). The pharmaceuticals frequently found in both untreated and treated wastewater, as well as in environmental water bodies around the world, include antibiotics (trimethoprim, metronidazole, ciprofloxacin, sulfamethoxazole, tetracycline,), analgesic/anti-inflammatory drugs (ketoprofen, naproxen, ibuprofen, diclofenac and salicylic acid), an antiepileptic drug (carbamazepine), lipid regulators (clofibric acid), a diuretic drug (furosemide), antacids (ranitidine), beta-blockers (metropolol, sotalol, atenolol), lipid-lowering drugs (bezafibrate, clofibrate, gemfibrozil), and stimulants (caffeine) (Hijosa-Valsero
∗ Corresponding author. E-mail address: [email protected] (F. Zurita).
et al., 2010a; Al-Khateeb et al., 2014; Li et al., 2014; Rivera-Utrilla et al., 2013; Zhang et al., 2014). Although, the ecotoxicological effects of these compounds as well as their impact on human health due to a continuous exposition are mostly unknown, there are evidences of their hazardousness. Studies with animals have demonstrated that some pharmaceuticals can be either carcinogenic and teratogenic agents or hormonal system disruptors (Rosal et al., 2010). Carbamazepine, an antiepilectic drug, is one of the pharmaceuticals most frequently detected in aquatic environment owing to its poor removal in conventional biological treatments (Hai et al., 2011). In activated sludge treatment systems, the removal of CBZ is generally lower than 10% (Zhang et al., 2008). Currently, constructed wetlands are attracting increasing attention as an alternative secondary wastewater treatment system or a wastewater polishing treatment system, for the removal of pharmaceuticals from wastewater (Ávila et al., 2010; Li et al., 2014). The great potential of this low-cost technology of being used for the removal of pharmaceuticals has been proved by different researchers. It is well-known that pollutant removal in constructed wetlands takes place by means of complex physicochemical and microbiological interactions during the slow flow of wastewater across the soil matrix, which includes rhizomes and roots of emergent vegetation. In the particular case of pharmaceuticals,
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the specific mechanisms responsible for their removal are microbial degradation, plant uptake, bed adsorption and volatilization (Kadlec and Knight, 1996; Matamoros et al., 2008). It has been reported that plants play a very important role in the removal of pharmaceuticals not only through the direct uptake, assimilation, translocation and degradation in its tissues, but also in promoting the development of microbial communities capable of degrading such pollutants. Plants release oxygen through their roots, produce exudates that catalyze the degradation processes and provide their roots for biofilm formation (Li et al., 2014; Zhang et al., 2014). The crucial role of macrophytes in drug removal in constructed wetlands, as well as the fact that specific macrophytes could influence the removal efficiencies of pharmaceuticals, underscore the need of the evaluation of a large variety of them (Zhang et al., 2014). So far, mainly three species, namely Phragmites australis, Thypha latifolia and Typha angustifolia has been broadly used when evaluating CWs for drug removal (Carvalho et al., 2012; Li et al., 2014). On the other hand, in general, the pharmaceutical removal efficiencies in constructed wetlands have been found to be higher than the efficiencies reported in conventional wastewater treatment plants (Zhang et al., 2011). Moreover, the efficiencies of elimination for some pharmaceuticals have reached values superior to 70% (Zhang et al., 2014). However, for carbamazepine, which is considered as one of the most recalcitrant pharmaceuticals (HijosaValsero et al., 2010b; Zhang et al., 2011) the removal efficiencies
has been certainly low. For example, Zhang et al. (2012) found CBZ removal efficiencies in a range of 24–28% in HSSF-CWs planted with Typha angustifolia; while Matamoros et al. (2007) found a removal less than 20% in HSSF-CW and a removal of 26% in VSSF-CWs both planted with Phragmites. Furthermore, Li et al. (2014) report an average removal of CBZ less than 30% in both HSSF-CWs and VSSFCWs. In addition, there are a limited number of studies in which the removal of CBZ have been assessed in hybrid wetland systems. Therefore, the aims of this study were to evaluate and compare the removal of carbamazepine in three hybrid wetlands with two stages of treatment, using a polyculture of three macrophytes that includes ornamental plants as emergent vegetation, as well as to study the performance of the plants in HSSF-CWs. 2. Materials and methods 2.1. Description of the experiment This study was carried out at Ocotlán, Jalisco, Mexico; located at 1530 m above sea level and a latitude of 20◦ 21 00 , with a humid subtropical climate and an annual average temperature of 21 ◦ C. The study was conducted during one year, from June 2013 to May 2014 in three duplicated pilot-scale hybrid wetlands (Fig. 1) located inside the Centro Universitario de la Ciénega, a campus of the University of Guadalajara. The systems were in operation since
Fig. 1. The three hybrid wetland systems showing the measurement points for the parameters in situ. System I: HSSF-CW—SPs; System II: HSSF-CWs—VSSF-CWs; System III: VSSF-CWs—HSSF-CWs.
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September 2009 and have been fed with a portion of the wastewater generated in the campus (Zurita and White, 2014; Zurita and Carreón-Álvarez, 2015). For this study, the primary effluent was pumped to a 400 L-feeding tank where it was spiked with carbamazepine (99% purity, Sigma-Aldrich) for a final concentration of 25 g/L. The systems are fully described in Zurita and White (2014). Briefly, system I consisted of a HSSF-CW followed by a SP. The horizontal flow CWs were continuously fed with a theoretical hydraulic retention time (THRT) of 3 days. The effluent from the HSSF-CWs flowed by gravity to the SPs (THRT of 8.9 d). System II was also configured with a HSSF-CW (THRT of 3 d) as a first stage which was then followed by a VSSF-CW as a second stage. The HSSF-CW operated in the same way as in the system I, but the effluent was collected in a tank and pumped intermittently every 2 h on to the substrate of the VSSF-CW (HLR of 118 mm/d). System III was configured with a VSSF-CW (HLR of 146 mm/d) followed by a HSSF-CW (THRT of 3 d). The vertical flow CW was intermittently fed by a pump programmed to discharge 2.8 L every 2 h on to the surface. The effluent discharged directly on to the HSSF-CW. The HSSF-CWs were originally planted with Canna indica, but for this study this species was removed totally and the systems were replanted with a polyculture of three macrophyte species, each species had three plants randomly distributed on the wetland surface. The three macrophytes were Zantedeschia aethiopica, Iris sibirica, and Typha latifolia. The use of a polyculture was to promote the growth of a higher variety of microorganisms (Karathanasis et al., 2003; Vacca et al., 2005; Zurita et al., 2009) and thus probably promote the carbamazepine biodegradation. In contrast, the VSSF-CWs were planted originally with only one plant species, Strelitzia reginae and were not modified for this study. Ground tezontle with d10 of 0.645 mm and d60 of 2.3 mm, as well as a uniformity coefficient of 3.6, was used as substrate in both types of wetlands. 2.2. Carbamazepine quantification in aqueous samples The systems were fed with wastewater since the beginning of the study, but without the addition of CBZ for three months. In this way the systems were provided a stabilization period in order to give the emergent plants the opportunity to be adapted to the environmental conditions before the exposition to CBZ. In addition, presumably internal chemical and microbiological processes became more stable along this period. Quantification of CBZ was started after the 3-month period of stabilization. Samples were taken in a weekly basis at the general inlet and outlets of each system, resulting in 13 total samples. In triplicate, 100 mL of each sample was filtered through filter paper (Whatman 41) to remove suspended solids and then it was subjected to a three successive extraction with 100 mL of methylene chloride (1:1 ratio). The organic phase was concentrated to dryness with a rotary evaporator (IKA HB 10) at 40 ◦ C, and nitrogen gas. Then the extracts were reconstituted by using 1 mL of methanol. Each resuspension was filtered through a 0.20 m PTFE filter. The recovery rate was 96.5 ± 1.5%. Finally, quantitation of carbamazepine was performed on a reverse-phase Waters HPLC comprising a binary pump (Waters 1525) and a UV–vis detector with diode array (Waters 2998). For analytical purposes the – c´ et al. techniques described by Dordio et al. (2010) and Ðordevi (2009) were modified. A Waters column (Symmetry C18), 75 mm long, 4.6 mm internal diameter and 3.5 m in particle size was used. The mobile phase was a mixture of acetonitrile, water and orthophosphoric acid (55:45: 0.1), the flow rate was 1 mL/min and carbamazepine was detected at 285 nm, at a retention time between 3.37 and 3.41 min. Duplicate injections were made for each sample and the injection volume was 20 L into a loop of 100 L. For each set of triplicate samples, calibration curves were obtained with carbamazepine (99% purity, Sigma-Aldrich)
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The curve fitting was verified with the coefficient of determination (r2) which was always greater than 0.999. The limit of detection and quantification was 0.47 ± 0.00 g/L. 2.3. Influent water quality parameters and parameters in situ Organic-N, Ammonia, Nitrate, total N, BOD, COD, TSS and total P, were measured at the influent of the three systems in order to better characterize the wastewater under evaluation. Chemical and biological water quality parameters were determined as described in the Standard Methods for the examination of Water and Wastewater (APHA, 2005). Additionally, measurements of dissolved oxygen, redox potential and pH, in each system were performed in situ in order to know the systems environmental conditions. An HQ40d series portable Hach meter with Intellical sensors was used for these three parameters. The measurements were performed in four different points (internal and external) in the hybrid systems (Fig. 1). Perforated pipes were installed at inlets and outlets zones inside the HSSF CWs in order to insert the measuring devices. With respect to SPs, such measurements were performed inside the ponds as well as in the deposit of the final effluent collection. Meanwhile, in VSSF CWs the parameter readings were taken at the influent and effluent (Fig. 1). 2.4. Calculation of carbamazepine mass removal efficiencies The mass removal efficiency is the more reliable calculation method to assess constructed wetland efficiency, because this method includes water gains and losses, in addition to influent and effluent concentrations (Hijosa-Valsero et al., 2010b). Therefore, this leads to more realistic removal results, in comparison to the results obtained only by pollutant concentration decrease (Kadlec and Wallace, 2009). The mass removal efficiency calculation (MRE) is expressed as follows: MRE (%) =
Mr C Q − Ce Q e × 100 = i i × 100 Mi Ci Qi
(1)
where Mr (mg/d) is the mass of the pollutant removed in the wetland, Mi (mg/d) is the pollutant mass which enters in the wetland, Ci (mg/L) is the influent pollutant concentration, Qi (L/d) is the influent flow rate, Ce (mg/L) is the effluent pollutant concentration and Qe (L/d) is the effluent flow. 2.5. Performance of the three macrophytes in HSSFC-CWs At the end of the study, the standing live biomass (both aboveground and belowground biomass) as well as the capacity of each macrophyte to assimilate CBZ and the total assimilation of CBZ by each species were estimated in the HSSF-CWs. Briefly, after 9 months of exposition to CBZ, the plants were removed from the HSSF-CWs, classified in species and washed with abundant tap water. Then, each plant was separated in aerial and underground part and rinsed three times with distilled water, dried with paper towels and weighed for the evaluation of standing live biomass. Thereafter, both the aerial and underground parts were cut in small pieces with stainless steel scissors and dried at 40 ◦ C for 120 h. Finally, the plants were ground with a coffee grinder, and mortar and pestle and weighed again. The samples were kept in a desiccator until their analysis for CBZ concentration. The extraction by sonication and solid phase extraction methods employed for carbamazepine in plant tissues were based on the method of Wu et al. (2012). Briefly, around 1 g of the dried and ground sample was transferred to a 50 mL-propylene tube and sonicated two times for 20 min, first with 15 mL of methanol and then with 15 mL of acetone. After each sonication, the supernatant was filtered through a 1.6 m GF/A Whatman fiber glass filter. Each plant sample was
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processed in triplicate. After the filtration, the extracts were collected and concentrated to 5 mL by means of a rotary evaporator (IKA 210) and finally, diluted with deionized water to 100 mL. The SPE was performed using Strata-X cartridges (200 mg/6 cc, Phenomenex). The cartridges were conditioned with 5 mL of methanol and 5 mL of deionized water at a flow rate of 5 mL/min. Then, the extracts were passed through the cartridge with a flow rate of 2 mL/min. In order to remove any interference, the cartridges were washed with 5 mL of deionized water and then dried under vacuum for 60 min. The elution of the compound was performed by adding 5 mL of methanol. Thereafter, 1 mL of the eluate was filtered through a 0.20 m PTFE filter. The WATERS liquid chromatograph described previously, was used for CBZ quantification in plant tissues. The same column and mobile phase were used. Gradient elution employed was based on the method of Matilla and Kumpulainen (2002). The detection and quantification limits were 0.43 g/L and 1.31 g/mL, respectively.
3. Results and discussion The mean characteristics of the wastewater used in the study is reported in Table 1. According to the COD and BOD, this wastewater could be classified as a weak one, although the ammonium concentration is higher in comparison to that concentration normally found in common domestic wastewater. 3.1. Parameter measured in situ 3.1.1. Dissolved oxygen behavior System I showed the lowest concentration of DO along the treatment (Fig. 2A). In the first stage this was due to the presence of HSSF-CWs in which anoxic conditions prevails due to the saturated water matrix that prevents the oxygen diffusion from the surface (Saeed and Sun, 2012).With regard to the low concentration of DO in the SPs, this was due to a low algae production (which means low photosynthetic activity) because of the indirect exposure of the systems to sunlight. With respect to the system II, the HSSF CWs in the first stage had a similar behavior to their parallels HSSF treatments in the system I. In contrast, in the second stage (VSSF-CWs) there was an increase in the DO concentration because of the intermittent feeding of this type of CW (Fig. 2A). Finally, in the system III, the DO increased noticeable in the VSSF treatment as the first stage. In this case, the direct discharge of DO-high concentration effluent amended the internal conditions of the HSSF CWs used as second stage. Although there was a DO concentration decrease, the average value was maintained above to 2 mg/L, indicating aerobic conditions inside the HSSF-CWs in contrast with their parallels in systems I and II (Fig. 2A).
2.6. Approximate CBZ mass balance calculation in HSSF-CWs At the end of the study, a CBZ mass balance was performed in each HSSF-CWs by taking into account the total CBZ-mass input, the total CBZ-mass output and the total CB retained in the plant biomass; the remaining loss of CBZ from the mass balance was considered the CBZ removal by other mechanisms (adsorption, biodegradation, biotransformation, etc.). The biomass dried and removed from the systems along the study was not considered for the balance. The total CBZ-mass input and output in each HSSF-CW was calculated from the cumulative total CBZ-mass inflow and outflow along the whole period of operation of 280 days. The CBZ mass balance was represented by the following equation:
3.1.2. Redox potential behavior Redox potential (Eh) is a quantitative measurement of either the pollutant’s oxidation or reduction trend within the system and similar to DO, indicates the microbial processes occurring inside the wetland (Kadlec and Wallace, 2009). The results regarding this parameter, were consistent with the DO results. System I showed negative Eh values at the first stage (HSSF-CWs), indicating, as expected, reductive conditions. However, the average value showed a slight increase at the outlet zone in comparison to the inlet zone (Fig. 2B). This could be explained by the BOD decrease as the wastewater passes through the treatment (Kadlec and Wallace, 2009), as well as the macrophyte’s constant oxygen supply into the matrix soil (Brix, 1997). Inside the SPs, the Eh showed again a new increase, reaching a small positive value. With respect to the SII, the behavior of Eh in the first stage (HSSF CWs) was similar to the results in its parallel in the SI. In contrast, in the second stage an increase in Eh was observed in the effluent, as a result of the wastewater oxygenation during its pass through the VSSF-CWs. The system III showed the most oxidative conditions throughout the treatment, with Eh values near and over 100 mV (Fig. 2B). These
CBZ-massin = CBZ-massoutintheeffluent + CBZinplants + CBZmassremovalbyothermechanisms.
2.7. Statistical analysis A randomized block design was used to analyze the mass removal efficiencies along the time in this study. Multifactor analysis of variance (ANOVA) was carried out using the Statgraphics Centurion XV.II software package to check differences amongst treatments (stage 1 and stage 2 in each individual hybrid system or total removal in each of the three systems). A significance level of p = 0.05 was used for all statistical tests, and values reported are the mean (average) ± standard error of the mean. When a significant difference was observed between treatments in the ANOVA procedure, multiple comparisons were made using the Least Significant Difference (LSD) test for differences between means.
Table 1 Characteristics of the wastewater in the three systems, along the period of evaluation (Average ± SD). Influent
SYSTEM I: HF-SP
Parameter (mg/L) Chemical Oxygen Demand Biochemical Oxygen Demand Phosphorus Organic N Ammonium Nitrate Total N Total suspended solids
1st stage HF-CW 170.9 130.8 6.9 4.3 68.6 4.2 77.1 30.4
± ± ± ± ± ± ± ±
149.3 52.5 5.3 2.0 47.9 1.4 47.9 18.4
85.5 23.8 7.8 2.9 58.0 2.0 62.9 17.7
± ± ± ± ± ± ± ±
78.3 8.2 5.0 1.4 41.0 1.4 41.0 18.0
SYSTEM II: HF-VF 2nd stage SP 115.7 79.7 6.8 3.6 33.1 21.6 58.3 60.5
± ± ± ± ± ± ± ±
100.7 26.2 2.6 2.5 21.8 11.3 29.3 53.6
1st stage HF-CW 48.6 20.4 6.3 1.9 61.8 0.7 64.4 9.5
± ± ± ± ± ± ± ±
32.8 5.7 3.6 0.9 35.7 0.5 36.0 6.9
SYSTEM III: VF-HF 2nd stage VF-CW 35.6 6.1 6.8 1.3 9.3 65.6 76.2 12.8
± ± ± ± ± ± ± ±
26.9 3.7 2.7 1.2 7.9 38.2 41.9 9.7
1st stage VF-CW 63.8 13.6 6.7 2.7 25.4 50.0 77.0 17.3
± ± ± ± ± ± ± ±
31.4 5.6 3.8 1.4 22.9 33.1 44.3 19.1
2nd stage HF-CW 44.8 3.7 6.3 1.4 15.9 50.6 68.0 10.7
± ± ± ± ± ± ± ±
59.3 2.0 3.5 0.7 17.2 25.2.2 39.5 6.0
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pH decreased at the first stage outlet (VSSF-CW) due to the common nitrification process in such wetlands. Then this value was kept along the second stage (HSSF-CW) due to its buffer capacity mentioned previously.
3.2. Carbamazepine removal
Fig. 2. Parameters in situ along the hybrid wetland systems (n = 47) Average ± SD. A. Dissolved oxygen; B. Redox potential; C. pH.
conditions remained even throughout the second stage, which supports the DO results. 3.1.3. pH behavior pH plays a very important role in pollutant removal in constructed wetlands by directly affecting the substrate sorption capacity (Li et al., 2014) and microbial processes (Meng et al., 2014). System I behavior was remarkably stable along the two stages, with pH values near 8 (Fig. 2C). This performance is the result of the buffer capacity of the HSSF-CWs and the low variability in pH in the stabilization ponds, likely because of the low algae production (Kadlec and Wallace, 2009). System II also showed a stable pH in its first stage, with very similar values at inlet and outlet zones. However, as expected, in the second stage (VSSF CW) a pH decrease was registered at the outlet as a consequence of the nitrification process that takes place inside vertical wetlands and leads to H+ ion generation (Vymazal and Kropfelová, 2008). In contrast, the system III performance was quite different in comparison to SI and SII, showing pH values close to 7 along the treatment (Fig. 2C). The
The final concentration of CBZ reached in each of the three hybrid CWs along the period of evaluation, is shown in Table 2. When analyzing the performance of the systems individually, it was found that in SI, the mean removal efficiency was 48.3 ± 7.4% in the HSSF-CWs and increased by 14.1 ± 9.5% in the SPs (p < 0.05). In a similar way, in SII, the removal efficiency was 49% in the HSSF-CWs and increased by 10% in the VSSF-CWs (p < 0.05). In contrast, in SIII, the removal efficiency was 38% in the VSSF-CWs and did not increase significantly in the HSSF CWs (p > 0.05), despite an apparent additional removal of 6%. With regard to the total removal efficiencies, it was found that SI and SII were the most efficient systems and statistically equal; while the least effective was SIII (p < 0.05). The average efficiencies were 62.5 ± 4.5%, 59.0 ± 4.5% and 44.2 ± 4.5% for SI, SII and SIII, respectively. According to these results, the HSSF-CWs (as a first stage) were mainly the responsible for the higher efficiencies in SI and II. This suggests that CBZ removal is favored by anoxic conditions which predominated in this type of CWs along the study, instead of the aerobic conditions in the VSSF-CWs. In SI, these conditions prevailed even in the SPs as was discussed previously. These outcomes are in agreement to those reported by other authors who found that CBZ was biologically degraded under anoxic conditions (Park et al., 2009). Hai et al. (2011), reached a removal of 68 ± 10% under near anoxic conditions (DO = 0.5 mg/L) in comparison to aerobic conditions (DO > 2 mg/L) in membrane bioreactors (MBR). Moreover, the removal efficiency of CBZ obtained in the HSSF-CWs as a first stage, was higher than the efficiencies reported by different researchers (Matamoros et al., 2008; Park et al., 2009; Hijosa-Valsero et al., 2010b; Zhang et al., 2011, 2012; Li et al., 2014). The better results in this study, were probably due to a greater biodegradation as a result of the presence of a more diverse microbial populations promoted by the polyculture of three macrophytes in comparison to monoculture systems (Karathanasis et al., 2003; Vacca et al., 2005; Zurita et al., 2009). In general, the presence of macrophytes stimulate the diversity of rhizosphere-inhabiting microorganisms (Healy et al., 2007) and has been recently found by Zhang et al. (2016) that enhance the specific taxonomic groups in HSSF-CWs receiving pharmaceuticalenriched wastewater. With a high diversity of microorganisms, the biodegradation of this type of compounds is more probable by means of fortuitous metabolism and co-metabolism (the recalcitrant compound is biodegraded by enzymes produced during the biodegradation of another primary pollutant). By these mechanisms, continual biodegradation of xenobiotic compounds is through the use of additional carbon and energy sources supplied from the action of other organisms in a mixed microbial community (Grady, 1985). In addition to the probable biodegradation, CBZ uptake by the different plants used was also important, as will be discussed later. In contrast, in the HSSF-CWs as second stage in SIII, the removal of CBZ was very low, probably owing to the aforementioned more aerobic conditions resulting from the direct discharge of the VSSF CWs effluent. On the other hand, the removal efficiency of 34% in VSSF CWs as first stage was also higher than the average 26% reported by Matamoros et al. (2007) who evaluated a range of HLR from 13 to 160 mm/d. Once again, these better result could be due to the presence of the ornamental species S. reginae, whose roots reached almost 1 m length at the end of the study.
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3.3. Standing live biomass and carbamazepine assimilation by tissues The species with the lowest standing biomass was T. latifolia (Fig. 3A) in comparison to the two ornamental species (p < 0.05) (Fig. 3B and C). This result was expected because T. latifolia was clearly the species that exhibited more signs of stress when being exposed to CBZ, in comparison to the two ornamental plants. After ∼5 weeks of feeding CBZ into the systems, chlorosis began to be observed in T. latifolia. This species continued desiccating throughout the study until its complete desiccation from three out of six cells. This result is opposite to those reported by other authors, with respect to the good tolerance of cattails to the exposure to CBZ even in higher concentrations (Dordio et al., 2010, 2011). However, many of these studies have been conducted only in hydroponic assays (Dordio et al., 2011) or in batch operation systems with periods of evaluation in days (Dordio et al., 2010). The most similar study to the present one is that carried out by Zhang et al. (2011) who evalu-
ated CWs planted with T. angustifolia, fed by synthetic wastewater with a concentration of 25 g/L of CBZ in two-month study. So, to the best of our knowledge this is the first time that this species was exposed to CBZ in such concentration under more realistic conditions in a long period of evaluation. With regard to CBZ uptake, the species with the lowest capacity was once more T. latifolia while the species with the highest capacity was I. sibirica, mainly in its roots (p > 0.05) (Fig. 4A–C). In the HSSF-CWs of the SI and SII, the uptake in I. sibirica roots varied from 14.6 to 35.9 g/g dw, and decreased in HSSF-CWs of the SIII, to a range of 7.0 a 10.3 g/g dw, likely because of the lower concentration of CBZ after the VSSF-CWs. Furthermore, the calculation of the total CBZ assimilated in the standing live biomass by each species (Fig. 5A–C.) showed once again, that T. latifolia was the species that assimilated the least quantity of CBZ in its tissues in comparison to the ornamental plants, as a result of a low standing biomass and poor uptake capacity. With regard to the I. sibirica, the species with the higher total CBZ assimilation, most of the CBZ
Fig. 3. Standing live biomass in the HSSF-CWs after one year of experimentation. A. T. latifolia; B. Z. aethiopica; C. I. sibirica.
Fig. 4. CBZ uptake by the three emergent plants in HSSF-CWs. A. T. latifolia; B. Z. aethiopica; C. I. sibirica.
Table 2 CBZ concentration in the three systems, along the period of evaluation (Average ± standard error of the mean). Influent
CBZ concentration (g/L)
25.0 ± 0.01
SYSTEM I: HF-SP
SYSTEM II: HF-VF
SYSTEM III: VF-HF
1st stage HF-CW
2nd stage SP
1st stage HF-CW
2nd stage VF-CW
1st stage VF-CW
2nd stage HF-CW
13.13 ± 0.05
9.32 ± 0.05
12.87 ± 0.04
10.12 ± 0.04
13.30 ± 0.05
12.76 ± 0.06
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Fig. 6. CBZ mass balance performed in HSSF-CWs after the whole period of experimentation.
increase of 20.6% in the removal of ibuprofen in HSSF-CWs planted with Thypha angustifolia. Additionally, the plants can metabolize pharmaceuticals to other products so the real uptake could be underestimated. Zhang et al. (2013), found in a 21-day hydroponic study, that the direct CBZ uptake by S. validus was much less than the total CBZ elimination, suggesting that CBZ must have been transformed to other products by catabolism. In addition, Dordio et al. (2011), observed in another hydroponic study, a decrease in the CBZ amount in the leaves of Thypa spp. between 14 and 21 days of exposition and found that this was because the plant was capable of translocating and metabolizing CBZ, which was evident with the detection of the metabolite 10,11-dihidro-10,11epoxycarbamazepine. 4. Conclusions
Fig. 5. Total CBZ assimilation in the standing biomass by each species in HSSF-CWs. A. T. latifolia; B. Z. aethiopica; C. I. sibirica.
was accumulated in its roots. In the system III, the proportion of CBZ in root/stem was almost 20 (Fig. 5C). In this way, apparently, Z. aethiopica exhibited a better ability to translocate CBZ in comparison to I. sibirica. Although, these species were evaluated as a polyculture and the competition amongst them could have been an additional stress source, these results suggest that the performance of macrophytes when being exposed to CBZ vary according to the species and more research is required in order to, probably, select the more appropriate species. 3.4. CBZ mass balance in HSSF-CWs According to the CBZ mass balance (Fig. 6), the percentage of CBZ accumulated directly in the plant biomass was only ∼2% in the HSSF-CWs in SI and II (as a first stage) and ∼4% in HSSF-CWs in SII (as a second stage). While the removal by other mechanisms, was ∼45% and ∼6%, respectively. However, the plants could have also contributed to these “other mechanisms” by modifying the environmental conditions and microbial communities as has been demonstrated in recent studies with planted and unplanted systems; such as that performed by Zhang et al. (2016) who found an
In this study we demonstrated that it is possible to obtain higher removal efficiency of the known recalcitrant CBZ in constructed wetlands by using hybrid systems in comparison to single-stage systems. This was possible under subtropical climate through the use of a ground local volcanic rock as filter material, a polyculture of three species in HSSF-CWs and an ornamental species in VSSF-CWs. Out of the three hybrid systems, two were equally effective (SI and SII). In these two systems (HSSF-CW- SP and HSF-CW-VSSF-CW) the average mass removals were 62% and 59%, respectively during the period of evaluation. Such results indicate that CBZ removal is more effective under reductive environment (∼ −60 to +50 mV) and near-anoxic conditions (<1.5 mg/L of DO). Moreover, HSSF-CWs were more effective than VSSF-CW, when comparing them as a first stage for the same reasons. Furthermore, under subtropical and tropical climate, it is possible to use ornamental species in HSSF-CWs such as I. sibirica and Z. aetiopica for CBZ removal. These species contributed to the treatment by assimilating CBZ in their roots, leaves and stems and probably transformed it to other products (as has been observed in other species), playing in this way, a crucial role in the elimination of CBZ from the systems. Additionally, out of the three macrophytes, apparently, the most recomendable species would be I. sibirica which showed the highest total assimilation capacity due to a combination of a high production biomass and a good ability to assimilate this pharmaceutical. However, further research is needed in order to better understand the metabolism of CBZ by these ornamental species and to achieve more conclusive results with regard to their performance when being exposed to CBZ.
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Acknowledgements The work was funded by a grant from the Ministry of Education through the Programa para el Desarrollo Profesional Docente (PRODEP) in the call 2013 “Fortalecimiento de Cuerpos Académicos”. The authors would like to thank Zaira López for technical assistance and to the many undergraduate students of the Centro Universitario de la Ciénega for supervising the proper operation of the systems. References Ávila, C., Pedescoll, A., Matamoros, V., Bayona, J.M., García, J., 2010. Capacity of horizontal subsurface flow constructed wetland system for removal of emerging pollutants: an injection experiment. Chemosphere 81, 1137–1142. – c, ´ S., Kilibarda, V., Stojanovic, ´ T., 2009. Determination of carbamazepine in Ðordevi serum and saliva samples by high performance liquid chromatography with ultraviolet detection. Vojnosanit. Pregl. 66 (5), 347–352. APHA, AWWA, WEF, 2005. Standard Methods for the Examination of Water and Wastewater. APHA (American Public Health Association), Washington DC. Al-Khateeb, L.A., Almotiry, S., Salam, M.A., 2014. Adsorption of pharmaceutical pollutants onto graphene nanoplatelets. Chem. Eng. J. 248, 191–199. Brix, H., 1997. Do macrophytes play a role in constructed treatment wetlands? Water Sci. Technol. 35 (5), 11–17. Carvalho, P.N., Basto, M.Cl.P., Almeida, C.M.R., 2012. Potential of Phragmites australis for the removal of veterinary pharmaceuticals from aquatic media. Bioresour. Technol. 116, 497–501. Dordio, A., Carvalho, A.J.P., Teixeira, D.M., Dias, C.B., Pinto, A.P., 2010. Removal of pharmaceuticals in microcosm constructed wetlands using Typha spp. and LECA. Bioresour. Technol. 101, 886–892. Dordio, A.V., Belo, M., Teixeira, D.M., Carvalho, A.J.P., Dias, C.M.B., Picó, Y., Pinto, A.P., 2011. Evaluation of carbamazepine uptake and metabolization by Typha spp.: a plant with potential use in phytotreatment. Bioresour. Technol. 102, 7827–7834. Grady, C.P., 1985. Biodegradation: its measurement and microbiological basis. Biotechnol. Bioeng. 27 (5), 660–674. Hai, F.I., Li, X., Price, W.E., Nghiem, L.D., 2011. Removal of carbamazepine and sulfamethoxazole by MBR under anoxic and aerobic conditions. Bioresour. Technol. 102, 10386–10390. Healy, M.G., Rodgers, M., Mulqueen, J., 2007. Treatment of dairy wastewater using constructed wetlands and intermittent sand filters. Bioresour. Technol. 98, 2268–2281. Hijosa-Valsero, M., Matamoros, V., Martin-Villacorta, J., Bécares, E., Bayona, J.M., 2010a. Assessment of full-scale natural systems for the removal of PPCPs from wastewater in small communities. Water Res. 44, 1429–1439. Hijosa-Valsero, M., Matamoros, V., Sidrach-Cardona, R., Martin-Villacorta, J., Bécares, E., Bayona, J.M., 2010b. Comprehensive assessment of the design configuration of constructed wetlands for the removal pharmaceuticals and personal care products from urban wastewaters. Water Res. 44, 3669–3678. Kadlec, R.H., Knight, R.L., 1996. Treatment Wetlands. CRC Press, Lewis Publishers, Boca Raton, FL. Kadlec, R.H., Wallace, S.D., 2009. Treatment Wetlands, 2nd ed. CRC Press, Boca Raton, New York. Karathanasis, A.D., Potter, C.L., Coyne, M.S., 2003. Vegetation effects on fecal bacteria, BOD, and suspended solid removal in constructed wetlands treating domestic wastewater. Ecol. Eng. 20, 157–169. Li, Y., Zhu, G., Jern, W., Keat, S., 2014. A review on removing pharmaceutical contaminants from wastewater by constructed wetlands: design, performance and mechanism. Sci. Total Environ. 468–469, 908–932. Matamoros, V., Arias, C., Brix, H., Bayona, J.M., 2007. Removal of pharmaceuticals and personal care products (PPCPs) from urban wastewater in a pilot vertical flow constructed wetland and a sand filter. Environ. Sci. Technol. 41, 8171–8177.
Matamoros, V., Caselles-Osorio, A., Garcia, J., Bayona, J.M., 2008. Behavior of pharmaceutical products and biodegradation intermediates in horizontal subsurface flow constructed wetland: a microcosm experiment. Sci. Total Environ. 394, 171–176. Matilla, P., Kumpulainen, J., 2002. Determination of free and total phenolic acids in plant-derived foods by HPLC with diode array detection. J. Agric. Food Chem. 50, 3660–3667. Meng, P., Pei, H., Hu, W., Shao, Y., Li, Z., 2014. How to increase microbial degradation in constructed wetlands: influencing factors and improvements measures. Bioresour. Technol. 157, 316–326. Park, N., Vanderford, B.J., Snyder, S.A., Sarp, S., Kim, S.D., Cho, J., 2009. Effective controls of micropollutants included in wastewater effluent using constructed wetlands under anoxic condition. Ecol. Eng. 35, 418–423. Rivera-Utrilla, J., Sánchez-Polo, M., Ferro-García, M.A., Prados-Joya, G., Ocampo-Pérez, R., 2013. Pharmaceuticals as emerging contaminants and their removal from water. A review. Chemosphere 93, 1268–1287. Rosal, R., Rodriguez, A., Perdigon-Melon, J.A., Petre, A., Garcia-Calvo, E., Gomez, M.J., Aguera, A., Fernandez-Alba, A.R., 2010. Occurrence of emerging pollutants in urban wastewater and their removal through biological treatment followed by ozonation. Water Res. 44, 578–588. Saeed, T., Sun, G., 2012. A review on nitrogen and organics removal mechanisms in subsurface flow constructed wetlands: dependency on environmental parameters, operating conditions and supporting media. J. Environ. Manag. 112, 429–448. Vacca, G., Wand, H., Nikolausz, M., Kuschk, P., Kästner, M., 2005. Effect of plants and filter materials on bacteria removal pilot-scale constructed wetlands. Water Res. 39, 1361–1373. Vymazal, J., Kropfelová, L., 2008. Wastewater Treatment in Constructed Wetlands with Horizontal Sub-surface Flow, 1st ed. Springer, Dordrecht, The Netherlands. Wu, X., Conkle, J.L., Gan, J., 2012. Multi-residue determination of pharmaceutical and personal care products in vegetables. J. Chromatogr. A 1257, 78–86. Zhang, Y., Geißen, S.-U., Gal, C., 2008. Carbamazepine and diclofenac: removal in wastewater treatment plants and occurrence in water bodies. Chemosphere 73, 1151–1161. Zhang, D.Q., Keat, S., Gersberg, R.M., Sadreddini, S., Zhu, J., Anh Tuan, N., 2011. Removal of pharmaceutical compounds in tropical constructed wetlands. Ecol. Eng. 37, 460–464. Zhang, D.Q., Gersberg, R.M., Hua, T., Zhu, J., Anh Tuan, N., Keat, S., 2012. Pharmaceutical removal in tropical subsurface flow constructed wetlands at varying hydraulic loading rates. Chemosphere 87, 273–277. Zhang, D.Q., Hua, T., Gersberg, R.M., Zhu, J., Ng, W.J., Tan, S.K., 2013. Carbamazepine and naproxen: fate in wetland mesocosms planted with Scirpus validus. Chemosphere 91, 14–21. Zhang, D.Q., Gersberg, R.M., Ng, W.J., Tan, S.K., 2014. Removal of pharmaceuticals and personal care products in aquatic plant-based systems: a review. Environ. Pollut. 184, 620–639. Zhang, D., Lou, J., Lee, Z.M.P., Maspolim, Y., Gersberg, R.M., Liu, Y., Tan, S.K., Ng, W.J., 2016. Characterization of bacterial communities in wetland mesocosms receiving pharmaceutical-enriched wastewater. Ecol. Eng. 90, 215–224. Zurita, F., Carreón-Álvarez, A., 2015. Performance of three pilot-scale hybrid constructed wetlands for total coliforms and Escherichia coli removal from primary effluent—a 2-year study in a subtropical climate. J. Water Health 13 (2), 446–458. Zurita, F., White, J.R., 2014. Comparative study of three two-stage hybrid ecological wastewater treatment systems for producing high nutrient, reclaimed water for irrigation reuse in developing countries. Water 6, 213–228. Zurita, F., De Anda, J., Belmont, M.A., 2009. Treatment of domestic wastewater and production of commercial flowers in vertical and horizontal subsurface-flow constructed wetlands. Ecol. Eng. 35, 861–869. Zurita, F., Roy, E.D., White, J.R., 2012. Municipal wastewater treatment in Mexico: current status and opportunities for employing ecological treatment systems. Environ. Technol. 33 (10), 1151–1158.
Please cite this article in press as: Tejeda, A., et al., Carbamazepine removal in three pilot-scale hybrid wetlands planted with ornamental species. Ecol. Eng. (2016), http://dx.doi.org/10.1016/j.ecoleng.2016.04.012