Iris sibirica and Zantedeschia aethiopica are ornamental species that have previously been used in pilot-scale treatment wetlands (TWs) focused on the removal of carbamazepine (CBZ), in which good results were obtained; however, the plant influence was not completely determined. In addition, plant uptake has been reported to play a crucial role in CBZ removal in comparison to other mechanisms. Therefore, the aim of this study was to evaluate the capacity of I. sibirica and Z. aethiopica to take up, translocate, and accumulate CBZ in hydroponic conditions using a nutrient solution spiked with the drug. The maximum CBZ tolerance threshold for the two species was found to be 10 mg/L, which was used to carry out the uptake experiments. The results showed a better performance of I. sibirica compared to Z. aethiopica reaching 31.1% and 20.9% of removal efficiency, respectively. The parent compound accumulated mainly on the leaves of both species. Furthermore, a high proportion of the CBZ taken up by the plants (up to 70%) was metabolized by both species. The performance of the two species suggests the importance of plant harvesting in TWs in order to promote CBZ removal and indicates the need for future works.
Abstract:In this study, the aim was to evaluate the adsorption capacity of a volcanic rock commonly used in Mexico as filter medium in constructed wetlands (locally named tezontle) for carbamazepine (CBZ) adsorption, as well as to analyze the change in its capacity with biofilm growth. Adsorption essays were carried out under batch conditions by evaluating two particle sizes of tezontle, two values of the solution pH, and two temperatures; from these essays, optimal conditions for carbamazepine adsorption were obtained. The optimal conditions (pH 8, 25 • C and 0.85-2.0 mm particle-size) were used to evaluate the adsorption capacity of tezontle with biofilm, which was promoted through tezontle exposition to wastewater in glass columns, for six months. The maximum adsorption capacity of clean tezontle was 3.48 µg/g; while for the tezontle with biofilm, the minimum value was 1.75 µg/g (after the second week) and the maximum, was 3.3 µg/g (after six months) with a clear tendency of increasing over time. The adsorption kinetic was fitted to a pseudo-second model for both tezontle without biofilm and with biofilm, thus indicating a chemisorption process. On clean tezontle, both acid active sites (AAS) and basic active sites (BAS) were found in 0.087 and 0.147 meq/g, respectively. The increase in the adsorption capacity of tezontle with biofilm, along the time was correlated with a higher concentration of BAS, presumably from a greater development of biofilm. The presence of biofilm onto tezontle surface was confirmed through FTIR and FE-SEM. These results confirm the essential role of filter media for pharmaceutical removal in constructed wetlands (CWs).
The aim of this 15-month study was to evaluate and compare two partially saturated (PS) vertical flow (VF) wetlands for total nitrogen (TN) removal. The PS VF wetlands, evaluated in duplicate, were added with corncob (CC) in two different heights of the free-drainage zone (FDZ). The FDZ had a height of 40 cm and the saturated zone (SZ) had a height of 30 cm. The configuration of the system I (SI) was a 20 cm-corncob bed above the SZ followed by a 20 cm-tezontle bed; in system II (SII) the order of the beds were inverted. The SZ was added with tezontle with a size of 1−2 cm. Weekly measurements of water quality parameters including oxygen demand (BOD 5 ), chemical oxygen demand (COD), color, total suspended solids (TSS), organic nitrogen (Org-N), ammonium (NH 4 + ), nitrate (NO 3 − ) and nitrite (NO 2 − ), were taken in the influent and effluents, and interfaces (nitrate and nitrite). Measurements of pH, dissolved oxygen (DO) and oxidation-reduction potential (ORP) were taken in the SZ. The addition of CC in the FDZ did not interfere with the capacity of the PS VF wetlands for BOD 5 , COD, TSS and true color removal, reaching mass removal efficiencies of 91.9% and 92.2%, 66.6% and 75%, 89.8% and 92%, 63.3% and 66.0%, for SI and SII, respectively; without significant difference between the systems (p > 0.05). The CC in the FDZ neither interfered with the PS VF wetlands nitrification capacity. The removal of TN was similar in SI and SII (p > 0.05), attaining average mass removal efficiencies of 68.2% and 66.0%, respectively. These efficiencies were not sufficiently high due to the limited denitrification process in the SZ as a result of the absence of biodegradable carbon, generated and consumed in the FDZ.
Tequila vinasse (TV) is a high-strength effluent generated during the production of tequila, with a chemical oxygen demand (COD) concentration of up to 74 g/L. In this study, the treatment of TV was evaluated in a 27-week study in two types of constructed wetlands (CWs), namely horizontal subsurface flow wetlands (HSSFWs) and vertical upflow wetlands (VUFWs). The pre-settled and neutralized TV was diluted at 10, 20, 30, and 40% with domestic wastewater (DWW). Volcanic rock (tezontle) was used as the substrate and Arundo donax and Iris sibirica as emergent vegetation. The two systems showed similar high removal efficiencies for COD, biochemical oxygen demand (BOD5), turbidity, total suspended solids (TSS), true colour (TC), electrical conductivity (EC), and total nitrogen (TN). The highest average percentages of removal were obtained at 40% of dilution: 95.4 and 95.8% for COD, 98.1 and 98.2% for turbidity, 91.8 and 95.9% for TSS, and 86.5 and 86.4% for TC in the HSSFWs and the VUFWs, respectively. This study demonstrates the potential of CWs for TV treatment as a major step in a treatment system.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.