Constructed wetlands for the removal of metals from livestock wastewater – Can the presence of veterinary antibiotics affect removals?

The presence of emergent antibiotics, in livestock wastewater may affect constructed wetlands (CWs) performance in the removal of other pollutants. The main objective of this study was to evaluate the influence of two antibiotics commonly used in livestock industry, enrofloxacin and ceftiofur, on metal removal by CWs. Microcosms (0.4 m×0.3 m×0.3 m), simulating CWs, were constructed with Phragmites australis to treat livestock wastewater spiked or not with 100 µg/L of enrofloxacin or ceftiofur (individually or in mixture). Wastewater was treated during 20 one-week cycles. After one-week cycle wastewater was removed and replaced by new wastewater (with or without spiking). At weeks 1, 2, 4, 8, 14, 18 and 20, treated wastewater was analysed to determine the removal rates of metals (Zn, Cu, Fe and Mn) and of each antibiotic. At weeks 1, 8 and 20 portions of the plant root substrate were collected and metals determined. At the end of the experiment metal levels were also determined in plant tissues. Removal rate of Fe from wastewater was 99%. Removal rates of Cu and Zn were higher than 85% and 89%, respectively, whereas for Mn removal rates up to 75% were obtained. In general, no significant differences were observed through time in the removals of the different metals, indicating that the systems maintained their functionality during the experimental period. Antibiotics did not interfere with the system depuration capacity, in terms of metals removals from wastewater, and ceftiofur even promoted metal uptake by P. australis. Therefore, CWs seem to be a valuable alternative to remove pollutants, including antibiotics and metals, from livestock wastewaters, reducing the risk the release of these wastewaters might pose into the environment, although more research should be conducted with other antibiotics in CWs. © 2016 Elsevier

This research was partially supported by the Strategic Funding UID/Multi/04423/2013 through national funds provided by FCT – Foundation for Science and Technology and European Regional Development Fund (ERDF), in the framework of the programme PT2020 and by the structured Programme of R&D&I INNOVMAR - Innovation and Sustainability in the Management and Exploitation of Marine Resources, reference NORTE-01-0145-FEDER-000035, namely within the Research Line ECOSERVICES (Assessing the environmental quality, vulnerability and risks for the sustainable management of the NW coast natural resources and ecosystem services in a changing world) within the R&D Institution CIIMAR (Interdisciplinary Centre of Marine and Environmental Research), supported by the Northern Regional Operational Programme (NORTE2020), through the European Regional Development Fund (ERDF).