Antibiotics in synthetic and hospital wastewater, raw and treated on anaerobic reactors: toxic effects on freshwater invertebrates

Abstract

Antibiotics have been classified as substances of emerging interest and potentially toxic to aquatic biota, due to their high consumption, presence in hospital and domestic effluents, and freshwater. In this scenario, the present project aims to investigate the toxic effects of synthetic wastewater containing 12 antibiotics (7 sulfonamides and 5 fluoroquinolones) and hospital wastewater, on three species of different trophic functions in continental waters: Allonais inaequalis, Chironomus sancticaroli and Daphnia magna. This project is included in the international cooperation entitled "Potential of innovative decentralized wastewater treatment processes for preventing the spread of antibiotic resistant microorganisms, organic micropollutants, pathogens and viruses", in which, universities of Denmark, Portugal, Germany, France, and Spain are involved. Samples of raw and treated effluents on (1) anaerobic fixed-bed and (2) immobilized biomass reactors will be obtained in partnership with researchers from the Laboratory of Biological Processes (LPB-USP). For the selected aquatic species, acute and chronic bioassays will be performed using synthetic and hospital wastewater in the following dilution proportions: 1; 6; 12.5; 25; 50 and 100%. In the first stage, samples of the raw and treated synthetic effluents will be obtained from reactors 1 and 2 in different hydraulic detention times: 16, 12 and, 8 h. In the second stage, the toxicity bioassays will be carried out using samples of raw hospital effluent and treated in a reactor (1 or 2, depending on removal efficiencies in the first stage). In A. inaequalis, the effects on mortality (acute effect) and reproduction (chronic effect) will be investigated. For C. sancticaroli, the responses analyzed will be mortality, body length, menta deformities, effects on rates and emergence times, sex ratio, potential fecundity, and geometric morphometry of the wings. In D. magna, the effects on immobility, longevity, reproduction (number and time of broods, production of neonates), molting process and body length will be studied. These animals will be cultivated at the Aquatic Ecology Laboratory (LEAA-USP) and will be kept according to methodologies described in the specific literature. Sensitivity tests will be performed in parallel to the exposures to validate the health of the individuals. Based on the results obtained in the bioassays and applied statistical analyzes, this project will contribute to better understand the impact of antibiotics and hospital wastewater on invertebrate species occurring in freshwater, as well as responding to the scientific gap related to the level of ecotoxicological safety of effluents containing pharmaceutical compounds, especially antibiotics. (AU)