Effects of different filtration techniques on quality and toxicology of post treatment effluent from an anaerobic reactor

Abstract The early stages of the fish life cycle correspond to the phase that is most susceptible to deleterious effects caused by exposure to pollution. The aim of this study was to evaluate the quality of the anaerobic reactor effluent after three filtration-based treatments, namely, Double-Filtration in gravel and sand (DF), Triple-Filtration in gravel, sand and Activated Charcoal (TF-AC) and Triple-Filtration in gravel, sand and clinoptilolite (TF-C). The toxic effects on the population dynamics of larvae and embryos of catfish (Rhamdia quelen) to the final effluent were evaluated using an individual-based model (IBM). The results indicate that the three post-treatments produced effluents with significant improvement of the physicochemical parameters evaluated in relation to the anaerobic reactor effluent. In addition, all post-treatments improved the removal of metal ions. Experimental data showed high mortality rates for Rhamdia quelen embryos and larvae for most treatments, except for the effluent treated by TF-C. The results demonstrated that the concentration of ammoniacal nitrogen in relation to AR treatments (69.0); DF (44.0); TF-AC (46.6) and TF-C (0.33) in mg/L can be a limiting factor for the development of embryos and larvae during the ecotoxicity tests.