This work evaluated the degradation of ivermectin, a veterinary drug widely used in the treatment of ectoparasites and endoparasites, and the removal of acute toxicity (using Daphnia similis) by Fenton (Fe
This paper compares the dichromate method with the photoelectrochemical method (PeCOD), with regards to the influence of chloride and turbidity with chemical oxygen demand (COD) determination. Whereas the upper limits of chloride concentration are well established for both techniques, the influence of turbidity and the combined interference of underdosing chlorides and turbidity together have never been reported. When only potassium hydrogen phthalate or sorbitol were analyzed, the results show no significant difference in either method when 607 mg Cl -L -1 or 230 NTU of turbidity were added to the samples within the range of 100-900 mg L -1 COD. However, a combined effect of these two interferents leads to significantly different results, mainly for low COD range, as evidenced by the Student's t-test for paired samples (p = 0.05).
Veterinary pharmaceuticals can reach the soil via animal excretions and cause impacts on aquatic and terrestrial ecosystems. In this work, we employed a standardized avoidance behavior test to assess the sublethal effects of antimicrobial sulfadiazine on the earthworm Eisenia andrei. Cultivation of red worms was based on an alternative substrate made of mostly household vegetable wastes and dry leaves. The bioassays were performed with tropical artificial soil spiked with the tests substance at five different concentrations ranging from 0.01 to 100 mg sulfadiazine kg -1 . The outcome resulted in avoidance response of 30% (maximum) and a nonlinear concentration-response curve, differing from classical pollutant responses and correlating with those asymmetric responses over the environment caused by some rare xenobiotics. Avoidance tests were validated with reference substance, resulting in an EC50-48h of 819 mg boric acid kg -1 (628-1066 mg boric acid kg -1 95% confidence interval). We concluded that the avoidance test with E. andrei is useful as a standardized tool for a rapid ecotoxicological screening of soil.
Resumo Formaldeído é encontrado naturalmente no ambiente e pode atingir concentrações de até 4000 mg L-1 em efluentes industriais. Embora germicida, pesquisas indicam sua possível degradação biológica em sistemas de tratamento, destacando-se os reatores com biomassa aderida e metabolismo aeróbio ou anaeróbio. Esse estudo verifica a eficiência físico-química e capacidade de redução da concentração de formaldeído adicionado a esgoto sanitário no tratamento biológico combinado (anaeróbio e aeróbio), e avalia a toxicidade aguda residual ao microcrustáceo Daphnia similis, em amostras de sistema composto por filtro anaeróbio (FA), biofiltro aerado submerso (BAS), ambos de leito fixo e fluxo ascendente, seguido de decantador secundário, nas fases: formaldeído afluente: 200 mg L-1 (F1: 7 bioensaios) e 400 mg L-1 (F2: 8 bioensaios). A eficiência de remoção de DQO e DBO foi de 93±4% e 97±2% (F1) e 93±7% e 99±1% (F2), respectivamente; a redução de formaldeído foi de 100% (F1) e 99,8±0,3% (F2). A toxicidade aguda (CE50-48h) foi de 7,22% e 3,40% (afluente), >67% e >60% (efluente FA), para F1 e F2, respectivamente. O efluente final não apresentou toxicidade aguda, comprovando a robustez do sistema combinado e a importância de tecnologias que visam à destinação adequada de resíduos e à proteção da vida aquática.
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