Degradation of the antibiotic ciprofloxacin in urine by electrochemical oxidation with a DSA anode.

Ciprofloxacin (CIP) is a commonly prescribed fluoroquinolone antibiotic that, even after uptake, remains unmetabolized to a significant extent-over 70%. Unmetabolized CIP is excreted through both urine and feces. This persistent compound manages to evade removal in municipal wastewater facilities, leading to its substantial accumulation in aquatic environments. This accumulation raises concerns about potential risks to the health of various living organisms. Herein, we present a study on the remediation of CIP in synthetic urine by electrochemical oxidation in an undivided cell with a DSA (Ti/IrO2) anode and a stainless-steel cathode. Physisorbed hydroxyl radical formed at the anode surface from water discharge and free chlorine generated from Cl- oxidation were the main oxidizing agents. The effect of pH and current density (j) on CIP degradation was examined, and its total removal was easily achieved at pH ≥ 7.0 and j ≥ 60 mA cm-2 due to the action of free chlorine. The CIP decay always followed a pseudo-first-order kinetics. The components of the synthetic urine were also oxidized. The main nitrogenated species released was NH3. A very small concentration of free chlorine was quantified at the end of the treatment, thus demonstrating the good performance of electrochemical oxidation and its effectiveness to destroy all the organic pollutants. The present study demonstrates the simultaneous oxidation of the organic components of urine during CIP degradation, thus showing a unique perspective for its electrochemical oxidation that enhances the environmental remediation strategies.

Nitrificação de águas amarelas em leito percolante de areia / Nitrification of yellow waters in bed percolating of sand

RESUMO O esgotamento sanitário ecológico conscientiza a população sobre a importância do reúso da água com maior eficiência e do uso de efluentes de sistemas de tratamento descentralizados. O presente trabalho descreve os resultados da nitrificação de águas amarelas em reator biológico com a utilização de materiais simples, por exemplo, a areia, como suporte, objetivando tornar esses resíduos líquidos disponíveis para aproveitamento do nitrogênio mineralizado na agricultura sustentável. O monitoramento do sistema foi realizado por meio dos indicadores pH, oxigênio dissolvido (OD), alcalinidade total (ALC), demanda química de oxigênio (DQO), nitrogênio total Kjeldahl (NTK), nitrogênio amoniacal (NA), nitrito (NO- 2) e nitrato (NO- 3). O sistema apresentou boa remoção de matéria orgânica e excelente conversão do nitrogênio para NO- 2 e NO- 3, com eficiência de transformação do NTK para NO- 3 da ordem de 93%.

ABSTRACT Ecological sanitation awares about the importance of a more efficient water reuse and the use of decentralized wastewater treatment systems. This paper describes the results of yellow waters' nitrification in a biological reactor made up of simple materials, like sand as support material, aiming to make this liquid waste available for the use of mineralized nitrogen in sustainable agriculture. The experimental system was monitored through pH, dissolved oxygen (DO), total alkalinity (ALK), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), ammonia nitrogen (AN), nitrite (NO- 2) and nitrate (NO- 3). The system showed good removal of organic matter and excellent conversion of nitrogen to nitrite and nitrate, with efficiency of transformation of TKN to nitrate of about 93%.