RESUMO
Sulfamethazine (SMZ) is an antibiotic from sulfonamides class widely used in veterinary medicine and reported in wastewater and sewage. Thus, it is essential to study technologies to reduce SMZ present in the aquatic environment. Anaerobic bioreactors are a low-cost technology applied for wastewater treatment. The objective of this paper is to study kinetics parameters related to SMZ removal using a horizontal flow-anaerobic immobilized biomass reactor (HAIB) and to evaluate its transformation products formed during this treatment. The bioreactor was operated at mesophilic condition with a hydraulic retention time of 12 h. The removal of SMZ was evaluated at three different concentrations: 200 ng L-1 (phase I), 400 ng l-1 (phase II) and 600 ng L-1 (phase III). The apparent first-order removal constant obtained for chemical oxygen demand was 0.885 ± 0.094 h-1 while SMZ showed a removal constant of 0.356 h-1. SMZ was removed with an efficiency of 56.0 ± 13.0 % (phase I); 62.0 ± 12.0 % (phase II) and 62.0 ± 6.00 % (phase III). Seven transformation products were detected and one of these with m/z 233 is reported for the first-time. The HAIB bioreactor has a potential to assist in wastewater treatment to remove contaminants at ng L-1 concentration level.
Assuntos
Anti-Infecciosos/metabolismo , Reatores Biológicos , Sulfametazina/metabolismo , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Anaerobiose , Biomassa , Cinética , EsgotosRESUMO
The use of anaerobic biomass attached to a support has been recently presented as a good prospect in the treatment of wastewater containing recalcitrant compounds, such as sulfamethazine (SMZ). SMZ has been found in swine wastewater and sewage treatment plants, which motivates assessing their degradation by new wastewater treatment technologies. Thus, this paper describes the use of a continuous fixed structured bed bioreactor for the purpose of evaluating SMZ removal kinetics present in lab-made wastewater. The analysis of SMZ used online solid-phase extraction coupled to liquid chromatography/tandem mass spectrometry (SPE online-LC-MS/MS). Chemical oxygen demand (COD) was also monitored to evaluate the organic matter removal. The bioreactor was operated under mesophilic conditions (30 ∘ C), with a hydraulic retention time of 24 h. In order to evaluate SMZ removal, four different concentration levels were studied: 200, 400, 600, and 800 ng L-1. COD removal efficiency obtained for filtered effluent kept at 91.01% and there was no interference due to the increase of SMZ concentration. For SMZ, the removal efficiencies were of 52.8±12.1% for 200 ng L-1 concentration level; 55.0±8.15% for 400 ng L-1; 53.0±6.14% for 600 ng L-1, and 48.8±5.44% for 800 ng L-1. COD removal kinetics presented a first-order apparent removal rate constant ( kapp ) of 0.281±0.0295 h-1. SMZ also showed a first-order apparent removal rate constant of 0.158±0.0093 h-1 for the following concentrations levels: 200, 400, 600, and 800 ng L-1.
Assuntos
Sulfametazina , Espectrometria de Massas em Tandem , Animais , Reatores Biológicos , Cromatografia Líquida , Cinética , Esgotos , Suínos , Eliminação de Resíduos LíquidosRESUMO
The antibiotics sulfamethoxazole (SMTX) and ciprofloxacin (CIP) are commonly used in human and veterinary medicine, which explains their occurrence in wastewater. Anaerobic reactors are low-cost, simple and suitable technology to wastewater treatment, but there is a lack of studies related to the removal efficiency of antibiotics. To overcome this knowledge gap, the objective of this study was to evaluate the removal kinetics of SMTX and CIP using a horizontal-flow anaerobic immobilized biomass reactor. Two different concentrations were evaluated, for SMTX 20 and 40â µgâ L(-1); for CIP 2.0 and 5.0â µgâ L(-1). The affluent and effluent analysis was carried out in liquid chromatography/tandem mass spectrometry (LC-MS/MS) with the sample preparation procedure using an off-line solid-phase extraction. This method was developed, validated and successfully applied for monitoring the affluent and effluent samples. The removal efficiency found for both antibiotics at the two concentrations studied was 97%. Chemical oxygen demand (COD) exhibited kinetic constants that were different from that observed for the antibiotics, indicating the absence of co-metabolism. Also, though the antibiotic concentration was increased, there was no inhibitory effect in the removal of COD and antibiotics.