Efficiency of an up-flow Anaerobic Sludge Blanket reactor coupled with an electrochemical system to remove chloramphenicol in swine wastewater.

The application and design of treatment systems in wastewater are necessary due to antibiotics' potential toxicity and resistant genes on residual effluent. This work evaluated a coupled bio-electrochemical system to reduce chloramphenicol (CAP) and chemical oxygen demand (COD) on swine wastewater (SWW). SWW characterization found CAP of <10 µg/L and 17,434 mg/L of COD. The coupled system consisted of preliminary use of an Up-flow Anaerobic Sludge Blanket Reactor (UASB) followed by electrooxidation (EO). The UASB reactor (primary stage) was operated for three months at an organic load of 8.76 kg of COD/m3d and 50 mg CAP/L as initial concentration. In EO, we carried out a 22 (time operation and intensity) factorial design with a central composite design; we tried two Ti cathodes and one anode of Ti/PbO2. Optimal conditions obtained in the EO process were 240 min of operation time and 1.51 A of current intensity. It was possible to eliminate 44% of COD and 64.2% of CAP in the preliminary stage. On bio-electrochemicals, total COD and CAP removal were 82.35 and >99.99%, respectively. This coupled system can be applied to eliminate antibiotics and other organic pollutants in agricultural, industrial, municipal, and other wastewaters.

Evaluation of the catalytic oxidation of soot by CeOX-LaMnO3 at different O2 pressures synthesized by ultrasonic-assisted hydrothermal method.

In this work, the synthesis of catalyst with perovskite structure and chemical formula La1-XCeXMnO3 at x = 0 - 0.5 were successfully obtained by an ultrasonic-assisted hydrothermal method. Results show that the addition of Ce in La1-XCeXMnO3 have not substantial effect in textural and morphological properties; however, the formation of a new crystalline phase with final composition CeOX-La1-XCeXMnO3 was detected at values x > 0.3. All synthesized catalysts were tested in the soot oxidation under both, loose and tight contact in 20% O2/N2 or 5% O2/N2 atmospheres. CeOX-La1-XCeXMnO3 at x = 0.3 resulted in the best catalytic activity with activation energy values of 57.9 kJ.mol-1. The interaction between Ce3+ and Mn4+ species in this catalyst can transfer electrons generating Mn3+ and Ce4+. This reduction from Mn4+ to Mn3+ is accompanied by migration of vacancies to the surface promoting the adsorbed oxygen from the gas phase, need for balancing the chemical states. By increasing the temperature above 300 °C, the bulk oxygen migration to the surface is enhanced being the responsible for the oxygen availability. The formation of CeOX-La1-XCeXMnO3 promotes a stable redox cycle allowing the reusability of this catalyst even at low oxygen pressures after three different reaction cycles.

Simultaneous removal of Cd2+ and Zn2+ from aqueous solution using an upflow Al-electrocoagulation reactor: optimization by response surface methodology.

The presence of heavy metals in the environment has increased, and cadmium (Cd) and zinc (Zn) are considered to be among the most dangerous. An upflow Al-electrocoagulation reactor was used to remove Cd2+ and Zn2+ ions from aqueous media. The system consisted of perforated aluminum circular electrodes for fluid distribution with elimination of external agitation. The effect of different parameters, i.e. current intensity, electrolysis time, concentration of Cd2+ and Zn2+ ions and electrolytic support dose were optimized by response surface methodology. The results indicated that increasing the current intensity and the electrolysis time had a positive effect on the elimination efficiency of the pollutant ions. Likewise, increasing the dose of electrolytic support and decreasing the concentration of the pollutants improved the efficiency of the system. The optimal results were: current intensity of 0.4 A, electrolysis time of 40 min, ion concentration of 44.6 mg·L-1 and electrolytic support dose of 0.56 mg·L-1, with the maximum elimination percentages of 96 ± 3.8% and 96 ± 2.7% for Cd2+ and Zn2+, respectively. This study showed that the electrocoagulation process in an upflow electrocoagulation reactor could be successfully applied to remove pollutants from water.