Chloramphenicol (CAP) is a broad-spectrum antibiotic widely used in animal farming and aquaculture industries. Despite its ban in many countries around the world, it is still used in several developing countries, with harmful effects on the surrounding aquatic environment. In this study, an electrooxidation process using a Ti/PbO anode was used to investigate the degradation of CAP in both synthetic solution and real aquaculture wastewater. A central composite design was used to determine the optimum conditions for CAP removal. Current intensity and treatment time had the most impact on the CAP removal. These two factors accounted for ∼90% of CAP removal. The optimum conditions found in this study were current intensity of 0.65 A, treatment time of 34 min, and CAP initial concentration of 0.5 mg L. Under these conditions, 98.7% of CAP removal was achieved with an energy consumption of 4.65 kW h m. The antibiotic was not present in the aquaculture wastewater, which received 0.5 mg L of CAP and was treated (by electrooxidation) under the optimum conditions. A complete removal of CAP was obtained after 34 min of treatment. According to these results, electrooxidation presents an option for the removal of antibiotics, secondary compounds, and other organic and inorganic compounds from solution.

In the present study, a novel laccase from ascomycete Gliomastix murorum was produced in agro-industrial wastes and entrapped in galactomannan beads for Reactive Blue 2 (Rb-2) decolorization. The maximum laccase production in agave bagasse-based medium occurred at 72 h (1798.6 UL−1). Entrapped laccase decolorized ˃80% of 0.5 mM Rb-2 in 2 h without the addition of redox mediator. Km for Rb-2 substrate was 1.42 mM, with a Vmax of 1.19 µmol min−1 for entrapped laccase. Galactomannan matrices produce stability to acid pH (2–5) and temperatures from 20–70 °C. Reusability assays showed that entrapped laccase could retain efficient Rb-2 decolorization of ˃80% six times. In general, galactomannan used for entrapment of laccase provides economic advantages in large-scale wastewater treatment due to its natural origin and efficient results.

No abstract

The purpose of this research is to produce and characterize bacterial cellulose (BC) films coated with chitosan (BC-CH). BC films were produced in a fermentation medium based on Camellia sinensis tea and dextrose (12 days at 25 °C) and subsequently treated with coating-forming solutions (CFSs) based on chitosan (BC-CH 0.5%, BC-CH 1.0%, and BC-CH 1.5%). As a result, the FTIR spectra of BC and BC-CH 1.5% showed the main characteristic bands of cellulose and chitosan. In the physicochemical characterization of the films, it was found that the incorporation of the chitosan coatings did not affect the thickness; however, it decreased the luminosity (L*) and increased redness (a*), yellowness (b*), and opacity (75.24%). Additionally, the light absorption properties in the UV-Vis range were improved. Furthermore, the application of the CFSs increased: the solubility (64.91%), the antimicrobial activity against S. aureus (6.55 mm) and E. coli (8.25 mm), as well as the antioxidant activity (57.71% and 24.57% free radical scavenging activity), and the content of total phenols (2.45 mg GAE/g). Finally, our results suggest that the BC-CH films developed in the present study show a potential application as active packaging material for food.

Response surface methodology was investigated to determine the operational parameters on the degradation of Congo red dye (CR) and chemical oxygen demand (COD) in two electrochemical systems evaluated individually on effluent pretreated by an up-flow anaerobic sludge blanket (UASB) reactor. The UASB reactor was fed with 100 mg L−1 of CR and was operated for 12 weeks at different hydraulic residence times (HRTs) of 12 h, 10 h, and 8 h. Once stabilized at an HRT of 8 h, the effluent was collected, homogenized, and independently treated by electrooxidation (EO) and electrocoagulation (EC) cells. On both electrochemical systems, two electrode pairs were used; solid for EC (Fe and stainless-steel) and mesh electrodes for EO (Ti/PbO2 and Ti), and the effect of intensity (A), recirculation flow rate (mL min−1), and experimental time (min) was optimized on response variables. The maximum efficiencies of sequential systems for COD degradation and CR decolorization were 92.78% and 98.43% by EC and ≥99.84% and ≥99.71% by EO, respectively. Results indicate that the coupled systems can be used in textile industry wastewater treatment for the removal of dyes and the decolorized by-products.