The use of low-cost brewery waste product for the production of surfactin as a natural microbial biocide.

Surfactin has potential as next generation antibiofilm agent to combat antimicrobial resistance against emerging pathogens. However, the widespread industrial applications of surfactin is hampered by its high production cost. In this work, surfactin was produced from Bacillus subtilis using a low-cost brewery waste as a carbon source. The strain produced 210.11 mg  L - 1 after 28 h. The antimicrobial activity was observed against all tested strains, achieving complete inhibition for Pseudomonas aeruginosa, at 500  µ g mL - 1 . A growth log reduction of 3.91 was achieved for P. aeruginosa while, Staphylococcus aureus and Staphylococcus epidermidis showed between 1 and 2 log reductions. In the anti-biofilm assays against P. aeruginosa, the co-incubation, anti-adhesive and disruption showed inhibition, where the greatest inhibition was observed in the co-incubation assay (79.80%). This study provides evidence that surfactin produced from a low-cost substrate can be a promising biocide due to its antimicrobial and anti-biofilm abilities against pathogens.

Harsh environment resistant - antibacterial zinc oxide/Polyetherimide electrospun composite scaffolds.

Strategies for developing materials with the functionality to combat bacterial infection are targets for applications such as smart bandages and bone tissue integration. This work milestone was to develop ZnO-polyetherimide (ZnO/PEI) composite scaffolds with antibacterial activity against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. The electrospinning process using suspensions of PEI with different ZnO nanoparticles content were heightened to promote spinnability, jet stability, and fibers with morphological homogeneity. Simulating harsh environments (laser ablation and solvent corrosion) was employed onto specimens and antibacterial functionality, morphology variations, contact angle, and tensile strength variability were evaluated. The antibacterial outcomes, accessed by a modified version of the Japanese Industrial Standard (JIS) Z 2801, presented an inhibition rate up to 100 and 99% after 24 h for S. aureus and E. coli, respectively. The treated samples presented alike responses against both bacteria, highlighting the robustness of the developed scaffolds.

Reuse of wastewaters on dyeing of polyester fabric with encapsulated disperse dye.

The textile industry can benefit from the use of microcapsules, both adding value to products through the production of technical or functional textiles and improving the processes in the production chain. Some applications have been widely explored in academic research, but many are not feasible for use in industrial scale. Thus, the aim of this study was to develop consistent and efficient methodologies for the encapsulation of active compounds commonly used in the textile industry, employing materials which are viable for large-scale application. In this study, polyurethane-urea microcapsules were formulated by interfacial polymerization and encapsulated with C.I Disperse Blue 60 for the dyeing of polyester fabric without the use of dispersing agents and other auxiliaries. The dyeing was carried out in a high temperature dyeing machine with a very simple dyebath, in which there are only dissolved dye molecules, microencapsulated dyes and the fabric. Additionally, the dyebath wastewaters were reused on a further dyeing as 100% bathwater and mixed with 50% distilled water. Colorimetric measurements show excellent colour removal in both samples.

Toxicity of enzymatically decolored textile dyes solution by horseradish peroxidase.

The oxidative systems including enzymatic systems have been widely studied as an alternative for textile effluents treatment. However, studies have shown that some oxidative processes can produce degradation products with higher toxicity than the untreated dye. In this work, enzymatic dye decolorization was evaluated by horseradish peroxidase enzyme (HRP) and the toxicity of discoloration products was evaluate against Daphnia magna, Euglena gracilis algae, and Vibrio fischeri. Dye decolorization kinetics data were evaluated and the pseudo-second-order model showed the best-fitting to the experimental data. In addition, it was observed an increased acute and chronic toxicity associated with the decolorization efficiency. The Reactive Blue 19 and Reactive Black dye showed the highest toxicity against D. Magna (16 toxicity factor) and V. Fischeri (32 toxicity factor) after enzymatic decolorization. For the chronic toxicity against D. Magna, Reactive Red was the only dye with no fertility inhibition. In relation to toxicity tests with E. gracilis algae, it was not observed photosynthetic inhibition for all dyes. This study verified the viability of the enzyme horseradish peroxidase in the textile dyes decolorization and the importance to evaluate the decolorization products.

Free and Ca-Alginate Beads Immobilized Horseradish Peroxidase for the Removal of Reactive Dyes: an Experimental and Modeling Study.

The aim of this work was to remove the dyes Reactive Blue 221 (RB 221) and Reactive Blue 198 (RB 198) of synthetic effluent using the immobilized enzyme horseradish peroxidase (HRP) in Ca-alginate beads. Experimental parameters affecting the dye removal process such as the effect of pH, temperature, hydrogen peroxide concentration, mass capsules, and reuse were evaluated, and a numerical model of mass transfer was developed. A maximum removal of 93 and 75%, respectively, for the dyes RB 221 and RB 198, at pH 5.5 and temperature of 30 °C, concentration of hydrogen peroxide of 43.75 µM for dye RB 221 and 37.5 µM for the dye of RB 198 was obtained. A removal reaction of 180 min for RB 221 and 240 min for RB 198 was observed. Three reuse cycles of use of immobilized enzyme were achieved for both dyes. The numerical model proposed led to a good fit compared to experimental data. The HRP enzyme immobilized in Ca-alginate capsules showed a great potential for biotechnological applications, especially for the removal of reactive dyes.

Removal of COD and color from hydrolyzed textile azo dye by combined ozonation and biological treatment.

The application of ozonation has been increasing in recent years, the main disadvantage of this type of treatment being related to the by-products, which can have toxic and carcinogenic properties, and therefore should be studied further. In this study, the combined treatment of ozonation and subsequent biological degradation with a biofilm, to reduce the color and chemical oxygen demand (COD), was investigated. The experimental part of the study consisted of two phases. The first phase was the ozonation process, the results obtained demonstrated that the ozonation of Remazol Black B dye at pH values of 3-11, was effective, partially oxidizing and completely decolorizing the effluent, even at relatively high concentrations of the dye (500 mg/L). Color removal efficiencies greater than 96% were obtained in all cases. The degradation kinetics of ozone is a pseudo-first-order reaction with respect to the dye concentration. It was possible to verify that the ozonation process as a pre-treatment increases the dye degradation efficiency. For the biological treatment, an increase in ozonization time increased the dye concentration reduction in hydrolyzed dye synthetic effluent. The toxicological results of the tests with Daphnia Magna showed that there is an increase in toxicity after ozonization and a decrease after submitting the ozonized synthetic wastewater to biological treatment with a biofilm.