Wagner Artifon’s research while affiliated with Universidade Federal de Santa Catarina and other places

Advances in chemical synthesis have increased the complexity and degradation resistance of dyes used in textile processes. This fact interferes drastically with conventional biological wastewater treatment and demands further methods to avoid environmental damage. In this sense, this work presents a bioflocculant produced by the alkaline hydrolysis of spent brewer's yeast, a residue from the brewing industry, as well as the evaluation of its performance in the precipitation of recalcitrant dyes. The optimum hydrolysis system was accessed by a full 2³ factorial design in terms of NaOH concentration, yeast mass, and temperature, followed by a kinetic study. The solid fraction composition of the produced flocculant agent is 46 % of proteins and 29 % of polysaccharides. The performance of the bioflocculant was evaluated in two different systems, real textile wastewater containing rhodamine and a synthetic solution with flavine. The effects of the flocculation variables pH, temperature, agitation, and flocculant agent dosage were taken into consideration. Color removal outcomes above 80 and 90 % were attained for rhodamine and flavine systems, respectively. Further analysis of real textile wastewater for treated and untreated samples in terms of BOD, COD, TOC, and light metals was performed. A biodegradability test showed the employed treatment could increase microbial assimilation of the sample and reduce its persistent compounds. This work shows, for the first time, the feasibility of the bioflocculant from spent brewer's yeast and features its potential applicability to recalcitrant compounds precipitation in textile wastewaters.

The world consumption of dyes has been increasing, mainly due to the textile industry (colorization of fibers). The textile industry generates a massive amount of wastewater. The incorrect disposal of colored effluent into the environment leads to the derangement of aquatic life. Several techniques have been applied to reduce this impact, including adsorption, coagulation, and filtration, among others that, on the one hand, are efficient; on the other hand, require additional management (e.g., a large volume of sludge). In this sense, specific biological pathways for dye degradation and wastewater discoloration have drawn attention to the industry since they can increase wastewater treatment yields. Therefore, this chapter describes the fundamental concepts of dye-containing textile wastewater treatments, particularly microbial and enzymatic approaches, including the most usual textile wastewater treatments and their trends (modern technology).KeywordsAzo dyesBioremediationBacterialFungalMicroalgaeGenetically modified organismsCombined treatments systemsBiofilmsResource recovery strategyMachine learning

Regarding environmental impact, the textile industry is one of the most relevant sectors. Worldwide, it is estimated that 700,000 tons of dyes are generated annually, and 12% of them are inappropriately disposal into aquatic resources. In this sense, flocculating systems can be a cost-effective treatment of dye-containing wastewater. One route that has attracted attention to this researching field is the flocculating effect of biological components. Known as bioflocculants, these extracellular molecules, mainly polysaccharides and proteins, are produced by microorganisms and present relevant effects on precipitating suspended particles or diluted substances from solutions. However, the flocculating phenomena related to bioflocculants and dyes are not fully comprehended. The complex structure of extracellular substances and the variance in dye molecules make their interactions hard to predict. This review aims to critically discuss the current state of the art and future trends related to bioflocculants and dye-containing wastewaters from the textile industry. It includes biological systems of bioflocculant-producing strains, chemical properties of bioflocculants and dyes, and physical parameters employed on flocculation processes. This review would lead to a better understanding of challenges and corresponding strategies to open up new ways of bioflocculation in wastewater treatment.

This study evaluated the effect of enzymatic hydrolysis on malt bagasse for fermentative sugar extraction in thermostatic and ultrasonic bath. The enzymatic reaction was performed using cellulase, α‐amylase, and amyloglucosidase (in separate and combined) on malt bagasse to analyze the hydrolysis effect. For this, a central composite rotational design was applied to evaluate the effect of solid:liquid (malt bagasse w/v) versus enzymatic concentration, considering cellulase, α‐amylase, and amyloglucosidase enzymes in mix solution, on fermentable sugars liberation. Then the kinetic fermentative sugars liberation was evaluated in a hydrolysis reaction using cellulase, α‐amylase, and amyloglucosidase (in separate and combined) after exposure in thermostatic and ultrasonic bath. From enzymatic mix, the maximum total reducing sugar (TRS) yield was 408.8 and 219.9 mg·g−1 in thermostatic and in ultrasound bath, respectively. Kinetic studies showed a TRS variation of 6 to 7 g·L−1 for all enzymes. Amyloglucosidase was more promising in assimilation of malt bagasse, responsible for 43% of sugar releasing. Briefly, a low‐cost procedure using thermostatic bath improved the hydrolysis reaction. The results from the experiments present a new application where malt bagasse can be employed showing the potential of this brewing industry residue in fomenting processes, as bioethanol production.

In this work, multifunctional cotton fabrics were developed by immobilizing TiO2 nanoparticles (TiO2-NPs) using an eco-friendly bath through a highly-scalable technique. The effects of TiO2-NPs, cross-linking agent, catalyst and curing temperatures were assessed by analysis of variance and surface response methodology. The results disclose an excellent performance of treated textiles for various applications: flame-retardant (char content enhanced by 1000 %), photocatalytic decontamination (>90 % of contaminant abatement and feasibility for multiple reuses), self-cleaning of intense stains (up to 80 % of stain vanishing), bacterial inhibition without TiO2 UV-activation (≈25 % of bacteria growth reduction). Moreover, those properties were durable for at least five domestic laundering cycles.

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.

Bioethanol production has been presented as an alternative for supplying energy demand and minimizing greenhouse gases effects. However, due to abrasively conditions employed on the biomass during pretreatment and hydrolysis processes, inhibitors for fermentation phase such as acetic acid and others can be generated. Based on this problem, the aim of this work was to evaluate the adsorption of acetic acid on microporous activated carbon and investigate the stripping of the same component with dried air. For adsorption process, three concentrations of acetic acid (5, 10, and 20%) were analyzed by adsorption kinetics and adsorption isotherms (Langmuir and Freundlich models). Pseudo-second order model showed to fit better when compared to Pseudo-first order model. The Intraparticle Diffusion model presented the first phase of the adsorption as the regulating step of the adsorption process. The Langmuir model showed the best fitting, and the maximum capacity of adsorption was found as 128.66 mg.g⁻¹. For stripping procedure an apparatus was set in order to insert dried air by a diffusor within the solution in study. Increasing temperature showed to be determinant on augmenting acetic acid evaporation in 2.14 and 6.22 times for 40 and 60°C when comparing it to 20°C. The application of the pickling process for removal of fermentation inhibitors in sugarcane bagasse hydrolyzed allowed the production 8.3 g.L⁻¹ of ethanol.

This study aims to evaluate the activity of the cellulase enzyme forward the use of ultrasound technology in different conditions of temperature, pH and exposure time, as well, to match the steps of pretreatment and enzymatic hydrolysis in one step. A central composite design (CCRD) and response surface analysis were used to evaluate the effect of ultrasound power, temperature and pH on enzyme activity. Optimum condition in the studied range was 30% for ultrasound power, pH 4.6 and 50 °C, yielding an enzyme activity of 15.5 UPF/mL. From this, we carried out kinetics of enzymatic hydrolysis on filter paper and bagasse malt, in optimized conditions. Total reducing sugars (TRS) were 3.85 and 0.46 mg/mL when the filter paper and bagasse malt were used as substrate, respectively. Ultrasound showed to be a good technology to increase the enzyme activity aiming to intensify enzymatic processes.