Lipolytic production from solid-state fermentation of the filamentous fungus Penicillium polonicum and its applicability as biocatalyst in the synthesis of ethyl oleate.

Lipases represent versatile biocatalysts extensively employed in transesterification reactions for ester production. Ethyl oleate holds significance in biodiesel production, serving as a sustainable alternative to petroleum-derived diesel. In this study, our goal was to prospect lipase and assess its efficacy as a biocatalyst for ethyl oleate synthesis. For quantitative analysis, a base medium supplemented with Rhodamine B, olive oil, and Tween 80 was used. Solid-state fermentation utilized crambe seeds of varying particle sizes and humidity levels as substrates. In the synthesis of ethyl oleate, molar ratios of 1:3, 1:6, and 1:9, along with a total enzymatic activity of 60 U in n-heptane, were utilized at temperatures of 30 °C, 37 °C, and 44 °C. Reactions were conducted in a shaker at 200 rpm for 60 min. As a result, we first identified Penicillium polonicum and employed the method of solid-state fermentation using crambe seeds as a substrate to produce lipase. Our findings revealed heightened lipolytic activity (22.5 Ug-1) after 96 h of fermentation using crambe cake as the substrate. Optimal results were achieved with crambe seeds at a granulometry of 0.6 mm and a fermentation medium humidity of 60%. Additionally, electron microscopy suggested the immobilization of lipase in the substrate, enabling enzyme reuse for up to 4 cycles with 100% enzymatic activity. Subsequently, we conducted applicability tests of biocatalysts for ethyl oleate synthesis, optimizing parameters such as the acid/alcohol molar ratio, temperature, and reaction time. We attained 100% conversion within 30 min at 37 °C, and our results indicated that the molar ratio proportion did not significantly influence the outcome. These findings provide a methodological alternative for the utilization of biocatalysts in ethyl oleate synthesis.

Aspergillus sclerotiorum lipolytic activity and its application in bioremediation of high-fat dairy wastewater environments.

Oils and grease (O&G) have low affinity for water and represent a class of pollutants present in the dairy industry. Enzyme-mediated bioremediation using biocatalysts, such as lipases, has shown promising potential in biotechnology, as they are versatile catalysts with high enantioselectivity and regioselectivity and easy availability, being considered a clean technology (white biotechnology). Specially in the treatment of effluents from dairy industries, these enzymes are of particular importance as they specifically hydrolyze O&G. In this context, the objective of this work is to prospect filamentous fungi with the ability to synthesize lipases for application in a high-fat dairy wastewater environment. We identified and characterized the fungal species Aspergillus sclerotiorum as a good lipase producer. Specifically, we observed highest lipolytic activity (20.72 U g-1) after 96 h of fermentation using sunflower seed as substrate. The fungal solid fermented was used in the bioremediation in dairy effluent to reduce O&G. The experiment was done in kinetic from 24 to 168 h and reduced over 90% of the O&G present in the sample after 168 h. Collectively, our work demonstrated the efficiency and applicability of fungal fermented solids in bioremediation and how this process can contribute to a more sustainable wastewater pretreatment, reducing the generation of effluents produced by dairy industries.

Analysis of herbicide biosorption by means of a phenomenological mathematical distributed parameter model.

A distributed parameter model and two lumped parameter models were used in order to find the rate-limiting step in the adsorption process of a herbicide (Diuron) by Moringa oleifera husks, a possible low-cost adsorbent. For that, four kinetics assays, differentiated by the initial Diuron concentration, were performed. Langmuir isotherm well represented the equilibrium data and through this evaluation, Moringa husks proved to be a potential adsorbent for Diuron removal from water. The internal mass transfer resistance, analysed as a distributed parameter model, was found to better represent the experimental data. This fact enabled the simulation of the process according to the variation of time and space, which contributed to the better understanding of the adsorption process.

Influence of bionanoparticles to treat a slaughterhouse wastewater.

Treatment of effluents from animal slaughterhouse industries is indispensable, standing out coagulation/flocculation/sedimentation processes. Bionanoparticles (BioNPs) (nanoparticles (NPs) functionalized with Moringa extracts (MO)) were studied as an alternative natural coagulant that would contribute to the microbial load reduction, without increasing the treated effluent toxicity. MO extracts were prepared with different salts, and then, in a kinetics study, different NPs mass and coagulant dosages were evaluated. In the best-defined conditions, microbial load, toxicity tests for the bioindicator Lactuca sativa, and NPs reuse evaluation were performed. Removals of 96.14% turbidity and 43.63% UV254nm were achieved when using 500 mg L-1 of BioNPs containing 60 mg of NPs for every 20 mL of MO extract prepared with 0.1 M CaCl2. The BioNPs with an external magnetic field also decreased the sedimentation time from 140 to 10 min compared to MO, and the process efficiency did not expressively decrease after reusing the recovered NPs. Through toxicity tests, BioNPs were not considered to leave residuals toxic to the Lactuca sativa in the treated effluent. Besides, the microbial load reduction was 97.33% for heterotrophic microorganisms and total mesophiles and 99.25% for moulds/yeasts. Therefore, a satisfactory primary treatment was achieved, contributing to the sustainability of industries.

Production of a synbiotic composed of galacto-oligosaccharides and Saccharomyces boulardii using enzymatic-fermentative method.

Motivated by the search for healthy alimentation and sustainable technological processes, this study aimed to produce a synbiotic composed of the prebiotic galacto-oligosaccharides (GOS) and the probiotic yeast Saccharomyces boulardii, simultaneously, using cheese whey permeate as substrate by enzymatic-fermentative method. A central composite rotatable design with center point was used to evaluate the influence of temperature and enzyme concentration in the GOS and S. boulardii production. The best condition to obtain the prebiotic was at 32 °C and enzyme concentration of 0.175% (w/w), providing 56.84 g L-1 of GOS concentration and Ln(3.59) 107 viable cells mL-1 of S. boulardii production. However, the condition that would favor the simultaneous production of GOS and S. boulardii studied through desirability function is 29.5 °C and 0.14% (w/w) of enzyme concentration. The simultaneous enzymatic-fermentative method showed promising results considering industrial application and can be easily incorporated into dairy production lines as functional food.

Synthesis and performance evaluation of a magnetic biocoagulant in the removal of reactive black 5 dye in aqueous medium.

In this study, a biocoagulant synthesized from the association of iron oxide (Fe3O4) nanoparticles and Moringa oleifera Lam (MO) extract was tested in different concentrations for the removal of the apparent colour and dye concentration (reactive black 5) of synthetic textile wastewater. Coagulation/flocculation process was performed and followed by magnetic sedimentation in Jar-Test equipment, the operational parameters studied were sedimentation time and biocoagulant dosage. The efficiency of the C/F/S process was determined by analysing the apparent colour and RB5 concentration, and removals of 93.7% apparent colour and 96.2% RB5 concentration were observed after 20 min of magnetic sedimentation. Reuse tests were performed, which indicated that the biocoagulant and the resulting sludge from the process could be used again for synthesis and used for three consecutive cycles without drastically reducing efficiency (69% for colour removal and 70% for dye concentration). All analyses were conducted considering 95% confidence level. Thus, the proposed biocoagulant demonstrated high potential for the removal of the evaluated parameters in the treatment of textile wastewater due to its high efficiency, simple and fast preparation, and its environmentally friendly qualities.

Spectral deconvolution associated to the Gaussian fit as a tool for the optimization of photovoltaic electrocoagulation applied in the treatment of textile dyes.

The objective of this study was to investigate the color removal in a binary mixture of azo dyes from the photovoltaic electrocoagulation (EC) technique, using spectral deconvolution and the Gaussian fit for qualitative and quantitative determination of the physical color parameter. Initially, a conventional energy source was used to feed the EC reactor and the experimental design was conducted according to the Rotational Central Compound Design (RCCD). The spectral deconvolution method associated to the Gaussian fit aided in the description of the composition of the sample matrix, In the first step, through the Analysis of Variance, the RCCD and the three-dimensional surface response graphs, the optimized operating conditions were identified, which corresponded to 1320 A m-2 with an reaction time of 16.6 min, and an expected removal of 98.40% for Scarlet Red (SR) dye and 1160 A m-2 with a run time of 15.7 min and 97.9% removal for Turquoise Blue (TB) dye. Using the photovoltaic module as the power source of the EC reactor, a maximum removal of 97 ± 0.43% for TB dye and 98% ± 0.81 for SR was obtained. The results encourage the applicability of photovoltaic module-fed EC technology as a promising alternative for the treatment of effluents containing textile dyes, as well as the use of the spectral deconvolution method associated with the Gaussian fit, for the reliability and precision of the results.

Mathematical modelling applied to the rate-limiting mass transfer step determination of a herbicide biosorption onto fixed-bed columns.

The herbicide removal of Diuron in a fixed-bed column packed with the Moringa oleifera bark biosorbent was investigated experimentally and through phenomenological mathematical modelling. To understand the physical phenomena involved, the steps of external mass transfer resistance, internal mass transfer resistance and the adsorption phenomenon itself were considered as possible limiting steps in the herbicide mass transfer from the liquid to the solid phase. In the developing process of the internal mass transfer resistance model, two hypotheses were considered: constant mass transfer coefficient and mass transfer coefficient as a function of the herbicide concentration in the biosorbent. The experimental breakthrough curves were obtained for different flow rates and feed concentrations, in order to evaluate the model's predictive capacity. The mass transfer parameter values of the mathematical models were estimated using the simplex downhill optimization method. The model that considers the resistance a mass transfer internal with parameter Ks variable represented effectively the dynamic behaviour of the herbicide biosorption process in fixed-bed column, in the various evaluated conditions, indicating that this mechanism controls the biosorption process. Thus, the phenomenological mathematical modelling proved to be an analysis important tool, understanding and the herbicide adsorption systems design in a fixed-bed column.

Adsorption of cephalexin in aqueous media by graphene oxide: kinetics, isotherm, and thermodynamics.

The present study proposes the synthesis and characterization of graphene oxide (GO) and its application in the adsorption of the antibiotic cephalexin (CFX) in aqueous solution. The characterization of graphene oxide was obtained by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zeta potential. The influence of pH on the batch adsorption process was investigated by analysing adsorption equilibrium isotherms and adsorption kinetics. The images obtained by SEM and TEM presented the typical morphology attributed to GO sheets. The kinetic adsorption tests showed that equilibrium was reached in 420 min, and an adsorption capacity of 164 mg g-1 was obtained. The models that best fit the experimental data were pseudo-second as well as the Langmuir isotherm. Therefore, GO was effective for removing the CFX antibiotic from aqueous solution by using a batch adsorption process.

Hybrid treatment of coagulation/flocculation process followed by ultrafiltration in TIO2-modified membranes to improve the removal of reactive black 5 dye.

Many efforts have been made to minimize the polluting effect of wastewater containing dyes that are potentially toxic to the environment. The association of the coagulation/flocculation (CF) process, using saline extract of Moringa oleifera Lam (MO) seeds and subsequently ultrafiltration (UF) in TiO2-modified membranes was performed to remove reactive black 5 dye (10 ppm, RB5) from aqueous solution. The efficiency of the hybrid process was measured by the removal of the dye concentration, apparent color and fouling parameters. The membranes were successfully modified as supported by characterization methods of SEM, FTIR-ATR and WCA. The efficiency of the processes, when applied separately was low. However, after CF and subsequently the filtration in a TiO2-modified membrane both parameters assessed (dye concentration, apparent color) reached 100% of the removal rate. The modified membranes substantially improved permeate fluxes, for instance, after CF the dye flux for modified membrane enhanced around 49% compared with the flux in the pristine membrane. According to these results, the combination of methods was able to effectively remove RB5 dye, in addition to improving permeate fluxes and keeping fouling at low levels.

Potential of the Moringa oleifera saline extract for the treatment of dairy wastewater: application of the response surface methodology.

In this work, the coagulation/flocculation/sedimentation treatment of dairy wastewater samples was investigated through serial factorial designs utilizing the saline extract obtained from Moringa oleifera (Moringa) as a coagulant. The sedimentation time (ST), pH, Moringa coagulant (MC) dose and concentration of CaCl2 have been evaluated through the response surface methodology in order to obtain the ideal turbidity removal (TR) conditions. The empirical quadratic model, in conjunction with the desirability function, demonstrated that it is possible to obtain TRs of 98.35% using a coagulant dose, concentration of CaCl2 and pH of 280 mg L-1, 0.8 mol L-1 and 9, respectively. The saline extract from Moringa presented its best efficiency at an alkaline pH, which influenced the reduction of the ST to a value of 25 min. It was verified that the increase in the solubility of the proteins in the Moringa stimulated the reduction of the coagulant content in the reaction medium, and it is related to the use of calcium chloride as an extracting agent of these proteins. The MC proved to be an excellent alternative for the dairy wastewater treatment, compared to the traditional coagulants.

Water treatment with exceptional virus inactivation using activated carbon modified with silver (Ag) and copper oxide (CuO) nanoparticles.

Continuous flow experiments (450 mL min-1) were performed in household filter in order to investigate the removal and/or inactivation of T4 bacteriophage, using granular activated carbon (GAC) modified with silver and/or copper oxide nanoparticles at different concentrations. GAC and modified GAC were characterized by X-ray diffractometry, specific surface area, pore size and volume, pore average diameter, scanning electron microscopy, transmission electron microscopy, zeta potential and atomic absorption spectroscopy. The antiviral activity of the produced porous media was evaluated by passing suspensions of T4 bacteriophage (∼105 UFP/mL) through filters. The filtered water was analyzed for the presence of the bacteriophage and the release of silver and copper oxide. The porous media containing silver and copper oxide nanoparticles showed high inactivation capacity, even reaching reductions higher than 3 log. GAC6 (GAC/Ag0.5%Cu1.0%) was effective in the bacteriophage inactivation, reaching 5.53 log reduction. The levels of silver and copper released in filtered water were below the recommended limits (100 ppb for silver and 1000 ppb for copper) in drinking water. From this study, it is possible to conclude that activated carbon modified with silver and copper oxide nanoparticles can be used as a filter for virus removal in the treatment of drinking water.

Adsorption of reactive blue BF-5G dye by soybean hulls: kinetics, equilibrium and influencing factors.

The textile industry is known for the high use of chemicals, such as dyes, and large volumes of effluent that contaminate waters, a fact that has encouraged research and improved treatment techniques. In this study, we used unprocessed soybean hulls for the removal of reactive blue BF-5G dye. The point of zero charge of soybean hulls was 6.76. Regarding the speed of agitation in the adsorption process, the resistance to mass transfer that occurs in the boundary layer was eliminated at 100 rpm. Kinetics showed an experimental amount of dye adsorbed at equilibrium of 57.473 mg g(-1) obtained under the following conditions: dye initial concentration = 400 mg L(-1); diameter of particle = 0.725 mm; dosage = 6 g L(-1); pH 2; 100 rpm; temperature = 30 °C; and duration of 24 hours. The pseudo-second order best showed the dye removal kinetics. The adsorption isotherms performed at different temperatures (20, 30, 40 and 50 °C) showed little variation in the concentration range assessed, being properly adjusted by the Langmuir isotherm model. The maximum capacity of dye adsorption was 72.427 mg g(-1) at 30 °C. Since soybean hull is a low-cost industrial byproduct, it proved to be a potential adsorbent for the removal of the textile dye assessed.