Greenhouse gases capture applying impregnated silica with ionic liquids, deep eutectic solvents, and natural deep eutectic solvents.

The development of technologies to capture greenhouse gases (GHGs) like carbon dioxide (CO2) and nitrous oxide (N2O) is vital for climate change mitigation. Ionic liquids (ILs), deep eutectic solvents (DES), and natural deep eutectic solvents (NADES) are promising absorbents to abate GHGs emissions. However, their high viscosity limits the gas-liquid contact, as consequence of the mass transfer. To overcome this, their impregnation onto porous silica gel has been carried out, increasing the gas-liquid contact area. The present study analyzes the effect of size particle of silica gel impregnated with ILs, DES, and NADES over the CO2 and N2O capture at atmospheric conditions. The degree of impregnation of silica particles was determined by thermogravimetric analysis (TGA). The identification of functional groups present on the surface of silica, ILs, DES, and NADES was performed using Fourier-transform infrared spectroscopy (FTIR), and their crystalline structure was determined by X-ray diffraction (XRD). The partition coefficient of CO2 and N2O between gas and ILs, DES, and NADES was determined by a static headspace method. Results show that the degree of solvent impregnation on silica gel ranged from 36.8 to 43.0% w/w, the partition coefficient of CO2 in the impregnated silica varied from 0.005 to 0.067, and for N2O, from 0.005 to 0.032. This suggests that impregnated particles have a greater affinity for N2O compared to CO2. Using impregnated particles requires only 40% of the bulk solvent to achieve a similar GHG capture capacity compared to using bulk solvents.

High biosorption of cationic dye onto a novel material based on paper mill sludge.

The valorization of paper mill sludge (PMS) is the main goal of this study. The emissions of PMS continue to increase at global scale, especially from packaging paper and board sectors. The raw sludge was used to prepare an adsorbent to remove toxic pollutants from wastewater, the methylene blue (MB), an organic dye. Firstly, the physico-chemical characterization of PMS was done determining the crystalline phases of PMS fibers, the content of main elements, and the pH zero point charge, which was determined at around pH 7. The adsorption of MB on PMS powder was studied at 18 °C with an agitation of 200 rpm, being the best operating conditions 30 min of contact time, 250 mg L-1 of initial MB concentration and 0.05 g in 25 mL of adsorbent dose. Experimental data of MB adsorption was fitted to Langmuir and Freundlich isotherm equations. The Langmuir model was more accurate for the equilibrium data of MB adsorption at pH 5.1. The PFOM and PSOM were adjusted to experimental adsorption kinetics data, being PSOM, which describes better the MB adsorption by PMS powder. This was confirmed by calculating the maximum adsorption capacity with PSOM, which was 42.7 mg g-1, being nearly similar of the experimental value of 43.5 mg g-1. The analysis of adsorption thermodynamics showed that the MB was adsorbed exothermically with a ΔH0 = - 20.78 kJ mol-1, and spontaneously with ΔG0 from - 0.99 to - 6.38 kJ mol-1 in the range of temperature from 291 to 363 K, respectively. These results confirm that the sludge from paper industry can be used as biosorbent with remarkable adsorption capacity and low cost for the treatment of wastewater. PMS can be applied in the future for the depollution of the effluents from the textile industry, which are highly charged with dyes.

Co-Fermentation of Agri-Food Residues Using a Co-Culture of Yeasts as a New Bioprocess to Produce 2-Phenylethanol.

Whey is a dairy residue generated during the production of cheese and yogurt. Whey contains mainly lactose and proteins, contributing to its high chemical oxygen demand (COD). Current environmental regulations request proper whey disposal to avoid environmental pollution. Whey components can be transformed by yeast into ethanol and biomolecules with aroma and flavor properties, for example, 2-phenyethanol (2PE), highly appreciated in the industry due to its organoleptic and biocidal properties. The present study aimed to valorize agri-food residues in 2PE by developing suitable bioprocess. Cheese whey was used as substrate source, whereas crab headshells, residual soy cake, and brewer's spent yeast (BSY) were used as renewable nitrogen sources for the yeasts Kluyveromyces marxianus and Debaryomyces hansenii. The BSYs promoted the growth of both yeasts and the production of 2PE in flask fermentation. The bioprocess scale-up to 2 L bioreactor allowed for obtaining a 2PE productivity of 0.04 g2PE/L·h, twofold better productivity results compared to the literature. The bioprocess can save a treatment unit because the whey COD decreased under the detection limit of the analytical method, which is lower than environmental requirements. In this way, the bioprocess prevents environmental contamination and contributes to the circular economy of the dairy industry.

Furfural degradation and its effect on Rhodosporidium toruloides-1588 during microbial growth and lipid accumulation.

The presence of furfural in the hydrolysates obtained from lignocellulosic biomass sources represents an enormous challenge during their fermentation because furfural is a toxic compound for different microorganisms. Rhodosporidium toruloides-1588 can grow and accumulate lipids using wood hydrolysate as a substrate containing up to 1 g/L of furfural. In this study, the capacity of R. toruloides-1588 to grow and accumulate lipids using furfural without glucose in the media has been observed. R. toruloides-1588 degraded up to 3 g/L of furfural into furfuryl alcohol (1.8 g/L) and 2-furoic acid (0.9 g/L). Furthermore, R. toruloides-1588 accumulated 52% and 30% of its dry weight into lipids using YM media and YM media without glucose, respectively. Fatty acids such as palmitic, stearic and oleic were the most abundant. Finally, R. toruloides-1588 could potentially utilize furfural as a carbon source.

Production of plant growth-promoting bacteria inoculants from composting leachate to develop durable agricultural ecosystems.

Composting process of residual organic material generates considerable amounts of liquid leachate which contains high organic load. This waste stream can be considered as potential nutrient source to support microbial growth. In the present work, the utilization of compost leachate as fermentation substrate for Bacillus species production was studied. The physicochemical properties of the leachate and two co-substrates (residual yeast and whey permeate) were determined. The characterization of leachate showed that it is a potential source of carbon, but its nitrogen content may limit the bacterial growth. In order to determine a good recipe of culture medium for fermentation of individual strains of Bacillus species, leachate was added with yeast and whey permeate. Raw and diluted leachates with and without amendments were tested in shake-flask fermentation assays. Results showed that Bacillus sp. grew better in diluted leachate than in raw leachate. When co-substrates were added, the growth was improved and the sporulation rate also increased. Since the aim was to produce plant growth-promoting bacteria, one of the objectives of fermentation assays was the production of viable bacteria when Bacillus sp. arrives to soil as component of a fertilizer. For this reason, the obtention of sporulated Bacillus cells was desired. The highest sporulation rate was obtained with co-substrates, inducing more than 89% of vegetative cells to develop spores. This approach of leachate valorization will produce economical benefits reducing the volume of leachate waste to be treated, as well as contribute in a cost-effective production of biological amendments in a circular economy mode.

Yeast-driven whey biorefining to produce value-added aroma, flavor, and antioxidant compounds: technologies, challenges, and alternatives.

Whey is a liquid residue generated during the production of cheese and yogurt. It has a pH between 3.9 and 5.6, and a high chemical oxygen demand (COD), from 60 to 80 g/L. Whey contains lactose, proteins, and minerals. Globally, approximately 50% of the whey generated is untreated and is released directly into the environment, which represents an environmental risk. To overcome whey management problems, conventional thermo-physical valorization treatments have been explored, which are complex, costly and energy-intensive. As an alternative, whey fermentation processes employing bacteria, fungi and yeast are economical and promising methods. Among them, yeast fermentation creates value-added products such as antimicrobials, biofuels, aromas, flavors, and antioxidants with no need for previous conditioning of the whey, such as hydrolysis of the lactose, prior to whey biorefining. The biorefining concept applied to whey is discussed using chemical and biological transformation pathways, showing their pluses and minuses, such as technical drawbacks. The main challenges and solutions for the production of fusel alcohols, specifically for 2-phenylethanol, are also discussed in this review.

Pulsed-ozonolysis assisted oxidative treatment of forestry biomass for lignin fractionation.

Lignocellulosic biomass has been used to produce biomolecules of industrial interest through thermochemical, biological, and chemical transformation. However, few works have been developed over lignin fractionation to obtain monolignols with commercial potentials, such as sinapyl, coniferyl, and p-coumaryl alcohols. This study is focused on developing a thermochemical method to delignify biomass. Additionally, an oxidative treatment with ozone was studied to increase the release of monolignol compounds. The results showed that with 30 sec of ozonation in liquid samples from softwood sawdust a total concentration of 368.50 ± 0.73 mg/kg of monolignols was released after microwave-assisted extraction (256.5 ± 0.51 mg/kg of sinapyl alcohol and 112 ± 0.22 mg/kg of coniferyl alcohol) and 629.20 ± 0.21 mg/kg was released after thermal treatment (453.70 ± 0.15 mg/kg of sinapyl alcohol and 175.5 ± 0.06 mg/kg of coniferyl alcohol). For p-coumaryl alcohol, 16.32 mg/kg was obtained only in hardwood samples. The results of the present study showed that ozonolysis improves monolignols release from forestry residues.

Biovalorization of glucose in four culture media and effect of the nitrogen source on fermentative alcohols production by Escherichia coli.

Glucose is one of the most abundant monosaccharides and the easiest carbon source to be consumed by bacteria. In this study, four culture media (LB, M9, M63 and MOPS) were supplemented with glucose at three different concentrations (4, 12.5 and 25 g/L) in the presence of a genetically modified strain of Escherichia coli with the purpose of selecting the most suitable culture medium to obtain ABD (acetoin (A) and 2,3-butanediol (2,3-BD)). The selected medium was M9, the cheapest culture medium, since the ABD yields obtained fermenting 12.5 and 25 g/L of glucose in M9 culture medium at 37°C, atmospheric pressure, initial pH 6.5, 100 rpm and 10% (v/v) of inoculum were similar compared to the ABD yields obtained using M63 and LB culture media. The influence of nitrogen on ABD yield was tested adding sodium nitrate (NaNO3) or urea ((NH2)2CO) to M9 culture medium at three different nitrogen concentrations (2.5, 5.0 and 7.0 g N/L). Adding urea (7.0 g N/L) to M9 supplemented with 25 g/L of glucose improved by 23% the ABD yield at 96 h compared to M9 without urea, reaching a value of 27.2% (g ABD/g glucose). In contrast, the use of NaNO3 had no significant effect on the ABD yield.

Data set of green extraction of valuable chemicals from lignocellulosic biomass using microwave method.

Lignocellulosic biomass is a promising alternative for the replacement of limited fossil resources to produce various chemical compounds, such as 5-hydroxymethylfurfural, furfural, vanillin, vanillic acid, ferulic acid, syringaldehyde, and 4-aminobenzoic acid. However, the complex biomass structure is a limitation to making effective use of this naturally found feedstock. This research presents a data set of different compounds obtained directly from forest residues, with special emphasis on achieving effective utilization of the biomass. The extraction method and the catalyst are considered as the two main factors in this valorization process.

Parameters determining the performance of passive flux samplers proposed as a tool to estimate N2O emissions: evaluation at farm level and perspectives.

The passive flux sampling is an economic and easy way to estimate gas emissions from agriculture sources. In the last decade, specific passive flux samplers (PFSs) have been developed to estimate nitrous oxide (N2O) emissions from agriculture sources. Packed with silica gel and zeolite 5A, the PFSs were placed facing the emission source direction close to the ventilation shafts. For validation, air samples were taken at different sampling time during 3 days on two commercial sites. The adsorbed mass of N2O in PFSs was recovered by thermal desorption in the laboratory. Results indicated that the mass of N2O adsorbed in PFSs was from 1.5 to 5.5 µg. A specific adsorption pattern was observed for each sampling. In farm 1, the mass of N2O adsorbed in the PFSs presented a linear behavior as a function of sampling time, and the most determined coefficient values were higher than 0.80. In farm 2, in addition to the sampling time, the N2O concentration and the air flow rate presented an effect on the mass adsorbed in the PFSs. On the other hand, comparison of PFSs versus other techniques indicated that PFSs offer different advantages. However, the selectivity and capacity of the adsorbent bed used need to be improved to enhance the use of PFSs proposed as a tool to estimate N2O emissions. Graphical Abstract PFSs enabled N2O sampling that followed a linear behavior as a function of sampling time. Sampling time, [N2O], and air flow rate determined the mass of N2O collected in PFSs.

Immobilized laccase on polyimide aerogels for removal of carbamazepine.

Since it is known that conventional wastewater treatment plants cannot completely remove pharmaceutical compounds, such as carbamazepine, the need for their removal has intensified. The use of biocatalysts, such as enzyme is an environmentally friendly method for carbamazepine biodegradation. Nevertheless, enzyme immobilization is required to facilitate the recovery and reusability and avoid the loss of enzyme. In this work, laccase was immobilized on modified polyimide aerogels by means of covalent bonding. Results showed that the immobilized laccase on polyimide aerogels possesses significantly improved activity under acidic or basic pH range in comparison with the free enzyme. Furthermore, for all the temperature range the activity of the immobilized enzyme was higher compared to the free enzyme form. The storage stability improved by the immobilization on this support material. The reusability tests towards oxidation of 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) showed that the immobilized laccase maintained 22% of the initial activity after 7 cycles. Immobilized laccase on polyimide aerogels for carbamazepine (CBZ) degradation exhibited 76% and 74% removal in spiked water and secondary effluent, respectively. Furthermore, after 7 cycles the CBZ removal efficiency remained higher (50% and 65% for spiked water and secondary effluent, respectively).

Supplement comprising of laccase and citric acid as an alternative for antibiotics: In vitro triggers of melanin production.

An indiscriminate use of antibiotics in humans and animals has led to the widespread selection of antibiotic-resistance, thus constricting the use of antibiotics. A possible solution to counter this problem could be to develop alternatives that can boost the host immunity, thus reducing the quantity and frequency of antibiotic use. In this work, for the first time, citric acid and laccase were used as extracellular inducers of melanin production in yeast cells and human cell lines. It is proposed that the formulation of laccase and citric acid together could further promote melatonin-stimulated, melanocyte-derived melanin production. Melanization as a probe of immunity described in this study, is an easy and a rapid test compared to other immunity tests and it allows performing statistical analyses. The results showed the synergistic effect of citric acid and laccase on melanin production by yeast cells, with significant statistical differences compared to all other tested conditions (p: 0.0005-0.005). Laccase and citric acid together boosted melanin production after 8 days of incubation. An increase in melanin production by two human colon cells lines (Cacao-2/15 and HT-29) was observed on supplementation with both laccase and citric acid in the cell growth medium. Produced melanin showed antimicrobial properties similar to antibiotics. Therefore, a formulation with citric acid and laccase may prove to be an excellent alternative to reduce the antibiotic use in human and animal subjects.

Alternatives to antibiotics in poultry feed: molecular perspectives.

The discovery of the growth promoting property of antibiotics led to their use as antibiotic feed additives (AFAs) in animal feed at sub-therapeutic doses. Although this has been beneficial for animal health and productivity, it has been, essentially, a double-edged sword. The continued and non-judicious use of AFAs has led to the selection and dissemination of antibiotic-resistant strains of poultry pathogens such as Salmonella, Campylobacter and Escherichia coli. The rapid spread of drug-resistant pathogens as well as emergence of antibiotic-related environmental pollutants is of global concern. Hence, the identification and development of new and effective alternatives to antibiotics that do not hinder productivity is imperative. For this, it is essential to understand not only the molecular basis of development of resistance to AFAs but also the mechanisms of action of AFA alternatives and how they differ from AFAs. This review provides a molecular perspective on the alternatives to antibiotics that have been proposed till date and their current trends, as well as novel approaches such as development of improved delivery systems.

Steady state and dynamic behaviors of a methane biofilter under periodic addition of ethanol vapors.

Ethanol was added to a methane (CH4) biofilter with inorganic packing materials over three cycles based on increasing the gas flow rates from 3 to 6 and finally to 12 L min-1 corresponding to empty bed residence times (EBRT) of 6, 3 and 1.5 min. The steady state performance of the CH4 biofilter was studied for CH4 inlet loads (ILs) of 33, 66 and 132 gCH4 m-3 h-1 prior and after each ethanol cycle. In addition, the steady state removal of a mixture of CH4 and ethanol for a CH4/ethanol mass ratio of around 7.5 gCH4 g -1ethanol was evaluated over three cycles (EBRTs of 6, 3 and 1.5 min). In the absence of ethanol, the CH4 removal efficiency (RE) dropped from 35 to 7% due to an EBRT decrease from 6 to 1.5 min. In addition, the presence of ethanol resulted in a CH4 RE reduction at a constant EBRT in every cycle. The CH4 REs dropped from 35 to 29%, 17 to 13% and 7 to 0% for corresponding ethanol ILs of 4.5, 9 and 18 gethanol m-3 h-1 over the cycles. Moreover, the periodic presence of ethanol in the CH4 biofilter allowed the study of transient behaviors of the biofilter during ethanol addition and the biofilter recovery after each cycle. The CH4 RE reduction as a result of ethanol addition in each cycle was instantaneous. However, the CH4 RE recovery after completion of ethanol addition took 10, 14 and 25 days for ethanol ILs of 4.5, 9 and 18 gethanol m-3 h-1 respectively. The recovery time was related to the ethanol concentration in the leachate which were 1100 ± 200, 1100 ± 350 and 2500 ± 400 gethanol m-3leachate for corresponding ethanol ILs of 4.5, 9 and 18 gethanol m-3 h-1, respectively. Based on steady state and dynamic process conditions of the biofilter, the lowest gas flow rate of 3 L min-1 (EBRT of 6 min) produced the best performance when both pollutants were present (CH4 IL of 33 gCH4 m-3 h-1 and ethanol IL of 4.5 gethanol m-3 h-1).

Life cycle assessment of swine and dairy manure: pyrolysis and combustion processes.

The valorization of three different manure samples via pyrolysis and combustion processes was evaluated. Dairy manure (sample Pre) was biologically pretreated by anaerobic digestion (sample Dig R) whereas swine manure (sample SW) was pretreated by a biodrying process. Thermal behavior of manure samples were studied by means of thermogravimetric analysis coupled with mass spectrometry (TGA-MS). These processes could be divided into four general stages: dehydration, devolatilization, char transformation (oxidation for combustion) and inorganic matter decomposition. The main differences observed among the samples were attributed to their different composition and pretreatment. The economic feasibility, energetic and environmental impacts of pyrolysis and combustion technologies for dairy samples were carried out by means of life cycle assessment (LCA) methodology. Four different scenarios were analyzed. The economic feasibility of the pyrolysis process was demonstrated, being sample Dig R the best environmental option. However, the combustion of sample Pre was the best energetic option.

Biofiltration of air polluted with methane at concentration levels similar to swine slurry emissions: influence of ammonium concentration.

An evaluation of the effect of ammonium on the performance of two up-flow inorganic packed bed biofilters treating methane was conducted. The air flow rate was set to 3.0 L min(-1) for an empty bed residence time of 6.0 min. The biofilter was fed with a methane concentration of 0.30% (v/v). The ammonium concentration in the nutrient solution was increased by small increments (from 0.01 to 0.025 gN-NH(4) (+) L(-1)) for one biofilter and by large increments of 0.05 gN-NH(4) (+) L(-1) in the other biofilter. The total concentration of nitrogen was kept constant at 0.5 gN-NH(4) (+) L(-1) throughout the experiment by balancing ammonium with nitrate. For both biofilters, the methane elimination capacity, carbon dioxide production, nitrogen bed retention and biomass content decreased with the ammonium concentration in the nutrient solution. The biofilter with smaller ammonium increments featured a higher elimination capacity and carbon dioxide production rate, which varied from 4.9 to 14.3 g m(-3) h(-1) and from 11.5 to 30 g m(-3) h(-1), respectively. Denitrification was observed as some values of the nitrate production rate were negative for ammonium concentrations below 0.2 gN-NH(4) (+) L(-1). A Michalelis-Menten-type model fitted the ammonium elimination rate and the nitrate production rate.

Biofiltration of air contaminated by styrene vapors on inorganic filtering media: an experimental study.

This paper presents a study on the biofiltration of styrene by using two inorganic filtering materials. The effects of styrene inlet load and nitrogen concentration present in the nutrient solution on biofilter performance were studied. The styrene inlet concentration was varied from 65 to 1115 parts per million by volume (ppmv), whereas the contaminated airflow rate was fixed at 1 m3/hr. The nitrogen concentration in nutrient solution was varied from 1 to 4 gN/L. The maximum elimination capacity obtained was 105 g/m3-hr, which corresponded to a removal efficiency of 80% for a styrene inlet load of 130 g/m3-hr. This study shows that the nitrogen content in the nutrient solution affects the removal rate of styrene, with an optimal nitrogen concentration of 3 gN/L. The performance comparison between two different inorganic bed types was undertaken and a comparative study on biofiltration of two aromatic compounds, styrene and toluene, is also presented.

Control of methanol vapours in a biotrickling filter: performance analysis and experimental determination of partition coefficient.

Methanol vapours were treated in a biotrickling filter (BTF) packed with inert polypropylene spheres. The effects of the nitrogen concentration in the nutrient solution, the empty bed residence time (EBRT) and the methanol inlet concentration, on the BTF performance, were all examined. The elimination capacity (EC), the biomass and the carbon dioxide production rates were all increased with the rising of the nitrogen concentration and the EBRT. The EC also rose with increasing methanol inlet load (IL) when the methanol inlet concentration and the EBRT were varied, from 0.3 to 37.0 g m(-3), and from 20 to 65 s, respectively. The BTF reached its maximum EC level of 2160 g m(-3) h(-1) when it was operated at an IL level of 3700 g m(-3) h(-1). The input methanol was removed through two mechanisms: biodegradation and absorption in the liquid phase. The partition coefficient for the methanol in the BTF was determined at five EBRTs and along the packed bed. It generally followed the Henry model, having an average value of 2.64 x 10(-4)[mol L(-1)](gas)/[mol L(-1)](liquid).

Kinetics of microbial growth and biodegradation of methanol and toluene in biofilters and an analysis of the energetic indicators.

The kinetics of microbial growth and the biodegradation of methanol and toluene in (a) biofilters (BFs), and (b) biotrickling filters (BTFs), packed with inert materials, has been studied and analyzed. The specific growth rate, mu, for the treatment of methanol was 0.037h(-1) for a wide range of operating conditions. In the BF, mu was found to be a function of the methanol and toluene concentrations in the biofilm. In the BF used for treating methanol, mu was found to be affected by (1) the nitrogen concentration present in the nutrient solution, and (2) the kind of packing material employed. The kinetics of the methanol and toluene biodegradations were also analyzed using "mixed order" models. A Michaelis-Menten model type provided a good fit for the elimination capacity (EC) of the BTF treating methanol, while a Haldane model type provided a good fit to the EC of the BF treating methanol and toluene. The carbon dioxide production rate was related to the packed bed temperature and the content of the volatile solids within the biofilm. For the BF, the ratio of temperature/carbon dioxide production rate (PCO(2)) was 0.024 degrees C per unit of PCO(2), and for the BTF it was 0.15 degrees C per unit of PCO(2).