Common operational issues and possible solutions for sustainable biosurfactant production from lignocellulosic feedstock.

Surfactants are compounds with high surface activity and emulsifying property. These compounds find application in food, medical, pharmaceutical, and petroleum industries, as well as in agriculture, bioremediation, cleaning, cosmetics, and personal care product formulations. Due to their widespread use and environmental persistence, ensuring biodegradability and sustainability is necessary so as not to harm the environment. Biosurfactants, i.e., surfactants of plant or microbial origin produced from lignocellulosic feedstock, perform better than their petrochemically derived counterparts on the scale of net-carbon-negativity. Although many biosurfactants are commercially available, their high cost of production justifies their application only in expensive pharmaceuticals and cosmetics. Besides, the annual number of new biosurfactant compounds reported is less, compared to that of chemical surfactants. Multiple operational issues persist in the biosurfactant value chain. In this review, we have categorized some of these issues based on their relative position in the value chain - hurdles occurring during planning, upstream processes, production stage, and downstream processes - alongside plausible solutions. Moreover, we have presented the available paths forward for this industry in terms of process development and integrated pretreatment, combining conventional tried-and-tested strategies, such as reactor designing and statistical optimization with cutting-edge technologies including metabolic modeling and artificial intelligence. The development of techno-economically feasible biosurfactant production processes would be instrumental in the complete substitution of petrochemical surfactants, rather than mere supplementation.

Efficient Lignin Fractionation from Scots Pine (Pinus sylvestris) Using Ammonium-Based Protic Ionic Liquid: Process Optimization and Characterization of Recovered Lignin.

Lignin-based chemicals and biomaterials will be feasible alternatives to their fossil-fuel-based counterparts once their breakdown into constituents is economically viable. The existing commercial market for lignin remains limited due to its complex heterogenous structure and lack of extraction/depolymerization techniques. Hence, in the present study, a novel low-cost ammonium-based protic ionic liquid (PIL), 2-hydroxyethyl ammonium lactate [N11H(2OH)][LAC], is used for the selective fractionation and improved extraction of lignin from Scots pine (Pinus sylvestris) softwood biomass (PWB). The optimization of three process parameters, viz., the incubation time, temperature, and biomass:PIL (BM:PIL) ratio, was performed to determine the best pretreatment conditions for lignin extraction. Under the optimal pretreatment conditions (180 °C, 3 h, and 1:3 BM:PIL ratio), [N11H(2OH)][LAC] yielded 61% delignification with a lignin recovery of 56%; the cellulose content of the recovered pulp was approximately 45%. Further, the biochemical composition of the recovered lignin and pulp was determined and the recovered lignin was characterized using 1H-13C heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy, quantitative 31P NMR, gel permeation chromatography (GPC), attenuated total reflectance (ATF)-Fourier transform infrared spectroscopy (ATR-FTIR), and thermal gravimetric analysis (TGA) analysis. Our results reveal that [N11H(2OH)][LAC] is significantly involved in the cleavage of predominant ß-O-4' linkages for the generation of aromatic monomers followed by the in situ depolymerization of PWB lignin. The simultaneous extraction and depolymerization of PWB lignin favors the utilization of recalcitrant pine biomass as feedstock for biorefinery schemes.

Extraction and isolation of lignin from ash tree (Fraxinus exselsior) with protic ionic liquids (PILs).

Protic ionic liquids (PILs) have been considered effective solvents for the selective separation and recovery of cellulose from lignocellulosic biomass. However, PILs can also be utilized for the extraction and conversion of lignin into fuels and value-added products. The objective of this work was to study the extraction of lignin from ash tree (Fraxinus exselsior) hardwood biomass using three different PILs-pyridinium acetate, pyridinium formate [Py][For], and pyrrolidinium acetate. Fiber analysis was used to determine the biochemical composition of the left-over biomass after lignin separation. FTIR and NMR were applied to determine the structure of dissolved lignin. Additionally, the regeneration potential and recyclability of PILs were assessed. Our results demonstrate that treatment with [Py][For] at 75 °C yields the highest percentage of lignin dissolution from biomass. This indicates that PILs could be used for Kraft lignin dissolution as well as separation of lignin from raw, milled biomass.

Effect of Ink and Pretreatment Conditions on Bioethanol and Biomethane Yields from Waste Banknote Paper.

Waste banknote paper is a residue from the banking industry that cannot be recycled due to the presence of ink, microbial load and special coating that provides protection against humidity. As a result, waste banknote paper ends up being burned or buried, which brings environmental impacts, mainly caused by the presence of heavy metals in its composition. To minimize the environmental impacts that come from the disposal of waste banknote paper, this study proposes to produce value-added products (bioethanol and biogas) from waste banknote paper. For this, the effect of ink and pretreatment conditions on bioethanol and biomethane yields were analyzed. Waste banknote paper provided by the Central Bank of Iran was used. The raw material with ink (WPB) and without ink (WPD) was pretreated using sulfuric acid at different concentrations (1%, 2%, 3%, and 4%) and the nitrogen explosive decompression (NED) at different temperatures (150 °C, 170 °C, 190 °C, and 200 °C). The results show that the use of NED pretreatment in WPD resulted in the highest glucose concentration of all studies (13 ± 0.19 g/L). The acid pretreatment for WPB showed a correlation with the acid concentration. The highest ethanol concentration was obtained from the fermentation using WPD pretreated with NED (6.36 ± 0.72 g/L). The maximum methane yields varied between 136 ± 5 mol/kg TS (2% acid WPB) and 294 ± 4 mol/kg TS (3% acid WPD). Our results show that the presence of ink reduces bioethanol and biogas yields and that the chemical-free NED pretreatment is more advantageous for bioethanol and biogas production than the acid pretreatment method. Waste banknote paper without ink is a suitable feedstock for sustainable biorefinery processes.

Biomass torrefaction: An overview on process parameters, economic and environmental aspects and recent advancements.

Torrefaction is one of the pretreatment processes used to overcome the disadvantages of using biomass as a fuel such as low energy density, high moisture, and oxygen contents. The torrefaction increases energy density, hydrophobicity, and reduces grinding energy requirement of biomass. This paper provides a review of the recent advancements in the torrefaction process. The discussion will cover the environmental and economic aspects of the torrefaction process and torrefied pellets, and various applications of torrefaction products. The cost competitiveness of torrefied pellets is one of the major concern of the torrefaction process. Integrating the torrefaction with other processes makes it economically more viable than as a standalone process.

Potential of cereal-based agricultural residues available for bioenergy production.

This data article ranks 294 countries worldwide with more potential available, of cereal based agricultural residues for bioenergy production. Nine different cereal-based agricultural waste products (barley, wheat, millet, oat, rice, and rye straw, sorghum straw/stalk, and maize cob) are used. The tables and figures are grouped by the most prevalent Köppen-Geiger climate classification (tropical/megathermal, dry (desert and semi-arid), temperate/mesothermal, continental/microthermal), continent and region. The data was collected by the authors from FAO bioenergy and food security rapid appraisal tool (excel-based tools) that uses crop yields and production with 10 years (2005-2014) average annual production to estimate the residue yield (t/ha), by feedstock.

Bioelectronic tongue and multivariate analysis: a next step in BOD measurements.

Seven biosensors based on different semi-specific and universal microorganisms were constructed for biochemical oxygen demand (BOD) measurements in various synthetic industrial wastewaters. All biosensors were calibrated using OECD synthetic wastewater and the resulting calibration curves were used in the calculations of the sensor-BOD values for all biosensors. In addition, the output signals of all biosensors were analyzed as a bioelectronic tongue and comprehensive multivariate data analysis was applied to extract qualitative and quantitative information from the samples. In the case of individual biosensor measurements, most accurate result was gained when semi-specific biosensor was applied to analyze sample specific to that biosensor. Universal biosensors or biosensors semi-specific to other samples underestimated the BOD7 of the sample 10-25%. PLS regression method was used for the multivariate calibration of the biosensor array. The calculated sensor-BOD values differed from BOD7 less than 5.6% in all types of samples. By applying PCA and using three first principal components, giving 99.66% of variation, it was possible to differentiate samples by their compositions.

Semi-specific Microbacterium phyllosphaerae-based microbial sensor for biochemical oxygen demand measurements in dairy wastewater.

Although the long incubation time of biochemical oxygen demand (BOD7) measurements has been addressed by the use of microbial biosensors, the resulting sensor-BOD values gained from the measurements with specific industrial wastewaters still underestimates the BOD value of such samples. This research aims to provide fast and more accurate BOD measurements in the dairy wastewater samples. Unlike municipal wastewater, wastewater from the dairy industry contains many substrates that are not easily accessible to a majority of microorganisms. Therefore, a bacterial culture, Microbacterium phyllosphaerae, isolated from dairy wastewater was used to construct a semi-specific microbial biosensor. A universal microbial biosensor based on Pseudomonas fluorescens, which has a wide substrate spectrum but is nonspecific to dairy wastewater, was used as a comparison. BOD biosensors were calibrated with OECD synthetic wastewater, and experiments with different synthetic and actual wastewater samples were carried out. Results show that the semi-specific M. phyllosphaerae-based microbial biosensor is more sensitive towards wastewaters that contain milk derivates and butter whey than the P. fluorescens-based biosensor. Although the M. phyllosphaerae biosensor underestimates the BOD7 value of actual dairy wastewaters by 25-32%, this bacterial culture is more suitable for BOD monitoring in dairy wastewater than P. fluorescens, which underestimated the same samples by 46-61%.

Comparative study of semi-specific Aeromonas hydrophila and universal Pseudomonas fluorescens biosensors for BOD measurements in meat industry wastewaters.

Aeromonas hydrophila P69.1 (A. hydrophila) was used to construct a semi-specific biosensor to estimate biochemical oxygen demand (BOD) in high fat and grease content wastewaters. A. hydrophila cells were grown in fat containing medium to induce necessary enzymes for transport and degradation of fatty substances. Universal biosensor based on non-specific Pseudomonas fluorescens P75 (P. fluorescens) was used to conduct comparison experiments. Biosensors were calibrated using OECD synthetic wastewater and steady-state method, subsequently several experiments with synthetic and industrial wastewaters were conducted. A linear range up to 45 mg l(-1) BOD(7) was gained using A. hydrophila biosensor, in comparison to 40 mg l(-1) BOD(7) obtained using P. fluorescens biosensors. The lower limit of detection was 5 mg l(-1) BOD(7). Service life of A. hydrophila and P. fluorescens biosensors were 110 and 115 days, respectively. The response time of the biosensors depended on the BOD(7) of measuring solution and was up to 20 min when analyzing different wastewaters. Both biosensors underestimated BOD in meat industry wastewater from 43% up to 71%, but more accurate results could be obtained with A. hydrophila biosensor. Semi-specific A. hydrophila biosensor was able to measure proportion of fat found in wastewater sample, while other refractory compounds remained undetectable to both biosensors.

BOD biosensors for pulp and paper industry wastewater analysis.

INTRODUCTION: Two semi-specific microbial biosensors were constructed for the analysis of biochemical oxygen demand (BOD) in high-cellulose-content pulp and paper industry wastewaters. The biosensors were based on living cells of Bacillus subtilis and Paenibacillus sp. immobilized in an agarose gel matrix. Semi-specific microorganisms were isolated from various samples (decaying sawdust and rabbit manure) and were chosen based on their ability to assimilate cellulose. MATERIALS & METHODS: The biosensors were calibrated with the Organization for Economic Cooperation and Development synthetic wastewater, and measurements with different wastewaters were conducted. RESULTS: The response time of biosensors using the steady-state method was 20-25 min, and the service life of immobilized microorganisms was 96 days. Detection limit was 5 mg/l of BOD(7) while linear ranges extended up to 55 and 50 mg/l of the BOD(7) for B. subtilis- and Paenibacillus sp.-based biosensors, respectively. Repeatability and reproducibility of both biosensors were within the limits set by APHA-less than 15.4%. In comparison, both biosensors overestimated the BOD(7) values in paper mill wastewaters and underestimated the BOD(7) in aspen pulp mill wastewater. CONCLUSIONS: The semi-specific biosensors are suitable for the estimation of organic pollution derived from cellulose, while the detection of pollution derived from tannins and lignins was minor. Better results in terms of accuracy and repeatability were gained with Paenibacillus sp. biosensor.

Potentiometric measurements in sequential injection analysis lab-on-valve (SIA-LOV) flow-system.

Advantages of using sequential injection analysis lab-on-valve (SIA-LOV) in potentiometric measurements are studied with Ca(2+) sensitive solid-contact ion-selective electrodes (SC-ISE) and pH electrode based on polyaniline (PANI). Experiments show that Ca(2+)-SC-ISE requires a stopped flow mode to be used in order to get longer equilibration time. On the other hand, PANI based pH electrode gives better results under flow conditions. SIA-LOV was found to be a flexible solution handling system for potentiometric measurements. The technique gives a possibility to fine-tune the calibration range or even recondition the electrode before every measurement without losing in linear range of calibration.

Chemical plume tracking. 3. Ascorbic acid: a biologically relevant marker.

Dynamic characteristics of the amperometric sensing system for tracking of turbulent chemical plumes have been studied. The correlation analysis requires that such sensors respond rapidly and have long-term stability and minimal or low-flow sensitivity. Moreover, for practical purposes, such sensors must respond to an electrochemical marker that would be found in or at least be compatible with the diet of marine animals. Ascorbic acid is such a compound and can be electrochemically oxidized. Its long-term dynamic behavior on several types of electrodes has been studied. It has been found that a Pt electrode coated with polyaniline satisfies all the above requirements. However, this system has a peculiar dynamic behavior that affects the results of the correlation analysis, namely, at the higher frequencies. The behavior of such system in the virtual plume setup has been characterized and its usability for detection of fluctuating concentration of ascorbic acid in saline solution has been confirmed.