Key Engineering Materials Vol. 850

Abstract: Pyrolysis plays a vital role in biomass conversion as one of the most promising thermal conversion routes. Solid, liquid and gaseous products are obtained from biomass pyrolysis. The liquid is considered as perspective fuel; however, the direct use of bio-oil as fuel may present many difficulties due to its high viscosity, poor heating value and relative instability. This creates a significant economic barrier for production of transportation fuel by pyrolysis process. Catalytic pyrolysis has been widely used as a convenient method for the direct conversion of biomass into higher quality liquid bio-fuels. Intermediate pyrolysis of cellulose (as a model substance for biomass) with or without catalysts was investigated using TGA-FTIR method in order to determine the influence of zeolite on the relative yield of the compounds. The addition of zeolite with medium and weak acidity increased the production of volatile matter from 86.1% to 88.5% and 88.9% under the catalyst of MCM-41 and ZSM-5 (70). Zeolite with high acidity contributes to the formation of coke and simultaneously causing the deactivation of the catalyst, thus decreasing the volatile matter of cellulose from 86.1% to 83.6% and 83.2% by using H-ZSM-5 (23) and H-ZSM-5 (50). All catalysts showed deoxygenation activity. Zeolites had higher activity in the deoxygenation of compounds containing hydroxyl group than compounds containing carbonyl and carboxyl groups. H-ZSM-5 (23) had a substantial effect on the production of monoaromatic hydrocarbons whereas the yield of olefins notably increased in the presence of ZSM-5 (70).

Abstract: The blends of varying proportions of biodiesel fuel containing fatty acid methyl esters and triacetin (FAME*), synthesised accordingly to Latvian patent LV 15 373 and summer diesel were prepared, analysed and compared with diesel fuel. The selected fuel properties (viscosity, density, carbon residue and cold flow properties) tested accordingly to standard LVS-EN 14214 have indicated a good potential of FAME*, obtained by synthesis of fatty acid methyl esters (FAME) by simultaneous conversion of glycerol to triacetin as a renewable diesel engine fuel. The results showed that blends containing 5 to 25% of FAME* in summer diesel yielded the properties closely matching that of diesel.Introduction

Abstract: SPEEK (sulfonated polyether ether ketone) membranes have been prepared and characterized. The SPEEK membrane geometry and theoretical vibration spectra calculated using density functional theory (DFT) as depending from membrane chain length and polymer cross-linking. Analyzed the limitations of the method by comparing theoretical and experimental IR spectra.

Abstract: In this study Fe₂O₃/SBA-15 catalyst was synthesized via direct synthesis method under acidic conditions using triblock copolymer Pluronic P123 as template, tetraethyl orthosilicate as a silica source and Fe (NO₃)₃∙9H₂O as iron source. Template was removed using extraction and calcination. The obtained catalyst was characterized using XRD analysis, WDXRF spectroscopy, N₂ adsorption-desorption analysis and STEM–EDX measurements. Results of catalyst characterization showed that the synthesized Fe₂O₃/SBA-15 is mesoporous silica with 2D p6mm hexagonal mesostructure loaded with 15.6 wt.% Fe₂O₃. Average pore size was 6.95 nm, homogeneous immobilized Fe₂O₃ nanoparticles do not disrupt the porous hexagonal structure of the support.

Abstract: Nutrients and their content in growth medium significantly affect the growth rate and quality of biomass. This review summaries the latest studies on microalgae Arthrospira spp. and Spirulina spp. growth media. Most of studied growth media are modified Zarrouk’s medium. Detailly discussed are effects of change in some microelement concentration and sources and salinity or NaCl concentration, however there are still lacking studies on microelement role and long-term studies. It should be highlighted that various species and strains of Arthrospira and Spirulina reacts to growth media composition change very differently. There is no single best growth media formulae for all species and strains of Arthrospira/Spirulina. Recycling for few times is possible but content of biomass changes.

Abstract: The worlds growing population demands more food and creates more waste. Economically viable and environmentally friendly would be to use sewage sludge for agricultural production. There are several limitations for this use – heavy metal content, pathogenic microorganisms, helminths etc.. The different methods of treatment of sewage sludge helps to overcome this problem. The aim of the study is to find the effects of treated sewage sludge on the growth of maize and changes in soil biological activity. Experiments were carried out with dry sewage sludge preparation (SSP) in the such combinations 1) SSP, 2) SSP+PK, 3) SSP+NPK. Controls- loamy soil without additional fertilizer, soil mixed with mineral fertilizer (Kristalon 18:18:18). Maize (Zea mays var. saccharata ‘Elan F1’) was grown. Experiments were arranged in 1L vegetation containers placed in open area with additional watering. Plant growth parameters and soil enzymatic activity was detected. The SSP alone and in combination with potassium and phosphorus fertilizers does not provide the maize with the mineral nutrients in appropriate value, therefore, the combination of SSP with nitrogen containing fertilizers significantly improves plant growth and promotes development. The use of SSP increases the microbiological activity of the soil. This can have a beneficial long-term effect on the mineral nutrition of plants.

Abstract: Conversion of organic-containing sludges to a high value fertilizer is considered to be a rational solution from a recycling point of view. Aerobic respiration could serve as an indicator of stability and maturity of the treated sewage sludge (SS). The aim of this study was to characterize two SS samples, obtained from different wastewater treatment plants („D” and „J”), i.e, at the initial stage of treatment, alone and with amendments. Two methods for estimation of microbial respiration, as well as dehydrogenase activity were used. The SS-J demonstrated the higher microbial biodegradation activity, as compared to SS-D. In experiments with OxiTop® device, statistically significant (p<0.05) differences of the pressure drop between SS-J and SS-D have been revealed. Addition of peat to SS resulted in a more intensive pressure drop, compared to non-amended SS, i.e., -145 hPa vs. -76 hPa for SS-D and-199 hPa vs. -180 hPa for SS-J, respectively. The obtained results represent a methodical approach for characterization of raw SS in order to evaluate the amount of aerobically degradable organic substances and intensity of their oxidation. Further research is needed for highlighting the mechanisms responsible for interrelation of respiration intensity, bacterial community activity and other metabolic changes towards SS stabilization.

Abstract: Tomatoes are one of the most consumed vegetables in the world. Unfortunately, obtaining a high quality tomato yield in our latitudes is inconceivable without additional lighting. Changes in biochemical composition are mainly dependent on the light received by the plant. During the winter months, natural daylight at 55 ° latitude is insufficient to provide the necessary vegetation for fruit-bearing vegetables. The aim of this study is to investigate the changes in the biochemical composition of tomato fruits by using less conventional lighting methods, which could offer potential energy savings by providing higher levels of biologically active substances in tomatoes. The study was conducted in a greenhouse of Latvia University of Life Sciences and Technologies during the winter season 2018-2019, using a 16-hour photoperiod. LED, Induction, and High Pressure Sodium Lamps (as control) were used in the study. These lighting devices, with some differences, simulate daylight. Three tomato cultivars: ‘Diamont F1’, Encor F1’and ‘Balzano F1’were studied. The study specified the tomato yield and the following biochemical parameters: soluble sugars (BRIX), vitamin C, organic acids, lycopene, carotenoids, phenols and flavonoids. As expected, the yield and species-specific pigment content of tomato fruit is largely dependent on the genetics of the variety. On the other hand, biologically active compounds such as organic acids, soluble sugars, ascorbic acid and flavonoids undergo more changes due to the composition of the light. The obtained biochemical parameters give an opportunity to consider different illumination methods and the need to carry out further studies in order to confirm the conclusions. Significantly higher yields were observed in the variant with conventionally used high pressure sodium lamps. In mean time, it should be noted that in the variant with LED lamps, higher content of lycopene as well as phenols and vitamin C were observed.

Abstract: The aim of this research is to evaluate the influence of wood ash as an additive fertilizer to forest soil and growing blueberries (Vaccinium myrtillus L.) in terms of metallic element content. To evaluate the effect of wood ash on the forest ecosystem, was selected two forest areas which was fertilized with a certain amount of wood ash (bottom ash and fly ash). The selected forest areas were divided into two types of sampling plots (fertilized with ash and control). Obtained results showed that in the bottom ash dispersion area the concentration of Ca, K, Ni, Cu is almost twice higher in the fertilized plots than control plots. In the blueberries, metallic element content is similar and does not depend on the type of sampling plot.

Abstract: In the research chokeberries from five different geographic regions of Latvia were analysed. All collected samples were split in two parts: one of them was frozen and the second part was dried. Then extracts were prepared from frozen or dried berries in 70% ethanol/water or 10% glycerol/ethanol and 50% – 95% ethanol/water/HCl mixtures. The total phenolic content for the extracts was determined using the Folin-Ciocalteu method, total flavonoid content by rutin as standard and antioxidant activity by DPPH method. To identify and quantify the chemical compounds in the chokeberries, the analyses were performed with HPLC-DAD using absolute calibration and UHPLC-MS methods.