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WYSŁODKI BURACZANE - PASZA, ODPAD CZY SUROWIEC?
Abstract
Wysłodki buraczane jest to produkt uzyskiwany przy produkcji cukru, składający się z ekstrahowanej i wysuszonej krajanki buraków cukrowych o przeznaczeniu paszowym (Dz. U. Nr 16, poz. 137, 19.01. 2005)[1]. Jedna trzecia światowej produkcji cukru wytwarzana jest z buraków cukrowych [2]. Z jednej tony tego surowca otrzymujemy około 150 kg cukru i 250 kg wysłodków buraczanych o średniej wartości suchej masy 20 % [3]. W Polsce produkuje się około 1,43 mln ton cukru rocznie [4], w wyniku przetwórstwa 9,53 mln ton buraków, a tym samym powstaje 2,38 mln ton wysłodków. W sezonie 2012/2013 cukrownie w Polsce wyprodukowały ponad 1,8 mln ton cukru i odpowiednio 2,99 mln ton wysłodków. W Unii Europejskiej roczna produkcja cukru wynosi 15,62 mln ton, co odpowiada 26 mln ton wysłodków. W przeliczeniu na suchą masę rocznie w Unii Europejskiej powstaje 14 mln ton tego odpadu [5]. Wysłodki buraczane z racji skali produkcji cukru w naszym kraju stanowią istotny pod względem objętości, produkt odpadowy. Zagospodarowanie ich jest ważnym zagadnieniem związanym nie tylko z rozwiązaniem problemów dotyczących utylizacji surowców odpadowych, ale również możliwością pozyskiwania alternatywnych źródeł energii. 2. Powstawanie wysłodków buraczanych Dostarczone do cukrowni buraki, po oczyszczeniu, zostają pocięte na małe, długie paski. Umożliwia to uzyskanie dużej powierzchni, która decyduje o stopniu ekstrakcji cukru. Krajanka jest mieszana z gorącą wodą o temperaturze ok. 70° C, która powoduje rozpuszczenie i wypłukanie cukru zawartego w komórkach buraków [6]. Po rozdzieleniu soku buraczanego i krajanki powstają tzw. wysłodki mokre (świeże) o zawartości ok. 12 % s.m. Pozostający w wysłodkach sok surowy zostaje z nich usunięty i w ten sposób powstają wysłodki prasowane z zawartością suchej masy na poziomie 22% ± 1%. (rys. nr 1) [7].
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This study utilizes sugar beet pulp as a low-cost absorbent to remove two different cationic dyes, methylene blue and safranin, in aqueous solutions. The effects of operational parameters on the efficiency of dye removal including pH, adsorbent mass, initial dye concentration and contact time have been investigated. All sets of experiments were carried out in batch mode. For both dyes, the maximum absorption was reached at pH 10 while point zero charge was known to be at pH 6. Boehm method showed that the amount of the acidic and basic groups have been 0.4075mmolg−1 and 0.0089mmolg−1, respectively. Freundlich and Langmuir models were used to analyse the obtained experimental data. In comparison, Langmuir model was understood to be a better fit for the experimental data than Freundlich model. Pseudo first-order and pseudo second-order models were used to determine the adsorption kinetics and it was observed that pseudo second-order model was the most suited model for both dyes. The equilibrium state for both dyes was reached after 210min of the absorption experiment with more than 93% removal of dyes. The absorption capacities were found to be 211mg/g and 147mg/g for methylene blue and safranin, respectively.
The adsorption of Cd(II) ions from aqueous solutions onto activated carbon obtained by carbonising sugar beet pulp impregnated with 30% phosphoric acid was studied. By increasing the temperature of carbonisation, the removal efficiency of Cd(II) ions increased. The maximum removal (95.8%) was attained by activated carbon samples obtained by carbonising acid-impregnated sugar beet pulp at 500°C for 90 min. The removal efficiency of Cd(II) ions is, to a large extent, dependent on pH of medium. The results of experiments carried out at various temperatures were applied to Langmuir and Freundlich isotherm equations. The values of Langmuir constant (qmax) at 20°C were calculated as 68.03, 71.99 and 72.99 mg/g for activated carbons obtained at 300, 400 and 500°C, respectively. The adsorption process was found to be exothermic and Langmuir isotherm data were evaluated to determine the thermodynamic parameters for the adsorption process. It was found that the values of qmax and Kf decreased with increasing temperature. The data are better fitted by the second-order kinetic model as compared to first-order kinetic model.
The adsorption ability of activated carbons from sugar beet pulp to remove the cadmium from aqueous solutions has been investigated. Optimum temperature and time for carbonization of sugar beet pulp were determined as 700 °C and 120 min. The results of adsorption experiments show that pH for effective removal of cadmium was 6.3 or greater. The maximum removal percentage of cadmium were found to be 99.0, 78.2 and 57.0 by using 2.5 g l-1 adsorbent dosage for initial cadmium concentration of 100, 250 and 500 mg l-1, respectively, at optimum pH and 20 °C for a contact time of 120 min. Langmuir and Freundlich adsorption models were applied to the isotherm data. The free energy change of process was found to be -18.03 Kj mol-1.
An experimental design was constructed to study the influence of different parameters of acidic extraction on yield, chemical composition and intrinsic viscosity of pectins from fresh sugar-beet roots. pH, and, to a lower extent, time and temperature of extraction, affected greatly the yield and features of extracted pectins whereas the type of acid had no effect. Influences of extraction conditions on pectins characteristics were quantified and second order models were built.
The potential of sugar beet pulp (SBP) and dried sugar beet pulp (DSBP) as economically cheap and renewable supports for immobilization of Saccharomyces cerevisiae cells was investigated. The hydrated supports showed similar cells retention capacities of 0.178 ± 0.038 g/g and 0.182 ± 0.041 g/g for SBP and DSBP, respectively. The DSBP-immobilized biocatalyst was used for repeated ethanol fermentation, because DSBP is more stable material. Yeast cells immobilization was confirmed by the scanning electron microscopy (SEM). Repeated batch ethanol fermentation of thick juice by yeast immobilized on hydrated DSBP was successfully carried out for at least seven successive cycles without any significant decrease in ethanol production, while in the case of molasses, after the third batch, significant decrease was observed. A maximum ethanol concentration of 52.26 ± 2.0 g/l and ethanol yield of 0.446 ± 0.017 g/g was achieved in the seventh fermentation batch of thick juice (initial sugar of 120 g/l) with almost complete utilization of sugar (97.52 ± 0.15%). The sugar beet thick juice was found to be more convenient industrial substrate for repeated batch ethanol fermentation than molasses and can be used without any nutrient supplementation. The production of bioethanol from sugar beet thick juice and molasses using DSBP-immobilized cell system enables one more opportunity for achieving the zero-waste goal, through a rational use of intermediate and by-products of sugar beet processing.
Anaerobic digestion (AD) is a promising option for the environmentally friendly recycling of agricultural by-products. However, overloading of the digester with sugar, starch or protein might cause inhibition of the anaerobic processes. The aim of the present project was to investigate the AD of sugar beet, starch potato by-products and effect of pre-treatment by steam on methane yield of potatoes pulp. The investigated by-products have been: sugar beet pulp silage (SBP), sugar beet tail silage (SBT), potato pulp (PP), potato peel pulp (PPP) and potato fruit water (PFW). All by-products were digested in 1l eudiometer-batch digesters at 37.5°C during 28–38 days. The specific methane yields of SBP and SBT were 430 and 481lNkg−1 volatile solids (VS), respectively. The specific methane yields of PP, PPP and PFW were 332, 377 and 323lN (kgVS)−1. A steam pre-treatment significantly increased the specific methane yield of PP up to 373lN (kgVS)−1.
In this study, different bioethanol production processes from sugar beet were analyzed to improve energy input/output ratio and process sustainability. As inputs for fermentative bioethanol production, sugar factory can use some intermediate products [e.g. raw sugar juice (≈15–18% sugar) or concentrated sugar syrup (≈65–67% sugar)] or by-products (e.g. molasses ≈50% sugar). From energetic point of view, the main energy consumption operations in bioethanol production are: sugar extraction from sugar beet chips, sugar juice concentration by evaporation, ethanol distillation as well as distillers mash concentration and beet chips drying. In decision-making processes for different bioethanol production processes from sugar beet the concept of ecological footprint was used. Results of ecological footprint pointed out that energy demand and sustainability of standard process can be significantly improved by introduction of new technologies, i.e. simultaneous sugar extraction, pulp fermentation and product recovery (SEFPR) combined with biogas production from fermentation residues.
Sugar beet pulp (SBP) as received has a fairly high moisture content of 75-85%, which makes SBP storage a challenge. Ensilage was studied over 90 days and was found to effectively preserve SBP without lactic acid bacterium inoculation. Higher packing density yielded a slightly better silage quality. Ensilage improved sugar yield upon enzymatic hydrolysis of ensiled SBP washed with water. However, neither washing nor sterilization improved ethanol production from ensiled SBP using Escherichia coil KO11, suggesting ensiled SBP could be used directly in fermentation. The ethanol yield from ensiled SBP was nearly 50% higher than raw SBP. Fed-batch fermentation obtained approximately 30% higher ethanol yield than batch. Fed-batch could also be carried out at 12% solid loading with a 50% lower enzyme dosage compared to batch at the same solid loading, indicating opportunities to improve the economics of SBP conversion into liquid fuels.
Enzymatic saccharification of sugar beet pulp was optimized on kg-scale to release the maximum amounts of monomeric galacturonic acid and arabinose with limited concomitant degradation of cellulose, using conditions that are feasible for industrial upscaling. A selected mixture of pectinases released 79% of the galacturonic acid and 82% of the arabinose as monomers from sugar beet pulp while simultaneously degrading only 17% of the cellulose. The recalcitrant structures that were obtained after hydrolysis were characterized using mass spectrometry. The most abundant structures had an average degree of polymerization of 4-5. They were identified as partially acetylated rhamnogalacturonan-oligosaccharides, mostly containing a terminal galacturonosyl residue on both reducing and non-reducing end, partially methyl esterified/acetylated homogalacturonan-oligosaccharides, mostly containing methyl and acetyl esters at contiguous galacturonosyl residues and arabinan-oligosaccharides, hypothesized to be mainly branched. It could be concluded that especially rhamnogalacturonan-galacturonohydrolase, arabinofuranosidase and pectin acetylesterase are lacking for further degradation of recalcitrant oligosaccharides.