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1

Influence of Temperature and Reaction Time on the Efficiency of Alkaline Pretreatment of Hay Biomass

Zdeb Magdalena, Skóra Aneta, Pawłowska Małgorzata

Journal of Ecological Engineering

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2021

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Vol. 22, nr 2

120--127

EN

Low biodegradability caused by polymeric structure is the main barrier in the use of lignocellulosic materials in biofuels production by using biological methods. Pretreatment of the biomass is the way to improve the suitability of hardly biodegradable biomass for biogas or bioethanol production. Evaluation of the influence of thermal and thermochemical alkaline pretreatment on the efficiency of hydrolysis of hay (mixture of various grass species) was the aim of the study. The batch scale experiment was carried out with the use of NaOH and distilled water as solvents, and the changes in pretreatment time (2, 4 and 8 hours) and temperature (22 and 80°C) were also considered. The efficiency of biomass solubilisation was assessed based on the results obtained from the measurements of chemical oxygen demand (COD) and volatile fatty acids (VFA) concentration in the hydrolysates. The solubility of the biomass, expressed as a percentage of soluble COD in total COD, was calculated. The experiment showed that the highest solubilisation of hay biomass was observed at 80°C under alkaline conditions. In this case, the solubility of the COD was 3-times higher, and the VFA concentration in hydrolysates was 4-times higher in comparison to the distilled water-based test at 22°C. It was noted that time of the process significantly influenced the efficiency of biomass solubilisation only during the experiment carried out at 22°C. Extension of hydrolysis time from 2 to 8 hours increased the value of soluble COD of 70% and 55% for water and alkaline solvent, respectively. The process conducted at 80°C was not time-dependent over the considered period.

2

Anaerobic Digestion of Wheat Straw Pretreated with Soaking in Water and Alkali Medium

Zdeb Magdalena

Journal of Ecological Engineering

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2021

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Vol. 22, nr 9

246--254

EN

The influence of the alkaline pretreatment of wheat straw with use 0.05M solution of NaOH by 22 hours at 25 °C temperature on the effectiveness of anaerobic digestion under mesophilic condition was the subject of this study. The water soaked straw was used as a control. The results showed that alkaline pretreatment improved the solubility of the straw biomass, increasing dissolved COD and concentration of VFA in the feedstock of 10% and 21%, respectively, compared to the water soaked samples. Consequently, the cumulative biogas yield was enhanced by 21.5%, reaching 412.1 mL gVS-1 for the pretreated biomass. The digestates were similar in terms of TS and VS, but it significantly differed in terms of phenols concentration, the content of which was considerably higher both in the feedstock as also as in digestate containing alkaline pretreated straw. Initial concentration of phenols in the feedstock of 27 mg L-1 did not block the anaerobic digestion, although its inhibiting effect is forecasted. It was concluded that soaking the straw at low loading of NaOH (4% of raw mass (w/w)) under ambient conditions can efficiently improve its usability for biogas production.

3

Carbon Sequestration in Soil as a Sustainable Way of Greenhouse Effect Mitigation

Żukowska Grażyna, Myszura Magdalena, Zdeb Magdalena, Pawłowska Małgorzata

Problemy Ekorozwoju

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2020

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Vol. 15, nr 2

195--205

EN

Due to natural mechanisms of transformation the carbon compounds contained in the atmosphere into the humus, soil is an important factor controlling the concentration of atmospheric CO2. The mass of carbon contained in organic matter accumulated in the surface layer of the Earth’s crust is greater than the mass of this element in the atmosphere or biomass of all the organisms living over the globe. Over the recent years, much attention has been paid to the role of soils in limiting the reasons of climate changes, considering the possibility of increasing carbon sequestration in this matrix. This way of approaching the problem of the greenhouse effect, which does not require an involvement of complex and expensive technological solutions aimed at capturing and storing the atmospheric CO2, and additionally contributing to improving the quality of soil and water environment, and soil productivity is fully sustainable and combines the environmental, economic and social issues.

PL

Dzięki istnieniu naturalnych mechanizmów transformacji związków węgla zawartych w atmosferze w związki próchniczne, gleba stanowi istotny czynnik kontrolujący stężenie atmosferycznego CO2. Masa węgla zawartego w materii organicznej nagromadzonej w powierzchniowej warstwie skorupy ziemskiej jest większa niż masa tego pierwiastka w atmosferze lub biomasie organizmów żywych. W ostatnich latach wiele uwagi poświęca się roli gleb w ograniczeniu przyczyn zmian klimatycznych, poddając pod rozwagę możliwości zwiększenia w nich sekwestracji węgla. Taki sposób podejścia do problemu efektu cieplarnianego, nie wymagający wprowadzania złożonych i drogich rozwiązań technologicznych nakierowanych na wychwytywanie i magazynowanie atmosferycznego CO2, a dodatkowo przyczyniający się do poprawy jakości środowiska gruntowo-wodnego oraz produktywności gleb jest w pełni zrównoważony, gdyż łączy ze sobą zarówno kwestie środowiskowe, gospodarcze i społeczne.

4

The Influence of Anaerobic Digestion on Selected Heavy Metals Fractionation in Sewage Sludge

Zdeb Magdalena, Pawłowska Małgorzata, Pacan Justyna

Journal of Ecological Engineering

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2020

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Vol. 21, nr 3

27--35

EN

Rising efficiency of wastewater purification systems causes an increase in the amounts of sewage sludge. Its land application is economically attractive because of low cost and high efficiency. Using sewage sludge in agriculture is one of the most preferred ways of its disposal. Only stabilized sludge and containing permissible concentrations of heavy metals can be used for this purpose. The heavy metals introduction into the environment may cause a potential problem for public health, especially when they percolate from soil to plants or groundwater. Therefore, the concentrations of heavy metals in sludge intended for agriculture are regulated. Determination of total content of heavy metals in digested sludge is not sufficient for the evaluation of a potential risk to the environment. The mobility and toxicity of heavy metals depend strongly on their specific chemical forms. The concentrations of particular heavy metal fractions are the most important parameters, which should be examined in order to estimate the influence of sludge on the environment. The aim of an article was to evaluate the influence of anaerobic digestion on the concentration and variability of chemical forms of selected heavy metals (Cr, Cu, Ni, Pb, Zn) in the sewage sludge coming from a municipal wastewater treatment plant in Pulawy (Poland). The content of particular forms of heavy metals in raw and digested sewage sludge was determined by means of the BCR (Community Bureau of Reference) method. The BCR method enables separating four fractions of heavy metals: exchangeable, reducible, oxidizable and residual. The results obtained after analyzing raw sludge showed that the majority of the analyzed heavy metals were predominantly associated with the oxidizable and residual fractions. Only in the case of Zn, the reducible form constituted a greater part. In the case of digested sludge, all studied heavy metals exhibited the most dominant oxidizable and residual fractions; however, the percentages of particular fractions were different than in raw sludge. It was noticed that all heavy metals concentrations were higher in digested sludge in comparison to sludge before anaerobic digestion. The content of heavy metals in the analyzed materials did not exceed the admissible Polish levels for the sludge intended for the agricultural use.

5

The Effect of Z-ion Zeolite Substrate on Growth of Zea mays L. as Energy Crop Growing on Marginal Soil

Chomczyńska Mariola, Zdeb Magdalena

Journal of Ecological Engineering

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2019

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Vol. 20, nr 9

253--260

EN

The presented study aimed at determining the influence of the increasing dose of new Z-ion zeolite substrate on the growth of maize (Zea mays L.) as species belonging to energy crops. In order to achieve the study aim, the pot experiment was carried out where the plants were grown on six series of media i.e.: on marginal soil (the control series I), on arable soil (the control series II) and on four mixtures of marginal soil with increasing Z-ion substrate addition (1%, 2%, 5%, 10 % v/v). The pot test was carried out in a phytotron with a 13/11 light/dark regime. After the end of the experiment, the mean values of the vegetative parameters (wet and dry biomass of roots and stems) characterizing the plant growth in particular media series were determined. The C:N ratio for maize stems was calculated as well. The obtained study results showed a favorable influence of Z-ion substrate additions on the vegetative growth of maize. Already a 1% (v/v) substrate addition to marginal soil increased the wet and dry stems biomass by 173–204%. At the same time, it turned out that in the sixth week of plant growth, a 5% substrate addition to the marginal soil enables to achieve the value of vegetation parameters at a level similar to that of the parameters characterizing the plant development on arable land. Thus, at an early stage of plant growth, a 5% substrate dose can be considered as one allowing a similar course of maize growing on marginal soil as in the case of arable soil. It is worth noting that at this substrate dose, the C:N ratio in maize stems reached the value of 13.05, at which the plant biomass is the substrate ensuring the fairly proper course of methane fermentation supplying fuel in the form of biogas.