Tag Archives: sewage sludge

xxx D. Urbancl, J. Krope and D. Goričanec
Torrefaction – the process for biofuels production by using different biomasses
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Torrefaction – the process for biofuels production by using different biomasses

D. Urbancl*, J. Krope and D. Goričanec

University of Maribor, Faculty of Chemistry and Chemical Engineering, Smetanova street 17, SI2000 Maribor, Slovenia
*Correspondence: danijela.urbancl@um.si

Abstract:

Torrefaction process is a mild pyrolysis, where biomass material is converted into solid fuel with higher heating value. The results of torrefaction at different temperatures in a range from 220 to 400 °C for three varied materials, oak wood, mixed wood and dehydrated, granulated sewage sludge are presented. The torrefaction process started with warm up stage, which took place for 30 minutes, after that sample was torrefied for 2 hours at constant temperature. The process continued with cool down stage. The energy demands were covered by electric power, while the flue gasses were not integrated in the process. The influence of the operating temperatures are analysed in order to determine optimal operation parameters to get the torrefied biomass with highest calorific value. Furthermore, the optimal operation time according to the largest increase in calorific value for each material is evaluated. The results of calorific value, mass drop and chemical compositions such as elemental analyses are also presented. Results show that heating values increase with raising temperature for both wood samples. The heating values for sewage sludge increases to approximately 320 °C, after that temperature are unchangeable. Torrefied oak wood samples were more fragile at higher temperatures in comparison to raw or torrefied oak wood samples at lower temperatures. At torrefied sewage sludge samples the changes in fragility are not detected due to pre-prepared granulates of sludge.

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1583-1600 E. Haiba, L. Nei, M. Ivask, J. Peda, J. Järvis, M. Lillenberg, K. Kipper and K. Herodes
Sewage sludge composting and fate of pharmaceutical residues –recent studies in Estonia
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Sewage sludge composting and fate of pharmaceutical residues –recent studies in Estonia

E. Haiba¹, L. Nei¹*, M. Ivask¹, J. Peda¹, J. Järvis¹, M. Lillenberg², K. Kipper³ and K. Herodes³

¹Tartu College, Tallinn University of Technology, Puiestee 78, EE51008 Tartu, Estonia
²Estonian University of Life Sciences, Kreutzwaldi 58A, EE51014 Tartu, Estonia
³Institute of Chemistry, University of Tartu, Ravila 14A, EE51010 Tartu, Estonia *Correspondence: lembit.nei@ttu.ee

Abstract:

This review is to reflect the work addressed to the application of biosolids and especially sewage sludge as a resource in composting. A considerable drop in the use of P fertilisers can be followed since early 1990s. Due to this fact crop production in Estonia takes place at the expense of soil phosphorous (P) resources. One of the ways of increasing the fertility of agricultural lands is to use nutrient-rich sewage sludge. Unfortunately, this may cause several undesired consequences due to biological and chemical contaminants. The presence of some widely used pharmaceuticals, as ciprofloxacin (CIP), norfloxacin (NOR), ofloxacin (OFL), sulfadimethoxine (SDM) and sulfamethoxazole (SMX), was evident in sewage sludge of the two Estonian largest cities, Tartu and Tallinn. The concentrations of pharmaceuticals decreased after sewage sludge digestion and composting, but they were still present in detectable amounts. Sewage sludge co-composting experiments with sawdust, peat and straw showed the degradation of fluoroquinolones (FQ) and sulfonamides (SA). Additions of sawdust clearly speeded up this process, whereas the mixtures with peat and straw performed lower abilities to decompose pharmaceutical residues. Novel methodologies were developed and experiments conducted to study the potential accumulation of fluoroquinolones FQs and SAs by food plants. Due to the low adsorption of SAs on soil particles they are ‘free’ to migrate into plants. Different behaviour is characteristic to FQs as they are accumulated in sludge. Recent years have also shown progress in vermicomposting work and in using compost in afforestation.

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1169–1179 V. Malijonytė,, E. Dace, F. Romagnoli and M. Gedrovics
Methodology for determining the mixing ratio of selected solid recovered fuels
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Methodology for determining the mixing ratio of selected solid recovered fuels

V. Malijonytė¹,², E. Dace¹*, F. Romagnoli¹ and M. Gedrovics¹

¹Riga Technical University, Institute of Energy Systems and Environment, Azenes 12/1, LV-1048 Riga, Latvia
²Kaunas University of Technology, Institute of Environmental Engineering, Donelaičio g.20, LT-44239 Kaunas, Lithuania
*Correspondence: elina.dace@rtu.lv

Abstract:

Energy recovery is a preferable waste management method for waste that cannot be reused or recycled. For energy recovery, various types of waste with differing properties are being used, e.g. mixed municipal solid waste or end-of-life tires. To achieve a more stable and homogeneous characteristics of the waste derived fuels (RDF, SRF), they can be mixed in a number of ratios. The paper presents a methodology for determining the optimal mixing ratio of three selected waste derived fuels (mixed municipal solid waste, sewage sludge, end-of-life tires) considering environmental and economic aspects. The developed method is based on combining life cycle assessment method, mass balance calculations and multi-criteria analysis (the technique for order of preference by similarity to ideal solution – TOPSIS). The results show that mixing the various waste derived fuels allows obtaining a more sustainable solution than in the case of each separate waste derived fuel.

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