The aim of this paper is to determine the difference in quality of the digested residue a�er the process of anaerobic digestion by using different input raw materials. The research was conducted in the Republic of Austria on four facilities for biogas production. The raw materials used for biogas production were chicken manure, pig manure, Sudan grass and organic household waste. The research included chemical analysis and bacteriological tests of the samples taken. It was found that the digested residue in all of the samples, all of which are mildly alkaline, contains a low level of dry ma�er, 70% of which is organic ma�er. Biogenic elements were present in moderate concentration; the values of heavy metals were within approved limits. This analysis leads to the conclusion that the digested residues of all input materials can be used in agricultural production, especially so in plant production and grassland cultivation. Mesophilic and thermophilic microorganisms were found in the digested residue samples, but there were no cryophilic microorganisms and no pathogenic bacteria.
High-Risk Biodegradable Waste Processing By Alkaline HydrolysisBiodegradable waste is by definition degraded by other living organisms. Every day, meat industry produces large amounts of a specific type of biodegradable waste called slaughterhouse waste. Traditionally in Europe, this waste is recycled in rendering plants which produce meat and bone meal and fat. However, feeding animals with meat and bone meal has been banned since the outbreaks of bovine spongiform encephalopathy (BSE). In consequence, new slaughterhouse waste processing technologies have been developed, and animal wastes have now been used for energy production. Certain parts of this waste, such as brains and spinal cord, are deemed high-risk substances, because they may be infected with prions. Their treatment is therefore possible only in strictly controlled conditions. One of the methods which seems to bear acceptable health risk is alkaline hydrolysis. This paper presents the results of an alkaline hydrolysis efficiency study. It also proposes reuse of the obtained material as organic fertiliser, as is suggested by the analytical comparison between meat and bone meal and hydrolysate.
Aware that exposure to stuffy indoor air with high levels of carbon dioxide (CO2) is associated with higher absenteeism and reduced academic performance in school pupils, the World Health Organization (WHO) Regional Office for Europe initiated indoor air quality surveys in schools, including CO2 monitoring, to assess ventilation and exposure to stuffy air. Here we report the findings of the first such survey in Croatia. It was conducted in 60 classrooms of 20 urban and rural elementary schools throughout the country during the heating season. Measurements of CO2 levels showed that all 60 classrooms exceeded the international guidelines of 1938 mg/m3. Mean CO2 concentrations ranged from 2771 to 7763 mg/m3. The highest concentration measured in urban schools was 7763 mg/m3 and in rural schools 4771 mg/m3. Average CO2 levels were higher in continental schools (3683 mg/m3) than the coastal ones (3134 mg/m3), but all demonstrate poor ventilation during the heating season all over Croatia.
Original scientific paper The present paper investigates the effectiveness of different levels of applied digested residue obtained after anaerobic digestion (AD) of meat-bone meal (MBM) on the morphologic and mineral characteristics of corn. The experiment was conducted in duration of two years and consisted of eight treatments: control (without any fertilizer); mineral fertilization only; treatments with minimum, medium and maximum dosage of digested MBM; fertilization of minimum, medium and maximum dosages of AD residue combined with mineral fertilizer. By combination of treatments with mineral fertilizer and different rates of AD residue, plants increased mass yield, they were larger and had more leaves. Content of mineral substances was within average values, both in plant material and in kernel, and variations in values were conditioned by total mass and ion interactions. MBM after AD treatment is possible to be applied as organic fertilizer. It has higher nutritive value and, as such, is suitable for treatment of agricultural plants, especially in crop production. Keywords: anaerobic digestion; corn; fertilization; meat bone meal Anaerobna digestija specifičnog biorazgradivog otpada i konačno zbrinjavanjeIzvorni znanstveni članka Ovaj rad istražuje učinkovitost primjene različitih razina digestiranog ostatka, dobivenog nakon anaerobne digestije (AD) mesno-koštanog brašna (MKB), na morfološka i mineralna svojstva kukuruza. Istraživanje je provedeno u trajanju od dvije godine, a sastojalo se od osam tretmana: kontrola (bez gnojiva); samo mineralna gnojidba; tretmani s najmanjom, srednjom i maksimalnom dozom digestiranog MKB-a; gnojidba minimalnom, srednjom i maksimalnom dozom digestiranog ostatka u kombinaciji s mineralnim gnojivom. Kombinacija tretmana s mineralnim gnojivom i različitom dozom ostatka anaerobne digestije, povećala je prinos mase biljke, bile su veće i imale više lišća. Sadržaj mineralnih tvari bio je prosječne vrijednosti, kako u biljnom materijalu tako i u jezgri. Varijacije vrijednosti uvjetovane su ukupnom masom i ionskim interakcijama. MKB nakon tretmana AD moguće je primijeniti kao organsko gnojivo. Ima veće hranjive vrijednosti i, kao takvo, prikladno je za tretiranje poljoprivrednih biljaka, posebno u ratarstvu.
Sažetak UVODJedan od ključnih ekoloških problema današnjice je otpad, odnosno njegovo zbrinjavanje. Prema Nacionalnoj Strategiji zaštite okoliša Republike Hrvatske (2002) najveći problem gradova je upravo zbrinjavanje otpada, odnosno neodrživo gospodarenje otpadom. Također, u velikom broju istraživanja provedenih u posljednjih tridesetak godina, problem neodgovarajućeg zbrinjavanja komunalnog otpada i gomilanje otpada stalno visoko rangira, a rezultati pokazuju i zabrinutost stanovništva za stanje okoliša kada je u pitanju komunalni otpad (Cifrić, 1999(Cifrić, , 2005(Cifrić, , 2008 Stanić i sur., 2009). Povećanje količina otpada koji nastaje i njegovo gomilanje rezultat je masovne proizvodnje i potrošnje. Potrošački mentalitet sve je izraženiji, a prekomjerna eksploatacija prirodnih resursa, gomilanje otpadnih tvari i uništavanje prirode i okoliša pridonose poremećaju biološke ravnoteže na Zemlji. Stvaranjem sve većih količina otpada čovjek znatno narušava prirodnu ravnotežu, pa pristup rješavanju problema otpada čini jedan od prioriteta u smanjenju onečišćenja okoliša (Evison i Read, 2001).
Globally, lignocellulosic biomass has great potential for industrial production of materials and products, but this resource must be used in an environmentally friendly, socially acceptable and sustainable manner. Wood and agricultural residues such as walnut shells as lignocellulosic biomass are one of the most affordable and important renewable resources in the world, which can partially replace fossil resources. The overall objective of the research is to provide background information that supports new applications of walnut shells in a biorefinery context and to increase the economic value of these non-wood forest products. This paper presents the properties characterization of liquefied biomass according to their chemical composition. All results were compared to liquefied wood. In this study, the liquefaction properties of five different walnut shell particle sizes were determined using glycerol as the liquefaction reagent under defined reaction conditions. The liquefied biomass was characterized for properties such as percentage residue, degree of liquefaction, and hydroxyl OH numbers. The chemical composition of the same biomass was investigated for its influence on the liquefaction properties. Accordingly, the main objective of this study was to determine the liquefaction properties of different particle sizes as a function of their chemical composition, also in comparison with the chemical composition of wood. The study revealed that walnut shell biomass can be effectively liquefied into glycerol using H2SO4 as the catalyst, with liquefaction efficiency ranging from 89.21 to 90.98%.
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