Neven Voća

Progress in ethanol production from corn kernel by applying cooking pre-treatment

In order to improve technological properties of corn kernel for ethanol production, samples were treated with a hydrothermal pre-treatment of cooking (steaming), prior to drying. Two types of cooking process parameters were applied; steam pressure of 0.5 bars during a 10 min period, and steam pressure of 1.5 bars during a 30 min period. Afterwards, samples were dried at four different temperatures, 70, 90, 110 and 130 degrees C. Control sample was also submitted to the aforementioned drying parameters. Since the results showed that starch utilization, due to the gelatinization process, was considerably higher in the samples pre-treated before the ethanol production process, it was found that the cooking treatment had a positive effect on ethanol yield from corn kernel. Therefore, the highest ethanol yield was found in the corn kernel samples cooked for 30 min at steam pressure 1.5 bars and dried at 130 degrees C. Due to the similarity of processes used for starch fermentation, introduction of cooking pre-treatment will not significantly increase the overall ethanol production costs, whereas it will result in significantly higher ethanol yield.

Concept of sustainable waste management in the city of Zagreb: Towards the implementation of circular economy approach

ABSTRACT Improvement of the current waste management is one of the main challenges for most municipalities in Croatia, mainly due to legal obligations set in different European Union (EU) directives regarding waste management, such as reduction of waste generation and landfilling, or increase of separately collected waste and recycling rates. This paper highlights the current waste management in the city of Zagreb by analyzing the waste generation, collection, and disposal scenario along with the regulatory and institutional framework. Since the present waste management system mainly depends upon landfilling, with the rate of separate waste collection and recycling far from being adequate, it is necessary to introduce a new system that will take into account the current situation in the city as well as the obligations imposed by the EU. Namely, in the coming years, the Waste Framework and Landfill Directives of the European Union will be a significant driver of change in waste management practices and governance of the city of Zagreb. At present, the yearly separate waste collection makes somewhat less than 5 kg per capita of various waste fractions, i.e., far below the average value for the (28) capital cities of the EU, which is 108 kg per capita. This is possible to achieve only by better and sustainable planning of future activities and facilities, taking into account of environmental, economic, and social aspects of waste management. This means that the city of Zagreb not only will have to invest in new infrastructure to meet the targets, but also will have to enhance public awareness in diverting this waste at the household level. The solution for the new waste management proposed in this paper will certainly be a way of implementing circular economy approach to current waste management practice in the city of Zagreb. Implications: Municipal waste management in the developing countries in the EU (new eastern EU members) is often characterized by its limited utilization of recycling activities, inadequate management of nonindustrial hazardous waste, and inadequate landfill disposal. Many cities in Eastern Europe and Zagreb as well are facing serious problems in managing municipal wastes due to the existing solid waste management system that is found to be highly inefficient. The proposed scenario for city of Zagreb in the paper is an innovative upgrading of municipal waste management based on the waste management hierarchy and circular economy approach.

Bioethanol production from corn kernel grown with different cropping intensities.

The aim of this paper is to determine the level of influence of the applied cropping intensity on the water release speed from the kernel on the field and in the process of convection drying, on the content of starch and on the yield of ethanol in five different corn hybrids belonging to the same vegetation group.

Biomass valorisation of Arundo donax L., Miscanthus × giganteus and Sida hermaphrodita for biofuel production

Abstract In the context of the growing demand for biomass, which is being encouraged by the EU directives on the promotion of the use of renewable energy, recent investigations have been increasingly focused on fast-growing energy crops. The aim of this study was to investigate the energy properties of three types of agricultural energy crops: Arundo donax L., Miscanthus × giganteus and Sida hermaphrodita. This investigation looked into the content of non-combustible and combustible matter, higher and lower heating values, lignocellulose content, and biomass macro-elements. The results indicate that the energy values of these crops are comparable, while their lignocellulose content shows significant variations. Thus, Arundo donax L. can best be utilised as solid biofuel due to its highest lignin content, while Miscanthus × giganteus and Sida hermaphrodita L. can be used for both liquid and solid biofuels production. As far as Arundo donax L. is concerned, a higher ash level should be taken into consideration.

High-risk biodegradable waste processing by alkaline hydrolysis.

High-Risk Biodegradable Waste Processing By Alkaline Hydrolysis Biodegradable 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. Oporaba visokorizičnog biorazgradivog otpada metodom alkalne hidrolize Biorazgradivi otpad definira se kao otpad koji razgrađuju živi organizmi. Klaonice i mesna industrija proizvode na dnevnoj bazi velike količine specifičnoga biorazgradivog otpada poznatog kao otpad životinjskog podrijetla. Tradicionalno se u Europi taj otpad reciklira u kafilerijama, pri čemu se proizvode mesno-koštano brašno i mast. No nakon pojave goveđe spongiformne encefalopatije (GSE) zabranjena je prehrana životinja mesno-koštanim brašnom. U potrazi za novim mogućnostima zbrinjavanja otpada životinjskog podrijetla razvijene su nove tehnologije oporabe i omogućena upotreba takvog otpada u energetske svrhe. Određeni dijelovi otpada životinjskog podrijetla, mozak i leđna moždina, pripadaju kategoriji visokorizičnog otpada zbog velike mogućnosti postojanja priona u njima. Njihova oporaba stoga je moguća samo u strogo kontroliranim uvjetima. Jedna od metoda koja se smatra prikladnom za oporabu visokorizičnih otpada jest metoda alkalne hidrolize. U radu su prikazani rezultati analiza mesno-koštanog brašna i hidroliziranog otpada te njegova uporaba kao organskoga gnojiva.

Energy valorization of Miscanthus x giganteus biomass: A case study in Croatia

The aim of this study is to determine the calorific values, chemical composition (proximate and ultimate analysis, micro and macro elements) and cell structure (composition of lignocellulose) of Miscanthus x giganteus biomass cultivated in Croatian. Research results represents the average values of biomass (n = 108) cultivated at two locations in Croatia (Bistra, Medvednica), during the three-year research period, three harvest periods (autumn, winter, spring) per year and two fertilizer treatments (N0 i N50). Determined average values of some important parameters are: low calorific value - 17.25 MJ/kg, ash content - 1.49 %, carbon content - 48.75 %, nitrogen content - 0.47 %, sulfur content - 0.07 %, cellulose content - 49.22 % and lignin content - 29.25 %. The obtained results have shown that Miscanthus x giganteus has potential to be a significant source of good quality raw material in the production of solids biofuels.

Effects of different air drying temperature on sunflower seeds oil and ash content

The aim of this paper was to determine the impact of different air temperature (60 °C, 80 °C and 100 °C) at air drying velocity of 1.0 ms-1 during convection drying thermal process on the sunflower seeds oil and ash content. The research was conducted at 4 different sunflower seeds hybrid Apollo, NK Brio, PR 63 and PR 90 A 63 D 82, which by their characteristics are early and medium early hybrids.. Based on the results, the curve of water speed release from the sunflower seeds, the activation energy, as well as changes in oil content and ash content before and after the convective drying was obtained. It was established that the NK Brio hybrid fastest release water compared to other hybrids during drying which is confirmed by minimum value of activation energy and that the increasing of air drying temperature increases oil content, while reduces ash content.

The influence of oilseed rape ripening on the drying process in a dryer

Drying is the oldest but also the most simple way of preservation. Grains are dried to the level of moisture equilibrium. It is well known that different parts of oilseed rape seeds, that have different initial moisture levels, behave in a different way during drying. Bristol, Eurol, and Alaska, which are „ 00” rapeseed cultivars were researched. Bristol and Alaska are French sorts produced by Monsanto S.A.S. Alaska is a German sort produced by KWS. The research was conducted on fields in Zdenci.The mean bootstrap value (“ bootstrap mean” ) of the correlation coefficient was 0.657 ; the bias was 0.00736 ; the standard failure (bootstrap estimation of standard failure) was 0.247 ; a normal 90% bootstrap interval of the correlation coefficient ranged from 0.23589 to 1.00. The real (population) correlation coefficient was higher than zero, i.e. there was a positive correlation between the length of time of the ripening in field and drying in a dryer. A linear regression model, which best describes the linear relation between the length of time of the ripening in field and the length of time of drying in a dryer can be expressed as y =1, 47564 x – 6, 6605. The mean bootstrap regression coefficient value was 1.5024 ; the bias 0.0267 ; the standard failure was 0.7401 ; a normal 90% bootstrap interval of the correlation coefficient ranged from 0.232 to 2.666. The real (population)correlation coefficient was higher than zero, i.e. there was a positive correlation between the length of the ripening in field and the drying in a dryer.