Search

Arar (Juniperus phoenicea L.) is a small monoecious or dioecious evergreen species presenting as a shrub or tree around the Mediterranean. This widespread plant is also causing problems in Croatia, along its Adriatic coastal area and in particular on the island of Pag. It affects the establishment and growth of other species that share its habitat and has also reduced the grazing areas of local sheep breeding and beekeeping communities. Arar is also a frequent cause of wildfires in the region. Its spread is indeed far-reaching, from its impact on plants and livestock to its adverse effects on the local population and its tourism, which is one of the main components of the island’s economy. This research aimed to evaluate biomass and biochar samples of arar, using standard methods to verify their potential energy value. Results of the study showed a favorable content of coke (16.28%) and volatiles (77.26%) in the samples. The C, H, S, N, and O ratios of the samples were 50.14%, 6.57%, 0.31%, 0.84% and 42.13%, respectively. The higher calorific value was 20.45 MJ·kg−1 for biomass and 29.01 MJ·kg−1 for biochar. Accordingly, this species can be used as a solid biofuel for direct combustion or similar processes and for other value-added applications.

Sve veće količine generiranog otpada od hrane odbačene na odlagališta velika su prijetnja u postizanju održivog razvoja, stabilnosti tržišta hrane, rastu ljudske populacije i dobrobiti ljudi. Odbačena hrana ima dalekosežne posljedice, kako na nacionalnoj tako i na globalnoj, ali i okolišnoj razini. Sve je manje obradivih poljoprivrednih površina, smanjuju se zalihe fosilnih goriva i sve je teže proizvesti hranu. Poljoprivredna proizvodnja se okreće obnovljivim izvorima energije i održivoj proizvodnji uz maksimalno iskorištavanje dostupnih resursa. Uzimajući u obzir sve to potpuno je neprihvatljivo proizvoditi velike količine otpada od hrane, dok se istovremeno bilježi stalan porast gladi. S obzirom da su potrošači odgovorni za veliki stupanj odbačene hrane, institucije uz pomoć znanosti orijentiraju se na istraživanja koja mogu ponuditi moguća rješenja u preventivnom djelovanju ili barem djelomičnom zaustavljanju negativnog trenda u bacanju hrane.

Porastom stanovništva dolazi do stvaranja sve većih količina otpada od hrane. Za planiranje smanjenja i stvaranja mehanizama rješavanja otpada od hrane potrebno je različitim modelima predvidjeti količinu otpada od hrane. Na stvaranje otpada od hrane utječu brojni socioekonomski i društveni čimbenici. Kao alat za nelinearno modeliranje i predviđanje nude se modeli u obliku umjetnih neuronskih mreža. U ovom istraživanju kreiran je model umjetnih neuronskih mreža za predviđanje ukupne količine otpada od hrane na području Europske unije. Provedenom analizom pogodnosti (R2=0, 99), utvrđena je mogućnost razvijenog za predviđanje ukupne količine otpada od hrane.

In this study, an evaluation of food waste generation was conducted, using images taken before and after the daily meals of people aged between 20 and 30 years in Serbia, for the period between 1 January and 31 April in 2022. A convolutional neural network (CNN) was employed for the tasks of recognizing food images before the meal and estimating the percentage of food waste according to the photographs taken. Keeping in mind the vast variates and types of food available, the image recognition and validation of food items present a generally very challenging task. Nevertheless, deep learning has recently been shown to be a very potent image recognition procedure, while CNN presents a state-of-the-art method of deep learning. The CNN technique was implemented to the food detection and food waste estimation tasks throughout the parameter optimization procedure. The images of the most frequently encountered food items were collected from the internet to create an image dataset, covering 157 food categories, which was used to evaluate recognition performance. Each category included between 50 and 200 images, while the total number of images in the database reached 23,552. The CNN model presented good prediction capabilities, showing an accuracy of 0.988 and a loss of 0.102, after the network training cycle. The average food waste per meal, in the frame of the analysis in Serbia, was 21.3%, according to the images collected for food waste evaluation.

Given that global amounts of waste are growing rapidly, it is extremely important to determine what amount of waste will be generated in the near future. Accurate waste forecasting is also important for planning and designing a sustainable municipal solid waste (MSW) management system. For that reason, there is a need to build a model to predict the amount of MSW generated in the near future. Based on previous research, artificial neural networks (ANN) show better results in predicting waste generation compared to other mathematical models. In this research, an ANN model using the iterative algorithm Broyden–Fletcher–Goldfarb–Shanno (BFGS) for the prediction of MSW fractions, based on the socio-demographic characteristics, economic and industrial data obtained in Croatia and summarized data of the member states of EU (EU-27 from 2020), showed good predictive capabilities. The coefficient of determination during the training cycle for the output variables; household and similar waste (HHS), paper and cardboard waste (PCW), wood waste (WW), textile waste (TW), plastic waste (PW) and glass waste (GW) were 0.993; 0.997; 0.999; 0.997; 0.998; and 0.998, respectively, while reduced chi-square, mean bias error, root mean square error, mean percentage error, average absolute relative deviation and sum of squared errors were found low. In this paper, Yoon′s method of interpretation shows the relationships between socio-demographic data and the amount of generated waste. The results indicate that the lowest level of education shows a negative impact on observed waste-types calculations, with a relative impact between −9.889 and −4.467%. The most pronounced positive impact on the calculation of HHS, PCW, WW, TW, PW and GW was observed for year variable, gross domestic product, exports of goods and services, imports of goods and services, wages and salaries, secondary income, arrivals in collective accommodation establishments, overnight stays in collective accommodation establishments and exports of petroleum and petroleum products to partner countries, with a relative influence of 4.063–7.028; 2828–4851; 5240–6197; 5.308–6.341; 4290–4810; 4533–5805; and 4.345–4.493, respectively. The obtained results indicate that the amount of HHS waste at the EU-27 level in 2025 will decrease by approximately 18% compared to the data from 2018. The quantities of other observed recyclable types of waste will increase by 34% for PCW, 310% for WW, 40% for TW, 276% for PW and about 67% for GW. The amount of waste generated provides the basic information needed to plan, operate and optimize the waste management system. It could also help in the transition to an environmentally friendly and economically profitable circular economy. The model created in this research could also help with the system of separate waste collection, which would lead to more efficient recycling and the achievement of the set goals for recycling 55% of municipal waste by 2025.

The paper discusses project of constructing a biogas plant for biological treatment of municipal biowaste in the Virovitica-Podravina and surrounding counties. In Virovitica-Podravina County the total amount of waste generated is 21,690 tons, which corresponds to 256 kg of waste per capita per year. If the neighbouring counties are included, the amount of waste generated increases to 190,172 t. In order to determine the potential of separately collected biowaste only kitchen (30.9%) and garden waste (5.7%) are included. The construction of the plant will significantly contribute to the improvement of the current waste management system and the reduction of biodegradable waste disposal. It is expected that the planned biowaste treatment plant could process about 12,948 t of biowaste per year, which corresponds to a plant capacity of 906 kWel. Total electricity production would be 7,251 MWel and 7,976 MWth based on an average of 8,000 operating hours per year.

The application of municipal sewage sludge as fertilizer in the production of non-food energy crops is an environmentally and economically sustainable approach to sewage sludge management. In addition, the application of municipal sewage sludge to energy crops such as Miscanthus x giganteus is an alternative form of recycling nutrients and organic material from waste. Municipal sewage sludge is a potential source of heavy metals in the soil, some of which can be removed by growing energy crops that are also remediation agents. Therefore, the objective of the research was to investigate the effect of municipal sewage sludge applied at three different rates of 1.66, 3.22 and 6.44 t/ha on the production of Miscanthus. Based on the analyses conducted on the biomass of Miscanthus fertilized with sludge from the wastewater treatment plant in three fertilization treatments, it can be concluded that the biomass of Miscanthus is a good feedstock for the process of direct combustion. Moreover, the application of the largest amount of municipal sewage sludge during cultivation had no negative effect on the properties of Miscanthus biomass. Moreover, the cellulose and hemicellulose content of Miscanthus is ideal for the production of second-generation liquid biofuels. Fertilizer treatments had no effect on the content of cellulose and lignin, while a significant statistical difference was found for hemicellulose.

The use of Posidonia oceanica (PO) waste biomass for energy production is under consideration in several countries of the Mediterranean region. The aim of this paper is an evaluation of using PO waste as a biomass source for direct combustion in territorial contexts where the presence of large quantities of beached seagrass is a problem for the tourism-orientated economy such as Istrian peninsula in Croatia. The presence of large PO leaves deposits on the Istrian beaches is responsible for some negative inconveniences, such as the odor released during the natural degradation processes. Other problems are connected with the visible appearance of the beach and negative connotation of PO with pollution of the touristic area. This condition reduces the possibility of touristic competitiveness of the hotels, apartments, bars, and restaurants that are located along the seaside promenade or beaches covered with PO biomass. This paper shows data of PO waste properties as a resource for energy generation which can help to decrease costs of their collection and could improve the quality of life of residents and tourists in the nearby areas. From energy properties, the heating values of fresh and dried onshore biomass samples of PO biomass were within the range of main agricultural and forest biomass and it was around 9–11 MJ/kg ; ash content is very high (16–36%) compared with other types of biomass. Due to the abovementioned data, PO waste carries some inherent limitations to its use as biomass in direct combustion and energy generation, primarily due to high ash content. Furthermore, PO waste can be recognized as a potential fuel for combustion or co- combustion due to its low sulphur (1.15–2.36%) and nitrogen (1.47–2.39%) content but the low carbon content (25–32%) is not a favorable characteristic. It can be concluded that PO waste is a potentially interesting source for energy production.

Growing consumer demand for safe and affordable food as well as the need for a sustainable food supply will force the producers to explore methods for production output increasing. The poultry industry has an important role in the provision of a sustainable food supply, especially because chickens have a high feed conversion efficiency compared to other birds or livestock and, chicken meat is a low greenhouse gas emission food compared to other sources of dietary protein and has accessible source of protein with a low-fat content. The most important aspect of broiler production is feeding, and it represents about 70% of total costs. In order to facilitate the broilers, feed mixture production, it is tending to replace corn component, with a new, cheaper but high-quality component. As an alternative, it is possible to use the old bread, which would enable its remediation. Its use in broiler feeding is possible only after thermal treatment. Following this work will include the possibilities of using 5 and 10% of the old white and brown bread share in broilers feed mixture after thermal processing by extrusion. Feeding with both types of old extruded bread proved to be satisfying and did not affect broilers performance so generally dried bread can be used in chicken feed by as a partial replacement for maize component. Although both breads have proved good feeding quality, slightly better results were obtained in feeding with 10% share of brown bread.

Invasive plant species (IAS), with their numerous negative ecological, health, and economic impacts, represent one of the greatest conservation challenges in the world. Reducing the negative impacts and potentially exploiting the biomass of these plant species can significantly contribute to sustainable management, protect biodiversity, and create a healthy environment. Therefore, the main objective of this study was to evaluate the nutritional potential, phytochemical status, and antioxidant capacity of nine alien invasive plant species: Abutilon theophrasti, Amaranthus retroflexus, Ambrosia artemisiifolia, Datura stramonium, Erigeron annuus, Galinsoga ciliata, Reynoutria japonica, Solidago gigantea, and Sorghum halepense. Multivariate statistical methods such as cluster and PCA were performed to determine possible connections and correlations among selected IAS depending on the phytochemical content. According to the obtained results, R. japonica was notable with the highest content of vitamin C (38.46 mg/100 g FW), while E. annuus (1365.92 mg GAE/100 g FW) showed the highest values of total polyphenolic compounds. A. retroflexus was characterized by the highest content of total chlorophylls (0.26 mg/g) and antioxidant capacity (2221.97 µmol TE/kg). Therefore, it can be concluded that the selected IAS represent nutrient-rich plant material with significant potential for the recovering of bioactive compounds.

Two artificial neural network (ANN) models were developed to predict the main quality parameters of the corn used for ethanol production. Five Croatian corn hybrids were evaluated in this study (introducing the hybrid type as the first input categorical variable for ANN modelling), grown during three vegetation periods (the second categorical variable), under two levels of agrotechnology (the third categorical variable), dried at four temperatures (the fourth input variable), using two different heating and pressure pre-treatments of corn kernels (the fifth variable for ANN calculation) in order to improve the properties of corn for ethanol production. The first model (ANN1) was used to predict the hectolitre weight, 1000-kernels weight, the gelatinisation rate, and the contents of: glucose, reducing sugars and ethanol during the drying process, according to the type of the corn hybrid and the drying temperature. The ANN2 model was developed to predict the corn weight and moisture during the process, based on the input parameters. The artificial neural network models gave a good fit to experimental data and were able to predict the output variables successfully, showing a reasonably good predictive capability (overall r2 for the corn kernel weight and moisture was 0.989, while r2 for other outputs was 0.856). On the basis of a developed ANN models, multi-objective optimization was performed showing the possible practical use in the corn kernel drying process.

The European Union produces over 200 million tonnes of municipal waste each year with 47% being recycled or composted. With the EU reuse and recycling targets set at 55% by 2025 and the introduction of the EU’s Circular Economy Action Plan there has never been more importance placed on waste and recycling education. A three- year transnational project ‘An Erasmus + Waste Education Initiative’ set out to investigate the level of waste and recycling education (WE) that is currently being delivered in five European cities with a view to develop a range of materials to be used in the classroom extracting the best practice from each. This paper highlights the responses from a questionnaire sent to schools and colleges to determine the baseline of WE currently being delivered in Bucharest, Hamburg, Manchester, Tallinn and Zagreb. Factors such as the local waste and recycling infrastructure and population density were also considered to determine the extent of their influence on the type and availability of WE in the classroom. The findings indicate a wide variation in the amount of WE currently being delivered in the five cities. Increased recycling rates and level of infrastructure have an inverse effect on the level of teacher engagement and involvement in waste management projects does not have an impact on the amount of WE that is present in the curriculum or number of registered Eco-Schools. Time constraints due to other curriculum topics, awareness and lack of resources were the main reasons for not including WE in the classroom.

The most important aspect of broiler production is feeding, whose costs represent about 70% of total costs. Thus, the growth of poultry production has been based on a strong consumer demand for products that are cheap, safe, and healthy. That kind of product is old bread, whose return from the store represent a problem for its remediation. For the use of the old bread as a feed, the European Union has promulgated a series of regulations and directives, which order a ban on its utilization without prior treatment. The most common treatments are pelleting and extrusion. In poultry, the upper limit for the use of the old bread in feedstuff is often prescribed and amounts to 15%. The aim of this paper was to determine a possibility to use 5 and 10% old brown pelleted bread in feed mixtures for broilers fattening. The study has shown that the addition of old bread significantly improves broiler production indicators. The best results and a more favorable ratio of omega 6 and omega 3 fatty acids in the chicken muscles were obtained in the group fed with a 10‐percent share of old brown bread (p, Najvažniji aspekt proizvodnje brojlera jest hranidba, čiji troškovi čine oko 70% ukupnih troškova proizvodnje. Tako se rast peradarske proizvodnje temelji na snažnoj potražnji potrošača za proizvodima koji su jeftini, sigurni i zdravi. Takav je proizvod stari kruh, čije vraćanje iz trgovine predstavlja problem sanacije. Za korištenje staroga kruha kao hrane za životinje Europska unija donijela je niz propisa i smjernica kojima se propisuje zabrana korištenja bez prethodne dorade. Najčešći tretmani su peletiranje i ekstruzija. Kod peradi je često propisana gornja granica za uporabu staroga kruha u hrani za životinje, a ona iznosi 15%. Cilj ovoga rada bio je utvrditi mogućnost korištenja 5 i 10% staroga crnog peletiranog kruha u krmnim smjesama za tov brojlera. Istraživanje je pokazalo da dodavanje staroga kruha značajno poboljšava proizvodne pokazatelje brojlera. Najbolji rezultati i povoljniji omjer omega 6 i omega 3 masnih kiselina u pilećem mišiću dobiveni su u skupini koja se hranila s 10% udjela staroga crnog kruha (p

Every year in the EU alone, almost 90 million tonnes of food is lost. The sectors contributing the most to this amount are households, accounting for 53% of total food waste. Bearing in mind the fact those two-thirds of this amount refers to the occurrence of waste which is theoretically avoidable, the greatest attention should be paid to the generation of food waste in households. In Croatia, there is no data on the quantities of food waste produced, but only estimates on the amount of such waste. The aim of this research paper was to determine the type and amount of household food waste and the differences in production of waste relative to the socio-demographic characteristics of household members. The research was carried out by 115 Croatian households, who self-reported the amount of food waste during seven days. According to the results, on average, 2.57 portions of food waste were reported as the amount of discarded food per household member per day, equivalent to 0.21 kg of food waste mass. In general, the typical Croatian household generates 75 kg of food waste per person on average. The age of respondents positively affected the prevention of waste, while the income level and the number of children under the age of 18 in the household had an adverse impact.

Prilikom prerade zrna ječma za potrebe prehrane ljudi, ječmu se skida ljuska te takvo zrno ječma ima smanjenu nutritivnu vrijednost. Kako bi se poboljšala nutritivna svojstva ječma nakon ljuštenja, ono se podvrgnulo termičkom tretmanu uparavanja zbog želatinizacije škroba. Stoga je bilo potrebno provesti istraživanje nutritivnih svojstava oljuštenog zrna ječma prije i poslije metode uparavanja (“cooking” postupak) i sušenja te odrediti utjecaj takve termičke dorade na nutritivni sastav zrna. U radu su obuhvaćene dvije sorte ječma, Bravo i Maxim. Oljuštenim zrnima spomenutih sorti određen je nutritivni sastav tj. kemijska svojstva prema standardnim metodama za određivanje udjela vlage, pepela, ulja, škroba i proteina. Nakon metode uparavanja (“cooking” metode) na tlaku od 0,5 bara i vremenu od 10 ili 15 minuta te sušenja uzoraka na temperaturama od 50 °C, 60 °C i 70 °C također je određen nutritivni sastav svakog uzorka. Istraživanje je pokazalo da metoda uparavanja utječe na promjenu nutritivnog sastava oljuštenog zrna ječma jer je kod svih komponenata nutritivnog sastava došlo do promjena u odnosu na početne uzorke.

In terms of improvement of the existing municipal solid-waste management system in city of Zagreb (Croatia) in a line with legal requirements and its shift towards circular economy, two scenarios were investigated. Life-cycle assessment (LCA) methodology was used to compare the existing municipal solid-waste management system mainly relay on landfilling of waste with expanded system combining mechanical separation of recyclable fractions of mixed municipal waste (MMW), anaerobic digestion of organic fraction, and thermal treatment of residual waste. The waste management-dedicated LCA software EASETECH was used for the assessment of the scenarios in accordance with the EDIP 1997 LCA method. Improved solid-waste management scenario showed superior results in terms of increased recycling rate of valuable materials and overall environmental performance. Because of introduction of convenient mechanical, biological, and thermal treatment technologies, it enables fulfilment of legal obligation concerning waste recycling targets and landfilling of waste.

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.

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.

Aim of study: The utilization of agricultural residues may become one of the major sources for production of energy from biomass. The objective of this paper is to analyse the type and quantity of agricultural residues and to determine their energy potential. Area of study: The area of study is the Međimurje County. The county is situated at the north part of Croatia. Material and methods: The paper analyses three models of sustainable agricultural residues management applying the multi-criteria analysis. The assessment included potentially available quantities of residues in crops, fruit, viniculture and livestock production. For determining the most appropriate model of residues utilisation the multi-criteria analysis was applied. Main results: The results show that total quantities of agricultural biomass amount to 323, 912 t with energy potential of 1, 092 TJ annually. The largest sustainably available potential of agricultural biomass consists of biomass from arable crops production, with total quantity of 33, 670 t followed by 281, 233 t of manure from livestock production. The lowest share of potential biomass are pruning residues in fruit and grapevine production with total available residual quantity of 8, 109 t. Also, it results from the multi-criteria analysis that a central large scale plant for biogas production is the most feasible facility for such production. Research highlights: The results of this paper provide ground for further development of the models for assessing the sustainability of using agricultural residues, and they can also serve as a basis for assessments of bioenergy projects in specific regions of the European Union.

Revitalization of marginal agricultural soils presents one of the main challenges of Croatian agriculture. One of the possible solutions could be the introduction of perennial energy crop Miscanthus x giganteus in intensive agricultural bioenergy production. Miscanthus is characterized by the possibility of the growth in different agro-ecological conditions, low requirements during the growth and high yield production of biomass. The aim of this paper is to determine possibility of the Miscanthus introduction on currently abandoned and marginal agricultural lands in Croatia. There are more than 600, 000 ha of that type of lands, identified as potentially interesting areas for planting various energy crops. Furthermore, it will be determined how much biomass and how many various biofuels can be produced from Miscanthus x giganteus, grown to a 5%, 10% and 15% of the potentially available abandoned land.

The improvement of waste management systems is one of the main challenges for most EU member states, and it should be done in line with current legal obligations set in different EU directives. Implementation of sustainable waste management in Zagreb should be performed through the introduction of source-separation of waste, and its utilization. One of the aspects is usage of biowaste as a feedstock for biomethane production. Produced biomethane could be distributed by dedicated network of filling stations within City area. The main objective of paper is presentation of environmental and economic benefits of proposed approach and citizen’s involvement in separate collection of waste from households. In this sense, a survey has been conducted among residents in order to assess their behaviours regarding the separate collection of waste fractions. The main motivation is the reduction of waste fee, creation of new jobs, stimulation of local economy and biofuel production. This paper presented the fact that paper/cardboard, glass and packaging are most suitable waste fractions for separate collection, while biowaste is most demanding due to odours issue and lack of space. Finally, large majority of the citizens are willing and motivated to participate in the process of waste separation.

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 directives regarding waste management, such as reduction of waste generation and landfilling, or increase of separately collected waste and recycling rates. This article highlights the current waste management in the City of Zagreb by analysing 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 which is far from being adequate, it is necessary to introduce a new system which will take into account the current situation in the city as well as the obligations imposed by European Union. 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/cap of various waste fractions, i.e., far below the average value for the capital cities of the EU (28), which is 108 kg/cap. This is possible to achieve only by better and sustainable planning of future activities and facilities with taking care of environmental, economic and social aspect of waste management. This means that the City of Zagreb will not only have to invest in new infrastructure to meet the targets, but will also 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 non-industrial 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 innovative upgrading of municipal waste management based on the waste management hierarchy and circular economy approach.

EU member states are facing many challenges in order to fulfil different legal obligations linked with the sustainable waste management. The EU legislation related to environmental protection, already implemented in the national legislation of the Republic of Croatia, aims to introduce a system of integrated and sustainable waste management. This puts a focus on material and energy utilization of different waste streams produced in urban areas. Therefore, this requirement represents main challenge for many municipalities, mostly due to various binding targets in waste collection and treatment. Some of them are: reduction of waste generation and disposal, increase of the separately collected waste amounts and recycling rates. Source-separation of biowaste combined with biofuel production is one of the key priorities for many cities, combined with biofuel production in urban areas and its distribution via existing gas grids. The objective of this research is to present environmental benefits of such concept for city of Zagreb. First step is involvement of citizens and assessment of available organic waste. Hence, the conducted analysis has been performed as a survey in order to understand their behaviour and to successfully assess the energy potential of organic fraction from municipal solid waste. The presented research show that 84% of citizens are willing and motivated to participate in biowaste separation. An estimation of energy potential through the anaerobic digestion of organic waste has been presented and calculated to 1,900 t of biomethane based on the analysis which can be utilized through almost 70 CNG busses. This paper proposed concrete solution for the biofuel consumption, and gave an overview of the required land demand for digestate utilization. Also, presented SWOT analysis is giving an overview and confirming the sustainability of proposed concept.

Agricultural solid biomass has been widely recognized as an important source of renewable energy with huge production potential. The utilisation of agricultural solid biomass as feedstock for energy production is continuously growing all over Europe. As shown in the current country’s balance of energy production and consumption, Croatia is highly dependent on imported fossil fuels. The aim of this paper is to determine the available agricultural solid biomass and its energy potential in Croatia. The quantity and energy potential of solid biomass refer to post-harvest residues, pruning residues, agro-industrial solid waste and biomass from Miscanthus energy crop. In relation to potentially available agricultural biomass, three scenarios have been developed (progressive – S1, optimistic - S2, and conservative – S3) of introducing solid biomass in the renewable energy production sector. On the basis of these scenarios, it can be concluded that in Croatia the following quantities of agricultural biomass are available: 3, 050.3 tonnes (S1) ; 1, 441.8 tonnes (S2) ; and 733.68 tonnes (S3). These quantities give energy potential of 51.14 PJ (S1), 24.06 PJ (S2), and 12.18 PJ (S3) respectively.

Although biomass of Miscanthus x giganteus shows a significant potential for production of second-generation biofuels, it is currently mostly used as a combustion fuel. The objective of this paper is to investigate: (I) dry matter yield and yield components; (II) biomass composition; and (III) potential divergences of the investigated parameters from the standard for solid fuels CEN/TS 14961:2005, in relation to two harvest seasons and six fertilizer treatments. The investigation has determined that there is a potential for producing significant quantity of biomass from M x giganteus in the investigated agro-ecological conditions of the mountain areas of Croatia. The laboratory analyses indicated the suitability of using biomass in direct combustion.

Sida hermaphrodita (Virginia fanpetals, Virginia Mellow) pripada porodici sljezovki (Malvaceae) porije- klom iz SAD-a i Kanade. To je ne prehrambeni, celulozni usjev, s brzim rastom i jako razvijenim korijenovim sustavom. Zahvaljujući njenom biokemijskom sastavu (sličnom lucerni), Sida se u zelenoj fazi, može koristiti i kao visoko nutritivna hrana, sa sadržajem proteina i do 30% u vrijeme cvatnje. Sida omogućava i proizvodnju do 120 kg/ha kasnog prinosa meda. Ova jedinstvena vrsta, kada se žanje u suhoj fazi primjenjuje se kao energetska kultura, te se koristi za izolacije i te u celulozno-papirnoj industriji. U zelenom fazi koristi se u različitim industrijama i to farmaceutskoj industriji, industriji stočne hrane, industriji meda te u bioplinskoj industriji. Kao posebno profitabilna vrsta energetske kulture, sirovine budućnosti, već je predodređena da se koristi u industriji biogoriva. Plantaže Side imaju životni vijek najmanje 15-20 godina. Sida dobro raste u mnogim uvjetima na terenu i ne zahtijeva nikakve posebne uvijete tla., Sida Hermaphrodita (Virginia fanpetals, Virginia Mallow) belongs to the Mallow (Malvaceae) family, is a species native to the USA and Canada. It is a non-food, cellulosic crop, with fast growth and strongly developed root system. Thanks of its bio-chemical composition (similar to alfalfa), Sida, in the green stage, can be used as a highly nutritious feed, with a protein content up to 30% During the flowering time, Sida allows to be produced up to 120 kg/ha of late yield honey. This unique species, by harvesting in the dry stage, has applications in the bioenergy, insulation and cellulose-paper industries. In the green stage its use is in the different industries, in pharmaceutical industry, fodder industry, honey industry, bio-gas industry. As a particularly profitable energy species, future feedstock, is already predestined to use it in bio-fuel industry. Sida plantations have a useful lifespan for at least 15-20 years. Sida grows well under many site conditions and does not have any special soil requirements.

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.