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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.

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 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 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.

Uporaba organskog otpada za anaerobnu digestiju ključna je tehnologija za postizanje raznih izazova u Europi i svijetu – recikliranje otpada, održivo gospodarenje otpadom i proizvodnja energije iz obnovljivih izvora.

In the EU around 40% of bio-waste (organic fractions of municipal solid waste including food waste) still goes to landfills. In some Member States this waste is almost completely landfilled. An estimation is that about one-third of Europe`s 2020 targets for renewable energy in transport could be met by using biogas produced from bio-waste (including food waste), and around 2% of the EU`s overall renewable energy target could be met if all bio-waste were turned into energy.Modern and environmentally friendly waste management is still not introduced in many European cities and regions. This problem is tackled by the Bin2Grid project which promotes the “food waste to biomethane” concept in four large European cities in order to serve as flagship examples for other cities.The objective of the Bin2Grid project is to support biomethane production and its use in transport by using segregated food waste from the food and beverage industry, catering sector, and from households(MSW) as feedstock. Focus of the Bin2Grid project is on the development of value chain concepts for four European cities: Zagreb (Croatia), Skopje (Macedonia), Malaga (Spain), and Paris (France). The Bin2Grid project highlights the multiple environmental benefits of source-separate waste collection and conversion of that feedstock into biomethane, in comparison to other treatment methods (landfilling, incineration, MBT, composting). A Benchmark Tool was developed by the project and is presented in this paper., Proceedings of the 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden, pp. 204-209

Effective waste management is heavily dependent on the development of innovative solutions for waste collection and treatment. This is where public procurement comes in: it can act as a key instrument to galvanise the market in order to preserve and recycle material resources. Public procurement of innovation (PPI), particularly, is a way to encourage the development of new, more efficient solutions, but can be hampered by a lack of cross-border coordination, limited access to best practice cases, and limited or no knowledge of close-to-market innovative solutions. The PPI4Waste project, among many other objectives, also gives an overview of the current waste management, and at the same time explores mechanisms to overcome barriers to public procurement of innovation in the waste management sector, where a number of activities are taking place within the project lifetime to help increase uptake of innovative waste solutions. Special focus has been given to the sustainable management of biowaste and plastic waste. In this sense, the PPI4Waste project aims to achieve resource efficiency, sustainable waste management and sustainable consumption throughout Europe by increasing innovative public procurement through networking, capacity building, and dissemination. In particular, the project aims to develop know-how on PPI procedures and make state-of-the-art solutions accessible to other procurers. In turn, this will encourage a quicker market uptake of such solutions and improve the quality and efficiency of services provided by public authorities. In order to achieve this, the common needs within the public sector in Europe have been identified, and presented in this paper, with an intention to move from product purchase towards the service delivery.

The novel device for measuring characteristics of the process that takes place when hydrocarbon liquids are subjected to elevated temperatures is described. The measuring cell has the form of a loop in which circulation is induced by a turbine stirrer. The stirrer contains magnets built into its blades, enabling mixing by a magnetic mixer positioned below the cell. No moving part protrudes from the cell. The fouling process takes place at the hot-wire probe positioned at the centre of the liquid stream. Thermo-graphic images of the cell with circulating liquid are used to establish the type of the flow within the cell. The tests were performed with various types of liquids and versatility of the device demonstrated.

Proizvodnja biometana iz biorazgradivog dijela komunalnog otpada može značajno doprinijeti ciljevima EU na području gospodarenja otpadom, povećanju udjela obnovljivih izvora energije i smanjenju emisija stakleničkih plinova. Proizvedeni biometan je obnovljivi energent pogodan za utiskivanje u distribucijsku mrežu prirodnog plina, za korištenje u prijevozu ili u kogeneracijskoj proizvodnji električne energije i topline. Koncept „Iz otpada do biometana“ je pogodan za primjenu u urbanim sredinama. Hrvatska treba osigurati postupno smanjenje količine biorazgradivog komunalnog otpada koji se odlaže na odlagališta, što je odlična prilika da se izdvojeni biorazgradivi otpad koristi za proizvodnju biometana. U radu su istaknute prednosti primjene koncepta „Iz otpada do biometana“, kako u djelu koji se odnosi na gospodarenje otpadom tako i u djelu koji se odnosi na proizvodnju i uporabu biometana. Temeljem iskustava iz zemalja s razvijenim tržištem biometana, dane su također preporuke za stvaranje potrebnih preduvjeta, kako bi se proizvodnja i uporaba biometana u bliskoj budućnosti implementirala i u Hrvatskoj.

The European Union's environmental 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. Within such a system, it is of utmost importance to have a better estimate of the amount of municipal waste generated, which directly influences future planning in the waste management sector. The aim of this research was to develop and optimize models for the estimation of generated municipal waste by application of methodology using neural network models, and taking into account the socio‐economic impact as well as the inputs regarding the actual waste management trends. In this paper, an artificial neural network models were used to predict the municipal waste generation in Zagreb, Croatia. The standardized socio‐economic and waste management variables were chosen to encompass 2013 to 2016 period. Moreover, the test prediction of the observed data was performed for 2017. Developed models sufficiently predicted the quantities of different municipal waste fractions and in that sense can contribute to better planning of upcoming waste management systems that will be sustainable and in order to meet the European Union commitments.