Heavy metal contamination of natural rivers and wastewaters is a problem for both the environment and human society. The accumulation and adsorption of heavy metals could happen with several organic and inorganic matters, but the most used adsorbents are (biological and chemical) organic compounds. This review article presents the basics of heavy metal adsorption on several organic surfaces. There are many organic matters, which seem to be useful as agents for heavy metal adsorption. All of the cited authors and articles present the adsorption kinetics by the most used isotherm models (such as Langmuir and Freundlich isotherms). By comparing several research results presented by a pre-selected assortment of papers, we would like to give an overview of the microbiological, organic chemical, and other surface adsorption possibilities. We draw conclusions for two new adsorption fields (adsorption with biosorbent and artificial materials). We present an optional possibility to study adsorption kinetics, efficiency and regeneration methods to successfully conclude the heavy metal treatment process, and we make some recommendations about the efficient water usage calculations using the water allowance coefficient (WAC) indicator.

Food consumption plays a pivotal role in the economy and the health of individuals. Foods and meals, in addition to sustaining life, also have many functions in society, such as human bonding. The purpose of our study is to present a qualitative research method to show the role of food consumption in the culture of several ethnic groups, and to introduce the ways in which cultural factors influence eating habits and local food supply conditions. In the first part of the research, the sample was a mix of multiple nationalities. During our investigations, the main questions were: What do you think about the culture and value food consumption? What kind of food do you consume the most? What differences do you find in the habits of different ethnic groups, especially regarding their eating habits? In the second part, we asked the main actors of the local supply system (restaurants, buffets, shops) about the ways they track the demand of foreign students. Our results have been implemented into two different SWOT matrixes. We can conclude that such research on food consumption attitudes and community behavior is essential. Most of the interviewed students are interested in comparing their diet and cultural traditions to those of other nations’, and prefer local foods. The study proved that eating habits in Hungary have an impact on the eating habits of international students, and they changed them from several perspectives. The study found that dietary choices are complex decisions that have a significant environmental and social impact, but we need to add that thanks to the strong cultural background, the students can keep their sustainable eating and community values abroad, which can also strongly influence the development of the local food supply practices.

Because of the climate change and emerging need for an environmentally sustainable production system, circular economic characteristics have come to the front in many studies. There are many challenges in this shift toward a circular value chain. Still, it is unquestionable that the analysis of consumers’ behaviour is crucial, because without their engagement, circular systems cannot work correctly. This article aimed to explore the circular characteristics of consumers’ attitude towards food purchasing in Hungary. Factor and cluster analyses were applied for market segmentation. The question to be answered was the following: “Are there any segments in the Hungarian food market that can be aimed at by different marketing tools to promote circular systems?” The hypothesis was that well-defined segments can be separated, garnering more engagement in the circular value chain in Hungary. We could separate two clusters, in which the members’ opinions were in line with the circular economic characteristics. Summing up the features of the different clusters, we can state that the members in cluster 1 (“Information-dependent”) and cluster 3 (“Direct purchasers”) were in the most local dimension; their attitude was the most adequate for the circular economic values. The “Information-dependent” consumer in particular was remarkable from the aspect of this investigation. This study showed that highly educated young people, who are very conscious consumers and live on good incomes, may be the target group for circular innovation. These young consumers usually buy organic food, are confident internet and software users, live in cities, and follow a healthy lifestyle. Finding the right marketing tools to integrate these consumers into more sustainable circular systems effectively and to be committed to the concepts of circular consumption is an essential mission in the future. Collecting from different databases and continuously analysing consumer feedback can be a huge step towards in achieving sustainable consumption and avoiding food waste. The significance of this analysis was that we found a defined segment that represents propensity towards accepting circular economy values and can be the target group of policies integrating circular systems.

The current trend of business model research shows an increased endeavour of conceptualizing business frameworks for circular economy (CE). While previous sustainability paradigms have failed to attract market stakeholders, their reaction differ regarding this concept. The reason is discovering that the benefits of former industrial systems have turned to be threats for modern companies. Thus, a circular transition seems beneficial not only in environmental but also in financial dimensions. Closing material and energy flows results in reduced costs and enables businesses to propose novel values to customers. The present study aims to investigate the current stage of circular transformation on a corporate level. In order to do that, it thoroughly analyses the business model evolution of an innovative and knowledge-intensive industry, biotechnology. The research employs a circular evaluation method to detect which parts of the applied business structures show the signs of transition. The findings indicate that the business innovation process in the sector is in line with the disciplines of CE. However, this phenomenon is rather the result of striving for market competitiveness, than making efforts for sustainable development. It proves the emergence of CE to be as much an economic concern as it is an environmental one.

Among the renewable energy sources, increasing the use of biomass (agricultural by-products) could be important from both an environmental and a climate protection perspective, but in many cases this is not a part of the current practice. Especially in developing countries, a large amount of agricultural waste suitable for energy use remains unused, remaining on the arable land or being burned in the field. Complicating matters is the fact that some countries have significant fossil energy reserves. This is also the case in Kosovo, which has the largest reserves of coal reserves (lignite) in southeastern Europe. An important question is how polluting and non-climate-friendly fossil fuels are to be replaced when they are available cheaply and in large quantities. The function of the political and economic models used in Europe has local specificity. It is not possible to copy the good solutions introduced by each country because of differences in the economic systems and farmers. Previous research has paid little attention to the producer conditions for available waste biomass sales. Studies have not examined the sales attitudes of farmers, or under what conditions they are willing to sell a larger proportion of the straw produced—of course, in such a way that they also meet the needs of animal husbandry, nutrients, and carbon supply. Using binary logistics regression and descriptive statistics not yet used in previous research, we analyzed the factors that influence farmers’ willingness to sell, sales barriers, and incentives. According to the respondents, the biggest barriers to selling straw are the lack of a market (74.1%) and baling machines (50.9%), while the main incentives may be a good price (75%) and a guaranteed contract (67.8%). The farmers surveyed believe that, in a safe market, with a multiyear contractual agreement, they would sell more than half of their straw for biomass energy production. The use of straw in animal husbandry is declining due to the introduction of new technological solutions, so the use of straw for energy purposes is an increasingly topical issue in the rapidly developing southeastern European countries as well. Based on our research results, it can be stated that the majority of farmers are willing to sell more than 50% of the amount of straw produced for energy purposes if the business model and state regulations are appropriate.