RESUMEN
The management of municipal solid waste in the Republic of Kazakhstan is still in its infancy. This situation poses a potential threat to the environment and public health and, therefore, it is necessary to introduce improved management schemes in the country. In this study, the life cycle assessment methodology was followed to evaluate the potential environmental benefits of implementing alternative management schemes based on low-waste generation and renewable energy production. The current situation of the capital city Astana was considered as the base case. Environmental results showed that air emissions in terms of landfill gases are the major contributor to climate change impacts, while landfill disposal of the non-recovered fraction of recyclable materials was responsible for the highest impacts in the other categories (especially land use). However, the reuse of recycled materials largely offsets the related environmental burdens, along with energy generation. In comparative terms, it was demonstrated that the proposed waste management scenarios are more environmentally friendly than current practices (S0), mainly owing to the credits associated with the valorisation of renewable energy (S2) and recovered materials (S3). Consequently, the evaluation showed that greater efforts should be made to exploit the energy potential of organic fraction, together with higher recycling rates, to move towards lower environmental impacts associated with municipal solid waste management.
Asunto(s)
Eliminación de Residuos , Administración de Residuos , Ciudades , Kazajstán , Residuos Sólidos , Instalaciones de Eliminación de ResiduosRESUMEN
The application of livestock manure on agricultural land is being restricted due to its significant content of phosphorus (P) and nitrogen (N), leading to eutrophication. At the same time, the growing demand for N and P mineral fertilizers is increasing their production costs and causing the depletion of natural phosphate rock deposits. In the present work, seven technologically feasible treatment schemes for energy (biogas) and nutrient recovery (e.g., struvite precipitation) and/or removal (e.g., partial nitritation/anammox) were evaluated from an environmental perspective. In general, while approaches based solely on energy recovery and use of digestate as fertilizer are commonly limited by community regulations, strategies pursuing the generation of high-quality struvite are not environmentally sound alternatives. In contrast, schemes that include further solid/liquid separation of the digestate improved the environmental profile, and their combination with an additional N-removal stage would lead to the most environmental-friendly framework. However, the preferred scenario was identified to be highly dependent on the particular conditions of each site, integrating environmental, social and economic criteria.
Asunto(s)
Fertilizantes , Estiércol , Nitrógeno , Fósforo , Animales , Ganado , EstruvitaRESUMEN
This study focuses on the assessment of the environmental profile of a milk farm, representative of the dairy sector in Northeast Spain, from a cradle-to-gate perspective. The Life Cycle Assessment (LCA) principles established by ISO standards together with the carbon footprint guidelines proposed by International Dairy Federation (IDF) were followed. The environmental results showed two critical contributing factors: the production of the livestock feed (e.g., alfalfa) and the on-farm emissions from farming activities, with contributions higher than 50% in most impact categories. A comparison with other LCA studies was carried out, which confirmed the consistency of these results with the values reported in the literature for dairy systems from several countries. Additionally, the Water Footprint (WF) values were also estimated according to the Water Footprint Network (WFN) methodology to reveal that feed and fodder production also had a predominant influence on the global WF impacts, with contributions of 99%. Green WF was responsible for remarkable environmental burdens (around 88%) due to the impacts associated with the cultivation stage. Finally, the substitution of alfalfa by other alternative protein sources in animal diets were also proposed and analysed due to its relevance as one of the main contributors of livestock feed.
Asunto(s)
Conservación de los Recursos Naturales/métodos , Industria Lechera/métodos , Abastecimiento de Agua/estadística & datos numéricos , Alimentación Animal , Animales , Huella de Carbono , Ambiente , Leche , EspañaRESUMEN
Biochar is obtained from the thermochemical conversion of biomass in an oxygen-limited environment. Beyond its use for soil amendment and carbon sequestration, other value-added applications, such as a green environmental sorbent for different types of pollutants, are also of increasing interest. This paper reviews the available literature on the use of various feedstocks for biochar production as an initial step to compile the required inventory data from material flow data analysis. The environmental evaluation of different schemes of biochar production in a life cycle perspective reports the environmental impacts of the different alternatives, with more sustainable profiles than the use of activated carbon as conventional adsorption material. Moreover, most systems were validated as negative carbon processes with favorable performance regarding climate change mitigation. In particular, materials based on lignocellulosic waste were responsible for the highest environmental benefits, mainly due to their largest energy potential in comparison with other feedstocks.