Browsing by Issue Date, starting with "2021-03-30"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Lignin extraction from waste pine sawdust using a biomass derived binary solvent systemPublication . Magalhães, Solange; Filipe, Alexandra; Melro, Elodie; Fernandes, Catarina; Vitorino, Carla; Alves, Luís; Romano, Anabela; Rasteiro, Maria G.; Medronho, Bruno; MDPILignocellulosic biomass fractionation is typically performed using methods that are somehow harsh to the environment, such as in the case of kraft pulping. In recent years, the development of new sustainable and environmentally friendly alternatives has grown significantly. Among the developed systems, bio-based solvents emerge as promising alternatives for biomass processing. Therefore, in the present work, the bio-based and renewable chemicals, levulinic acid (LA) and formic acid (FA), were combined to fractionate lignocellulosic waste (i.e., maritime pine sawdust) and isolate lignin. Different parameters, such as LA:FA ratio, temperature, and extraction time, were optimized to boost the yield and purity of extracted lignin. The LA:FA ratio was found to be crucial regarding the superior lignin extraction from the waste biomass. Moreover, the increase in temperature and extraction time enhances the amount of extracted residue but compromises the lignin purity and reduces its molecular weight. The electron microscopy images revealed that biomass samples suffer significant structural and morphological changes, which further suggests the suitability of the newly developed bio-fractionation process. The same was concluded by the FTIR analysis, in which no remaining lignin was detected in the cellulose-rich fraction. Overall, the novel combination of bio-sourced FA and LA has shown to be a very promising system for lignin extraction with high purity from biomass waste, thus contributing to extend the opportunities of lignin manipulation and valorization into novel added-value biomaterials.
- Parcerias público-privadas para a dessalinização e reutilização de água: o caso de TaviraPublication . Carvalho, João Luz Nunes Cantarino de; Matias, António Jorge Peres; Cardoso, Fernando Manuel FélixThe present work focused on the study of Public-Private Partnerships (PPPs), as a way of making seawater desalination and effluent reuse projects viable for public water supply. This work had the aim to understand the advantages of PPPs in comparison with other traditional forms of procurement; to understand what is the best option between the reuse of effluents and the seawater desalination; and to apply the studied concepts and best practices in a project in Tavira. The aim was to make recommendations, guidelines and enumerating potential problems and difficulties. The first part of this work begins with an empirical investigation, where the various subjects related to PPPs are analysed, such as the main advantages and disadvantages, possible models of PPPs, their life cycle, their legal and financial structure, financing models, management and human resources. The next chapter analyses the water sector and the various seawater desalination and effluent reuse techniques, their costs, energy consumption and requirements. Then, the following chapter studies a scenario of a PPP for the application of these two water supply techniques in the municipality of Tavira. The study of this scenario allowed to realize that, at current market prices, a similar project would have to be subsidized by public funds to be viable and that there would be several risks associated with this type of procurement. Although, as long as the partnership framework is well done from the first moment, it may take advantage of private financing and from the private sector's flexibility and initiative to achieve better value for money, thus better serving the citizens of Tavira. However, if the contract does not adequately protect the public interest, the PPP may work as a catalyst for capital outflows in the region, sacrificing companies' diversity and damaging the local business, among other negative aspects. This work also allowed to realize that the reuse of effluents is a considerably cheaper and a more environmentally friendly solution than seawater desalination. Therefore, between the two solutions, water reuse may be the most suitable solution to reduce water scarcity in the region of Tavira.