Search

This work aims to contribute to the discussion of using a waste (sewage sludge) to obtain a valuable product (organic-rich fertilizer), based on a circular economy perspective. The compo- sition of sewage sludge (SS) was considered, highlighting important characteristics as raw ma- terial for fertilizer production (e.g., macronutrients, microbiological contamination, phytotoxicity). Particularly, the biological stability of SS was evaluated measuring the oxygen uptake rate (OUR) using the Oxitop® method, and the phytotoxicity using germination tests. The potential of thermal drying to stabilize the SS was evaluated at two temperatures (100 and 130◦C). The results showed that the organic matter (OM), N, and P levels are within the range of interest for agronomic valorization, while the content of some potentially toxic metals (e.g., Zn and Cu) may exceed the legal limits. The phytotoxicity assessment showed that raw SS samples negatively impacted the germination phase. Concerning the biological stability, results showed that raw anaerobic digested samples were characterized by OUR values above 50 mmol O2/kg OM.h (the limit for stable SS). Although thermal treatment of SS at 100 and 130◦C eliminated pathogens and significantly stabilized SS to OUR values below 50 mmol O2/kg OM.h, it was not enough to reach the limit established for a stable fertilizer (25 mmol O2/kg OM.h). Globally, SS has potential for soil application, within the scope of circular economy, but it is essential to control its microbiological contamination and stability. info:eu-repo/semantics/publishedVersion

Sewage sludge (SS) is a global environmental, social, and economic problem that requires a sustainable management approach. Still, the production of other industrial wastes, such as lime mud (LM), has recently gained considerable attention to avoid landfilling. This work aims to present a new approach for converting SS and LM into value-added products within the circular economy perspective. In particular, the effect of LM and calcined lime mud (CLM) as drying adjuvants and SS sanitation agents are investigated. Two out of three SS samples show Escherichia coli contamination above the Portuguese limit established for soil application, while no Salmonella spp. was detected in the searched samples. The addition of CLM to SS in a ratio between 0.05 and 0.15 g CLM/gwb, lead to complete elimination of the microbiological contamination in almost all cases. Contrarily, the use of LM does not seem efficient to act as a sanitation agent. Both LM and CLM show a positive impact on the drying process when compared to the raw SS, increasing the drying rate, and reducing the drying time. The most favourable drying conditions to maximize the drying rate and minimize the drying time (until 30% of moisture) are 130 °C, 0.15 g adj/gwb, and 2.5 mm of plate thickness. The thermal treatment (100 and 130 °C) without adjuvants reduces the microbiological contamination below the legal limit. Overall, a beneficial effect is observed by adding CLM to SS, open the possibility of producing a safer organic soil improver.

The agro-industry of tomato generates three types of residues: ripe rotten tomato (unfit for consumption) (RT), green (unripe) tomato (GT), and tomato branches including leaves and stems (TB). These materials are commonly wasted or used as feed for livestock. Energy production through anaerobic digestion is an alternative way to manage and simultaneously valorise these materials. Initially, the operating conditions of mono anaerobic digestion were investigated using RT. Thus, a design of experiments based on a two-level fractional factorial design with resolution V was performed to determine the factors that affect biochemical methane potential (BMP). The substrate to inoculum ratio (SIR), total volatile solids concentration (VSt), working volume (WV), presence of nutrients (Nu), and the pre-incubation of the inoculum (Inc) were investigated. The results showed that SIR is the most important factor. The maximum BMP for RT was 297 NmLCH4/gVS with SIR = 0.5, tVS = 20 g/L, WV = 20%, no pre-incubation and the presence of nutrients. Using these optimum operating conditions, co-digestion was investigated through a mixture design approach. The substrates RT and GT presented similar BMP values, whereas TB led to a significantly lower BMP. Indeed, when high concentrations of TB were used, a significant decrease in methane production was observed. Nonetheless, the highest BMP was achieved with a mixture of 63% RT + 20% GT + 17% TB, with a production of 324 NmLCH4/gVS, corresponding to a synergetic co-digestion performance index of about 1.20. In general, although the substrate RT generates the highest BMP, the mixture with GT did not impair the methane yield. Overall, the co-digestion of tomato residues must be conducted with SIR close to 0.5 and the content of tomato branches in the reaction mixture should be kept low (up to 20%).

Phosphorus (P) is a non-renewable resource, irreplaceable for life and food production, and currently considered a Critical Raw Material to the European Union (EU). Due to concerns about the rate of consumption and limited reserves in countries with sensitive geopolitical contexts, it is urgent to recover P from urban and industrial flows. Indeed, the municipal wastewater treatment plants (WWTP) are considered relevant sources with several hot spots, especially sewage sludge with estimated recovery efficiencies of >80%. The most promising recovery strategies are based on thermal treatments (e.g., incineration of sludge) following by wet-chemical or thermochemical leaching, precipitation, and adsorption. The direct application of sludge on soil is no longer a primary route for P reintegration in the value-chain for countries as Switzerland, Germany, and The Netherlands. In fact, Switzerland and Austria paved the way for implementing P recovery legislation, focusing on recovery from raw sewage sludge or ashes. Indeed, industrial technologies with sludge ash as input show high recovery efficiencies (Ashdec® and Leachphos® with 98 and 79%) and lower environmental impacts, whereas Pearl® technology has about 12% recovery efficiency with wastewater as input. After all, struvite emerges as the most recovered product with recent access to the internal market of EU fertilisers and similar growth performance compared to triple-super-phosphate. However, several studies leave open the possibility of introducing loaded adsorbents with P as soil amendments as a new alternative to conventional desorption. Briefly, P recovery should be a compromise between efficiency, environmental impacts, and economic revenues from the final products info:eu-repo/semantics/publishedVersion

Thermal drying allows the reduction of the moisture contained in the sewage sludge (SS) formed in wastewater treatment plants (WWTP) to less than 80%. The management of the dried SS is easier and may have good properties as a soil amendment (carrying organic matter and N, P nutrients). This work aims to select the most appropriate drying adjuvant for application in full-scale and produce a material adequate for agriculture soil applications by applying two multi-criteria decision making (MCDM) methods, the MOORA and TOPSIS. The criteria weights were determined using the CRITIC method. Within the circular economy framework, four industrial wastes were considered as drying adjuvants: weathered coal fly ash (CFA), green liquor dregs (GLD), eggshell (ES), and rice husk (RH). Then, small cylinders of SS were extruded with 0.15 g adjuvant g−1 SSwb and dried at a constant temperature of 70 and 130 °C. Eleven criteria were grouped into three categories (environmental, technical, and economic). Both methods MOORA and TOPSIS showed that the use of GLD at 130 °C is the best option. Moreover, ES at 130 °C and GLD at 70 °C are also good options, and the choice should consider the need for removal of pathogenic contamination. The worst alternatives were CFA and RH at 70 °C according to both MCDM methods. The most influential criteria for decision making were the removal efficiency of pathogenic microorganisms, acid neutralization capacity (ANC) and germination index (GI).

This study aims to investigate the sewage sludge (SS) drying process by incorporating a by-product formed in the pulp and paper industry (green liquor dregs - GLD) as drying adjuvant. Through an innovative approach, the drying kinetics was modelled, and the final dried product was tested for soil applications. After the characterization phase, small cylinders of SS without and with 0.15 g GLD g SS−1wb (SS_GLD) were dried in isothermal conditions at 70, 100, and 130 °C. The experimental data were fitted by Fick's second law and thin-layer models, and good results were achieved in both cases (R2 > 0.98 and RMSE

A crise financeira iniciada no contexto americano há uma década, ocorrida em paralelo com a digitalização da economia e do trabalho, intensificou a precariedade laboral, colocando desafios acrescidos à representação política e coletiva da classe trabalhadora. Na Europa, nomeadamente em Portugal, essas transformações e as políticas de austeridade produziram alterações significativas ao nível das relações industriais, fomentando diversas ações de protesto. A par da ação dos sindicatos, emergiram vários atores coletivos que se situam no espectro dos movimentos sociais em rede, sublinhando a relevância de respostas coletivas no caso dos trabalhadores precários. Com base em pesquisas empíricas que recorreram à observação participante e a entrevistas em profundidade, neste artigo são apresentados dois estudos de caso, um confederal e outro setorial, que confrontam fatores de cooperação e tensão entre sindicatos e organizações emergentes de trabalhadores precários, no quadro do combate à precariedade laboral imposta pela austeridade. O nosso objetivo é identificar, com base nessas clivagens e aproximações, possíveis caminhos para o fortalecimento da identidade coletiva dos trabalhadores dando especial atenção ao segmento dos precários, pela sua importância enquanto parte integrante da força de trabalho, ao mesmo tempo que é enfatizado o papel dos recursos de poder e das novas tecnologias na emergência de respostas inovadoras. The fnancial crisis that brook out in the American context one decade ago, which occurred in parallel with economy and labour digitalization, intensifed labour precariousness, presented further challenges to the political and collective representation of the working class. In Europe, namely in Portugal, those transformations and austerity policies produced signifcant changes on the industrial relations level, fostering several protest actions. Simultaneously to trade unions action, several collective actors that can be placed within the network social movements’ spectrum have emerged, underlining the relevance of collective responses in the precarious workers’ case. Relying on empirical researches that fell back upon participant observation and in-depth interviews technics, in this article two case studies are presented, one confederal and other sectorial, that put in evidence the existence of cooperation and tension elements between trade unions and precarious workers’ emerging organizations in the context of the struggle against labour precariousness imposed by austerity. Our goal is to identify, based on those cleavages and approximations, possible roads for the invigoration of workers’ collective identity paying special attention to precarious segments, given their importance as part of the work force, while emphasizing the role of power resources and new technologies in the emergence of innovative responses. La crise fnancière née en Amérique il y a dix ans, survenue aux côtés de la digitalisation de l’économie et du travail, a intensifé la précarité du travail et posé des défs accrus à la représentation politique et collective de la classe ouvrière. En Europe, notamment au Portugal, ces transformations et les politiques d’austérité ont produit des modifcations signifcatives au niveau des relations de travail, donnant lieu à plusieurs actions de protestation. Parallèlement à l’action syndicale, des acteurs collectifs ont émergé en tant que mouvements sociaux en réseau, soulignant l’importance des réponses collectives concernant le précariat. Partant de recherches empiriques basées sur de l’observation participante et des entretiens en profondeur, cet article présente deux études de cas, l’un confédéral et l’autre sectorielle, qui démontrent l’existence d’éléments de coopération et de tension entre syndicats et organisations émergentes de travailleurs précaires, dans le cadre de la lutte contre la précarité du travail imposée par l’austérité. Il s’agit pour nous d’identifer les chemins possibles de renforcement de l’identité collective des travailleurs précaires, signalant en même temps le rôle des ressources de pouvoir et des nouvelles technologies dans l’émergence de réponses novatrices de la part des structures d’organisation collective et de représentation des travailleurs. La crisis fnanciera iniciada en el contexto estadounidense hace una década, en paralelo con la digitalización de la economía y del trabajo, intensifcó la precariedad laboral, planteando desafíos añadidos a la representación política y colectiva de la clase obrera. En Europa, concretamente en Portugal, esas transformaciones y la política de austeridad generaran alteraciones importantes en las relaciones industriales, fomentando acciones de protesta. Paralelamente a los sindicatos, varios actores colectivos del espectro de los movimientos sociales en red aparecieron, subrayando la signifcación de las respuestas colectivas en el caso de los trabajadores precarios. Teniendo por base investigaciones empíricas que se replegaron sobre técnicas de observación participante y entrevistas en profundidad, son presentados dos estudios de caso que señalan elementos de cooperación y de tensión entre sindicatos y las organizaciones de trabajadores precarios en el contexto de la austeridad. Nuestro objetivo es identifcar, a partir de las fracturas y acercamientos, caminos posibles para el fortalecimiento de la identidad colectiva de los trabajadores prestando especial atención al segmento precario, por su importancia como parte integrante de la fuerza de trabajo, al mismo tiempo que es señalado el papel de los recursos de poder y de las nuevas tecnologías en la emergencia de respuestas innovadoras.

A análise de indicadores estatísticos sobre a justiça tutelar cível aponta para um aumento dos processos de incumprimento e de alteração do exercício das responsabilidades parentais. Neste artigo defende-se que o contexto de crise e as políticas austeritárias contribuem direta e indiretamente para a alteração não só do volume, como do caráter dos conflitos familiares judicializados, aumentando os processos de incumprimento e alteração das responsabilidades parentais relativos a alimentos e os processos de regulação das responsabilidades parentais para aceder a mecanismos de proteção social The analysis of the juvenile justice statistics points to an increase in child custody disputes. In this article it is argued that the crisis' context and the implementation of austerity policies contribute directly and indirectly to the alteration not only of the volume, but also of the nature of the judicialized family conflicts, increasing child custody and child support disputes, namely to access social protection mechanisms L'analyse des indicateurs statistiques sur la justice des mineurs révèle une augmentation des conflits relatifs à la garde des enfants. Dans cet article, on soutien que le contexte de crise et les politiques d'austérité contribuent directe et indirectement à la modification non seulement du volume, mais aussi de la nature des conflits familiaux judiciarisés, en augmentant les litiges relatifs aux pensions alimentaires pour les enfants et la réglementation des responsabilités parentales afin d'accéder aux mécanismes de protection sociale El análisis estadístico de la justicia de menores apunta a un aumento de las disputas de custodia de menores. En este artículo se argumenta que el contexto de crisis y las políticas de austeridadcontribuyendireta e indiretamente a la alteración no sólodelvolumen, sino también de la naturaleza de los conflictos familiares judicializados, aumentando las disputas de prestación de alimentos a favor de los niños y las disputas de custodia para acceder a mecanismos de protección social