Potential of duckweed for swine wastewater nutrient removal and biomass valorisation through anaerobic co-digestion

Over the last decades, phytodepuration has been considered an efficient technology to treat wastewaters. The present study reports a bench scale depuration assay of swine wastewater using Lemna minor. The highest observed growth rate obtained in swine wastewater was 3.1 ± 0.3 gDW m−2 day−1 and the highest nitrogen and phosphorus uptake were 140 mg N m−2 day−1 and 3.47 mg P m−2 day−1, respectively. The chemical oxygen demand removal efficiency in the swine wastewater assay was 58.9 ± 2.0%. Furthermore, the biomass valorisation by anaerobic co-digestion with swine wastewater was assessed. Results showed a clear improvement in specific methane production rate (around 40%) when compared to mono-substrate anaerobic digestion. The highest methane specific production, 131.0 ± 0.8 mL CH4 g−1 chemical oxygen demand, was obtained with a mixture containing 100 g of duckweed per liter of pre-treated swine wastewater. The water-nutrients-energy nexus approach showed to be promising for swine waste management.info:eu-repo/semantics/publishedVersio

Contributos das actividades práticas em ciências para a inovação pedagógica e didáctica no ensino das ciências: perspectivas dos professores

Dissertação mest., Biologia e Geologia, Universidade do Algarve, 2007It is the aim of this study to know the perceptions of a group of teachers of the ?3? Ciclo do Ensino B?sico? about the contribution of practical activities in Science for the pedagogic and didactic innovation in teaching this discipline. In order to do so, a group of teachers of those school levels was interviewed. The interview, applied individually to the six subjects who make up the sample, was a semi- structured one. The collected data were the object of a qualitative analysis and the results show that this group of teachers validates the official curriculum of Physical and Natural Sciences for those levels of education, especially in what concerns the compulsory implementation of practical scientific activities, suggesting implementation through scenarios favouring mainly cooperative and constructivist working methods, but also recognizing the importance of the more interactive forms of the delivery mode of teaching . Simultaneously, the subjects recognise the importance of scientific activities as a valuable practice for the process of teaching and learning, not only because of their intrinsic qualities, but also because they give the students the possibility of learning how to learn, of thinking scientifically and developing important attitudes and competences, stimulating students and teacher to become more autonomous and more motivated for practicing action-research. The study also reveals the subjects? perceptions about some of the aspects they think can make the implementation of scientific activities in class easier or more difficult. In the first group of factors, the very nature of science and the scientific attitude of the teacher stand out; the latter factors consist, mainly, of the length of curricula, the poor logistics and the reality of classes at our schools. Finally, there is a discussion of the conclusions of this study, where innovative aspects found in the practice of scientific activities, and consequences of their application, are analysed. The real classroom situation, according to the teachers? perception, is confronted with the ideal situation. Finally, a reflection is made on the meaning of the present study, as well as some suggestions for further investigation

Performance study for membrane fractionation of second cheese whey from sheep

Second ovine cheese whey (SCW) is a by-product resulting from the production of sheep whey cheeses, by thermal aggregation of whey proteins. Its nutritional value is high because it contains about half of the soluble protein that is present in the original whey, free amino acids, small peptides, lactose, oligosaccharides, vitamins and minerals. However, despite high volumes generated (about 18 L of SCW by kg-1 of whey cheese produced), SCW is not recovered, causing problems in water treatment plants due to its high biological oxygen demand (BOD5) and chemical oxygen demand (COD), about 10,200 mg O2 L-1 and 69,500 mg O2 L-1, respectively. In order to valorize this by-product, the performance of a sequence of membrane processes, namely wide ultrafiltration (UF1), tight ultrafiltration (UF2) and nanofiltration (NF) was evaluated. In our previous work, we selected a wide ultrafiltration membrane of cellulose regenerated acetate, RC70PP with a nominal cut-off (MWCO) of 10 kDa) and hydrophilic characteristics, for recovering protein fraction. In this work, the membrane was used to concentrate SCW till a volume concentration factor (VCF) of 3.0. The permeates were then subjected to a second UF with a tight UF membrane (MWCO of 1 kDa), ETNA01PP, till a VCF of about 2.5. ETNA01PP is a surface-modified poli(vinylidene fluoride (PVDF) membrane, with hydrophilic characteristics. Nanofiltration of permeates of the second UF was performed using a membrane made of polypiperazine amide, NF99, till a VCF of 2.5. In all experiments, the membrane area used was 0.072 m2. Both ultrafiltration processes were carried out at a transmembrane pressure of 2.0 bar, whereas nanofiltration was realized at a transmembrane pressure of 20.0 bar. The feed flow rate was kept at 0.92 m s-1, in all experiments. Results showed that during UF1 and UF2, permeate fluxes decreased about 22%, while in NF experiments a sharp decrease occurred (about 50%), till the VCF studied (Fig.1), perhaps due to scaling on the membrane. Please click Additional Files below to see the full abstract

Enhancement of sewage sludge bioconversion to methane by addition of exhausted coffea biowaste liquid fraction

Original PaperAnaerobic co-digestion of organic rich wastes and wastewater sludge has become an attractive economic possibility for water utilities as it enhances biogas production. The suitability of the organic rich waste depends on its biodegradability as well as on its synergetic effect on the anaerobic digestion process. The feasibility of sewage sludge (SS) treatment via co-digestion was studied in a semi-continuous mode at mesophilic conditions (36 ± 1 °C), with a hydraulic retention time of 17 days and an average organic loading rate of 0.94 ± 0.05 gVS Lreactor day− 1, using the liquid fraction of pre-treated exhausted coffee biowaste (LECB) as a co-substrate. An anaerobic co-digestion trial (T1) was performed using as feeding mixture 80% SS and 20% LECB (v:v) and compared against a reference scenario of mono-digestion of SS (T0). The stability along assays was ensured by monitoring the digestate characteristics (pH, electrical conductivity, total alkalinity and ammonia content) and the specific energy-loading rate (SELR). Along the operation time of T1, methane yield and VS removal were significantly higher in comparison to mono-digestion of SS. Results showed that the addition of the co-substrate had a positive effect on specific methane production (3 times higher) and methane content (12% higher), indicating this is a feasible strategy towards self-sufficient wastewater treatment plantsinfo:eu-repo/semantics/publishedVersio

Integrated renewable energy systems in fruit and vegetable processing industries: a systematic review

Review ArticleThe exponential population growth will put great pressure on natural resources, agriculture, energy systems and waste production. New business models and innovative technological approaches are necessary to tackle these challenges and achieve the energy transition targets set by the European Commission. Renewable energy technologies and processes such as solar photovoltaic, solar thermal and anaerobic co-digestion have become a subject of interest and research as a solution that could be fully implemented in industries and solve several environmental and economic problems. This paper discusses the possibility of integrating and complement these technologies to maximize renewable energy production and circularity. The review was performed with a funnel approach aiming to analyze broad to specific subjects. Beginning with a literature review on the various definitions of circular economy, bioeconomy, and circular bioeconomy, ultimately proposing a single definition according to an industrial and academic scope combination, followed by a systematization and assessment of data and literature regarding energy systems present state and projections. The next phase was to assess data and literature of the fruit and vegetable processing industry from an energy consumption and biowaste production perspective to consequently discussing technologies that could help manage problems identified throughout this review. This paper culminates in propounding an Integrated Renewable Energy System conceptual model that promotes energy and waste circularity, envisioning how industries could be designed or redesigned in the future, coupled with a circular bioeconomy business modelinfo:eu-repo/semantics/publishedVersio

Nexus água-nutrientes-energia: uma abordagem integrada no tratamento de efluentes suinícolas

A preocupação com os impactes ambientais associados a explorações pecuárias de produção intensiva tem vindo a aumentar nos últimos anos. Em especial, a elevada concentração de azoto e fósforo dos efluentes suinícolas poderá induzir a poluição dos cursos de água, se a sua gestão não for adequada. Com a crescente procura por energias alternativas às fósseis, novas perspetivas têm sido aplicadas à gestão dos efluentes suinícolas, onde para além do tratamento e redução da carga contaminante dos efluentes, se dá importância à sua valorização. Neste trabalho, estudou-se a depuração dos efluentes suinícolas por Lemna minor e a valorização energética da biomassa produzida por co-digestão anaeróbia. Foram realizados ensaios experimentais comparativos do crescimento da Lemna minor em meio artificial sintético e em efluente suinícola simulando as condições da última lagoa de uma suinicultura. A eficiência de remoção de CQO nos ensaios de depuração foi de 60,0 ±1,0 %. A maior taxa de crescimento observada em efluente suinícola foi de 28,7 ± 2,3 g m-2 dia-1 e as taxas de absorção de nutrientes obtidas foram de 140 mg N m-2 dia-1 e de 3,5 mg P m-2 dia-1. A avaliação do potencial de valorização energética da biomassa foi considerado em ensaios de co-digestão anaeróbia, comparando os ensaios de digestão anaeróbia utilizando efluente suinícola como mono-substrato e a co-digestão, utilizando Lemna minor como co-substrato. Os resultados obtidos evidenciaram o aumento na taxa de produção de biogás e da produção específica de metano em 40% e 44%, respetivamente. Esta abordagem integrada baseada no nexus-água-nutrientes-energia revelou-se promissora para a gestão de efluentes suinícolas. Novos estudos deverão explorar os benefícios combinados e potenciais vantagens e desvantagens destas tecnologias em diferentes escalas.info:eu-repo/semantics/publishedVersio

Enhancing Bioenergy Recovery from Agro-food Biowastes as a Strategy to Promote Circular Bioeconomy

Agro-food industries produce large amounts of wastes challenging innovative and efficient valorisation strategies promoting the circular bioeconomy concept. Anaerobic digestion technology is an interesting route for bioenergy recovery in the agro-food chain sector. In this work, a simple approach is proposed for assessing energy performance of livestock manure and mixed sewage sludge, as substrate by coupling the potential addition of several agro-food biowastes (co-substrate: fruit and vegetable biowastes, fish canning industry, other manures, coffee wastes, and non-edible crops). The results obtained showed an increase of energy performance indicator ranging from 30 to 250% and 62 to 539%, for livestock manure and mixed sewage sludge, respectively. This conceptual approach for feedstocks promotes the circular bioeconomy as it encourages the stakeholders to a smart use of anaerobic biotechnology at rural-level or urban-levelinfo:eu-repo/semantics/submittedVersio

Bioconversion of Jatropha curcas seed cake to hydrogen by a strain of Enterobacter aerogenes

Hydrogen (H2) gas is considered the future energy carrier as a clean fuel. Biological processes to produce hydrogen are very attractive due to less energy expenditures and the possibility to use organic wastes as substrate. In this work, Jatropha curcas L. seed cake (JSC), a solid residue remaining after oil extraction from J. curcas seeds for biodiesel production, was used as substrate in a dark fermentation process by a pure strain of the bacteria Enterobacter aerogenes. Batch assays were performed using the substrate (2.5 gVolatile Solid/LFermentation Medium) submitted to thermal pretreatment in an autoclave for two different exposure times (15 and 30 min) and the results were compared with the ones obtained when the JSC was used without pretreatment. The best specific biohydrogen production (68.2 mL H2/gVSiJSC) was attained for the conditions of no substrate pretreatment, which is an advantage from the view point of energy saving. In the best conditions, the increase of the initial JSC concentration from 2.5 to 10 gVS/LFM led to the increase of the cumulative hydrogen production and to higher bioH2 production rates. However a decrease on the specific H2 production from 68.2 to 23.5 mL H2/gVSiJSC was observed

Recombinant proteins in differentiation of stem cells

Dissertação de Mestrado, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2016A utilização de cardiomiócitos derivados de células estaminais embrionárias (ESC) permite-nos acesso a um grande número de células para investigação biomédica e uso de fármacos ou ensaios toxicológicos. Apesar de ser possível aumentar a eficiência de diferenciação através de manipulação genética sobre expressando fatores cardíacos específicos, os protocolos atuais são bastante morosos, têm baixo rendimento e são dificilmente reprodutíveis. A transdução proteica é um método alternativo para aumentar a eficácia de diferenciação de células estaminais embrionárias em cardiomiócitos. O objetivo consistiu na construção de uma proteína quimérica com a capacidade intrínseca de transdução celular. Produzimos e purificámos esta proteína recombinante, com a capacidade de atravessar a membrana celular, sendo composta por dois domínios: a proteína humana CITED2, ligada através do domínio terminal-N a um Domínio de Transdução Proteica (PTD), rico em argininas, que confere a capacidade de transduzir proteínas biologicamente ativas e entregá-las no interior da célula. Com este trabalho, conseguimos demonstrar que esta proteína recombinante CITED2, quando adicionada ao meio de cultura celular, atravessa a membrana celular, alcança o núcleo, e é funcional. Em células embrionárias de ratinho (mESC), o knockout do gene Cited2 leva à diferenciação destas células em cardiomiócitos. A suplementação com a proteína recombinante CITED2, no segundo dia de diferenciação, no meio de cultura em que as células tinham sofrido a depleção de Cited2, tem a capacidade de compensar os defeitos na diferenciação cardíaca. Por outro lado, se o meio de cultura for suplementado na fase inicial de diferenciação (dia 0), enquanto as células ainda se encontram num estado de pluripotência, sugere um atraso no processo de diferenciação geral. Apesar de serem necessários estudos mais aprofundados, a aplicação direta da proteína desenvolvida parece ter a capacidade de substituição dos efeitos causados pela proteína endógena, sugerindo assim que a proteína CITED2 desempenha um papel importante tanto em cardiogénese como em pluripotência

Challenges for modern wine production in dry areas: dedicated indicators to preview wastewater flows

Wine production is an important socio-economic activity in Mediterranean countries. This study is focused on wine production under warm and dry climate conditions in south Portugal, in two major wine-producing regions (Tejo and Alentejo), characterized by small to medium sized wineries. Vineyards have been expanding in this region of Portugal, where about 50–70% of the vineyards are irrigated, increasing regional water demand. The aim of this study is to propose an integrative approach for wine production, where a simple calculation model has been developed and validated to preview water consumption and wastewater production, as functions of winemaking periods and type of processed grapes. Results revealed a global ratio of 2.2 ±0.45 and 2.1 ±0.17 Lwater/Lwine. Concerning dedicated indicators, 60–75% of the wastewater was produced during Period I and the red wine production represented a 50–64% increase in water consumption. This tool will enable winemakers to calculate Global and Dedicated Indicators, based on their own parameters, which provide information on flow volumes and peak flows. In this context, it will be possible to identify improvements for wastewater treatment and management towards water reuse as a promising solution for the wine sector in the framework of the circular economyinfo:eu-repo/semantics/publishedVersio