Operação sequencial de um sistema batch para biosorção e mineralização anaeróbia de efluentes de lacticínios

Um efluente lácteo real enriquecido em gordura foi mineralizado a metano num processo em reactor fechado. Realizaram-se três ciclos de adição/degradação, tendo-se monitorizado em cada ciclo a CQO solúvel, os AGV e a produção de metano em diferentes intervalos de tempo. O consórcio anaeróbio tinha sido previamente aclimatado a ácido oleico. A eficiência de remoção da CQO solúvel aumentou ao longo da operação, os AGV totais diminuíram sucessivamente e a produção cumulativa de metano aumentou significativamente do primeiro para o terceiro ciclo. Estes resultados vêm confirmar que a chave para a degradação de efluentes com elevado conteúdo em lípidos reside na sequenciação das fases de acumulação na biomassa e degradação

Biosorption and mineralization of a dairy wastewater under sequential operation mode

This work aimed to apply a sequential batch operation mode to promote the biomethanation of a real dairy wastewater enriched in fat. Three cycles were conducted with biomass previously acclimated to oleic acid. Soluble COD, VFA and methane content were analyzed in each cycle at different time intervals. The soluble COD removal efficiency improved slightly in each new feed and the total VFA levels detected decreased successively. The maximum cumulative methane production also improved from cycle 1 to cycle 3. These results contribute to support the idea that the key for the degradation of effluents with high lipid content is to sequence adsorption and degradation steps during the treatment process

The association between fungi exposure and hypersensitivity pneumonitis: a systematic review

A systematic review of published studies focused on the association between hypersensitivity pneumonitis (HP) and fungi exposure was conducted on PubMed, following PRISMA guidelines for systematic reviews. A total of 14 studies met the inclusion criteria but only 6 of these studies were eligible, as the remaining 8 represented case reports that were separately included for further discussion. HP is an interstitial lung disease (ILD) characterized by a hypersensitization response to inhalable antigens and represents 1.5% to 12% of all ILD in the European population. Several fungi species that populate the indoor environment have been associated with the incidence of HP upon cumulative exposure, with Penicillium spp and Aspergillus spp being the fungi species most frequently associated with the onset of disease. Although some studies have shown that avoiding exposure to causative HP fungi tends to improve patients’ symptoms, other studies were unable to identify the source of sensitization. More microbial exposure studies are needed to properly estimate the risk of HP development in the built environment.This study has been performed in the framework of the EXALAR 21 project, which was funded by the European Regional Development Fund (FEDER), through the Competitiveness and Internationalization Operational Program, and by national funding from the Foundation for Science and Technology (FCT) under the reference info:eu-repo/grantAgreement/FCT/9471 - RIDTI/PTDC/GES-AMB/30193/2017/PT (POCI-01-0145-FEDER-030193, 02/SAICT/2017—Project n° 30193)

Estudo da sinistralidade laboral em meio hospitalar - Aspeto fundamental para a integração da segurança no trabalho na gestão de unidades de saúde

O tipo de atividade profissional e as condições em que é desempenhada constituem fatores determinantes do risco para a saúde dos trabalhadores. Os últimos estudos realizados sobre acidentes de trabalho nas instituições de saúde revelam um aumento da incidência dos acidentes de trabalho com o consequente aumento do absentismo laboral e dos encargos financeiros inerentes.Realizamos um estudo descritivo-correlacional, retrospetivo, compreendendo um período de análise de quatro anos, utilizando os dados do serviço de saúde ocupacional, relatórios anuais e balanços sociais de cada ano em estudo. Os resultados revelaram um aumento progressivo do índice de frequência e do índice de gravidade dos acidentes de trabalho. O maior número de acidentes ocorreu nos enfermeiros, a trabalhar por turnos. A lesão mais declarada é a picada e as mãos o local mais atingido, no entanto são os esforços excessivos e a cervicalgia/lombalgia que produzem uma maior incapacidade para o trabalho com o consequente aumento dos dias de absentismo. Constatamos que o tempo em dias perdido vai gradualmente aumentando ao longo dos 4 anos, assim como as implicações financeiras. Os gestores de topo devem tomar medidas no sentido de garantir uma melhor qualidade de vida dos profissionais, contribuindo para uma melhoria da qualidade da prestação de serviços nas unidades de saúde, preservando os recursos humanos e proporcionando dotações seguras de técnicos de saúde/utente

Fed-batch anaerobic degradation of long chain fatty acids

Efficient mineralization of effluents with high lipid content is possible in anaerobic digesters when a sequential operation mode is applied, favoring the adsorption of LCFA onto the sludge and then allowing the adsorbed substrate to be biodegraded1-3. The study of adsorption along time can help to optimize the process. Five batch assays were conducted in 160mL vials inoculated with flocculent biomass and fed with sodium oleate (1g CQO/gVSS). Feeding was applied during 10min (0.8ml/min), after which (t=0) a vial was immediately sacrificed and analyzed for soluble COD, VSS and biomass-associated LCFA. After 0.5, 1, 24 and 1000 hours of incubation at 37±1°C, 150rpm, one vial was sacrificed and analyzed for the parameters stated before. Two additional vials prepared and fed in a similar way and two blank controls (without substrate) were incubated in the same conditions to follow cumulative methane production. At the end of the feeding period, soluble COD removal efficiency was 73%, corresponding exclusively to LCFA accumulation onto the sludge. During the first 24 hours, methane or VFA production were negligible probably due to residual substrate degradation. Palmitic acid accounted for 46 to 54% of the biomass-associated LCFA and oleic acid for 31 to 40%. After 1000 hours of incubation soluble COD removal was 86% and palmitic acid accounted for 100% of the biomass-associated LCFA (45mg COD-LCFA/g VSS)

Development of a novel reactor for high-rate anaerobic treatment of LCFA containing wastewater

treatment. More than 2,000 full-scale installations are running worldwide (Van Lier, 2007) and mainly treat wastewaters containing readily degradable organic pollutants such as volatile fatty acids and carbohydrates. Lipids do not belong to this group, since their hydrolysis results in the production of long chain fatty acids (LCFA). Until recently these were considered toxic to anaerobic bacteria and a nuisance because they induce floatation of biomass (Hwu, 1997). Since the success of conventional anaerobic treatment systems is based on optimisation of biomass sedimentation, floatation leads to washout and subsequent process disruption. Therefore, lipids are normally removed from wastewater prior to anaerobic treatment using e.g. dissolved air floatation. Pereira et al. (2002) showed that lipids are not toxic and can be converted to biogas. As to prevent washout induced by LCFA adsorption, a sequential process including at least a feeding and reaction phase was proposed as the preferred technology for anaerobic LCFA removal from wastewater (Pereira et al., 2005). It was further postulated that the specific contact area between bacteria and LCFA should be maximised as to maximise LCFA adsorption and minimise mass transfer limitations. The sequential process was applied at la

Efficient methane production from lipid-rich wastewater in high-rate anaerobic treatment

In this work, high rate anaerobic mineralization of a synthetic dairy effluent containing 50% COD as oleic acid was accomplished in two reactors operated in parallel. The anaerobic reactors were able to accommodate organic loading rates up to 21 kg COD m-3 day-1, HRT of 9 hours, attaining 99% of soluble COD removal efficiency and methane yield higher than 70%. Long chain fatty acids (LCFA) accumulated inside the reactor only during the last two phases of operation and palmitic acid was the main LCFA quantified, representing 40–100% of the total LCFA detected. High specific methanogenic activity was determined at the end of the operation, in the presence of acetate (1346±87 mg COD-CH4 gVS-1 day-1) and H2/CO2 (3582±309 mg COD-CH4 gVS-1 day-1). The specific activity of the anaerobic consortia present in the reactors during the operation was also determined, and a maximum value of 1170±170 mg COD-CH4 gVS-1 day-1 was obtained. The high performance accomplished in the reactors was a consequence of the discontinuous acclimation strategy applied, that produced an anaerobic microbial community specialized in the efficient mineralization of LCFA.Fundação para a Ciência e Tecnologia (FCT) projecto FAT-METHANE (POCTI/CTA/46328/2002), bolsa de doutoramento SFRH/BD/24256/200

Enhancement of methane production from long chain fatty acid based effluents

Two anaerobic sludges previously loaded with oleate and palmitate accumulated 4570 ± 257 and 5200 ± 9 mgCOD-LCFA gVSS−1, respectively. These sludges were incubated in batch assays and methane production was recorded after addition of 100–900 mg L−1 of oleate and palmitate, respectively. The batch assays were conducted before and after allowing the depletion of the biomass-associated LCFA. The presence of biomass-associated LCFA decreased the capacity of both sludges to convert the added LCFA to methane. After the degradation of biomass-associated LCFA, the lag phases observed before the onset of methane production were significantly reduced, evidencing an increase in the tolerance of the acetotrophic methanogens to the presence of LCFA. In another experiment, three recurrent pulses were performed with a real dairy wastewater containing 3.6 gCOD L−1, from which 53% was fat. Methane yields of 0.45 ± 0.01, 0.88 ± 0.02 and 1.29 ± 0.08 gCOD- CH4 gCODfed-1 were achieved in the first, second and third pulses, respectively, evidencing an increasing capacity of the sludge to convert substrate accumulated in previous additions.Fundo Social Europeu (FSE)Fundação para a Ciência e a Tecnologia (FC

LCFA accumulation and biodegradation during anaerobic discontinuous treatment of an oleate-rich wastewater

The dynamics of medium and long-chain fatty acids (LCFA) accumulation and biodegradation was studied during the anaerobic treatment of an oleate-rich wastewater. This treatment was made in an upflow sludge bed reactor operated in cycles during 213 days. Five cycles were performed, each one with a feeding phase in continuous and a reaction phase in batch. Saturated and unsaturated fatty acids from C6 to C18 were extracted and analyzed by gas chromatography on biomass samples collected at different key moments of the reactor operation. These biomass samples were also incubated in batch assays and methane production from the accumulated substrate was followed. LCFA accumulated onto the sludge during the first two cycles, reaching a maximum value of 1.7 gCOD-LCFA.gVSˉ¹. Palmitate and stearate were the dominant intermediates quantified, approximately in equal quantities. On the subsequent cycles only residual amounts of LCFA were detected. Methane production on batch assays was higher than expected from the LCFA accumulated, suggesting that other substrates could also be entrapped with the sludge. The results show that during the first two cycles a specialized microbial consortium developed, able to treat oleate-rich wastewaters.European Commission - LIFE03 ENV/P/000501.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/CTA/46328/2002

Discontinuous operation promotes efficient continuous anaerobic treatment of effluents with high lipid content

A mixture of skim milk and sodium oleate was fed to an upflow sludge bed reactor operated in cycles. Each cycle had a feeding phase under continuous operation and a reaction phase in batch. Five cycles were performed with organic loading rates applied during feeding phases varying between 4.4 and 8 kg COD.mˉ³.dˉ¹ and a constant hydraulic retention time of 1.6 days. In the first two cycles, 70% of the methane-COD was produced in the reaction batch phase, whereas from the third to the fifth cycles, biogas production in the reaction phase was less than 3% of total production. Overall methane yields increased steadily, from 0.67 to 0.91 kg COD-CH4.kg COD removedˉ¹. LCFA accumulated into the sludge in the first two cycles, being palmitate and stearate the dominant intermediates quantified. In the subsequent cycles no LCFA were detected in the solid or liquid phases. The specific methanogenic activity in the presence of acetate and H2/CO2 increased significantly along the operation, particularly between time zero and the end of the third cycle. These results show that a discontinuous operation promoted the development of an active anaerobic community able to efficiently convert a continuous organic load of 8.2 kg COD.mˉ³.dˉ¹, from which 50% was oleate.European Commission - LIFE03 ENV/P/000501.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/CTA/46328/2002