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

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)

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

Microbial syngas conversion by mesophilic and thermophilic anaerobic mixed-cultures

Synthesis gas (or syngas) can be produced from the gasification of a variety of recalcitrant or biodegradable wastes. Syngas is a mixture composed of mainly H2, CO and CO2 that can be used in a biological process for the production of fuels or usable chemicals. The main goal of this work was to study the physiology and microbial composition of anaerobic cultures able to utilize syngas. The results indicated that the thermophilic sludge inoculum presents a promising carboxydotrophic potential comparing to the mesophilic sludge inoculum. Monitoring of microbial structure of thermophilic enriched cultures by using PCR-DGGE and cloning techniques showed that bacterial community profiles clustered in three different groups

Biological fermentation of syngas

Este resumo faz parte de: Book of abstracts of the Meeting of the Institute for Biotechnology and Bioengineering, 2, Braga, Portugal, 2010. A versão completa do livro de atas está disponível em: http://hdl.handle.net/1822/1096

Continuous high rate anaerobic treatment of oleic acid based wastewater is possible after a step feeding start-up

Mineralization of a synthetic effluent containing 50% COD as oleic acid was achieved in a continuous anaerobic reactor at organic loading rates up to 21 kg COD m−3 day−1, HRT of 9 h, attaining 99% of COD removal efficiency and a methane yield higher than 70%. A maximum specific methane production rate of 1170 ± 170 mg COD-CH4 g VS−1 day−1 was measured during the reactor’s operation. A start-up strategy combining feeding phases and batch degradation phases was applied to promote the development of an anaerobic community efficient for long chain fatty acids (LCFA) mineralization. Through the start-up period, the methane yield increased gradually from 67% to 91%, and LCFA accumulated onto the sludge only during the first 60 days of operation. For the first time, it is demonstrated that a step feeding start-up is required to produce a specialized and efficient anaerobic community for continuous high rate anaerobic treatment of LCFA-rich wastewater.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/CTA/46328/2002, PTDC/BIO/69745/ 2006, SFRH/24256/2005European Commission (EC) - LIFE03 ENV/P/00050

Apple juice reverse the oxidative effect of vanadium pentoxide in Saccharomyces cerevisiae

The Malus domestica, Borkh, tients for over 2500 years, was domesticated and expanded in Europe by the Greeks and Romans. Due to their high adaptability to different climates and soils, the apple orchards were quickly installed throughout the world, from countries with relatively cool to subtropical climates. In Portugal, Romans have carried out their introduction and later by religious influence led to the spread of different varieties. The region of Beira Alta, Portugal, with its diversity of microclimates, of harsh winters and hot summers with high brightness, distinguished himself early as a conducive area to apple growing, being denominated IPG ( Protect geographical region) for the Golden Delicious variety. In the literature phenolic compounds of apples are described as potential inhibitors of oxidative processes, involving reactive oxygen species (ROS), implicated in chronic disorders such as cancer and cardiovascular disease. The main objective of this study was to evaluate the role of Golden Delicious apple juice in cell proliferation of yeast S. cerevisiae UE-ME3, and stress molecular markers, in the presence of a well-know oxidant, vanadium pentoxide

Caracterização nutritiva, antioxidante e de conservação da variedade tradicional de maçã Bravo de Esmolfe da Beira Alta

A capacidade antioxidante da variedade Bravo de Esmolfe medida pelo DPPH e pelo FRAP manteve-se estável ao longo do período de conservação de 83 dias, a 4 ºC (p <0,05). Por outro lado esta variedade exibiu propriedades de conservação promissoras, tendo em conta o nível baixo e tardio da actividade PPO detectada. O aumento do teor em glúcidos redutores e em fenóis ao longo do período de conservação de 83 dias, com um máximo no segundo caso aos 55 dias, seguido pelo máximo de actividade POD, sugere a ocorrência de um aumento da formação de peróxidos ao longo do tempo, acompanhado pela concentração de glúcidos redutores (p <0,05)

Bioelectrochemical systems (BESs) towards conversion of carbon monoxide/syngas: A mini-review

Microbial conversion of carbon monoxide (CO)/syngas has been extensively investigated. The microbial conversion of CO/syngas offers numerous advantages over chemically catalyzed processes e.g. the specificity of the biocatalysts, the operation at ambient conditions and high conversion efficiencies. Bioelectrochemical systems (BESs) exploit the capacity of electrochemically active bacteria (EAB) to use insoluble electron acceptors or donors to produce electricity or added-value compounds. Electricity production from different organic sources in BESs has been broadly demonstrated, whereas electricity production from CO/syngas has been very little reported. Acetate oxidation by a consortium of carboxydotrophic and CO-tolerant EAB has been suggested to be the main pathway responsible for indirect electricity generation from CO/syngas. Although electricity production in BESs from several organic sources has been widely investigated, the interest on BESs research is currently moving to the production of added-value compounds by electro-fermentation (EF) processes. EF allows to modify redox balances by the use of electric circuits to fine tune metabolic pathways towards obtaining products with high economic value. Although EF has been widely studied, the potential of use CO-rich gas streams as substrate has been under explored. This review presents and discusses current advances on microbial conversion of CO/syngas in BESs.This study was supported by the Portuguese Foundation for Science and Technology (FCT), within the scope of the project “INNOVsyn - Innovative strategies for syngas fermentation” (POCI-01-0145-FEDER- 033177). This study was also supported by the FCT under the scope of the strategic funding of UIDB/04469/2020 unit and BioTecNorte oper-ation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio