14 documents found, page 1 of 2
Monitoring the stability of aerobic granular sludge under increasing fractions ...
Silva, Sérgio Alves; Duarte, Maria Salomé Lira; Amaral, A. Luís; Ferreira, Eugénio C.; Alves, M. M.; Mesquita, D. P.This work investigates the effects of increasing fraction of slowly biodegradable chemical oxygen demand (sbCOD) on the morphology, stability, and performance of aerobic granular sludge (AGS) used for wastewater treatment. A sequencing batch reactor (SBR) was supplied with synthetic wastewater containing acetate as readily biodegradable COD (rbCOD) and increasing concentrations of oleate as slowly biodegradable...
The effect of oleate in the biological nitrogen removal
Silva, Sérgio Alves; Duarte, Maria Salomé Lira; Amaral, A. L.; Ferreira, Eugénio C.; Lucas, M. S.; Alves, M. M.; Mesquita, D. P.Lipids can make up to 40% of the chemical oxygen demand (COD) in wastewaters and can easily be converted into long-chain fatty acids (LCFA), which can induce negative effects on biological wastewater treatment, such as inhibition and sludge flotation. The concentration of LCFAs in domestic wastewaters is typically low (around 100 mg L-1) and oleate (oleic acid; C18:1) is the most commonly found unsaturated LCFA...
Assessing the influence of long-chain fatty acids on aerobic granular sludge st...
Silva, Sérgio Alves; Duarte, Maria Salomé; Amaral, A. Luís; Ferreira, Eugénio C.; Alves, M. M.; Mesquita, D. P.The presence of long-chain fatty acids (LCFA) in biological wastewater treatment systems can cause various operational issues. This study evaluated the effect of LCFA, at typical concentrations found in domestic wastewater, on the performance and stability of aerobic granular sludge (AGS) in a sequencing batch reactor. At an oleate concentration of 61 ± 2 mg L-1, oleate started to accumulate in the reactor, res...
Modelling anaerobic digestion of sewage sludge: mechanistic models vs machine l...
Duarte, Maria Salomé Lira; Martins, Gilberto; Oliveira, João Vítor; Oliveira, P.; Silva, Sérgio Alves; Novais, Paulo; Pereira, M. A.; Alves, M. M.Anaerobic digestion processes are one of the technologies most used by wastewater treatment plants (WWTPs) to stabilize and decrease the organic content of sludge. This process decreases the costs of disposal while increasing the energetic efficiency of WWTPs. In order to optimize this process, three model approaches were implemented. First, we calibrated and validated the anaerobic digestion model no.1 (ADM1) ...
Monitoring morphological changes from activated sludge to aerobic granular slud...
Silva, Sérgio Alves; Val del Río, Angeles; Amaral, António Luís; Ferreira, Eugénio C.; Alves, M. M.; Mesquita, D. P.Quantitative image analysis (QIA) was used for monitoring the morphology of activated sludge (AS) during a granulation process and, thus, to define and quantify, unequivocally, structural changes in microbial aggregates correlated with the sludge properties and granulation rates. Two sequencing batch reactors fed with acetate at organic loading rates of 1.1±0.6 kgCOD m3 d1 (R1) and 2.0±0.2 kgCOD m3 d1 (R2) and ...
Novel insights to develop and characterize aerobic granular sludge for wastewat...
Silva, Sérgio AlvesA lama granular aeróbia (LGA) é uma nova tecnologia compacta que apresenta potencial de sustentabilidade em relação aos processos aeróbios convencionais. No entanto, o extenso período necessário para a formação dos grânulos, bem como a sua estabilidade a longo prazo, são ainda limitações para o estabelecimento mais amplo e robusto desta tecnologia. A caracterização e a avaliação de LGA tem suscitado interesse c...
Effect of sub-stoichiometric Fe(III) amounts on LCFA degradation by methanogeni...
Cavaleiro, Ana Júlia; Guedes, Ana P.; Silva, Sérgio Alves; Arantes, Ana Luísa; Costa, João Carlos Sequeira; Salvador, Andreia Filipa FerreiraLong-chain fatty acids (LCFA) are common contaminants in municipal and industrial wastewater that can be converted anaerobically to methane. A low hydrogen partial pressure is required for LCFA degradation by anaerobic bacteria, requiring the establishment of syntrophic relationships with hydrogenotrophic methanogens. However, high LCFA loads can inhibit methanogens, hindering biodegradation. Because it has bee...
Inhibition studies with 2-bromoethanesulfonate reveal a novel syntrophic relati...
Salvador, Andreia F.; Cavaleiro, Ana Júlia; Paulo, Ana M. S.; Silva, Sérgio Alves; Guedes, Ana P.; Pereira, M. Alcina; Stams, Alfons Johannes MariaDegradation of long-chain fatty acids (LCFAs) in methanogenic environments is a syntrophic process involving the activity of LCFA-degrading bacteria and hydrogen-utilizing methanogens. If methanogens are inhibited, other hydrogen scavengers are needed to achieve complete LCFA degradation. In this work, we developed two different oleate (C18:1 LCFA)-degrading anaerobic enrichment cultures, one methanogenic (ME) ...
Monitoring morphological changes of suspended sludge during aerobic granulation...
Silva, Sérgio Alves; Rio, Angeles Val del; Alves, M. M.; Mesquita, D. P.Aerobic granular sludge (AGS) technology depends on the growth of a self immobilizing microbial community to form granules, typically achieved through environmental and operational selective pressures. Long star-up periods and granules stability in long-term operation are described as the main drawbacks of this technology. During granulation, it is expected that most of the sludge achieve a granular form howeve...
Toxicity of long chain fatty acids towards acetate conversion by Methanosaeta c...
Silva, Sérgio Alves; Salvador, Andreia Filipa Ferreira; Cavaleiro, A. J.; Pereira, M. A.; Stams, Alfons Johannes Maria; Alves, M. M.Long-chain fatty acids (LCFA) can inhibit methane production by methanogenic archaea. The effect of oleate and palmitate on pure cultures of Methanosaeta concilii and Methanosarcina mazei was assessed by comparing methane production rates from acetate before and after LCFA addition. For both methanogens, a sharp decrease in methane production (> 50%) was observed at 0.5 mmol L1 oleate, and no methane was formed...