Comparison of oleate conversion under microaerophilic and anaerobic conditions

Excessive accumulation of Long Chain Fatty Acids (LCFA) in methanogenic bioreactors fed with lipids or mixtures of LCFA is the cause of process failure associated to a severe decrease in methane production. In particular, the fast and persistent accumulation of palmitate is critical and still not elucidated. Bacteria known as aerobes or facultative anaerobes are commonly detected in those reactors, suggesting that they may be involved in the conversion of lipids/LCFA to palmitate. To get insight into the influence of oxygen in this process, two bioreactors were operated in parallel under microaerophilic and anaerobic conditions, with applied organic loading rates of oleate of 1 and 4 g COD L-1 d-1. Palmitate accumulated up to 2 g COD L-1 and 16 g COD L-1 in the anaerobic and microaerophilic reactor, respectively, which suggests that oxygen is important for oleate conversion to palmitate. A second experiment was designed to get insight into the dynamics of oleate to palmitate conversion in continuous bioreactors. A continuous stirred tank reactor (CSTR) and a plug flow reactor (PFR) were assembled in series and were fed with oleic acid at a COD of 4 g L-1 under microaerophilic conditions and increasing hydraulic retention times from 6 to 24 hours in the CSTR and 14 to 52 minutes in the PFR. Growth of the target bacteria was not affected by the HRT in the CSTR. However in the PFR, a biofilm was formed where palmitate accounted for 82 % of the total LCFA. Bacterial community composition of the PFR biofilm was evaluated by 16S rRNA gene sequencing using the Illumina MiSeq platform. Pseudomonas was the predominant genus (42 %) in the sample, highlighting the role of aerobic and facultative anaerobic bacteria in LCFA bioconversion

Applying anomaly detection models in wastewater management: a case study of nitrates concentration in the effluent

With an increase in the diversity of data that companies in our society produce today, extracting insights from them manually has become an arduous task. One of the processes of extracting knowledge from the data is the application of anomaly detection models, which allows for finding unusual patterns in a given dataset. The application of these models in the context of Wastewater Treatment Plants (WWTPs) can improve water quality monitoring in these facilities, alerting decision-makers to act more quickly and effectively on anomalous events. Hence, this study aims to conceive and evaluate several candidate models based on Isolations Forest and Long Short-Term Memory-Autoencoders (LSTM-AE) to detect anomalies in the WWTP effluent, namely in the concentration of nitrates. Considering the obtained results, the best candidate was the LSTM-AE-based model, which had the best performance with an F1-Score of 97% and an AUC-ROC of 98%.This work is financed by National Funds through the Portuguese funding agency, FCT - Fundação para a Ciência e a Tecnologia within project DSAIPA/AI/0099/2019

As opções efectuadas pela Roménia no âmbito do artigo 5º do regulamento 1606/2002/CE

Mestrado em Contabilidade - AuditoriaO presente trabalho propõe-se dar a conhecer os impactos, as opções, e as soluções legislativas desenvolvidas pela Roménia em consequência da aprovação do Regulamento 1606/2002, do Parlamento Europeu e do Conselho. Para tanto procurámos evidenciar o efeito que a estrutura empresarial romena, assente maioritariamente em micro e pequenas empresas, tem na concepção de um novo modelo e, também, as condições da sua adaptação. O estudo dos impactos de alteração de normativo, em países como a Roménia, tem ainda um atractivo adicional que tem a ver com o facto de as IAS/IFRS introduzirem um novo paradigma. Nesse enquadramento damos a conhecer as principais alterações que as sucessivas mudanças trouxeram para o normativo contabilístico romeno, de modo a compreender e estimar os efeitos previsíveis na produção da informação financeira, na mudança de comportamentos e no paradigma contabilístico. Para o efeito analisam-se os impactos da adopção das IAS/IFRS pelas empresas sediadas na Roménia, e apresentam-se as soluções legislativas propostas e suas principais divergências, em consequência das opções efectuadas pela Roménia.This paper aims to get to know, about the impacts, options, and legislative solutions developed by Romania as a result of the adoption of Regulation 1606/2002 of the European Parliament and Council. For this purpose, we tried to highlight the affect that the Romania business structure, based mostly in micro and small enterprises have to design a new model and also the conditions for its a adaptation. The study of the impacts of regulatory change in countries like Romania still has an added attraction that has to do with the fact that IAS/IFRS introduce a new paradigm. In This framework we know the main changes brought to the Romanian accounting standards in order to understand and estimate the likely effects on the production of financial information on behaviour change and the paradigm accounting. To this end we analyse the impacts of adopting IAS/IFRS by companies based in Romania, and present the proposed legislative solutions and their main differences, as a result of choices made by Romania

Using deep learning models to predict the electrical conductivity of the influent in a wastewater treatment plant

Nowadays, human population face increasing water pollution problems, so treating and managing this resource is crucial. Wastewater Treatment Plants (WWTPs) provide essential services for human life since they treat wastewater and monitor its parameters to preserve water quality standards. One of these parameters is electrical conductivity, essential in quantifying water salinity levels. Therefore, this paper aims to forecast the influent conductivity in a WWTP for the next two timesteps. Hence, several experiments were conducted, considering the use of Transformers and Long Short-Term Memory (LSTMs) candidate models that were developed, tuned, and evaluated, utilising a recursive multi-step forecasting approach. The best candidate model was based on a Transformer architecture with encoding and obtained a RMSE of 155.2 μ S/cm.This work is financed by National Funds through the Portuguese funding agency, FCT - Funda¸c˜ao para a Ciˆencia e a Tecnologia within project 2022.06822.PTDC. The work of Pedro Oliveira was supported by the doctoral Grant PRT/BD/154311/2022 financed by the Portuguese Foundation for Science and Technology (FCT), and with funds from European Union, under MIT Portugal Program

Anaerobic digestion supplemented with carbon materials as a sustainable approach for the bioremediation of PFAS

Per- and polyfluoroalkyl substances (PFAS) are recalcitrant fluorinated organic compounds that tend to persist in soils and aquatic ecosystems and cause adverse effects on the environment and human health, so its remediation is crucial. Anaerobic digestion (AD) mediated by carbon materials (CM), has shown high efficiency in the removal of organic pollutants from wastewater. In this work, the feasibility of applying AD in the bioremediation of PFAS was studied. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were evaluated. These compounds promoted an inhibition in the activity of acetoclastic methanogens and acetogenic communities below 15 %, at a concentration higher than the usually found in wastewater treatment plants (WWTP) (0.1 mg L-1), while hydrogenotrophic methanogens were not affected. When supplementing AD of PFAS with CM the negative effect was reduced. Moreover, the methanization percentage of sewage sludge contaminated with PFAS increased 41 % in the presence of 1.2 g L-1PFOS and AC, demonstrating the benefit of bringing AD and CM together for PFAS bioremediation.Fundação Luso-Americana para o Desenvolvimento (FLAD)info:eu-repo/semantics/publishedVersio

Optimizing lab-scale wastewater treatment reactors operation for enhanced assays

Book of Abstracts of CEB Annual Meeting 2017[Excerpt] Wastewater treatment plants (WWTP) comprise a complex set of sequenced operations that ensure the safe discharge of water, previously contaminated by anthropogenic activities, into the environment. Roughly, these operations are divided in: preliminary treatment, primary treatment and secondary treatment. The secondary treatment is the most critical operation, encompassing a feeble equilibrium between physicochemical conditions and biological processes. It commonly consists in an aeration tank and a clarifier [1]. The microbial community present in the aeration tank is responsible for metabolizing most of the influent nutrient load. Pure oxygen, or air, is injected in this process to guarantee an adequate concentration of dissolved oxygen, in order to promote a rapid aerobic metabolism. Simultaneously preventing anoxic conditions, which denote a slower nutrient consumption and the generation of foul substances. Worldwide, the most commonly used microbial community for this process in the WWTP is activated sludge. Consisting of a highly complex community comprising bacteria, fungi, small protozoa and protozoa, the activated sludge “healthiness” is a critical factor for the efficiency of the wastewater treatment process. In addition, “healthy” activated sludge also possess a key physicochemical property for the downstream process of the aeration tank, namely, flocculation. In the clarifier the activated sludge flocs will sediment by the sole action of gravity, thus preventing a high microbial load in the effluent [2]. [...]info:eu-repo/semantics/publishedVersio

Aesthetic And Functional Rehabilitation Of The Primary Dentition Affected By Amelogenesis Imperfecta.

The objective of this case report was to describe the oral rehabilitation of a five-year-old boy patient diagnosed with amelogenesis imperfecta (AI) in the primary dentition. AI is a group of hereditary disorders that affects the enamel structure. The patient was brought to the dental clinic complaining of tooth hypersensitivity during meals. The medical history and clinical examination were used to arrive at the diagnosis of AI. The treatment was oral rehabilitation of the primary molars with stainless steel crowns and resin-filled celluloid forms. The main objectives of the selected treatment were to enhance the esthetics, restore masticatory function, and eliminate the teeth sensitivity. The child was monitored in the pediatric dentistry clinic at four-month intervals until the mixed dentition stage. Treatment not only restored function and esthetic, but also showed a positive psychological impact and thereby improved perceived quality of life. The preventive, psychological, and curative measures of a young child with AI were successful. This result can encourage the clinicians to seek a cost-effective technique such as stainless steel crowns, and resin-filled celluloid forms to reestablish the oral functions and improve the child's psychosocial development.201579089

Untangling the role of facultative bacteria in LCFA conversion to methane

Book of Abstracts of CEB Annual Meeting 2017[Excerpt] Palmitate accumulation is frequently reported in continuous methanogenic bioreactors fed with lipidrich wastewater, and facultative bacteria were suggested to be involved in this conversion. In this work, the possible effects of limited oxygen conditions in triggering palmitate formation from oleate were studied. Two bioreactors were operated in parallel, one under strict anaerobic conditions (AnR) and the other with the feeding tank open to the air (FR). Palmitate was the main LCFA in both reactors, but it reached approximately 7 times higher concentrations in the FR than in the AnR (16 and 2 g·L-1 in COD, respectively). Moreover, oleate was more abundant in the AnR than in the FR, presenting concentrations of 1.3 and 0.5 g·L-1, and oxidation-reduction potential values (ORP) of -366 mV and -255 mV were measured. [...]info:eu-repo/semantics/publishedVersio

The protective effect of Pseudomonas in syntrophic fatty acids degradation under microaerophilic conditions

Micro-aeration has been used in anaerobic digestion (AD) systems to improve some aspects of this multifunctional and flexible technology. The addition of vestigial amounts of oxygen is usually associated with an increase of the relative abundance of facultative anaerobic bacteria (FAB) in the microbial community. Besides being involved in fermentation/acidogenesis, FAB have been referred to act as a protective shield against the damaging effects of oxidative environments to the strict anaerobic organisms of these communities. The microbial relationships between FAB, syntrophic bacteria and methanogens were investigated, during the degradation of short (C4), medium (C8) and long (C16) chain fatty acids by two syntrophic cultures (Syntrophomonas species and a methanogenic partner) in the presence of facultative bacteria (two Pseudomonas sp.). Pseudomonas were added to the pre-grown syntrophic pair, along with the substrate and a range of O2 concentrations (0-10% v/v). The grown cultures then were transferred a second time, with the same substrate and to all the O2 conditions previously tested. The cultures were followed through CH4, VFA, LCFA and pH measurements. In the presence of O2 (up to 2%) an effective syntrophic relationship, as well as the maintenance of methanogenic activity, was only possible in the presence of FAB. Cultures exposed to O2 in the first incubation performed well when transferred back to anaerobic conditions. Moreover, at the second phase, Pseudomonas maintained its protective shield effect and most of the cultures previously developed under micro-aerobic conditions could also maintain its activity. This work demonstrates that the presence of Pseudomonas contributes for a more resilient and functional syntrophic consortium degrading fatty acids under micro-aerobic conditions.info:eu-repo/semantics/publishedVersio

Pseudomonas empower syntrophic fatty acids degradation in the presence of oxygen

Anaerobic digestion (AD) processes specifically directed towards biogas production are currently of great interest worldwide, due to the urgent need of more sustainable energy sources. Although not consensual, oxygen has been shown as an ally of AD processes, resulting in more efficient biogas production when added to the systems in vestigial doses. It has been suggested that it stimulates facultative anaerobic bacteria (FAB), which are generally present in the anaerobic communities. These bacteria are involved in several steps of AD (fermentation and acidogenesis) but have also been referred to protect the strict anaerobes from oxidative stress [1]. In this work, the influence of FAB in the degradation of short-, medium- and long-chain fatty acids (C4, butyrate; C8, octanoate; C16, hexadecanoate) by two syntrophic co-cultures was investigated. Syntrophomonas wolfei (Sw)/ Methanospirillum hungatei (Mh) and S. zehnderi (Sz)/ Methanobacterium formicicum (Mf) were pre-grown and Pseudomonas sp. (FAB) were further added, along with each substrate over a range of O2 concentrations (0-2 % v/v). In a second transfer, each culture was exposed to the same O2 concentration range. Both syntrophic co-cultures (Sw+Mh and Sz+Mf) had their activity highly reduced, or even completely inhibited, in the presence of O2. Interestingly, the theoretical CH4 production expected from C8 was reached by consortium Sw+Mh+Ps at days 3, 8 and 28 under 0%, 1% and 2% O2, respectively. The same trend was observed for consortium Sz+Mf+Ps. C4 and C16 degradation occurred similarly to C8 degradation, presenting similar results and the same tendency for both tested consortia. This data suggests a positive interaction and network establishment between these organisms. Apparently, Pseudomonas consumed the oxygen allowing the creation of a reduced environment, a requirement for an effective development of the strict anaerobic syntrophic co-cultures. In the 2nd transfer, the protective support of Pseudomonas was maintained. Moreover, it was verified that the cultures (Sw+Mh+Ps and Sz+Mf+Ps) previously exposed to O2 preserved their activity either under anoxic or microaerophilic conditions. These results show the essential role of Pseudomonas in the protection of syntrophic co-cultures activity, empowering fatty acids degradation under microaerophilic conditions. Furthermore, it highlights the FAB/Pseudomonas importance in real AD systems (where vestigial amounts of O2 can be detected) for the stability and resilience of the system maintaining syntrophic communities functionality and biogas production.info:eu-repo/semantics/publishedVersio