1,720,952 research outputs found
Anaerobic membrane bioreactor (AnMBR) for the treatment of lipid-rich dairy wastewater
No full textThe ongoing growth of the global population has led to increased resource consumption, particularly in the realm of water resources, resulting in potential shortages and environmental concerns. The surge in industrialization has intensified the demand for freshwater, consequently causing significant contamination of global water sources through the discharge of industrial wastewater. This wastewater contains harmful contaminants, such as heavy metals and organic compounds, which pose significant threats to both aquatic ecosystems and human health (Corcoran, 2010). To effectively address this issue, it is imperative to strengthen regulatory measures, promote industrialized initiatives for wastewater reduction and treatment, and foster technologicaladvancements in wastewater management.Lipids within wastewater systems present both opportunities and challenges. Their high energy content holds promise for bioenergy conversion, yet they can also disrupt anaerobic wastewater treatment processes. Consequently, it is often advisable to extract lipids before commencing biological treatment processes (Alves et al., 2009). Lipids are commonly referred to as fats, oils, and grease (FOG) (Cavaleiro et al., 2008). At the core of FOG composition are triglycerides, formed through the esterification of glycerol with long-chain fatty acids (LCFA) (Alves et al., 2009). Within lipid-rich wastewaters, the prevailing LCFAs identified include palmitic acid (C16:0) and oleic acid (C18:1), as highlighted by Hwu et al. (1996). Anaerobic digestion (AD) plays a central role in advancing various sustainable development objectives by seamlessly integrating energy and resource recovery from organic residues and wastewater, all while effectively managing pollution. AD's ability to produce renewable gaseous energy, recycle essential nutrients, and minimize excess sludge production, combined with an enhanced understanding of microbiology and ecophysiology, has propelled AD technologies to the forefront. These technologies now serve as environmentally friendly treatment options for a wide range of wastes and wastewaters, as evidenced by their widespread adoption at the global level (van Lier et al., 2020). Sustainable and efficient conversion of these waste lipids into methane within anaerobic reactors is met with impediments including adsorption, sludge flotation, washout, and inhibition. However, these complications can be circumvented through feeding protocols, optimized mixing, and adept solid separation methods, underpinned by cutting-edge reactor designs and operational methodologies. More recently, developments such as the anaerobic membrane bioreactor (AnMBR) and flotation-based bioreactors have emerged as solutions tailored for lipid-intensive wastewater treatment (Cavaleiro et. al., 2008). AnMBR, a nexus of anaerobic digestion and membrane filtration, has proven particularly adept for dairy wastewater treatment. It alleviates the challenges tied to gravity-based separation, yielding effluents devoid of suspended solids and of superior quality (Judd, 201).The central focus of this research centered on the assessment of solids retention time (SRT) and its critical role in the operational parameters of AnMBR. This was accomplished by studying sludge filterability and membrane filtration performance. Additionally, we investigated how the acclimatization of biomass impacted the transformation of longchain fatty acids (LCFA) in lipid-rich wastewater. Initial evaluations emphasized the role of SRT on AnMBR efficiency during the treatment of synthetic dairy wastewater laden with lipids. Employing two distinct AnMBR configurations with SRTs of 20 and 40 days, both systems manifested approximately 99%efficiency in waste removal at an organic loading rate of 4.7 g COD L-1 d-1. Significantly,lipid sedimentation was absent, facilitating their continued anaerobic degradation. LCFAaccumulation was minimal in both systems, with the 40-day SRT configuration showing slightly enhanced biological conversion and stability. Subsequently, the study delved into the effects of SRT on the filtration efficacy of AnMBR using lipid-rich synthetic dairy wastewater. When confronted with 40-day SRT, the system encountered elevated pressures and resistances, presumably due to escalated contaminant levels, including fats, oils, and LCFAs. While both systems showcased analogous filterability, the 20-day configuration exhibited superior membrane performance, suggesting potential membrane operational refinements for the 40-day SRT. Lastly, the influence of LCFA on anaerobic sludge processes was investigated. Trialing three distinct sludge samples—two lipid-acclimated and one non-acclimated—they were exposed to varying oleic and palmitic acid concentrations, ranging between 50 to 600 mg COD/L. Oleic acid showed superior degradation capabilities compared to palmitic acid across all samples, with heightened methane production. Lipid-acclimated sludges demonstrated augmented LCFA degradation potential. However, upon reaching LCFA concentrations beyond 400 mg/L, degradation of both acids into intermediate products was inhibited, albeit without affecting methane production. Intriguingly, specific bacterial taxonomies associated with LCFA degradation were identified in lipid-acclimated sludge samples, underscoring the potential of sludge adaptation strategies in enhancing anaerobic treatment of lipid-rich effluents.In this doctoral research, we elucidated the prospects and challenges associated with the utilization of AnMBR for treating lipid-rich dairy wastewater. We highlighted the critical importance of Solid Retention Time (SRT), a key operational parameter that exerts a profound influence on both the biological and membrane aspects of the system.Furthermore, our study underscored the paramount role played by the two most prevalent Long-Chain Fatty Acids (LCFAs), namely oleic and palmitic acid, within the domain of anaerobic digestion.Sanitary Engineerin
Principles, Advances, and Perspectives of Anaerobic Digestion of Lipids
No full textSeveral problems associated with the presence of lipids in wastewater treatment plants are usually overcome by removing them ahead of the biological treatment. However, because of their high energy content, waste lipids are interesting yet challenging pollutants in anaerobic wastewater treatment and codigestion processes. The maximal amount of waste lipids that can be sustainably accommodated, and effectively converted to methane in anaerobic reactors, is limited by several problems including adsorption, sludge flotation, washout, and inhibition. These difficulties can be circumvented by appropriate feeding, mixing, and solids separation strategies, provided by suitable reactor technology and operation. In recent years, membrane bioreactors and flotation-based bioreactors have been developed to treat lipid-rich wastewater. In parallel, the increasing knowledge on the diversity of complex microbial communities in anaerobic sludge, and on interspecies microbial interactions, contributed to extend the knowledge and to understand more precisely the limits and constraints influencing the anaerobic biodegradation of lipids in anaerobic reactors. This critical review discusses the most important principles underpinning the degradation process and recent key discoveries and outlines the current knowledge coupling fundamental and applied aspects. A critical assessment of knowledge gaps in the field is also presented by integrating sectorial perspectives of academic researchers and of prominent developers of anaerobic technology.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Sanitary Engineerin
Inhibitory effects of long chain fatty acids on anaerobic sludge treatment: Biomass adaptation and microbial community assessment
No full textThe study investigated the effects of long-chain fatty acids (LCFA) on anaerobic sludge treating lipid-rich wastewater. It involved batch experiments with three sludge samples: two acclimated to lipids and one non-acclimated. The experiments aimed to observe the degradation of LCFA, specifically oleate and palmitate, by dosing them at concentrations ranging from 50 to 600 mg/L. Measurements of the cumulative methane production and the LCFA concentration, quantified as fat, oil, and grease (FOG) were performed. To ensure the sludge was free from other biodegradable substrates, part of the samples was pre-incubated without feed. The tests were conducted with both pre-incubated and non-incubated inoculum sludge. The findings revealed that oleate was degraded more efficiently than palmitate across all sludge samples, with a greater conversion rate to methane. Sludge samples acclimated to lipids showed a superior capacity to degrade LCFA compared to non-acclimated ones. It was noted that at concentrations above 400 mg/L, the conversion of LCFAs to intermediate compounds was inhibited, although this did not affect the subsequent methane production. The study concludes with a recommendation for sludge adaptation strategies to boost the efficiency of anaerobic wastewater treatment systems dealing with lipid-rich waste. The presence of LCFA-degrading bacteria families like Kosmotogaceae, Petrotogaceae, and Synergistaceae in the acclimated sludge samples underscores the adaptation and potential for improved degradation performance.Sanitary EngineeringBT/Environmental Biotechnolog
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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