1,721,015 research outputs found
Treatment of dairy wastewater using enzyme pre-treatment coupled with an expanded granular sludge bed reactor
Full text linkDairy consumption is rising due to the rapid growth of the population, necessitating increased dairy production to meet this demand. Consequently, the wastewater produced by dairy plants is also increasing significantly. The dairy industry, already one of the biggest contributors to pollution, generates large volumes of wastewater contaminated with toxic substances. These substances adversely affect the water sources into which the wastewater is released, whether fully or partially. Contaminants such as high concentrations of fats, oils, and greases (FOGs), nitrogen, phosphate, chemical and biological oxygen demand (COD and BOD) are found in the wastewater. This study investigates the treatment of dairy wastewater (DWW) using a biological pretreatment coupled with an anaerobic down-flow expanded granular sludge bed reactor (DEGBR). The DEGBR system, previously utilized in the treatment of PSW, showed satisfactory removal efficiencies with the use of a bioremediation agent, Eco-Flush. However, Eco-Flush was found to contribute to the increase in dissolved oxygen (DO) levels due to aeration, leading to the identification and use of a new enzyme named Momar in this study. The pre-treatment stage aimed to determine the optimum dosage of Momar, focusing on the removal of FOGs to mitigate clogging in the DEGBR. The results of the pre-treatment stage were satisfactory, with a 42% reduction in DO, and removal efficiencies of 16% for COD, 20% for Total Suspended Solids (TSS), and 70% for FOG. The pre-treatment stage successfully removed a significant amount of FOGs from the wastewater. The DEGBR was operated with three different hydraulic retention times (HRTs), and the removal efficiencies of COD, TSS, and FOG were compared. At 36 hours, the removal efficiencies were 38% for COD, 55% for TSS and 76% for FOG; at 24 hours, they stood at 36%, 48% and 68%, and at 12 hours, the values were 48%, 43% and 74%. The overall average removal efficiencies of the DEGBR for COD, TSS, and FOG were 39%, 49%, and 73%, respectively. Overall, the combined system produced satisfactory results with removal efficiencies of COD, TSS, and FOG, which are 48%, 56%, and 71%, respectively. In conclusion, the biological system coupled with a biological pre-treatment effectively treated high-fat wastewater. It is recommended that a thorough analysis be conducted on Momar to identify the impact of the enzymes on wastewater. In the future, the system should be operated again with dairy wastewater for a longer period, addressing system issues, and incorporating regular backwashing to prevent clogging
Evaluation and optimisation of the performance of a multi-integrated lab-scale plant for the treatment of dairy wastewater
No full textSouth Africa's dairy sector, producing 3.4 million tonnes of milk in 2019, generates significant wastewater, estimated at 2.5 times the volume of processed milk, or approximately 8.5 million tonnes annually. This wastewater poses serious environmental risks due to its high organic content, potentially leading to eutrophication and hypoxic zones in water bodies. Effective treatment methods are essential to mitigate these impacts. This study evaluates the performance of a lab-scale wastewater treatment plant, combining various biological processes previously used for abattoir wastewater (AWW), given the similarities between AWW and dairy wastewater (DWW) in terms of high organic and fat content. In anticipation of the challenge of clogging which has been prevalent in previous studies, an investigation was done into the use of okra as a biological coagulant which could possibly be integrated with the system. The research focuses on optimizing individual treatment units and assessing their collective performance in treating DWW. Initial challenges included operational errors, such as the overuse of Morma in pre-treatment, leading to increased biomass production and elevated Chemical Oxygen Demand (COD). Despite subsequent corrections improving system stability, fluctuations persisted, particularly in the Expanded Granular Sludge Bed Reactor (EGSBR). COD removal rates ranged from 60% in week 3 to 26% in week 5, highlighting the system's potential but falling short of traditional anaerobic digestion (AD) systems, which can achieve up to 90% COD removal. However, the system performed better with higher raw COD levels, indicating its efficacy in treating wastewater with elevated COD content. EGSBR stability issues were attributed to clogging and biomass washout, exacerbated by a reduced pre-treatment hydraulic retention time (HRT) of 12 hours. Analysis of fat, oil, and grease (FOG) removal revealed inconsistent performance, with the highest removal rates occurring in weeks with FOG content exceeding 6000 mg/L DWW. FOG removal rates ranged from 27% to 94%, surpassing those of previous AD reactor studies. The observed correlation between FOG content and system performance warrants further investigation. Total Suspended Solids (TSS) removal rates served as indicators of reactor stability issues, with increased TSS indicating biomass washout. Decreasing pre-treatment HRT adversely affected reactor stability, highlighting the importance of optimizing pre-treatment parameters. Additionally, the use of okra seeds as a coagulant was explored, showing promising results in reducing TSS and COD from DWW. The optimal dose was 5g per 2L of DWW, achieving the highest removal rates for both TSS and COD. This suggests that okra seeds offer an eco-friendly alternative to traditional coagulants like alum. Integrating coagulant treatments with biological agents could enhance the removal of solids and FOGs, addressing the stability issues observed in the EGSBR and improving overall system performance
Performance evaluation of an up- and down-flow anaerobic reactor for the treatment of poultry slaughterhouse wastewater in South Africa
No full textThesis (DTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017.The process of anaerobic digestion (AD) is one of the most cost-effective and environmentally sustainable technologies to treat wastewater in the agricultural sector. In South Africa, in some industries in the agricultural sector, such as the poultry industry in particular, slaughterhouses have the highest consumption of potable water, culminating in the production of a large quantity of high strength wastewater. This high consumption of potable water has become a concern in South Africa due to water scarcity and reduced rainfall attributed to global warming, including weather changes. Furthermore, the generation of a large volume of wastewater poses environmental pollution concerns. The wastewater from poultry slaughterhouses can be quite easily treated to a suitable quality for reuse, using various bioreactor systems that utilise low cost anaerobic digestion processes. However, as this wastewater contains a high quantity of biodegradable organic matter – with the primary pollutants being proteins, blood, fats, oil and grease (FOG) – selecting a suitable anaerobic reactor configuration (up-flow vs down-flow) plays an important role in achieving high reactor performance. In this study, both the up-flow, (i.e. Expanded Granular Sludge Bed Reactor) and the down-flow (i.e. Static Granular Static Granular Bed Reactor), were studied to quantitatively determine their performance in treating poultry slaughterhouse wastewater.
Firstly, the feasibility of treating poultry slaughterhouse wastewater with an up-flow Expanded Granular Sludge Bed Reactor (EGSB) coupled with anoxic and aerobic bioreactors was investigated at an HRT of 7 (168 hr), 4 (96 hr) and 3 (72 hr) days using organic loading rates of 0.5, 0.7 and 1.0 gCOD/L.day. The averaged tCOD removal for the EGSB reactor was 40%, 57% and 55%, respectively, at the various OLRs and HRTs investigated. The overall tCOD removal of the system (EGSB-anoxic/aerobic) at high OLR of 1.0 gCOD/L.day was increased to 65%. The redundant performance of the up-flow EGSB reactor was attributed to the periodical sludge washout experienced during its operation due to high FOG and TSS concentrations in the influent. Due to the periodic sludge washout, the reactor required continuous re-inoculation resulting in the EGSB being operated for a short period (i.e. 26 days). As a result of such system deficiency, it was recommended that to improve the performance of the up-flow EGSB reactor in treating poultry slaughterhouse wastewater, a pre-treatment system – such as a Dissolved Air Floatation system (DAFs) or a FOG skimmer – is required to reduce the FOG and total suspended solids (TSS) load prior to the wastewater fed to the EGSB. This will minimise system failure and the need for a continuous re-inoculation of the system (see Appendix C for improved operation strategy of the EGSB reactor). Furthermore, a system redesign was recommended, thus the use of the SGBR.
Secondly, after the EGSB system evaluation, the performance of a down-flow system (i.e. SGBR) for the new design, the following were deemed appropriate for improved system (SGBR) design: 1) reduced HRT for high wastewater treatment through-put rates; 2) the ability to adequately treat the wastewater with higher organic loading rates; and 3) reduction of the plant footprint by using a membrane filtration system (i.e. a single process unit) to effectively reduce process requirements needed for the anoxic/aerobic bioreactors (i.e. n=2 process unit) used with the EGSB. Similarly, for large-scale operations, it is advisable to have a backwash system to adequately handle declogging processes (i.e. these systems modifications were evaluated in the SGBR).
The SGBR, coupled with an ultra-filtration (UF) membrane system, was then investigated for treating the poultry slaughterhouse wastewater at an HRT of 55 hrs and 40 hrs, including average OLRs of 1.01 and 3.14 gCOD/L.day, respectively. The average maximum performance of the SGBR in terms of tCOD, TSS and FOG removal was > 90% at the OLRs and HRTs investigated. The UF membrane system used as a post-treatment system further yielded a system performance improvement for tCOD, TSS and FOG of 64%, 88% and 60%, respectively. The overall performance of the combined system (SGBR and UF membrane system) in terms of tCOD, TSS and FOG removal was 98%, 99.8% and 92.4%, respectively. The highest performance for the down-flow SGBR was attributed to its ability to retain granulated sludge in the reactor while maximizing the digestion of the organic matter fed into the reactor, even at higher OLRs. Furthermore, for effective declogging, the implementation of a periodic backwash system to effectively remove dispersed fine sludge particles in the underdrain and excessive suspended solids entrapment was observed to ease the system operational deficiencies
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
Implementation of blended learning: The experiences of students in the chemical engineering extended program physics course
No full textThe emergence of the 'Fees Must Fall' (FMF) protest in South African Higher Education institutions has necessitated discussions on the improvement of the implementation of Blended Learning to supplement on campus face-to-face lecture delivery. While Blended Learning might be seen as a success in some developed countries, its implementation in a developing country such as South Africa, where there is differential access to resources must be done with caution. Otherwise, the implementation of Blended Learning may further alienate students from under-resourced communities. In the year 2016, the Chemical Engineering Department at the Cape Peninsula University of Technology introduced a web-based homework system, WileyPLUS in its first year physics course, to provide students with support through interaction with technology and also to assist the lecturer in providing timely feedback on assessments. Additionally, a social media application WhatsApp group was formed in order to facilitate learner-to-learner interactions outside the classroom. This paper presents findings of the students' experience of the system in the physics course using "Moore interaction" framework. The data was generated through focus groups with the students, which were carried out to gain insights into the students' experience of the implementation of the Blended Learning practice used in this study. Additionally, the student's paper based test and student's assessments were analyzed against each otherto deduce if online students' performance translates to paper-based tests. Student's comments on a WhatsApp group discussion during the "FMF" protests university shutdown is incorporated to show how a lack of interaction with the computer interface impacted on their experiences of blended learning. The results show that students who reside in the university residences, and have access to the university's resources such as computer and Wi-Fi, have a higher chance of improving their scores in the physics course compared to students who reside outside campus and have no access to computers and data to connect to the Internet. Furthermore, the results suggest that blended learning using the above technologies, if not employed carefully, has the potential to further alienate the group of students with limited access to resources. Some students from under-resourced backgrounds reported that the limited access to computers and Wi-Fi usually led them to cheating in their collaborations due to lack of time to interact with the online system. They indicated that they collaborated with some of their peers who reside on campus in order to get high scores in WileyPLUS, however, failed to perform equally in paper-based written assessment. Findings presented in this paper have important lessons and implications for universities in a developing country as it draws attention to the potential challenges that may arise from the implementation of Blended Learning
Proactive Student Psychosocial Support Intervention Through Life Coaching: A Case Study of a First-Year Chemical Engineering Extended Curriculum Programme
Full text linkHigher Education Institutions in South Africa continue to experience considerable dropout rates of students during the first year, especially those from previously marginalised population groups. The aim of this research was to evaluate how the use of life coaching interventions providing first year students with psychosocial support, influenced their first-year experience. Both quantitative and qualitative data was collected through a questionnaire at the end of the academic year, approximately four months after the intervention, to evaluate students’ experiences of the intervention. Results indicate that students felt that the intervention helped them avoid dropping out of university prematurely, respond better to failure during the year, and improve their self-awareness and academic performance. In conclusion, the results suggest that the use of life coaching intervention as a proactive means of harnessing student agency, may be beneficial to their academic performance, and in improving their lives in general. The study recommends that further research be conducted to explore the use of small group life coaching for providing students with psychosocial support, and also exoplore this intervention’s cost-effectiveness in different context
The effect of Wiley PLUS Web-Based Homework system on student performance in the Chemical Engineering Extended Curriculum Program: Introductory Physics course
No full textConference PaperThe importance of providing student feedback on their learning is well document. However, providing feedback to individual student is often impossible and time consuming. To address the need for a more efficient and effective approach to giving individualized feedback to students, a Wiley PLUS web-based homework (WBH) system that provides automated grading to individual student was piloted in a physics class for this study. Thus, this paper presents results on the effects of the use of Wiley PLUS web-based automated grading homework system in a first year introductory Engineering Physics course. The study investigated how the Wiley PLUS web-based homework system impacted on the student’s paper based tutorial mock test, mid-term-test and Final Integrated Summative Assessment (FISA) performance. This study was informed by Laurilland’s educational media conversational framework for teaching and learning supporting the ‘interactive activity’ learning process using Web-based homework as an adaptive media. Adaptive media is a computer-based media capable to change its state in response to user action and assist in facilitating learning process such as providing individualised instant feedback to students and as a result help them to understand the course material. Both quantitative and qualitative methods of collecting data were used in this study. A comparison between students performance on the Wiley PLUS online web-based homework, paper based written tutorial mock test, mid-term test and FISA was done to evaluate if there was a correlation in students performance. Additionally, during the final class of the semester, Chemical Engineering Extended Curriculum Program students who enrolled for introductory Physics course responded to a survey and focus group interviews to gauge their perceptions and experiences on the use of the Wiley PLUS web based system. Quantitative data was analysed using descriptive statistics and inferential statistics, while qualitative data was analysed using inductive strategy. Results indicated that students were in agreement that Wiley PLUS WBH system enhanced students learning and collaboration among learners. There was a strong positive correlation between WBH score and score on tutorial mock test, mid-test and FISA
- …
