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Simultaneous nitrification and denitrifying phosphate uptake in a continuous moving bed biofilm reactor (The HIAS-process)
Get PDFNutrients such as nitrogen (N) and phosphorus (P) can cause eutrophication and harmful algal blooms in waterbodies. Removal of these nutrients from wastewater discharges are therefore necessary to insure healthy waters. The increased focus on the world s limited phosphate reserves have led to an increased interest for biological phosphorus removal enhancing P-recovery from wastewater. A newly developed biological phosphorus removal process, the HIAS-process, has shown good removal for phosphorus, but have also detected some nitrogen removal. By enhancing removal of nitrogen in this process, the process could be a more compact and cost-effective treatment option compared to today s treatment processes for both phosphorus and nitrogen.
In this study, three main parameters influencing the HIAS-process were investigated to get further knowledge about the process, so that an optimization of N-removal in the process could be done. The parameters investigated were anaerobically carbon consumption, oxygen concentrations and temperature, and were investigated through batch experiments at the laboratory and grab sample experiments in the pilot plant at HIAS Wastewater Treatment Plant.
Results show that high oxygen concentration gives high nitrification rates, which results in a high production of nitrite/nitrate. It is also seen that higher denitrification rates are present when the nitrite/nitrate concentrations are initially higher. However, high oxygen concentration over time does indicate that lack of an anoxic layer in the biofilm could occur when oxygen consumption by nitrifyers and phosphate accumulating organisms (PAOs) decreases. This further decreases the denitrification, due to the need for an anoxic layer to be present for denitrification to occur. Experiments conducted with initially high oxygen concentration, followed by low oxygen concentration, showed that better N removal could occur due to maintenance of the anoxic layer.
Results from the batch experiments show that higher anaerobically carbon consumption gives higher denitrification rates and that carbon taken up in the anaerobic period can effectively be utilized for N removal, with a potential C/N-ratio found in the batch experiments to be approximately 5 mg sCOD/mg N. Results have also shown higher N removal efficiencies under higher temperatures.
The results from the experiments performed in this thesis give reasons to believe that optimization of the process could be done by controlling the DO concentration in the aerobic period of the reactor, to have high oxygen concentrations in the first chambers, and lower oxygen concentrations in the last chambers. Optimization of the process can also be done by adding an external carbon source if the organic carbon load into the reactor has too low capacity to remove the desired amount of ammonium. The aerobic retention time can also be extended to improve the nitrogen removal
Simultaneous nitrification and denitrifying phosphate uptake in a continuous moving bed biofilm reactor (The HIAS-process)
No full textNutrients such as nitrogen (N) and phosphorus (P) can cause eutrophication and harmful algal blooms in waterbodies. Removal of these nutrients from wastewater discharges are therefore necessary to insure healthy waters. The increased focus on the world s limited phosphate reserves have led to an increased interest for biological phosphorus removal enhancing P-recovery from wastewater. A newly developed biological phosphorus removal process, the HIAS-process, has shown good removal for phosphorus, but have also detected some nitrogen removal. By enhancing removal of nitrogen in this process, the process could be a more compact and cost-effective treatment option compared to today s treatment processes for both phosphorus and nitrogen.
In this study, three main parameters influencing the HIAS-process were investigated to get further knowledge about the process, so that an optimization of N-removal in the process could be done. The parameters investigated were anaerobically carbon consumption, oxygen concentrations and temperature, and were investigated through batch experiments at the laboratory and grab sample experiments in the pilot plant at HIAS Wastewater Treatment Plant.
Results show that high oxygen concentration gives high nitrification rates, which results in a high production of nitrite/nitrate. It is also seen that higher denitrification rates are present when the nitrite/nitrate concentrations are initially higher. However, high oxygen concentration over time does indicate that lack of an anoxic layer in the biofilm could occur when oxygen consumption by nitrifyers and phosphate accumulating organisms (PAOs) decreases. This further decreases the denitrification, due to the need for an anoxic layer to be present for denitrification to occur. Experiments conducted with initially high oxygen concentration, followed by low oxygen concentration, showed that better N removal could occur due to maintenance of the anoxic layer.
Results from the batch experiments show that higher anaerobically carbon consumption gives higher denitrification rates and that carbon taken up in the anaerobic period can effectively be utilized for N removal, with a potential C/N-ratio found in the batch experiments to be approximately 5 mg sCOD/mg N. Results have also shown higher N removal efficiencies under higher temperatures.
The results from the experiments performed in this thesis give reasons to believe that optimization of the process could be done by controlling the DO concentration in the aerobic period of the reactor, to have high oxygen concentrations in the first chambers, and lower oxygen concentrations in the last chambers. Optimization of the process can also be done by adding an external carbon source if the organic carbon load into the reactor has too low capacity to remove the desired amount of ammonium. The aerobic retention time can also be extended to improve the nitrogen removal
Nitrogen removal in the Hias Process with a side-stream nitrification reactor
Get PDFThe Hias Process, developed by Hias IKS and Hias How2O, is an enhanced biological phosphorus removal process based on the moving bed biofilm reactor technology. The Hias Process has already shown results for efficient phosphorus removal, but to widen this process’ application, both within Norway and internationally, it is also desired to increase the nitrogen removal efficiency. Currently the nitrogen removal of the Hias process happens through simultaneous nitrification and denitrification, but nitrogen removal efficiencies within the requirements of the Norwegian or European regulations have not yet been reached. Through this Master’s thesis a pilot scale side-stream two-reactor setup for nitrification was implemented to the Hias process. To achieve Norwegian and European removal requirements of at least 70% total nitrogen removal, an initial goal of 60% removal of the sum of ammonia, nitrite and nitrate through the Hias Process was proposed. The experiments were conducted from January through April at Hias wastewater treatment plant. The results show a tendency of increasing nitrogen removal though the experiments, and an average reduction of 57% for ammonia and 54% for the sum of ammonia, nitrite and nitrate was achieved for the last four weeks of the analysis. This was a significant increase relative to the previous test that have been done for nitrogen removal with the Hias Process. Although the 60% mark was not achieved, this side-stream setup shows great promise regarding nitrogen removal in the Hias Process, while not significantly impacting the phosphorus removal
Sluttpolering etter Hias-prosessen : et pilotforsøk med to-media sandfilter
No full textDenne masteroppgaven er skrevet i samarbeid med Hias IKS. Et pilotanlegg ble etablert på Hias renseanlegg i Stange kommune. Pilotanlegget bruker renset avløpsvann hentet fra siste trinn i nåværende renseprosess, diskfilterparken. Forsøksriggen er bygget opp som et nedstrøms to-media filter, med Filtralite NC (1,4-2,5 mm) og Filtralite HC (0,8- 1,6 mm) som filtermedie. Forsøkene er gjennomført i perioden januar til april.
Hovedmålet var å undersøke hvorvidt et tertiært rensetrinn med et sandfilter fungerer som et sluttpoleringstrinn og oppnår partikkelreduksjon samt opprettholder utslippskravet for fosfor på 0,4 mg/L. Det ble gjennomført forsøk for fire ulike drifter av filteret; koagulant før diskfilter, uten tilsatt koagulant, koagulant tilsatt på filterkolonne og polymer tilsatt på filterkolonne. Som koagulant ble EkoFlock 90 (metallbasert polyaluminiumskloridløsning) benyttet, og den kationiske polymeren som ble benyttet var Zetag 8147. For hver driftsbetingelse ble forsøkene gjennomført for middelhastighetene 8 , 10 og 12 m/h.
Resultatene viser at gjennomsnittlig middelhastighet på 8 m/h presterer best, da kombinert med tilsettingen av koagulant på filterkolonnen. Det gir høyest reduksjon og lavest utslipp av partikler. Disse resultatene indikerer at videre undersøkelser bør gjøres med koagulant og polymerdoseringer. Videre vil det være hensiktsmessig å drifte pilotanlegget over lengre tid, med varierende innløpsverdier for å finne gunstige driftsrutiner for tilbakespyling
Final polishing according to the Hias- process : a pilot trial with a two-media sand filter
Get PDFDenne masteroppgaven er skrevet i samarbeid med Hias IKS. Et pilotanlegg ble etablert på Hias renseanlegg i Stange kommune. Pilotanlegget bruker renset avløpsvann hentet fra siste trinn i nåværende renseprosess, diskfilterparken. Forsøksriggen er bygget opp som et nedstrøms to-media filter, med Filtralite NC (1,4-2,5 mm) og Filtralite HC (0,8- 1,6 mm) som filtermedie. Forsøkene er gjennomført i perioden januar til april.
Hovedmålet var å undersøke hvorvidt et tertiært rensetrinn med et sandfilter fungerer som et sluttpoleringstrinn og oppnår partikkelreduksjon samt opprettholder utslippskravet for fosfor på 0,4 mg/L. Det ble gjennomført forsøk for fire ulike drifter av filteret; koagulant før diskfilter, uten tilsatt koagulant, koagulant tilsatt på filterkolonne og polymer tilsatt på filterkolonne. Som koagulant ble EkoFlock 90 (metallbasert polyaluminiumskloridløsning) benyttet, og den kationiske polymeren som ble benyttet var Zetag 8147. For hver driftsbetingelse ble forsøkene gjennomført for middelhastighetene 8 , 10 og 12 m/h.
Resultatene viser at gjennomsnittlig middelhastighet på 8 m/h presterer best, da kombinert med tilsettingen av koagulant på filterkolonnen. Det gir høyest reduksjon og lavest utslipp av partikler. Disse resultatene indikerer at videre undersøkelser bør gjøres med koagulant og polymerdoseringer. Videre vil det være hensiktsmessig å drifte pilotanlegget over lengre tid, med varierende innløpsverdier for å finne gunstige driftsrutiner for tilbakespyling.This master's thesis is written in collaboration with Hias IKS. A pilot plant was established at Hias treatment plant in Stange municipality. The pilot plant uses treated wastewater obtained from the last step in the current cleaning process, the disc filter park. The test rig was a downstream two-media filter, with Filtralite NC (1.4-2.5 mm) and Filtralite HC (0.8-1.6 mm) as filter media.
The main objective of this thesis was to investigate whether a tertiary purification step with a sand filter function as a final polishing step and achieves particle reduction as well as for the emission requirement for phosphorus 0.4 mg / L. Attempts were made to four various operations of the filter; coagulant before disc filter, without added coagulant, coagulant added on filter column and polymer added on filter column. EkoFlock 90 (metal-based polyaluminum chloride solution) were applied as coagulant and the cationic polymer used was Zetag 8147. Attempts were made for each operating condition for the average filter velocities of 8, 10 and 12 m / h.
The results show that the filter velocity of 8 m / h has the highest performance of the tested velocities. When combined with the addition of coagulant on the filter column, it gives the highest reduction and lowest emission of particles.
The operating condition with a coagulant added to the filter column, is the condition that has the highest reduction and lowest emission of particles. These results indicate that further investigations with coagulant and polymer dosages should appear. Furthermore, it will be appropriate to operate the pilot plant over a longer period, with varying inlet values to find favorable operating routines for backwashing.M-V
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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