Dissertations / Theses: 'Water - Purification - Dissolved air flotation'

1

Löf, Ludwig. "Evaluation of Dissolved Air Flotation for Water Purification: With Focus on Floc Characteristics and PFAS." Thesis, KTH, Kemiteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298378.

Full text

Abstract:

I detta projekt har experiment utförts med mål att förse kommunalförbundet Norrvatten med data som kan användas som underlag för beslutsfattande angående om deras fällningslinjer i vattenreningsprocessen ska köras i flotation eller sedimentering. För detta ändamål har koncentrationen av poly- och perfluorerade alkylsubstanser (PFAS) samt karaktär av agglomererade partiklar (flockar) undersökts och jämförts mellan fällningslinjer som körs i olika konfigurationer. För flockkaraktär har skapandet och stabiliteten av flockar varit av intresse, eftersom flotation har ett mer turbulent flöde där flockarna riskerar att brista. Partikelstorlek, storleksfördelning och zeta potential identifierades som egenskaper som reflekterar flockarnas karaktär, dessa analyserades i en zetasizer. Koncentrationen av elva vanligt förekommande PFAS ämnen analyserades i projektet. Resultatet av flockkaraktär tyder på att det ej fanns någon större skillnad i skapandet av flockar samt deras stabilitet mellan de olika fällningslinjerna som undersökts. Detta eftersom zeta potentialen var identisk (-6.45 mV) för de analyserade proverna från respektive process. Analyserna och provberedningen bedömdes ha en hög mätosäkerhet, och några förbättringar som föreslås för att öka säkerheten är genomförande av komplementerande fotoanalys för att bekräfta likheter i utseende mellan flockar, samt att genomföra mer analyser så att en statistisk giltighet av analysen kan kvantifieras. För PFAS koncentrationen så var koncentrationen av PFAS lägre i utgående vatten från fällningslinje som körs i sedimentation (7.5 ng/l), jämfört med prov från linje som körs i flotation (9.2 ng/l). För fällningslinjen som kördes i flotation så skapades skum med höga koncentrationer av PFAS (3800 ng/l) jämfört med analyserade vattenprover (5.5–9.2 ng/l), detta identifierades som en potentiell källa för PFAS-avlägsning. Resultaten av PFAS baserades endast på en provtagningsserie, och förbättringar av validitet kan åstadkommas genom samling av mer analysdata för samma processer, och genom att analysera ett av proverna i två olika instrument, som båda analyserar PFAS koncentration.
In this project, attempts have been made to collect data that allows the municipal association Norrvatten in the decision-making process on the flotation/ sedimentation step of their water treatment process. In this sense, poly- and perfluorinated alkyl substances (PFAS) concentration and the characteristics of agglomerated particles (flocs) have been investigated and compared between the two modes that the process can be operated. For the floc characteristics, the creation and stability of the flocs were investigated, and the particle size, size distribution and zeta potential was identified as important properties and thereafter analysed using the instrument zetasizer. The concentration of eleven different PFAS compounds were analysed. The results of floc characteristics show that there is no major difference in creation and breakage of flocs in the two investigated modes, since the analysed samples had the same zeta potential, -6.45 mV. The results were deemed uncertain because of varying results, and improvement suggestions include using photoanalysis to confirm similar floc appearances and to produce more data so a statistical validity can be quantified. As for the PFAS concentration, the concentration of PFAS were slightly lower in the treatment step in which sedimentation was utilized (7.5 ng/l) compared to when flotation was utilized (9.2 ng/l). The flotation mode did, however, create foam with a high PFAS concentration (3800 ng/l) compared to the liquid samples (5.5-9.2 ng/l), so a potential PFAS removal source was identified. The results were based on one sample series, so improvements of validity can be achieved by gathering more data, analysing more samples, and analysing the same sample in two different instruments measuring PFAS concentrations.

APA, Harvard, Vancouver, ISO, and other styles

2

Dlangamandla, Cynthia. "Bioflocculant dissolved air flotation system for the reduction of suspended solids-lipids-Proteinaceous matter from poultry slaughterhouse wastewater." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2485.

Full text

Abstract:

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2016.
Poultry slaughterhouse wastewater (PSW) contains organic matter that can be degraded by microorganisms. Such matter can further be used by the microbial community as a nutrient source for growth. Moreover, this type of wastewater also contains a high quantity of particulate matter, lipids and proteins, including antimicrobial compounds such as triclosan (TCS) and trichlorocarbanilide (TCC) used during cleaning and sanitising of processing facilities. Lipids and particulate matter lead to clogging of pipes and fouling of diffusers in the wastewater treatment plants (WWTPs). To overcome this problem, a pre-treatment system such as a dissolved air flotation system (DAFs) in which synthetic flocculants are used, is commonly used prior to the biological treatment of the wastewater. Synthetic flocculants add to the environmental burden associated with the use of synthetic compounds, particularly when these compounds are used in WWTPs. This study focused on the reduction of suspended solids, lipids and proteinaceous matter using a bioflocculant- supported DAF for the treatment of PSW.

APA, Harvard, Vancouver, ISO, and other styles

3

Mukandi, Melody. "Modelling of a bioflocculant supported dissolved air flotation system for fats oil and grease laden wastewater pretreatment." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2637.

Full text

Abstract:

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017.
In the recent past, the poultry industry in South Africa has grown due to an increased demand of poultry products as a result of population growth and improved living standards. Furthermore, this has led to poultry slaughterhouses generating high strength wastewater which is laden with a high concentration of organic and inorganic pollutants from the slaughtering process and sanitation of equipment and facilities. As a result, South Africa has promulgated restrictions and a set of quality standards for effluent discharged into the environment to minimize ecological degradation and human health impact. Hence, there is a need for improved Poultry Slaughterhouse Wastewater (PSW) pre-treatment prior to either discharge into municipal wastewater treatment plants (WWTP) or on-site secondary treatment processes such as anaerobic digesters. Additionally, amongst the pre-treatment methods for Fats, Oil and Grease (FOG) laden wastewater, flotation remains the most popular with Dissolved Air Flotation (DAF) system being the most applied. However, modelling and optimization of a biological DAF system has never been attempted before in particular for a bioflocculant supported DAF (BioDAF) for PSW pre-treatment. Process modelling and optimization involves process adjustment to optimize influential parameters. In this study, Response Surface Methodology (RSM) was used to develop an empirical model of a BioDAF for pre-treatment of PSW, for which a bioflocculant producer including production conditions, flocculant type and its floc formation mechanism, were identified. Twenty-one (n = 21) microbial strains were isolated from the PSW and their flocculation activity using kaolin clay suspension (4g/L) was quantified, with a mutated Escherichia coli (mE.coli) [accession number LT906474.1], having the highest flocculation activity even in limited nutrient conditions; hence, it was used for further analysis in other experiments. Furthermore, the optimum conditions for bioflocculant production achieved using RSM were pH of 6.5 and 36°C conditions which induced instantaneous bioflocculant production with the highest flocculation activity. The bioflocculant produced by the mE.coli showed the presence of carboxyl/amine, alkyne and hydroxyl functional groups, which was indicative that the bioflocculant contained both polysaccharides and some amino acids.

APA, Harvard, Vancouver, ISO, and other styles

4

Magalhães, Aléx Fabiano Ribeiro de. "Proposição, implantação, partida e ajustes de reatores biologicos e fisico-quimicos para tratamento e reciclagem de efluentes de lavadores de veiculos em escala real." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258217.

Full text

Abstract:

Orientador: Carlos Gomes da Nave Mendes
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-04T11:01:23Z (GMT). No. of bitstreams: 1 Magalhaes_AlexFabianoRibeirode_M.pdf: 2242026 bytes, checksum: b4ae2e107eb7317d892ade5a7815f862 (MD5) Previous issue date: 2005
Resumo:Com a intenção de preencher a lacuna decorrente de poucos estudos sobre o tratamento de efluentes da lavagem de veículos, na presente pesquisa, propõe-se um sistema de tratamento composto de biofiltros aerados submersos seguidos por flotação por ar dissolvido na remoção dos principais contaminantes contidos nos mesmos. Para isso, foi concebida, instalada e operada uma instalação protótipo em escala real, visando possibilitar a reutilização do efluente tratado. O sistema foi montado em uma transportadora e destinado ao tratamento dos efluentes de lavagens de caminhões tipo baú através de lavador tipo ¿rollover¿. Apesar de terem sido previstos três meses para a operação do sistema, vários problemas de origem operacional do próprio lavador de veículos impediram a realização dos testes de longa duração. Mesmo assim, o período de testes foi útil para estabelecer-se quais alterações físicas deveriam ser incorporadas à instalação proposta para a solução de diversos problemas específicos relativos à concepção original do sistema, subsidiando dados para a otimização de futuros sistemas a serem implantados em escala real. Concluiu-se que, após as modificações introduzidas, tais como a alteração de dispositivos de entrada e saída dos reatores, substituição de acessórios de controle de pressão e vazão, entre outros, a alternativa proposta para tratamento e reúso deste tipo de efluente é plenamente viável
Abstract: With the intention to contribute for aim of filling out the emptiness provoked by few studies on the treatment of carwash affluent, in this research, it intends to create a treatment system composed of aerated submerged biological filter (BAS) following for the dissolved air flotation (FAD) on the removal of the main pollutants present in this effluent type. For that, it was become designed, installed and operated an installation prototype in real scale, seeking the water recycling. The system was installed at cargo transport interprise and destined to the treatment of the carwash effluent type "rollover". In spite of it have been preview three months for the operation time of the system, several operational problems of the washer accomplish of the long time tests. Even so, the time of tests was useful to establish which physical alterations should be incorporate in the installation proposed for the solution of problems to the original conception of the system, subsidizing data for the otimization of the future systems to be implanted in real scale. This research was finish, after the modifications, such as the alteration of inlet and outlet devices of the reactors, pressure and flow control, among other, the proposal alternative for treatment and reuse of rollover type carwash effluent type is fully viable
Mestrado
Saneamento e Ambiente
Mestre em Engenharia Civil

APA, Harvard, Vancouver, ISO, and other styles

5

Vašalovská, Petra. "Modelový výzkum účinnosti separačních technologií úpravy vody." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225461.

Full text

Abstract:

Goal of this research was to recognize dissolved air flotation efficiency by the help of turbidity and UV absorbance removal for different conditions. As different conditions are meant the efficiency for different baffle position, different detention time in separation zone and checking results with adding chemicals compared to results without adding chemicals.

APA, Harvard, Vancouver, ISO, and other styles

6

Petiraksakul, Anurak. "The efficiency of particle removal by dissolved air flotation." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/11168.

Full text

Abstract:

The efficiency of flotation processes may be improved through an understanding of the flotation models. Two mathematical models, particle trajectory and mixing zone models, have been modified and used to describe flotation results obtained from a semi-continuous flotation rig. Two types of clay suspensions, kaolin and Wyoming bentonite, were used as representative raw materials treated with a cationic surfactant, hexadecyltrimethylammonium bromide (HT AB), and/or coagulants i.e. alum, ferric chloride and polyaluminium chloride (PAC). HT AB concentrations were varied in the range of I x 10-6 to 3 x 10-5 mol/L. Alum at a concentration of 40 mg/L, ferric chloride at 40 mg/L and PAC at 10 mg/L were the selected coagulant dosages to be used in flotation tests. For the clay-HT AB-coagulant system, a HT AB concentration of I x 10-s mol/L was used in the flotation tests. Suspension flow rate was chosen at 2 Llmin and recycle ratios were varied in the range of 6-40% at room temperature. Two categories, suspensions with and without flocs, have been considered. The trajectory model gave a good match even taking account of the decreases In flotation efficiency at high recycle ratios where flocs had been broken by shear gradients. This model included hydrodynamic and surface forces i.e. electrostatic, van der Waals and hydrophobic forces and was calculated by a Runge Kutta technique. The effect of the shear force on a size reduction was determined from particle size measurements (Lasentec apparatus) in a mixing tank and the results showed a decrease of floc sizes with increasing agitator speeds. Bubble zeta potentials obtained using a modified rectangular cell in a Rank Brothers' apparatus gave points of zero charge at concentrations of 1.61 x 10-9 mollL for HTAB, 1.69 x 10-8 mol/L for tetradecyltrimethylammonium (TTAB) and 2.37 x 10-7 mol/L for dodecyltrimethylammonium bromide (DTAB) at 2SoC respectively. Van der Waals and hydrophobic or hydration forces were obtained from contact angle measurements on solid surfaces. The hydrophobic forces were increased by increasing HT AB concentrations while the hydration effects occurred upon the addition of coagulants to the suspensions. A flocculation model using the extended-DLVO theory showed a good correlation when compared to experimental results. For the mixing zone model, an attachment efficiency for the aggregation of a particle and a bubble was proposed from a ratio between the energy barrier (E1) and the maximum free energy at equilibrium. When particle size is constant, the attachment efficiency values rise with increasing hydrophobic force levels. On the other hand, when floc sizes are increased, the attachment efficiencies are decreased due to the increase in the repulsive long range van der Waals force.

APA, Harvard, Vancouver, ISO, and other styles

7

Al-Shamrani, Abdullah A. M. "Destabilisation of oil-water emulsions and separation using dissolved air flotation." Thesis, University of Manchester, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488142.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

McLoughlin, Liam. "A comparative study of flocculative water treatment by dissolved air flotation and sedimentation." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284679.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Sjölander, Anna. "The effect of water chemistry and fibre-size distribution on dissolved air flotation efficiency." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-19306.

Full text

Abstract:

The purpose of this diploma work was to investigate the problem of insufficient fibre recovery in the dissolved air flotation-cell at the new thermomechanical pulping-line at Braviken Paper Mill. An investigation of the effect of process parameters on the removal efficiency in the micro-flotation process was undertaken.

The experiments were carried out for two setups at the Noss pilot plant with a small-scale flotation unit. Factorial design helped plan the experiments and four factors were controlled; temperature, fibre-size distribution, water quality and feed concentration. Three samples, feed, overflow and filtrate, were taken from each experiment and concentration measurements were made. The results were analyzed using the software MODDE.

The results from showed an influence from the fibre-size distribution. To see if the fibre-size distribution really had an effect on the results, follow-up experiments were carried out. These experiments showed no influence from temperature, fibre-size distribution or water quality. This concludes that none of those three factors influenced the results significantly.

Additional experiments were done to examine the influence from concentration and fibre-size distribution on the flotation efficiency and these showed an influence from the feed concentration. When increasing the feed concentration the efficiency of the flotation process decreased.

APA, Harvard, Vancouver, ISO, and other styles

10

Mohamad, Radzi Aliff R. "Removal of oil droplets from oil-in-water mixtures by dissolved air flotation (DAF)." Thesis, University of Surrey, 2017. http://epubs.surrey.ac.uk/813553/.

Full text

Abstract:

Dissolved air flotation (DAF) is a separation technique, often used after a primary gravity separator to enhance the quality of the wastewater, so it can be released to streams, rivers, and the sea in a manner not to violate the environment. DAF works by removing oil droplets from oil-in-water mixtures by air bubbles of an average diameter of 50 μm with a standard deviation of 5.5 μm. The air bubbles used in these experiments were generated as a result of rapid pressure reduction of water saturated with air when it released from the bottom of the DAF tank. The main aim of the DAF experiments reported here was to measure the removal efficiency of oil droplet mostly in a diameter range between 15 and 80 μm that were created using a static mixer. The DAF tank located at the University of Surrey was a scale model of existing DAF unit used by Thames Water plc. The effects of seven operating parameters that are believed to affect the performance of DAF were investigated. The operating parameters consist of inlet oil concentration, air saturator pressure, temperature, the salinity of continuous phase, type of oil, flow rate of the mixture and coagulant dosage. Two independent analysis methods were used to estimate the removal efficiency of oil droplet. They are a droplet counting and an oil-in-water measuring methods. The droplet counting method used a Coulter Counter that provided numbers of oil droplet passed through the aperture based on the selected size range. The oil-in-water measuring method used an ultraviolet and visible spectroscopy (UV-Vis), which the removal efficiencies were estimated from the absorbance values that were measured at the optimum wavelength of 400 nm. The analyses done with these two methods found that the inlet oil concentration and flow rate of the mixture into DAF tank were inversely proportional to the oil droplet removal efficiency. The other parameters such as saturator pressure, temperature, water salinity and alum dosage were directly proportional to the oil droplet removal efficiency. Vegetable oil, which has larger spreading coefficient than lamp oil obtained a better oil droplet removal efficiency. Coulter Counter showed that a better removal efficiency for vegetable oil obtained at larger oil droplet ranges size, 50μm and above. This was because the oil droplets were removed by gravity and enhanced by air bubbles. Contrary to lamp oil, which the worst removal efficiency was obtained at larger size ranges due to the coalescence of oil droplets. Results from these experiments were used to obtain a correlation that can predict removal efficiency. This was done by performing dimensional analysis. It was carried out using Buckingham Pi and scaling methods. It involved with the identification of two non-dimension and nine dimensional parameters. The dimensional analysis concluded that the removal efficiency is a function of eight other dimensionless groups, which are ratio of inlet oil and mixture flow rate.

APA, Harvard, Vancouver, ISO, and other styles

11

Bakeev, Emil Almazovich. "The risk of tank geometry on the performance of dissolved air flotation in portable water treatment." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268363.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Gonzalez, Galvis Juan Pablo. "Development of a Large Batch Bench-Scale Dissolved Air Flotation System for Drinking Water Treatability Tests." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39336.

Full text

Abstract:

The dissolved air flotation (DAF) has been used in drinking water treatment for its excellent algae and natural organic matter (NOM) removal. DAF drinking water treatability test are often conducted in a DAF jar test apparatus. Although, DAF jar test studies showed that they were able to predict NOM removals at full-scale facilities well, they have not always been successful in predicting the turbidity removals. One possible reason of the DAF jar test inaccuracy results could be associated to the small jar diameter, which may create wall effects. Therefore, the first two objectives of this research are: a) to develop and test a new, larger diameter and larger volume batch bench-scale dissolved air flotation system (LB-DAF) to better simulate turbidity removals in drinking water applications; b) to confirm these results by comparing the LB-DAF and full-scale DAF turbidity removals for two other source waters. The raw water characteristics of the three plants were quite different and the testing was performed at different times of the year. The development/optimization of the LB-DAF evaluated the impact of different variables (i.e., mixing intensity, water depth/tank diameter ratio, impeller shape, saturator pressure and recycle ratio). The results showed that the LB-DAF predicted well the full-scale DAF turbidity removals at three water treatment plants, and these predictions were better than those of DAF jar tests. For the LB-DAF design and operational variables evaluated had a limited impact on the turbidity removals. The LB-DAF predicted well DAF full-scale turbidity removals regardless of water temperature. This is an indication of the robustness of the DAF system. Ballasted sedimentation (BS) is a compact coagulation/flocculation and sedimentation process combination that has become very popular because it is very compact and because it can handle large variations in raw water turbidity and NOM. The literature survey did not initially identify studies on the BS treatment of algal impacted waters, for which DAF is considered particularly suitable. Thus, the third main objective of this dissertation was to compare the efficiency of BS with that conventional gravity settling (CGS), and that of DAF for the treatment of an algal impacted water via jar tests. These comparisons were performed at the Belleville Water Treatment Plant using Bay of Quinte water, one of the most eutrophic zones of Lake Ontario. Unfortunately, a change of weather prior to the testing resulted in raw water samples with relatively low concentrations of algae and cyanobacteria. The testing showed that DAF and BS had very similar NOM, cyanobacteria/algae (chlorophyll a and phycocyanin) removals.; however, the BS required microsand addition, polymer addition and a slightly higher alum dose. Only for turbidity removal the DAF was somewhat superior. It is suggested that these comparison experiments be repeated with waters that are more impacted by algae and cyanobacteria.

APA, Harvard, Vancouver, ISO, and other styles

13

Slacke, Mark Philip. "The potential use of lignin Mannich bases as flocculating agent in white water clarification using dissolved air flotation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0005/MQ33754.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Sartori, Luci. "Influência do uso de polímeros sintéticos no desempenho da flotação por ar dissolvido aplicada no tratamento de água para abastecimento." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-12092016-105327/.

Full text

Abstract:

O uso de polímeros sintéticos como auxiliares de floculação no tratamento de águas para abastecimento é uma prática que vem sendo bastante estimulada. Contudo o uso na floculação visando a flotação de águas para abastecimento tem sido pouco estudado. Neste trabalho, são apresentados os resultados de estudo da influência da aplicação de polímeros sintéticos como auxiliares de floculação na clarificação, por flotação, de água preparada com cor elevada (100 ± 9,0 uC) e baixa turbidez (6,80 ± 1,0 uT). Foram investigados três diferentes tipos de polímeros (catiônico, aniônico e não iônico), aplicados conjuntamente ao coagulante primário (sulfato de alumínio). Após a otimização da dosagem deste coagulante (40 mg/L), sem emprego de polímeros, foi estudado o desempenho da flotação diante a redução da dosagem de coagulante conjugado à aplicação de diferentes dosagens de polímeros. Também foram investigadas a influência do tempo decorrido após a mistura rápida para a adição do polímero, e do tempo e gradiente médio de velocidade na floculação para a flotação. Foram utilizadas duas unidades de flotação por ar dissolvido, uma em escala de laboratório (Flotateste) e outra em escala piloto (com escoamento contínuo). Após a adequação dos parâmetros de floculação, os ensaios obtidos com o flotateste mostraram que a aplicação de 0,25 mg/L de polímero não iônico permitiu a redução de 50% na dosagem de coagulante, sem queda significativa na eficiência de remoção de cor e turbidez (96% e 93% respectivamente). Por sua vez, o polímero catiônico, na dosagem de 0,25 mg/L, possibilitou redução de 70% na dosagem de sulfato de alumínio, com eficiência de remoção de cor e turbidez de 90%. A instalação piloto de flotação operando com TASap de 262 m3/m2d, e aplicação de polímeros, nas condições otimizadas com o flotateste, foi capaz de fornecer bons resultados de remoção de cor aparente (82% e cor no efluente de 18,6 uC) e de turbidez (80% com turbidez de 1,40 uT no efluente). Nos ensaios com a unidade piloto de flotação operando com TASap de 525 m3/m2d, com redução de 70% na dosagem de coagulante (aplicação de 0,25 mg/L de polímero catiônico), observou-se redução de até 79% na massa de Iodo gerada.
The usage of synthetic polymers as flocculation aids for the treatment of supply water is a practice which have been widely stimulated, however its usage in flocculation aiming supply water flocculation has been scarcely studied. This work presents the results of the study of the influence of synthetic polymer application as a flocculation aids for clarifying prepared water containing high levei of color (100 ± 9.0 CU) and low turbidity (6.80 ± 1.0 NTU) through flotation. Three different kinds of polymers were investigated - cationic, anionic and non-ionic - which were applied together with the primary cogulant (aluminium sulphate). After the optimization of this coagulant dosage (40 mg/L), without the utilization of polymers, it was studied the flotation performance by the reduction of the coagulant dosage together with the application of different polymer dosages. It was also studied the influence of the time after rapid mixing for the polymer addition, and of time and average velocity gradient and flotation. Two units of dissolved air flotation were used, a bench unit and a pilot plant unit (with continuous flow). After the flocculation parameters adequacy, the essays obtained with FLOTATESTE showed that the application of 0.5 mg/L of non-ionic polymer allowed a reduction of 50% on coagulant dosage, without meningful drops of the color and turbidity removal efficient (96% and 93% respectively). On the other hand, the cationic polymer, at 0.25 mg/L, enabled a 70% reduction on the aluminium sulphate dosage with color and turbidity removal efficiency of 90%. The plant flotation unit, operating under a flow rate of 262 m3/m2d and with polymer application, under conditions optimized by FLOTATESTE, was able to provide good results of colour removal (82% and effluent color of 18.6 CU) and turbicity removal (83% with turbicity of 1.23 NTU in the effluent). In the essays with the pilot plant flotation unit, operating under a flow rate of 525 m3/m2d after reduction of 70% on the coagulant dosage (application of 0,25 mg/L of cationic polymer) , an up to 79% reduction in mass of sludge generated was observed.

APA, Harvard, Vancouver, ISO, and other styles

15

Paz, Júnior Gilberto José da [UNESP]. "Uso de floculador hidráulico de manta de lodo acoplado a flotador por ar dissolvido no tratamento de água de abastecimento." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/98069.

Full text

Abstract:

Made available in DSpace on 2014-06-11T19:29:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-10-09Bitstream added on 2014-06-13T19:38:24Z : No. of bitstreams: 1 pazjunior_gj_me_ilha.pdf: 2578429 bytes, checksum: 46851cc20a1e31876058f21101609b1f (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Novas tecnologias para o tratamento de água vêem sendo desenvolvidas e suas combinações podem apresentar bons resultados principalmente quando submetidas a variações sazonais de origem natural e antropicas. A crescente poluição dos corpos d’água causa florescimentos de algas e cianobactérias nos mananciais, com aparecimento de sabor e odor na água bruta, podendo ocorrer também a liberação de toxinas pelas cianobactérias. Os processos de tratamento de água convencionais têm apresentado deficiências quanto à remoção de cianobactérias e cianotoxinas, principalmente quanto ao aspecto de remoção das células viáveis e na capacidade de remover as toxinas extracelulares. As cianobactérias retidas no lodo dos decantadores representam riscos à qualidade final da água tratada. O presente projeto de pesquisa consistiu em experiência com floco-decantador de manta de lodo acoplado a flotador por ar dissolvido, formando um conjunto composto pelos dois tipos de equipamentos ou tecnologias e ainda com dispositivo limitador de manta. O objetivo da pesquisa foi avaliar o desempenho da instalação proposta quando submetida a variações da qualidade da água bruta, principalmente quando submetido à sobrecarga de algas e cianobactérias, simulando possíveis florações nos mananciais. Os resultados dos ensaios no modulo experimental com água natural apresentaram remoção satisfatória de turbidez , com valores abaixo de 3,0 uT da água floco-floto-decantada e em torno de 0,1 uT da água filtrada. Os ensaios realizados com água natural com presença elevada de algas e cianobactérias, evidenciaram a importância da unidade de flotação, com remoção de clorofila_a de 82% na água decantada/flotada e próximo de 99% na água filtrada, em relação à água bruta, sendo que a turbidez manteve-se abaixo de 3 uT na saída do modulo floco-floto-decantador e a turbidez...
New technologies for water treatment have been developed and their combinations can produce good results especially when subjected to seasonal variations of natural and anthropogenic. The increasing pollution of water bodies causes blooms of algae and cyanobacteria in water sources, with the appearance of taste and odor in raw water, but may also occur the release of toxins by cyanobacteria. The processes of conventional water treatment have shown deficiencies in the removal of cyanobacteria and cyanotoxins, especially on the aspect of removal of viable cells and the ability to remove extracellular toxins. Cyanobacteria retained in the sludge of the sedimentation tanks pose to the final quality of treated water. This research project was to experiment with floc-settling sludge blanket coupled to dissolved air flotation, forming a group composed of two types of equipment or technology, and with relief device blanket. The research aimed to evaluate the performance of the proposed development when subjected to variations in raw water quality, especially when subjected to the overload of algae and cyanobacteria to simulate possible blooms in the springs. The results of tests on an experimental module with natural water showed satisfactory removal of turbidity, with values below 3 uT decanted and around 0,1 uT filtered water. Tests conducted with water with high presence of algae and cyanobacteria, have highlighted the importance of unity flotation Chlorophyll “a” with removal of 82% in the decanted water / rappel and around 99% in filtered water compared to raw water, and the turbidity remained below 3 uT the output of modulo-flake-floto sedimentation and turbidity of filtered water was below 0,6 uT. The limiting device of the ground and periodic removal of sludge, decreased the retention time of the cells retained in the sludge which may have prevented the release of toxins into the water... (Complete abstract click electronic access below)

APA, Harvard, Vancouver, ISO, and other styles

16

Chaves, Karina Oliveira. "Desenvolvimento e aplicaÃÃo de sistema de Floco-FlotaÃÃo por Ar Dissolvido para tratamento de Ãgua de lavagem do filtro da ETA GaviÃo." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8123.

Full text

Abstract:

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
No cenÃrio brasileiro, os resÃduos de EstaÃÃes de Tratamento de Ãgua (ETAs) sÃo normalmente lanÃados in natura em corpos hÃdricos, apresentando-se como potencialmente danosos ao meio ambiente, sendo necessÃrio tratÃ-los para que sejam descartados conforme os aspectos legais. Estudos demonstram que a tecnologia da FlotaÃÃo por Ar Dissolvido (FAD) tem sido viÃvel para este fim. Acredita-se que a incorporaÃÃo da floculaÃÃo em cortinas numa mesma unidade de flotaÃÃo possa promover elevada eficÃcia ao sistema, traduzindo-se como uma inovaÃÃo tecnolÃgica: o Floco-Flotador por Ar Dissolvido (FFAD). Uma unidade piloto de FFAD foi construÃda para o tratamento da Ãgua de lavagem dos filtros da ETA GaviÃo, pertencente Ã Companhia de Ãgua e Esgoto do CearÃ (CAGECE). Esta pesquisa teve como objetivo quantificar e verificar o atendimento da Ãgua de lavagem dos filtros (ALF) desta ETA e da Ãgua clarificada via FFAD aos padrÃes de lanÃamento de efluentes conforme as ResoluÃÃes nÂ 430/11 e 357/05 do CONAMA e Portaria nÂ 154/2002 da SEMACE. Estudos de tratabilidade da ALF em Jartest foram realizados para avaliar a influÃncia da dosagem de polÃmeros catiÃnicos e a viabilidade de gradientes de velocidade decrescente (35 a 5,6 s-1) a serem empregados no equipamento de FFAD desenvolvido. Ensaios de flotaÃÃo foram realizados a fim de avaliar a dosagem do polÃmero e os parÃmetros de processo como taxas de recirculaÃÃo (TR) e taxas de aplicaÃÃo superficial (TAS). ApÃs definidos estes parÃmetros, ensaios de FFAD foram realizados em triplicata para coleta da AC a fim de comparÃ-la com os principais padrÃes de lanÃamento de efluente em corpos hÃdricos classe II. Somente os parÃmetros pH, Fluoreto, AmÃnia, E. coli e SÃlidos dissolvidos da ALF atenderam aos padrÃes de lanÃamento. Ao aplicar polÃmero a 1 mg.L-1, taxa de recirculaÃÃo de 15%, gradientes de velocidade decrescente (19,3 a 5,6 s-1), taxa de aplicaÃÃo superficial de 57 m3.m-2.d-1 com tempo de detenÃÃo hidrÃulico de 22 minutos no FFAD, os resultados alcanÃaram elevada eficiÃncia na remoÃÃo de turbidez (superior a 98%) mesmo enfrentando variaÃÃes bruscas na qualidade da ALF (94,4 a 410 UT). Observou-se tambÃm significativa eficiÃncia mÃdia na remoÃÃo de coliformes totais (98,5%), cor aparente (97,6%), DQO (92,6%) e remoÃÃo de alumÃnio (84,1%). Diante destes resultados, constatou-se que a ALF da ETA GaviÃo tratada via Floco-flotaÃÃo por ar dissolvido atendeu aos referidos padrÃes de lanÃamento em corpos hÃdricos.
In Brazil the filter backwash wastewater is normally released in to the water resources without proper treatment, representing a potential danger to the environment. Thus, it is necessary to treat this wastewater in order to dispose it in accordance to federal and state environmental laws. Studies show that Dissolved Air Flotation (DAF) technology has been feasible for this purpose. It is believed that the incorporation of flocculation in curtains and air dissolved flotation system in the same unit can promote high efficiency and significant size reduction, which translates in a technological innovation: the Floculator - Dissolved Air Flotation (FFAD) unit. A FFAD pilot unit was built to evaluate the treatment of GaviÃo Water Treatment Plant filter backwash wastewater, owned by the Water and Wastewater Company of CearÃ (CAGECE). This research had as main objective to quantify and verify the compliance of the filter backwash wastewater parameters to the Resolution No. 430/11 and 357/05 of CONAMA and Ordinance No. 154/2002 of SEMACE. Treatability studies were performed with filter backwash wastewater using Jartest to evaluate the influence of cationic polymer dosages and the feasibility of decreasing flocculation velocity gradients (35 to 5.6 s-1) in the FFAD. Experimental runs of the flocculation - flotation system were performed to evaluate the best polymer dosage and the process parameters such as recirculation rates (TR) and surface application rates (TAS). These parameters were compared by observing the lower residual turbidity and best removal efficiency in the clarified water (AC). The treated wastewater was again characterized using physicalchemical and bacteriological parameters and compared to the specific legislation. The results showed that the use of 1 mg.L-1 of polymer, recirculation rate of 15% and surface application rate of 57 m3.m-2.d-1, presented the highest turbidity efficiency removal (> 98%) and a very stable performance against sudden changes in the influent quality (94.4 to 410UT). It should be noted that the unity showed also a high average efficiency total coliforms removal (98.5%), apparent color removal (97.6%), DOC removal (92.6%), of aluminum (84.1%) removal and turbidity (99.2 %) removal. Given these results, it was concluded that the AC coming from the treatment of ALF by ETA WTP GaviÃo FFAD met the discharge parameters listed for water resources.

APA, Harvard, Vancouver, ISO, and other styles

17

Paz, Júnior Gilberto José da. "Uso de floculador hidráulico de manta de lodo acoplado a flotador por ar dissolvido no tratamento de água de abastecimento /." Ilha Solteira : [s.n.], 2009. http://hdl.handle.net/11449/98069.

Full text

Abstract:

Orientador: Edson Pereira Tangerino
Banca: Dib Gebara
Banca: Carlos Gomes da Nave Mendes
Resumo: Novas tecnologias para o tratamento de água vêem sendo desenvolvidas e suas combinações podem apresentar bons resultados principalmente quando submetidas a variações sazonais de origem natural e antropicas. A crescente poluição dos corpos d'água causa florescimentos de algas e cianobactérias nos mananciais, com aparecimento de sabor e odor na água bruta, podendo ocorrer também a liberação de toxinas pelas cianobactérias. Os processos de tratamento de água convencionais têm apresentado deficiências quanto à remoção de cianobactérias e cianotoxinas, principalmente quanto ao aspecto de remoção das células viáveis e na capacidade de remover as toxinas extracelulares. As cianobactérias retidas no lodo dos decantadores representam riscos à qualidade final da água tratada. O presente projeto de pesquisa consistiu em experiência com floco-decantador de manta de lodo acoplado a flotador por ar dissolvido, formando um conjunto composto pelos dois tipos de equipamentos ou tecnologias e ainda com dispositivo limitador de manta. O objetivo da pesquisa foi avaliar o desempenho da instalação proposta quando submetida a variações da qualidade da água bruta, principalmente quando submetido à sobrecarga de algas e cianobactérias, simulando possíveis florações nos mananciais. Os resultados dos ensaios no modulo experimental com água natural apresentaram remoção satisfatória de turbidez , com valores abaixo de 3,0 uT da água floco-floto-decantada e em torno de 0,1 uT da água filtrada. Os ensaios realizados com água natural com presença elevada de algas e cianobactérias, evidenciaram a importância da unidade de flotação, com remoção de clorofila_a de 82% na água decantada/flotada e próximo de 99% na água filtrada, em relação à água bruta, sendo que a turbidez manteve-se abaixo de 3 uT na saída do modulo floco-floto-decantador e a turbidez... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: New technologies for water treatment have been developed and their combinations can produce good results especially when subjected to seasonal variations of natural and anthropogenic. The increasing pollution of water bodies causes blooms of algae and cyanobacteria in water sources, with the appearance of taste and odor in raw water, but may also occur the release of toxins by cyanobacteria. The processes of conventional water treatment have shown deficiencies in the removal of cyanobacteria and cyanotoxins, especially on the aspect of removal of viable cells and the ability to remove extracellular toxins. Cyanobacteria retained in the sludge of the sedimentation tanks pose to the final quality of treated water. This research project was to experiment with floc-settling sludge blanket coupled to dissolved air flotation, forming a group composed of two types of equipment or technology, and with relief device blanket. The research aimed to evaluate the performance of the proposed development when subjected to variations in raw water quality, especially when subjected to the overload of algae and cyanobacteria to simulate possible blooms in the springs. The results of tests on an experimental module with natural water showed satisfactory removal of turbidity, with values below 3 uT decanted and around 0,1 uT filtered water. Tests conducted with water with high presence of algae and cyanobacteria, have highlighted the importance of unity flotation Chlorophyll "a" with removal of 82% in the decanted water / rappel and around 99% in filtered water compared to raw water, and the turbidity remained below 3 uT the output of modulo-flake-floto sedimentation and turbidity of filtered water was below 0,6 uT. The limiting device of the ground and periodic removal of sludge, decreased the retention time of the cells retained in the sludge which may have prevented the release of toxins into the water... (Complete abstract click electronic access below)
Mestre

APA, Harvard, Vancouver, ISO, and other styles

18

Pioltine, Andre. "Influência do tamanho de partículas floculadas na eficiência da clarificação de águas para abastecimento por flotação." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-06062013-113030/.

Full text

Abstract:

A presente pesquisa teve por objetivo a investigação da influência do tamanho de partículas floculadas na eficiência da clarificação de águas para abastecimento por flotação por ar dissolvido (FAD) com o emprego de método e equipamento para a aquisição e análise de imagens especialmente desenvolvidos, tendo em vista à caracterização da distribuição de tamanho de flocos e microbolhas de ar, bem como, o estudo dos aglomerados bolhas-floco (em termos de número de microbolhas de ar aderidas e velocidade ascensional) presentes no processo de flotação e comparação dos dados experimentais àqueles obtidos em simulação com o emprego do modelo matemático proposto por Reali (1991). Os ensaios foram realizados com água sintética (turbidez de 7,5±0,2 NTU; cor aparente de 38±1 uC; alcalinidade de 29,8±0,6 mg\'CA\'CO IND.3\'/L; condutividade de 59,3±0,8 \'mü\'S/cm; UV254nm de 0,128±0,004 \'CM POT.-1\'), a qual foi coagulada com a aplicação de 1,9 mg/L de \'AL POT. 3+\' (pH de 6,6±0,05) e divididos em duas Fases: Fase 1 - ensaios preliminares realizados em escala de laboratório, com o emprego do flotateste; Fase 2 - ensaios realizados em unidade piloto de flotação. Os resultados alcançados demonstraram que: i) a distribuição de tamanho de partículas floculadas influenciou diretamente a clarificação por flotação da água em estudo, sendo que as melhores condições de floculação foram aquelas que conduziram à formação, em sua maioria, de partículas floculadas com diâmetro médio de Feret acima de 300 \'mü\'m; ii) os menores valores residuais dos parâmetros analisados na água em estudo foram alcançados com o emprego do tempo de floculação de 17 min, entretanto a FAD foi capaz de operar também com boa eficiência com a utilização de tempo de floculação de 10 min; iii) o método e equipamento desenvolvidos nesta pesquisa para a aquisição e análise de imagens demonstraram constituir importantes ferramentas para a obtenção das distribuições de tamanho de flocos e microbolhas de ar, bem como, para a determinação do número de microbolhas de ar aderidas às superfícies dos flocos e da velocidade ascensional dos aglomerados bolhas-floco gerados no processo de flotação; iv) mesmo com as diversas simplificações adotadas no desenvolvimento do modelo matemático analisado e considerando as condições experimentais utilizadas nesta pesquisa, foi possível verificar para a água em estudo e para as condições operacionais empregadas nesta pesquisa, que a modelação matemática proposta por Reali (1991) foi capaz de fornecer subsídios para uma adequada estimativa do número de microbolhas de ar aderidas aos flocos, bem como, das velocidades ascensionais dos aglomerados bolhas-floco.
The goal of this research was to investigate the flocculated particles size distribution influence on the dissolved air flotation (DAF) efficiency. Special image acquisition method and equipment were used to characterize the flocculated particles and air microbubbles size distribution, as well as, the clusters (in terms of microbubbles number adhered and rise velocity) in the contact zone outlet of the DAF unit. Besides that, the experimental results were compared with those obtained from the DAF modeling proposed by Reali (1991). The trials were carried out with synthetic water (temperature of 26.0 ± 0.5oC; turbidity of 7.5±0.2 NTU; apparent color of 38±1 CU; alkalinity of 29.8±0.6 mg\'CA\'\'CO IND.3\'/L; conductivity of 59.3±0.8 \'mü\'S/cm; UV254nm of 0.128±0.004 \'CM POT.-1\'), that it was coagulated by applying 1.9 mg/L of \'AL POT.3+\' (22.5 mg/L alum). The trials were divided into two phases: Phase 1 - preliminary tests carried out in laboratory facilities (flotatest); Phase 2 - tests carried out in pilot facilities (DAF pilot unit). The results showed that: i) the flocculation conditions interfered directly on the efficiency of DAF process, and the best flocculation conditions were those that conducted to formation of flocculated particles size with Feret mean diameter above 300 \'mü\'m; ii) the best results were obtained applying flocculation time of 17 min, however, DAF was also capable of operating with a satisfactory efficiency when applying flocculation time of 10 min; iii) the special image acquisition method and equipment developed in this research proved to be a important tool to characterize the flocculated particles and air microbubbles size distribution, as well as, the number of air microbubbles adhered to the flocs surface and the clusters rise velocity; iv) the DAF modeling developed by Reali (1991) provided a reliable prediction of the microbubbles number adhered to the flocs surface, as well as, the clusters rise velocity.

APA, Harvard, Vancouver, ISO, and other styles

19

Oliveira, Gislayne Alves. "REMOÇÃO DE CIANOBACTÉRIAS DE ÁGUAS POR PROCESSO DE FLOTAÇÃO POR AR DISSOLVIDO." Universidade Federal de Santa Maria, 2016. http://repositorio.ufsm.br/handle/1/7655.

Full text

Abstract:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Human activities generate qualitative and quantitative impacts of water resources which vary in intensity with the occupation and urbanization of a watershed, create a big problem due to the high concentration of nutrients. The nutrients released into waterways, when they exceed the limit self-purification of water resources can cause algal blooms and the development of cyanobacteria, which can be toxic organisms and has been negatively highlighting the water treatment system for public supply. This is because the conventional treatments are not effective for the removal of the cyanobacteria, and cause harmful effects to human health, but often the conditions are more precarious not occurring treatment before consumption. Many chemical agents used in the treatment can be reacted with cyanobacteria, causing cell lysis (breakage) worsening the dispersion of toxins in water. Accordingly, it was evaluated the removal efficiency of Dolichospermum cylindrica cyanobacterial species, as well as identify the best operating conditions and comparison of the application of natural coagulant - tannin with aluminum sulfate, using dissolved air flotation (DAF). The experiments were developed in bench scale using the equipment: pitchers test (coagulation / flocculation) and the bench flotation (DAF). The tests were conducted at different phases when using the two tested coagulants. In the first step we tried to determine the zeta potential of cyanobacteria, in the second part we build the coagulation diagram (pH coagulation x coagulant dosage), followed by flocculation tests which sought better results for the velocity gradient (Gf) and time flocculation (Tm) and at the end evaluate the FAD testing the design parameters such as saturation pressure (Psat), recirculation rate (R) and flotation velocity (Vf). The performance of the treatment system was evaluated from the cell count. The results show that the cells of cyanobacteria had no change in zeta potential in relation to different pH ranges, and negative behavior ranging from -25.7 to -20.1 mV. In the construction of the coagulation diagram aluminum sulfate coagulation showed a broad pH range (4.5 to 9), reducing a bit pH range when used as the tannin coagulant (6-9). Both coagulants showed excellent results using the DAF, but aluminum sulfate showed higher removal (97.93%), even with the lowest removal (87.97%) tannin ends up being more suitable for being biodegradable, and having adsorption capacity for metals in the water. In relation to the parameters of this design, it was noticed that it is better removal using aluminum sulphate Gf to 25 s-1, Tm 15 minutes, Psat 300 kPa, and R 10% Vf 2.5 cm.min-1 and tannin Gf 50 s-1, Tm 10 minutes, Psat 300 kPa, and R 15% Vf 2 cm.min-1. In general, FAD has shown good results for your application in the removal of cyanobacteria.
As atividades humanas geram impactos quali-quantitativos nos recursos hídricos que variam de intensidade com a ocupação e urbanização de uma bacia hidrográfica, gerando um grande problema devido à alta concentração de nutrientes. Os nutrientes lançados nos cursos d água, quando superam o limite de autodepuração dos recursos hídricos podem provocar a proliferação de algas e o desenvolvimento de cianobactérias, que são organismos que podem ser tóxicos e vem se destacando negativamente no sistema de tratamento de água para abastecimento público. Isso porque os tratamentos convencionais não são eficientes para a remoção das cianobactérias, e provocam efeitos deletérios à saúde humana, porém muitas das vezes as condições são mais precárias não ocorrendo o tratamento antes do consumo. Muitos agentes químicos utilizados no tratamento podem reagir com as cianobactérias, provocando a lise celular (rompimento) agravando a dispersão de toxinas na água. Nesse sentido, avaliou-se a eficiência na remoção de cianobactérias da espécie Dolichospermum cylindrica, assim como identificação das melhores condições de operação e comparação da aplicação do coagulante natural - tanino com o sulfato de alumínio, utilizando a flotação por ar dissolvido (FAD). Os experimentos foram desenvolvidos em escala de bancada utilizando os equipamentos: teste de jarros (coagulação/floculação) e o flotador de bancada (FAD). Os testes foram realizados em fases distintas sempre utilizando os dois coagulantes testados. Na primeira etapa procurou-se determinar o potencial zeta das cianobactérias e na segunda etapa construir o diagrama de coagulação (pH de coagulação x dosagem de coagulante), seguido dos testes de floculação a qual buscou melhores resultados para o gradiente de velocidade (Gf) e tempo de floculação (Tf) e por final avaliar a FAD testando os parâmetros de projeto como pressão de saturação (Psat), taxa de recirculação (R) e velocidade de flotação (Vf). O desempenho do sistema de tratamento foi avaliado a partir da contagem das células. Os resultados mostram que as células de cianobactéria não tiveram variação no potencial zeta em relação a diferentes faixas de pH, tendo um comportamento negativo variando de -25,7 a -20,1 mV. Na construção do diagrama de coagulação o sulfato de alumínio apresentou uma ampla faixa de pH de coagulação (4,5-9), reduzindo um pouco a faixa de pH quando utilizado o tanino como coagulante (6-9). Ambos os coagulantes apresentaram resultados excelentes utilizando a FAD, porém o sulfato de alumínio apresentou remoções mais elevadas (97,93%), mesmo com a remoção mais baixa (87,97%) o tanino acaba sendo mais indicado por ser biodegradável, além de ter a capacidade de adsorção de metais presentes na água. Em relação aos parâmetros de projeto avaliados, verificou-se melhores remoções utilizando o sulfato de alumínio para Gf 25 s-1, Tf 15 min, Psat 300 kPa, R 10% e Vf 2,5 cm.min-1 e para o tanino Gf 50 s-1, Tf 10 min, Psat 300 kPa, R 15% e Vf 2 cm.min-1. A FAD de modo geral apresentou bons resultados para sua aplicação na remoção de cianobactérias.

APA, Harvard, Vancouver, ISO, and other styles

20

Rosa, Andrey Alexsandro. "Pré-cloração associada à adsorção em carvão ativado em pó e flotação por ar dissolvido na remoção de microcistina presente em três diferentes concentrações em águas provenientes de reservatório eutrofizado." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-11072008-154329/.

Full text

Abstract:

O crescimento desordenado das cidades, a utilização de áreas para plantio próximas aos mananciais e o lançamento de águas residuárias domésticas e industriais sem tratamento são consideradas as principais fontes de poluição dos corpos d´água. Tal poluição contribui para o enriquecimento dos corpos hídricos em relação aos nutrientes. Isto, combinado com fatores climáticos proporciona condições para a ocorrência de florações de algas que podem apresentar espécies potencialmente tóxicas. Desta forma, aumenta a preocupação com desenvolvimento de técnicas de tratamento que forneçam água de qualidade garantindo a saúde da população consumidora. Nesta pesquisa, foram preparadas águas de estudo com diferentes concentrações de microcistina, com as quais foram testados alguns processos de tratamento, em escala de bancada, que consistiram na pré-cloração, adsorção em carvão ativado em pó, coagulação/floculação, flotação por ar dissolvido e centrifugação. O fluxograma de tratamento com aplicação de carvão ativado logo após a mistura rápida foi o que apresentou melhores resultados em termos de cor aparente, turbidez e concentração residual de microcistina. Foi avaliada a influência da concentração de microcistina nos tratamentos simulados. Constatou-se que para 104,92 µg/L de microcistina a aplicação de 3,0 mg\'CL IND.2\'/L (10 segundos antes da mistura rápida) e 30 mg/L de CAP (logo após a mistura rápida) não foram capazes de reduzir a concentração de microcistina para menos de 1 µg/L, conforme o limite estabelecido pela Portaria 518/04 do Ministério da Saúde. Assim, optou-se pela estimativa da dosagem mínima de carvão ativado em pó (CAP) em função da concentração inicial de microcistina das três águas preparadas. O residual de microcistina em cada água preparada, após a aplicação da dosagem estimada de CAP, foi: Água de Estudo 1 = 0,80 µg/L, Água de Estudo 2 = 0,82 µg/L e Água de Estudo 3 = 0,23 µg/L.
The disordered growth of cities, the use of planting areas near the water sources and the launch of domestic and industrial wastewater without treatment are the main sources of water bodies\' pollution. Such pollution contributes to increase the nutrient loading in the water bodies. In association with climatic factors, this enrichment of nutrient provides suitable conditions for the bloom of potentially toxic algae. Thus, increases the concern over to develop treatment techniques that provide water quality able to ensure the health of the consumer population. In this research, waters were prepared with different concentrations of microcystin and some treatments were tested in bench scale. These tests consisted in prechlorination, adsorption on powdered activated carbon, coagulation/flocculation, dissolved air flotation and centrifugation. The diagram of treatment with activated carbon application after the rapid mix showed better results of apparent color, turbidity and residual concentration of microcystin. The influence of the concentration of microcystin in the simulated treatments was evaluated. It was found that for 104.92 µg/L of microcystin the application of 3.0 mg\'CL IND.2\'/L (10 seconds before rapid mix) and 30 mg/L of PAC (after a quick mixture) were not able to reduce the concentration of microcystin to less than 1 µg/L, as the limit established by Order 518/04 of the Health Ministry. Thus, it was decided to estimate the minimum dosage of powdered activated carbon (PAC) according to the initial concentration of microcystin found in the three prepared waters. The residual concentration of microcystin in each water, after the estimated dosage application of PAC was: Water 1 = 0.80 µg/L; Water 2 = 0.82 µg/L; Water 3 = 0, 23 µg/L.

APA, Harvard, Vancouver, ISO, and other styles

21

Julio, Marcelo De. "Efeito da massa molecular das substâncias húmicas na eficiência da coagulação com o reagente de Fenton, floculação e flotação de águas de mesma cor verdadeira." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-10102016-151804/.

Full text

Abstract:

A presença de substâncias húmicas em águas destinadas ao abastecimento tem ocasionado diversos problemas, entre eles a formação de subprodutos halogenados, principalmente quando se emprega a pré-oxidação com cloro. Com o reagente de Fenton não há a possibilidade de formação desses indesejáveis compostos halogenados, pois o forte poder oxidativo do reagente de Fenton é devido ao radical hidroxila (OH). Aliado a isto, com o mesmo produto químico se pode ter a pré-oxidação e coagulação de compostos orgânicos, pois o reagente de Fenton consiste na aplicação de íons de Fe+2 e peróxido de hidrogênio em meio ácido, sendo o Fe+2 oxidado a Fe+3. Como esses íons formam espécies hidrolisadas que atuam como coagulantes, o reagente de Fenton pode ter a dupla função de oxidação e coagulação nos processos de tratamento. Por isso, neste trabalho foi proposta uma metodologia para emprego do reagente de Fenton como agente coagulante no tratamento de águas contendo cor elevada causada pela introdução de substâncias húmicas extraídas de turfa. Além disto, foi estudado o efeito da massa molecular das substâncias húmicas na eficiência da coagulação, floculação e flotação de águas; para isto foram preparadas 4 águas distintas apresentado a mesma cor verdadeira, mas com substâncias húmicas de diferentes massas moleculares, obtidas por fracionamento por ultrafiltração. Por meio da otimização da dosagem de coagulante e respectivo pH de coagulação e posterior construção dos diagramas de coagulação para cada água de estudo, verificou-se que a água preparada com as substâncias húmicas de menor massa molecular apresentou maior grau de dificuldade para tratamento, requerendo dosagens de coagulante (reagente de Fenton) bem mais elevadas em relação às águas preparadas com substâncias húmicas de maior massa molecular. Adicionalmente, foram realizados ensaios de filtração em areia após a flotação, procurando-se simular tratamento em ciclo completo, tendo sido constatado que com o reagente de Fenton empregado como agente coagulante, a água filtrada atendeu ao padrão de potabilidade vigente no Brasil em relação aos parâmetros medidos (cor aparente < ou = 3 uH, turbidez < 0,5 uT e ferro total residual < 0,005 mg/L). Os valores de absorvância e carbono orgânico total da água filtrada também foram muito pequenos, indicando que a formação dos subprodutos da desinfecção com cloro seriam insignificantes.
Humic substances\' presence in water destined for supply has brought many problems, such as halogenated byproducts formation, mainly when chlorine is used as preoxidant. With Fenton\'s reagent there is no formation possibility of these undesirable halogenated compounds, since the strong oxidative power of Fenton\'s reagent is due to hydroxyl radical (OH). In addition, with the same chemical product, it is possible to have the preoxidation and coagulation of organic compounds, because Fenton\'s reagent consists of Fe+2 ions and hydrogen peroxide application under acid conditions, with Fe+2 oxidized to Fe+3. Since these ions form hydrolyzed species that act as coagulants, Fenton\'s reagent can have the double function of oxidation and coagulation on treatment processes. Because of this, the current work proposed a methodology to use Fenton\'s reagent as coagulant agent in the treatment of waters having high true color caused by the introduction of humic substances extracted by peat. Besides this, humic substances molecular weight effect on coagulation, flocculation and flotation of waters was studied; for this, 4 distinct waters having the same true color were prepared, but with different humic substances molecular weights, obtained by ultrafiltration fractioning. Through optimization of coagulant dosage and respective coagulation pH and posterior construction of coagulation diagrams for each studied water, it was verified that the water prepared withthe smallest molecular weight humic substances was more difficult to treat, requiring higher coagulant (Fenton\'s reagent) dosages compared with the waters prepared with larger molecular weight humic substances. Furthermore, experiments of filtration after flotation were carried out, trying to simulate a complete cycle treatment, which verified that with Fenton\'s reagent, employed as coagulant agent, the filtered water reached the brazilian potable standards concerning the measured parameters (apparent color < ou = 3 HU, turbidity < 0.5 TU and residual total iron < 0.005 mg/L). The absorbance and total organic carbon values of filtered water were also very low, indicating that the disinfection byproducts formation with chlorine would be insignificant.

APA, Harvard, Vancouver, ISO, and other styles

22

Oliveira, Nilton Fernandes de. "Avaliação da qualidade da água de lavagem de filtros e de lodo de decantador após tratamento sequencial por leito de drenagem, flotação por ar dissolvido e filtração." Universidade Federal de Uberlândia, 2015. https://repositorio.ufu.br/handle/123456789/14212.

Full text

Abstract:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
In this study, we evaluated the quality of filter backwash water and sludge decanter Water Bom Jardim Treatment Plant, located in Uberlandia, Minas Gerais, after sequential treatment with drainage bed, flotation and filtration dissolved air, all bench scale. Compounds were evaluated drainage bed effluent three different types of geotextile webs: RT-21, RT-26 and RT-31, and tested three kinds of constituents of the sand grain size filters. The effluent drained, after passage through the drainage bed, passed through the flotation unit dissolved air and then by filtration units. Preliminary tests with crude sample of filter backwash water and sludge decanter, in order to characterize it and evaluate it as its physical, chemical and biological were performed. The geotextile webs used were chosen from results of previous studies, performed with the same type of system. The experiments were divided into stages I and II. In step I were conducted without addition of coagulant or auxiliary experiments on coagulation / flocculation flotation. The samples, after passage through the system, evaluating physical parameters pH, turbidity, true color and apparent color and about the chemical parameters, remaining concentrations of aluminum and iron. Step II The same tests were carried out in the same step I and determination of quality parameters, however, with aluminum sulphate dose of 5, 10 and 15 mg / L in the coagulation / flocculation flotation. Tests conducted in step I showed better performance were performed with the RT-26 blanket in the output of filter 01 with a reduction of 91.8% of the apparent color, 41.4% of true color and 97.6% turbidity. In phase II trials conducted in the best performance was drained with the RT-mat 26 the output of the filter 02 when subjected to a dosage of 15 mg / L aluminum sulfate as a coagulant agent. There was a reduction of 96.4% of the apparent color, 86.2% of true color and 99.6% turbidity. The presented results confirm the efficiency of the system in removing solids present in the water washing of filters and ETA decanter sludge studied and confirmed the capability of using this system as an alternative to disposal or optionally for a new water supply line treated.
Neste trabalho foi avaliada a qualidade da água de lavagem de filtros e de lodo de decantador da Estação de Tratamento de Água Bom Jardim, localizada na cidade de Uberlândia-MG, após tratamento sequencial por leito de drenagem, flotação por ar dissolvido e filtração, todos em escala de bancada. Foram avaliados efluentes de leitos de drenagem compostos de três tipos de mantas geotêxteis distintas: RT-21, RT-26 e RT-31, e testados três tipos de granulometria de areia constituintes dos filtros. O efluente drenado, após passagem pelo leito de drenagem, passava pela unidade de flotação por ar dissolvido e em seguida pelas unidades de filtração. Foram realizados testes preliminares com amostra bruta da água de lavagem de filtros e de lodo de decantador, com o objetivo de caracterizá-la e avaliá-la quanto as suas características físicas, químicas e biológicas. As mantas geotêxteis utilizadas foram escolhidas a partir de resultados de trabalhos anteriores, realizados com o mesmo tipo de sistema. Os experimentos foram divididos nas etapas, I e II. Na etapa I foram conduzidos experimentos sem adição de agente coagulante ou auxiliares na coagulação/floculação da flotação. As amostras, após passagem pelo sistema, foram avaliadas quanto aos parâmetros físicos pH, turbidez, cor verdadeira e cor aparente e quanto aos parâmetros químicos, concentrações remanescentes de Alumínio e Ferro. Na etapa II foram realizados os mesmos ensaios da etapa I e mesmas determinações dos parâmetros de qualidade, entretanto, com dosagem de sulfato de alumínio de 5, 10 e 15 mg/L na coagulação/floculação da flotação. Os ensaios conduzidos na etapa I que mostraram melhor desempenho foram os realizados com a manta RT-26 na saída do Filtro 01 com redução de 91,8% da cor aparente, 41,4% da cor verdadeira e 97,6% da turbidez. Nos ensaios conduzidos na etapa II o melhor desempenho foi com o drenado da manta RT-26 na saída do Filtro 02 quando submetido a uma dosagem de 15 mg/L de sulfato de alumínio, como agente coagulante. Houve redução de 96,4% da cor aparente, 86,2% da cor verdadeira e 99,6% da turbidez. Os resultados apresentados confirmam a eficiência do sistema na remoção de sólidos presentes na água de lavagem de filtros e de lodo de decantador da ETA estudada, e confirmam a potencialidade de utilização deste sistema como alternativa ao descarte e como opção de nova linha de fornecimento de água tratada.
Mestre em Engenharia Civil

APA, Harvard, Vancouver, ISO, and other styles

23

Dobiáš, Pavel. "Flotace rozpuštěným vzduchem – od poloprovozního modelu po plnou realizaci." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2018. http://www.nusl.cz/ntk/nusl-385284.

Full text

Abstract:

The thesis deals with the use of dissolved air flotation (DAF) in water treatment technology in the Czech Republic. It summarizes the knowledge gained at pilot plant studies as well as the experience with full-scale flotation units which have been built in potable water treatment plants in the Czech Republic in years 2006-2018. This thesis provides a broad background of experimental studies of a modern separation process, which does have great advantages in the removal of natural organic matter and microorganisms from water in the drinking water treatment industry. In this thesis, there are presented some examples of the excellent efficiency of the microorganisms removal, both under the experimental conditions as well as water treatment plants, which were improved by DAF units installation in full scale. In addition to the high separation efficiency, it is shown, how DAF units could influence the subsequent separation steps as for example filtration through the granular media. The negative influence of the pre-ozonization on the DAF separation efficiency in Hradec Králové WTP is demonstrated too. The results of the pilot experiments support the idea, that the key condition for high removal efficiency is the optimal coagulation process chemistry. Design of pilot experiments was based on the factorial planning theory and some results are discussed in this thesis. The very big portion of the pilot experiments was made for estimating of the full-scale DAF design parameters before the water treatment plants reconstruction phase

APA, Harvard, Vancouver, ISO, and other styles

24

L?do, Patr?cia Guilhermina da Silva. "Flota??o por ar dissolvido na clarifica??o de ?guas com baixa turbidez utilizando sulfato de alum?nio e sementes de Moringa oleifera como coagulantes." Universidade Federal do Rio Grande do Norte, 2008. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15886.

Full text

Abstract:

Made available in DSpace on 2014-12-17T15:01:47Z (GMT). No. of bitstreams: 1 PatriciaGSL.pdf: 4325839 bytes, checksum: ed5182708cd9548f2c8eca5937447cd6 (MD5) Previous issue date: 2008-12-22
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
This work aims to investigate the process of Dissolved air Flotation (DAF) for clarifying water samples with low turbidity using aluminum sulphate and Moringa oleifera seeds as coagulants. The experimental procedure was carried out in a bench scale flotation unit. The influences on the pre-treatment conditions (coagulant dosage and flocculation time) and flotation parameters (superficial application rate and recirculation rate) were evaluated considering the efficiency of the process. The efficiency was evaluated by determining the turbidity of the untreated and treated water samples. The results obtained showed that turbidity reduction can be obtained very efficiently by using DAF and the latter coagulant in low turbidity water. Using aluminum sulphate in pH?s 5.0 and 6.0 better efficiencies were obtained with low concentrations (15 mg/L), achieving values of 92% of turbidity reduction. In the case of use of Moringa oleifera better efficiencies of reduction of turbidity were reported when using a concentration of 50 mg/L in all range of pH?s, achieving 86% of reduction. The zeta potential was also determined, in an attempt to aid comprehension of the coagulation mechanisms involved. The coagulation mechanisms with Moringa oleifera seeds were shown to be adsorption and charge neutralization, as well as adsorption and bridging. Concerning aluminum sulphate, the predominant mechanisms are adsorption and charge neutralization and enmeshment in a precipitate. The results indicate that for low turbidity water, Moringa oleifera seeds could potentially be a viable substitute for aluminum sulphate
O presente trabalho tem como objetivo investigar o processo da flota??o por ar dissolvido sob press?o - FAD para clarifica??o de ?guas com baixa turbidez utilizando sulfato de alum?nio e sementes de Moringa oleifera como coagulantes. O procedimento experimental foi realizado em uma unidade de flota??o em escala de bancada. Foram avaliadas as influ?ncias das condi??es do pr?-tratamento (dosagem de coagulante e tempo de flocula??o) e par?metros de processo da flota??o (taxa de aplica??o superficial e taxa de recircula??o) na efici?ncia do processo. A efici?ncia foi avaliada pela determina??o de turbidez nas amostras de ?gua bruta e tratada. Os resultados obtidos mostraram que elevadas efici?ncias de redu??o da turbidez podem ser conseguidas com o uso da FAD em ?guas com baixa turbidez utilizando estes coagulantes. Para o sulfato de alum?nio, nos pHs 5,0 e 6,0 as melhores efici?ncias foram alcan?adas com baixas dosagens (15 mg/L), alcan?ando valores de at? 92% de redu??o. Para a Moringa oleifera, as melhores efici?ncias de redu??o de turbidez foram ? dosagem aproximada de 50 mg/L para todos os pHs, alcan?ando valores de 86% de redu??o. Determinou-se tamb?m o potencial zeta, com o objetivo de auxiliar na compreens?o dos mecanismos envolvidos na coagula??o. Os mecanismos de coagula??o com sementes de Moringa oleifera indicam ser adsor??o e neutraliza??o de cargas e adsor??o e forma??o de pontes. No que diz respeito ao sulfato de alum?nio os mecanismos predominantes s?o adsor??o e neutraliza??o de cargas e varredura. Os resultados indicam que para ?guas de baixa turbidez, as sementes de Moringa oleifera podem ser um substituto potencialmente vi?vel em rela??o ao sulfato de alum?nio

APA, Harvard, Vancouver, ISO, and other styles

25

Souza, Irene Monteiro da Franca. "Influência do gradiente médio de velocidade na zona de contato na eficiência de clarificação de água para abastecimento por flotação." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-17102012-103326/.

Full text

Abstract:

O presente trabalho teve como objetivo estudar a influência do gradiente médio de velocidade (Gzc), associado ao tempo de detenção hidráulico (tzc) e à taxa de aplicação superficial (TASzc), na zona de contato, na eficiência de clarificação de uma unidade retangular de flotação por ar dissolvido, em escala piloto, tratando água para abastecimento. Foram estudadas duas configurações da Unidade Piloto de Flotação por Ar Dissolvido (UPFAD) (A e B), as quais diferem no comprimento da zona de contato A (90 mm) e B (140 mm). A TASzc - A (133 ± 3 m/h) e B (86 ± 1 m/h) - e o tzc - A (54 ± 1s) e B (84 ± 1 s) - são diferentes. Foram avaliados três valores do Gzc A (1,8; 6,5;10,2) e B (0,9; 4,7; 6,3), através da inserção de telas com características diferentes no interior da zona de contato. E, Para cada valor de Gzc, foram investigados três valores de A/V (3,73; 4,90; 6,41). Em todos os ensaios realizados, foram fixados os seguintes parâmetros: vazão da água bruta preparada (5,4 m³/h); temperatura da água bruta preparada (26 ± 1ºC); pH de coagulação (6,5 ± 0,1); tempo de floculação (17,2 min); gradiente médio de velocidade de floculação (110 s-1); vazão de descarte após a floculação (0,8 m³/h); vazão de entrada para a flotação (Qe) (4,6 m³/h); velocidade de entrada para a flotação (ve) (180 m/h); velocidade cross-flow (45 m/h); TASzs (14,6 ± 0,2 m/h); pressão de saturação (4,5 ± 0,1 Kgf/cm²). A unidade piloto FAD foi alimentada com água preparada, que apresentou turbidez em torno de 7,4 ± 0,6 UNT, e cor aparente, em torno de 39,4 ± 4,3 UH. A fração removida dos parâmetros analisados para cada Gzc é menos sensível a variações de A/V na configuração A que na configuração B. Na configuração A, a tela que apresentou Gzc em torno de 6,5 s-1 gerou melhores resultados para cada A/V analisado. Na configuração B, a tela que gerou Gzc em torno de 4,7 s-1 proporcionou melhor fração removida de turbidez e cor para cada A/V estudado. Além disso, na configuração B, a fração removida de turbidez e cor foi menos sensível a variações de A/V, para Gzc de 4,7 s-1 que para os demais valores de Gzc. A tela que gerou resultados mais eficientes na configuração A foi a mesma para a configuração B. Portanto o uso da referida tela favoreceu o desempenho das configurações A e B. Comparando todas as situações estudadas nas duas configurações, o ensaio com a configuração A (com tzc de 54 s) com Gzc de 6,3 s-1 e A/V de 4,9 g/m³, apresentou as maiores frações de remoção de cor e turbidez.
The present work aimed to study the influence of velocity gradient (Gzc) associated with the hydraulic detention time (tzc) and the rate of surface application (TASzc) in the contact zone in the efficiency of clarification of a unit rectangular dissolved air flotation pilot scale, treating water supplies. Two different kinds of configurations of the reactor dissolved air flotation in pilot scale (UPFA) (A and B) were studied, which differ in the length of the contact zone - A (90 mm) and B (140 mm). The TASzc - A (133 ± 3 m/h) and B (86 ± 1 m/h) - and tzc - A (54 ± 1 s) and B (84 ± 1 s) were different. Three different values of Gzc were analysed - A (1.8, 6.5, 10.2 s-1) and B (0.9, 4.7, 6.3 s-1) by insertion of grilles with different characteristics within the zone contact. And for each value of Gzc, three values of A/V (3.73, 4.90, 6.41 g/m³) were investigated. In all trials, the following parameters were set: flow of synthetic raw water (5.4 m³/h), synthetic raw water temperature (26 ± 1ºC), coagulation pH (6.5 ± 0.1); flocculation time (17.2 minutes), the speed gradient flocculation (110 s-1); flow disposal after flocculation (0.8 m³/h), input flow to the flotation (Qe) (4, 6 m³/h), input speed for flotation (ve) (180 m/h), cross-flow velocity (45 m/h), TASzs (14.6 ± 0.2 m/h), saturation pressure (4.5 ± 0.1 kgf/cm ²). The pilot plant was fed with synthetic water, which showed turbidity of approximately 7.4 ± 0.6 NTU, and apparent color, about 39.4 ± 4.3 HU. The removal efficiency of the analyzed parameters for each Gzc is less sensitive to variations in the A/V in the configuration A than in the configuration B. In configuration A, the grille that showed Gzc about 6.5 s-1 gave better results for each A/V analysis. In configuration B, the grille that has generated Gzc around 4.7 s-1 provided the best removal efficiency of turbidity and color for each A/V studied. Furthermore, in the configuration B, the removal efficiency of color and turbidity was less sensitive to variations in A/V for Gzc 4.7 s-1 than for other values of Gzc. The grille that generated the best results in the configuration A was the same for the configuration B. Therefore the use of that grille favored the performance of configurations A and B. Comparing all the situations studied in two configurations, the test with the configuration A (with tzc the 54 s) with Gzc of 6.3 s-1 and A/V of 4.9 g/m³, had the highest removal efficiencies of color and turbidity.

APA, Harvard, Vancouver, ISO, and other styles

26

Meca, Karen Soraia. "Influência do tempo de detenção hidráulica e do gradiente médio de velocidade na zona de contato no desempenho de unidade piloto de flotação por ar dissolvido aplicado à clarificação de água para abastecimento." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-14112017-104621/.

Full text

Abstract:

O desempenho de unidades de flotação por ar dissolvido (FAD) depende significativamente do projeto da zona de contato (ZC) dessas unidades, situada na entrada das mesmas e responsável por promover condições adequadas para que ocorram taxas satisfatórias de colisão entre as microbolhas de ar e os flocos formados na etapa antecedente de floculação da água para abastecimento. Os dois principais parâmetros de projeto da ZC são o tempo de detenção hidráulico ou tempo de contato (Tzc) e o gradiente médio de velocidade na ZC (Gzc). A presente dissertação apresenta os resultados de estudo sobre a influência do Tzc e do Gzc na ZC de uma unidade piloto de flotação por ar dissolvido (UPFAD) com escoamento contínuo aplicada ao tratamento de água para abastecimento. Foram utilizados módulos contendo tela metálica em seu interior com malha de #25 mm com diferentes dimensões, de modo a se obterem diferentes valores de Gzc e Tzc. Foram investigadas duas configurações na unidade de FAD (Configurações A e B), nas quais o comprimento (Lzc) e a altura (Hzc) da ZC foram variados, permitindo a alteração do Tzc e mantendo-se controlados os valores de Gzc (com a introdução ou não de diferentes módulos de tela metálica na ZC) e vice versa. Os demais parâmetros do processo de FAD não sofreram variações, tais como taxa de aplicação superficial (TAS) na zona de separação, tempo de floculação, entre outros. Para a configuração A, foram estudadas três alturas diferentes na ZC e para a configuração B, quatro alturas diferentes na ZC, o que acarretou, para cada valor de Gzc variação do Tzc. Para cada configuração da ZC, também foram testados três valores de vazão de recirculação de água saturada com ar de modo a se obterem três diferentes concentrações de ar (A/V) no processo de flotação. Para todos os parâmetros analisados (Turbidez, Cor, Absorbância), as maiores eficiências de remoção foram obtidas nos ensaios realizados com o uso da tela #25 mm tanto na configuração A (TASzc = 136 m/h e G = 6,1 s-1) quanto na configuração B (TASzc = 87 m/h e G = 3,2 s-1). Os resultados permitem concluir que o par de valores (Tzc, Gzc) é mais apropriado para o projeto da zona de contato de unidades FAD do que o par (Tzc, TASzc) usualmente adotado pelos projetistas, sendo que, na faixa de valores investigados a UPFAD apresentou melhor desempenho para o par: Tzc de 41 s e Gzc de 6,1 s-1.
The performance of units dissolved air flotation (DAF) depend significantly of design on the contact zone (CZ) of these units, situated at the entrance thereof and responsible for promoting appropriate conditions to occur satisfactory collision rates between air microbubbles and the flocs formed in the step of flocculation of potable water. The two main design parameters of the CZ are the hydraulic detention time or contact time (Tcz) and the velocity gradient in the CZ (Gcz). This work presents the results of study of the effects of varying the Tcz and Gcz at the contact zone of pilot unit DAF with continuous flow applied to the treatment of potable water. Were used modules containing metal grille with mesh of #25 mm, with different dimensions in order to obtain different values of Gcz and Tcz. Were investigated two configurations in the unit FAD ( configurations A and B) where the length (Lcz) and height (Hcz) of contact zone were varied, allowing the variation of Tzc and keeping the values of Gcz controlled (with the introduction or not of different modules in the metal grille in CZ) and vice versa, without changes in other process variables FAD, such as rate of surface application (TAS) in the separation zone, flocculation time, among others. For the configuration A were studied three different heights in the CZ and in configuration B, four different heights in the CZ, which resulted, for each value of Gcz (relative to the chosen value of Lcz) the variation of Tzc. For each configuration of CZ were also tested three values of recirculation flow of air saturated in order to obtain three different values of concentration in air (A/V) in the flotation process. For all parameters analyzed (turbidity, color, absorbance), the highest efficiencies were obtained in assays performed using the grille #25 mm, both in configuration A (TAScz = 136 m/h and L = 6,1 s-1) and configuration B (TAScz = 87 m/h and G = 3,2 s-1). The results indicate that the pair of values (Tcz, Gcz) is more suitable for project of the CZ of units FAD than the pair (Tcz, TAScz) usually adopted by the designers, and values in the range investigated in UPFAD showed performed better for Tcz of 41 s and Gcz of 6,1 s-1.

APA, Harvard, Vancouver, ISO, and other styles

27

Steinbach, Sandra. "Dissolution and precipitation of air in dissolved air flotation." Thesis, 2012. http://hdl.handle.net/10210/6178.

Full text

Abstract:

D.Ing.
The use of dissolved air flotation (DAF) as a water clarification process has gained momentum over the past two decades. Despite its increased application there is a lack of information concerning the understanding of the underlying principles of the process. Plants are being designed based mainly on empirical guidelines, especially with respect to the bubble production system. Bubbles are generated in the DAF process when water, supersaturated with air under pressure, is released under atmospheric conditions. The efficiency of air dissolution and precipitation determines the quantity of air available for flotation and thus, to a large extent, the success of the whole DAF process. The first part of this thesis deals with a rational model for predicting the air transfer efficiency in packed saturators which are used in most modern DAF plants to dissolve air into water. The model assumes the Lewis-Whitman two-film theory for interfacial mass transfer and uses the Onda correlations to estimate the mass transfer coefficient. The model provides good insight into the effects of key design parameters on the air transfer efficiency. The experimental verification of the model required a method for predicting the saturator air composition and a technique to practically determine the air transfer efficiency in the packed bed of an operating saturator. Both methods are described in detail in this study. The verification of the mass transfer model showed a close agreement of experimental and theoretical results and the model thus provides a powerful tool for the design of packed saturators. The second part of the thesis deals with air precipitation and the quantity of air released after depressurization. Based on a literature review on this subject it was assumed that the air release is incomplete and that it would be a function of the operating conditions of the saturation system as well as of the design of the injection nozzle across which the pressure is released. Since the injection nozzles play an important role in the DAF process numerous experiments were carried out which measured the released air volume for different nozzle configurations and saturator pressures. The results of this study showed that the air release after depressurization is indeed incomplete and that it takes a long time for all the excess air to come out of solution. It was found that the efficiency with which the air was released is a function of the saturator pressure and the nozzle design. The experimental observations led to the formulation of a two-step air release model, which explains the precipitation process in terms of a slow and fast release step. The mathematical framework for quantification of the model is provided. Once the model is quantified it will be possible to compare the performance of different injection nozzles solely with regard to their design features and independent of any parameters influencing the air release downstream of the nozzle. This model may then help to further the understanding of the precipitation process and could lead to the development of some rational guidelines for nozzle design and prediction of nozzle performance.

APA, Harvard, Vancouver, ISO, and other styles

28

Rajagopaul, Rachigan. "The evaluation of polymeric organic coagulants for potable water treatment by dissolved air flotation." Thesis, 2001. http://hdl.handle.net/10321/2767.

Full text

Abstract:

Submitted in fulfilment of the academic requirements for the Degree of M.Tech: Chemical Engineering, M. L. Sultan Technikon, 2001.
Historically inorganic coagulants were the coagulants of choice for OAF treatment of potable water. Water treatment practitioners using OAF technology preferred ferric chloride, an inorganic coagulant. Ferric chloride formed light, floatable floes at relatively low flocculation intensities and detention times. The inorganic coagulant was also more forgiving during incidents of overdosing and raw water and pH variability
M

APA, Harvard, Vancouver, ISO, and other styles

29

Bickerton, Benjamin James. "Optimization of Dissolved Air Flotation for Drinking Water Treatment." Thesis, 2012. http://hdl.handle.net/10222/15344.

Full text

Abstract:

The use of dissolved air flotation (DAF) for drinking water treatment has steadily grown in popularity in Atlantic Canada for the treatment of low turbidity water supplies with high levels of algae or dissolved organic matter. Runoff from high intensity rainfall events may cause a rapid increase in turbidity and dissolved organic matter in rivers and lakes used for drinking water. A technical evaluation of a DAF water treatment plant (WTP) was conducted to determine the contributing factors to clearwell turbidity increases resulting from increased raw water turbidity and colour during intense rainfall and runoff events. The effect of chemical and operational factors on treatment of a low turbidity and colour water source as well as a high turbidity and colour water source were examined, including coagulant dose, coagulation pH, polyaluminum chloride (PACl) coagulant basicity and DAF recycle rate. In response to deteriorating water quality, it was found that increased coagulant addition inadvertently caused the loss of coagulation pH control in a full-scale DAF WTP, resulting in potentially elevated dissolved aluminum residuals entering the clearwell. This would have led to excessive aluminum hydroxide precipitation in the clearwell, and resulted in turbidity increases above the acceptable limit of 0.2 NTU. Turbidity was found to be better removed, and dissolved aluminum residuals minimized, when coagulation pH was set to the pH of minimum aluminum solubility vs. a lower pH of 6.0 during bench-scale DAF testing. A higher dose of coagulant was required to produce optimal removal of turbidity and dissolved organics at the pH of minimum solubility. The difference in bench-scale DAF treatment performance was found to be minimal when comparing sulphated PACl coagulants with 50 and 70+ % basicity. Charge analysis parameters zeta potential and streaming current were found to have a strong correlation in bench-scale testing, though the relationship between the two was affected by the coagulation pH. The results suggest that utilizing streaming current for coagulant dose control at a full-scale WTP would be best accomplished by establishing a consistent relationship between raw water quality, pH and other factors with streaming current experimentally before relying streaming current targets for dose control. Equivalent or improved DAF efficacy for solid-liquid separation was found when the recycle rate was lowered from 12 to 6 % in bench-scale tests and 12 to 8% in full-scale tests. The results suggested that maintaining an optimum air:solids ratio improved treatment performance, possibly by providing adequate bubble contact opportunities while minimizing excess shearing of the sludge blanket. The most significant finding of this research was that maintaining the coagulation pH in WTPs utilizing PACl coagulants is of utmost importance during source water quality deterioration in order to optimize treatment performance as well as prevent excess dissolved and precipitated aluminum from entering a public drinking water supply.

APA, Harvard, Vancouver, ISO, and other styles

30

Jaji, Kehinde Temitope. "Treatment of Oilfield Produced Water with Dissolved Air Flotation." 2012. http://hdl.handle.net/10222/15347.

Full text

Abstract:

Produced water is one of the major by products of oil and gas exploitation which is produced in large amounts up to 80% of the waste stream. Oil and grease concentration in produced water is the key parameter that is used for compliance monitoring, because it is easy to measure. For Canadian offshore operations, the current standard is a 30-day volume weighted average oil-in-water concentration in discharged produced water not exceeding 30 mg/L. Treatment of produced water may therefore be required in order to meet pre-disposal regulatory limits. The measurement of oil in produced water is important for both process control and reporting to regulatory authorities. Without the specification of a method, reported concentrations of oil in produced water can mean little, as there are many techniques and methods available for making this measurement, but not all are suitable in a specific application. The first part of this study focused on selecting a suitable analytical method for oil and grease measurement in oil field produced water. Petroleum ether was found to offer a comparative dissolution of crude oil as dichloromethane and hexane; it was therefore used as the solvent of choice for the UV-Vis spectrophotometric analysis of oil and grease in synthetic produced water. Results from the UV-Vis spectrophotometric and FTIR spectrometric analytical methods were found to be comparable; it confirmed that UV-Vis spectrometry could potentially serve as an alternative method for measuring oil and grease in oil field produced water. However, while the UV-Vis method may have limitations in measuring oil and grease concentrations below 30 mg/L, the FT-IR method was found to be equally efficient at measuring both high and low oil and grease concentrations. Dissolved air flotation (DAF) was the primary treatment technology investigated in this study for removing oil and grease from synthetic produced water. By itself, DAF achieved less than 70% oil and grease (OG) removal, and was not able to achieve a clarified effluent OG concentration of 30 mg/L required for regulatory discharge limits. At an optimum condition of 20 mg/L ferric chloride (FeCl3) at pH 8 (70.6% OG removal), coagulation was found to significantly improve the performance of the DAF unit (p < 0.05). At the optimum conditions of 100 mg/L PAC dose, pH 8 and a mixing time of 10 minutes (77.5% OG removal) and 300 mg/L OC dose, pH 8 and a mixing time of 10 minutes (78.1% OG removal), adsorption was also found to significantly improve the performance of the DAF unit (p < 0.05 in both cases). Adsorption with organoclay was recommended as the best pre-treatment for optimizing the performance of DAF in removing oil and grease from offshore oil field produced water. The bench-scale experiments showed that turbidity removal results were consistent with the OG removal results. Without pre-treatment, DAF achieved significant removal of benzene from produced water due to the volatile nature of benzene. Therefore comparable levels of benzene removal was observed by the DAF, FeCl3/DAF, PAC/DAF and OC/DAF treatment schemes; 79.3 %, 86.6 %, 86.5 %, 83.5% respectively. Finally, as benzene is known to be carcinogenic to humans, this study recommends the incorporation auxiliary equipment in its design, for the treatment of the off-gas (VOCs, particularly BTEX) released during the removal of dissolved oil from the oil field produced water.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Water - Purification - Dissolved air flotation'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles