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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Otimização do tratamento de efluente de matadouro e frigorífico de suínos pela eletrofloculação e combinação eletrofloculaçào/coagulação orgânica / Treatment optimization of effluent from a swine slaughterhouse and packing plant by eletrofloculation and electrofloculation / organic coagulation combination

Orssatto, Fábio 14 February 2017 (has links)
Made available in DSpace on 2017-07-10T19:24:25Z (GMT). No. of bitstreams: 1 Fabio_ Orssatto.pdf: 2716052 bytes, checksum: ab171ebc4e483c9c113d55a88d8297cf (MD5) Previous issue date: 2017-02-14 / This trial aimed at evaluating the electrofloculation performance and its combination with organic coagulation to treat effluents from a swine slaughterhouse and packing plant. This thesis was written and composed of three papers. The first one reports on the removal of COD, turbidity, color, TKN and total phosphorus in the studied effluent according to the electroflocculation technique. It also optimized variables such as potential differential (pd) and hydraulic retention time (HRT) in a batch reactor of electroflocculation using aluminum electrodes. The second paper aimed at evaluating the removal of COD, turbidity, color and TKN from the effluent by electrochemical technique and optimized variables as electric current and HRT in a continuous flow reactor of electroflocculation using aluminum electrodes. The third paper aimed at evaluating the removal of COD, turbidity, color and TKN in the effluent using the combination of electroflocculation / organic coagulation technique. It also optimized variables such as electric current, HRT and tannin-based coagulant concentration in a batch reactor. The effluent used in this study comes from a swine slaughterhouse in the western region of Paraná. For the first paper, the main results were: maximal removal of 99.28% for turbidity, 98.93% for color, 81.01% for COD, 67.15% for TKN and 99% for total phosphorus. According to the statistical analysis, it was possible to obtain mathematical models as well as removal of analyzed parameters, but phosphorus. When the desirability function was calculated, the best optimized treatment conditions were at 30 minutes for HRT and 20 volts for pd, corresponding to 0.86 A of electric current and a 17.2 mA cm-2 current density. The analysis of residual aluminum in the effluent treated in the essays recorded a high concentration, which varied from 15.254 to 54.291 mg L-1. For each cubic meter (m3) of effluent treated by electroflocculation, 10.75 kWh of electric energy and 0.18036 kg of aluminum were used, with a cost of R$ 7.90 m-3. While for the second paper, the main results were: 74.47% of maximum efficiency for turbidity, 91.76% for color and 61.07% for COD. But the system was not efficient for TKN removal, since the maximum removal percentage was 20%. Based on the statistical analysis, it was possible to obtain mathematical models to remove the analyzed parameters. And, when desirability function was calculated, the best optimized treatment conditions were at 18 minutes for HRT, 1.5 A for electric current and a current density of 16.67 mA cm-2. The residual aluminum analysis recorded a concentration range from 1.21 to 4.61 mg L-1. At each cubic meter (m3) of treated effluent, 5.17 kWh of electrical energy and 0.0938 kg of aluminum were used, with a cost of R$ 3.84 m-3. Finally, the main results of the third paper were: the maximum efficiency of removal for turbidity was 98.37%, color was 97.82%, COD was 64.73% and TKN was 65.57 %. Based on the statistical analyses, it was possible to obtain mathematical models to remove parameters of color and turbidity. And when desirability function was calculated, the best optimized treatment conditions were at 10 minutes for HRT, 0.774 mL L-1 of coagulant concentration based on tannin, 0.68 A for electric current and a 13.6 mA cm-2 current density. When analyzing the residual aluminum in the effluent treated during the studied tests, a concentration range from 0.0 to 2.11 mg L-1 was observed. For each cubic meter (m3) of effluent treated by electrocoleculation / organic coagulation combination, 2.96 kWh for electric energy and 0.0475 kg aluminum were used, resulting in R$ 3.49 m-3 cost. The electroflocculation technique and the combination of electroflocculation and organic coagulation were good alternatives to remove pollutants from the studied effluent from swine slaughterhouse and packing plant. / O objetivo deste trabalho foi avaliar o desempenho da eletrofloculação e da combinação eletrofloculação/coagulação orgânica no tratamento de efluentes de um matadouro e frigorífico de suínos. A presente tese foi desenvolvida na forma de três artigos. O primeiro artigo avaliou remoção da DQO, turbidez, cor, NTK e fósforo total no efluente em estudo a partir da técnica eletrofloculação e otimizou as variáveis diferencial de potencial (ddp) e tempo de detenção hidráulica (TDH) em um reator batelada de eletrofloculação utilizando eletrodos de alumínio. O segundo artigo avaliou remoção da DQO, turbidez, cor e NTK do efluente através da técnica eletroquímica e otimizou as variáveis corrente elétrica e tempo de detenção hidráulica (TDH) em um reator de fluxo contínuo de eletrofloculação utilizando eletrodos de alumínio. Já o terceiro artigo avaliou a remoção de DQO, turbidez, cor e NTK do efluente através da combinação eletrofloculação/coagulação orgânica e otimizou as variáveis corrente elétrica, tempo de detenção hidráulica e concentração de coagulante à base de tanino em um reator batelada. O efluente utilizado no estudo provém de um matadouro e frigorífico de suínos localizado na região Oeste do Paraná. Para o primeiro artigo, os principais resultados foram: remoção de até 99,28 % para turbidez, 98,93 % para cor, 81,01 % para DQO, 67,15% para NTK e 99% para fósforo total. Foram utilizadas análises estatísticas para a obtenção de modelos matemáticos e a remoção dos parâmetros analisados, com exceção do fósforo. Ao se calcular a função da desejabilidade, as condições otimizadas de tratamento foram de 30 minutos para o TDH e 20 volts para a ddp, correspondendo a 0,86 A de corrente elétrica e uma densidade de corrente igual a 17,2 mA cm-2. A análise do alumínio residual no efluente tratado nos ensaios registrou elevada concentração, a qual variou de 15,254 a 54,291 mg L-1. A cada metro cúbico (m3) de efluente tratado através da eletrofloculação, utilizam-se 10,75 kWh de energia elétrica e 0,18036 kg de alumínio com um custo de R$ 7,90 m-3. Para o segundo artigo, os principais resultados foram: 74,47 % de eficiência máxima para turbidez, 91,76 % para cor e 61,07 % para DQO. Para a remoção de NTK, o sistema não se mostrou eficiente, cuja remoção máxima foi de 20%. A partir das análises estatísticas, foi possível a obtenção de modelos matemáticos para remoção dos parâmetros analisados. E, ao se calcular a função da desejabilidade, as condições otimizadas de tratamento foram de 18 minutos para o TDH, 1,5 A para a corrente elétrica e uma densidade de corrente igual a 16,67 mA cm-2. A análise do alumínio residual no efluente tratado nos ensaios registrou uma concentração que variou de 1,21 a 4,61 mg L-1. A cada metro cúbico (m3) de efluente tratado, utilizaram-se 5,17 kWh de energia elétrica e 0,0938 kg de alumínio com custo de R$ 3,84 m-3. Por fim, os principais resultados do terceiro artigo foram: a eficiência máxima de remoção de turbidez foi de 98,37 %, para cor, o resultado foi de 97,82 %, para DQO foi de 64,73 % e para NTK, o resultado foi de 65,57 %. A partir das análises estatísticas, foram obtidos modelos matemáticos para os parâmetros de remoção de cor e turbidez. E, ao se calcular a função da desejabilidade, as condições otimizadas de tratamento foram de 10 minutos para o TDH, 0,774 mL L-1 de concentração do coagulante à base de tanino, 0,68 A para a corrente elétrica e densidade de corrente igual a 13,6 mA cm-2. A análise do alumínio residual no efluente tratado nos ensaios registrou uma concentração que variou de 0,0 a 2,11 mg L-1. A cada metro cúbico (m3) de efluente tratado através da combinação eletrofloculação/coagulação orgânica, foram utilizados 2,96 kWh de energia elétrica e 0,0475 kg de alumínio, com custo de R$ 3,49 m-3. A técnica de eletrofloculação e a combinação entre eletrofloculação e coagulação orgânica apresentaram-se como boas alternativas na remoção de poluentes dos efluentes provindos dos matadouros e frigoríficos de suínos
32

Tratamento eletroquímico de esgotos sanitários / Electrochemical Treatment for Municipal Sewage

Formentini, Diana Fatima 28 February 2012 (has links)
Made available in DSpace on 2017-07-10T15:14:44Z (GMT). No. of bitstreams: 1 Diana Formentini.pdf: 3787958 bytes, checksum: 0c6f648ab36ecd404919056defc52426 (MD5) Previous issue date: 2012-02-28 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Basic sanitation is a public service with the most deficiency in infrastructure in Brazil, in particular the service of collection and treatment of sewage followed by collection services and waste treatment. The scenary of sanitation in Brazil, especially in the big cities, it becomes increasingly costly and challenging because the population is increasingly concentrated in urban areas. In this regard, it is necessary to adopt minimization and water conservation programs, and the implementation of decentralized treatment systems such as compact units which require a smaller area and offer similar performance. Another concern in the area of sanitation is about the removal efficiency of compounds present in small concentrations in sewage treatment plants as medicines for human and veterinary use, as well as beauty and personal care products. This study aimed to evaluate the efficiency of the electrochemical process (electrocoagulation and electro-oxidation) with three different electrodes (aluminum, iron and graphite) for COD removal in sewage and estimate the energy consumption. Evaluate the electro-oxidation in sewage for the degradation of two drugs (diclofenac and clofibric acid). The aluminum electrodes were more efficient for COD removal and achieved efficiency up to 80% for most of the tests performed. Iron electrodes achieved similar result, but it gives residual color in the effluent. Aluminum electrodes save energy compare with iron and graphite electrodes. The electrochemical process is a promising technique for removal pharmaceutical compounds used in this research. / A maior deficiência do Brasil na área de serviços públicos e infraestrutura é o saneamento básico, em especial o serviço de coleta e tratamento de esgotos sanitários, seguido do serviço de coleta e tratamento de resíduos sólidos. A situação do saneamento básico no Brasil, principalmente nos grandes centros urbanos, torna-se cada vez mais onerosa e desafiadora já que a população está cada vez mais concentrada nas áreas urbanas. Nesse sentido, faz-se necessária a adoção de programas de minimização e conservação de água, além da implantação de sistemas de tratamento descentralizados, como, por exemplo, unidades compactas de tratamento que exigem menor área e oferecem igual desempenho. Outra preocupação na área do saneamento diz respeito à eficiência deremoção de compostos presentes em pequenas concentrações nas estações de tratamento de esgotos como fármacos de uso humano e veterinário, bem como produtos de beleza e higiene pessoal. Dentro desse contexto, o presente trabalho teve como objetivo avaliar a eficiência do Processo Eletroquímico (Eletrocoagulação e Eletro-oxidação) em esgoto sanitário para remoção de DQO, utilizando eletrodos de alumínio, ferro e grafite e estimar o consumo de energia para cada sistema. Avaliou-se ainda o uso da Eletro-oxidação em esgoto sanitário para degradação de dois fármacos (diclofenaco sódico e ácido clofíbrico). A eletrocoagulação com eletrodos de alumínio mostrou-se mais eficiente para remoção de DQO, obtendo eficiências acima 80% para a maioria dos ensaios realizados. Os eletrodos de Ferro apresentaram eficiência semelhante, entretanto, forneceram coloração residual ao efluene final. Os eletrodos de alumínios requerem menor consumo de energia. O processo eletroquímico mostrou-se uma técnica promissora para remoção de determinados compostos farmacêuticos que não sofrem remoção ou degradação pelas técnicas convencionais.
33

Efeitos da radiofreqüência nas características mecânicas da cápsula anterior do ombro de coelhos / Radiofrequency effects on mechanical characteristics of anterior shoulder capsule of rabbits

Raymundo, José Luiz Pozo 17 July 2007 (has links)
INTRODUÇÃO - A literatura mostra a utilização da radiofreqüência como alternativa em casos de redundância ou frouxidão de tecido, podendo ser empregada como solução em alguns casos de instabilidade de ombro. O presente estudo avalia os efeitos mecânicos da radiofreqüência em cápsulas anteriores de ombros de coelhos vivos. MÉTODOS O estudo é comparativo e randomizado, tendo sido realizado em trinta e sete ombros de coelhos, machos, da raça Nova Zelândia, na faixa etária de 4 meses 6 meses, com peso médio de 3kg 250mg, criados para o projeto e mantidos no Biotério Central da Universidade Federal de Pelotas UFPEL - RS. O trabalho consta de dezoito ombros do grupo controle sendo estes abertos para gerar instabilidade e não submetidos ao procedimento de radiofreqüência; e dezenove ombros do grupo experimento (radiofreqüência), abertos para gerar instabilidade e submetidos a radiofreqüência com tempo fixado em 7segundos numa temperatura fixa de 650C, com tecido embebido em solução salina. Após cinqüenta dias de pós operatório, os animais foram levados à eutanásia. O material foi mantido em -21,40C por quinze dias e, após transportado para o Laboratório de Investigação Medica 21 da Universidade de São Paulo USP - SP, para avaliação de nove variáveis: altura, comprimento inicial sem carga, área da cápsula, força máxima, deformação máxima, tensão máxima, deformação relativa, rigidez e módulo de elasticidade. RESULTADOS Foram encontradas diferenças estatisticamente significantes entre os grupos controle e o grupo radiofreqüência, para as variáveis força máxima e rigidez (p<0,05), sendo maiores em média, no grupo controle. CONCLUSÃO Desse modo a força máxima e a rigidez da cápsula anterior de ombros de coelhos vivos, submetidas à radiofreqüência em um único ponto, diminui após cinqüenta dias / INTRODUTION literature presents radiofrequency as an alternative tool to be used in redundancy or tissue looseness cases, and to be employed as a potencial solution for shoulder instability. The present study evaluated the mechanical effects of radiofrequency usage in anterior shoulder capsules of living rabbits. METHODS - the study is comparative and randomized, it was carried out with thirty seven shoulders of male rabbits (New Zealand breed), with ages between 4 to 6 months, weighing on average 3kg250g that were raised for the project and kept at Central Biotery from Federal University of Pelotas RS. The study groups encompassed eighteen shoulders as a control group that were operated to generate instability but were not submitted to radiofrequency procedure; and nineteen shoulders as intervention group (radiofrequency), that underwent the same operation procedure but were submitted to radiofrequency by the period of seven seconds at a steady temperature of 650C, the tissue was Embedded in salt solution. Fifty days after surgery the rabbits were taken to euthanasia. The material was kept at - 21,40C for fifteen days and later was taken to the São Paulo University-USP Medical Investigation Laboratory(#21), for the assessment of nine variables: height, unloaded inicial length, capsule area, maximum strength, maximum deformation, maximum tension, relative deformation, stiffness and elasticity module. RESULTS Statistical differences were observed between groups concerning maximum strength and stiffness(p<0.05), that were higher on average in the contrl group. CONCLUSION Maximum strength and stiffness of the anterior shoulder capsule in living rabbits, submitted to radiofrequency in a single spot, decreases after fifty days
34

Removal of arsenic and perchlorate from water by the EC/EF process using a TMCS-modified tubular ceramic membrane

Yang, Shih-hong 30 June 2011 (has links)
Arsenic and perchlorate are two types of emerging contaminants commonly found in various water bodies worldwide. Therefore, the development of effective removal technologies has become an important issue today. To this end, the following research studies were conducted. First, trimethylchlorosilane (TMCS) was used for the surface modification of a laboratory-prepared outside-in tubular TiO2/Al2O3 composite membrane aiming at enhancing the filtration performance of the said membrane layer. Second, the TMCS-modified tubular ceramic membrane coupled with the simultaneous electrocoagulation/ electrofiltration (EC/EF) process was tested and evaluated their combined performance in the remediation of arsenic- and perchlorate-spiked waters and one actual As-contaminated groundwater. In this research, the results of a preliminary electrocoagulation study have indicated that aluminum outperformed iron as the anode material. Thus, aluminum was selected as the sacrificial anode for the EC/EF tests throughout this work. In the course of various EC/EF testing, the removal efficiencies of the target contaminant in the test water specimens were compared for the tubular TiO2/Al2O3 composite membranes with and without surface modification. Also evaluated included the permeate flux, unit mass of target contaminant removed, and relevant power consumption. Though surface modification might not yield a better removal efficiency of the concerned contaminant, it gave rise to a greater permeate flux resulting in a greater removed mass of the contaminant for each of the synthetic wastewaters. Meanwhile, lower power consumption was found as compared with the case of no surface modification. As for the actual As-contaminated groundwater, the optimal EC/EF conditions for the tubular composite membrane without surface modification could low the As concentration to meet the local irrigation water quality criteria.
35

Removal of Environmental Hormones and Pharmaceuticals from Aqueous Solution via Nano-Fe3O4/S2O82- Oxidation Assisted by the Simultaneous Electrocoagulation/Electrofiltration Process

Chou, Tsung-Hsiang 24 February 2012 (has links)
Water recycling has become a global trend because of water scarcity and increased demand of water supply. Therefore, attentions to the improvement of reclaimed water quality have been paid. In the past decade various environmental hormones and PPCPs (pharmaceuticals and personal care products) have been detected in different aquatic environments. Even though their concentrations are in the range of ng/L to £gg/L, these emerging contaminants might cause harm to human health and the environment. Nanoscale contaminants are another type of emerging contaminants cannot be neglected because many nanomaterials have been used in household goods of our daily lives. Thus, how to effectively separate and/or recover those nanomaterials from aqueous solution to reduce their potential hazards is an important issue The first objective of this study was to assess the efficiency of nano-Fe3O4/S2O82- oxidation against selected environmental hormones (i.e., di(2-ethylhexyl)phthalate (DEHP) and perfluorooctane sulphonates (PFOS)) and pharmaceuticals (i.e., erythromycin (ERY) and sulfamethoxazole (SMX)) in aqueous solution. The optimal operating conditions obtained from the above-indicated oxidation process were then transferred to a simultaneous electrocoagulation and electrofiltration (EC/EF) treatment module into which a tubular TiO2/Al2O3 composite membrane was incorporated. The purpose of this practice was to evaluate whether the EC/EF process could further enhance the removal of target contaminants. In this work nanoscale magnetite (nano-Fe3O4) used for activation of S2O82- oxidation was prepared by chemical coprecipitation. Then, X-ray powder diffractometry was used to confirm the crystal structure of the prepared particles as magnetite. The employment of 3 wt% soluble starch was found to be sufficient to stabilize nano-Fe3O4 for later uses. Further, slurries of nano-Fe3O4 and S2O82- (sodium persulfate) were prepared with three dosage ratios, namely 1:2.5, 1:5 and 1:10. Nano-Fe3O4/S2O82- slurries thus prepared were used for evaluating their efficiencies in removing target contaminants (i.e., DEHP, PFOS, ERY, and SMX) of two concentration levels. In this study the high concentration level referred to 38 mg/L for DEHP and 10 mg/L each for the rest of target contaminants, whereas 10 £gg/L as the low concentration level for each of target contaminants. Batch experiments of nano-Fe3O4/S2O82- oxidation against target contaminants were first carried out in glass beakers. In the case of high concentration level with a nano-Fe3O4-to-S2O82- dosage ratio of 1:10, the respective removal efficiencies for all target contaminants were greater than 98%. Using the same dosage ratio for the case of low concentration level, however, the respective removal efficiencies for all target contaminants decreased to 78-91% except for ERY. When all target contaminants of low concentration level co-existed in the reaction vessel, the residual concentrations of environmental hormones were found to be greater than that of pharmaceuticals. Under the circumstances, the removal efficiency of DEHP dropped to 70% or so. The reaction pathways of nano-Fe3O4/S2O82- oxidation against each of target contaminants with a high concentration level were also investigated. The degradation intermediates detected for all target contaminants were all in line with the literature. Besides, the degradation intermediates were all close to their respective end products except those originated from DEHP. In other words, nano-Fe3O4/S2O82- per se had a phenomenal oxidation rate against each target contaminant. The performance of EC/EF-assisted nano-Fe3O4/S2O82- oxidation against target contaminants of low concentration level was also evaluated in this study. In each test every contaminated aqueous solution was physically preconditioned within the EC/EF treatment module for 20 min prior to the application of an electric field to enact electrocoagulation and electrofiltration. The optimal operating conditions obtained were given as follows: aluminum anode, electric field strength of 60 V/cm, transmembrane pressure of 98 kPa, and crossflow velocity of 3.33 cm/s. Under such conditions, the removal efficiencies for DEHP, PFOS, ERY, and SMX were determined to be 95%, 99%, 100%, and 99%, respectively. In the case of mixed environmental hormones and pharmaceuticals, the respective removal efficiencies slightly decreased to 85-99%. It is evident that the coupling of the EC/EF process with nano-Fe3O4/S2O82- oxidation yielded a substantial removal increase for selected target contaminants. Additionally, in all tests of EC/EF-assisted nano-Fe3O4/S2O82- oxidation against target contaminants, no residual nano-Fe3O4 was found in permeate. After a simple adjustment of pH, permeate thus treated would be ready for reuse in cooling towers.
36

A Parametric Comparative Study Of Electrocoagulation And Coagulation Of Aqueous Suspensions Of Kaolinite And Quartz Powders

Gulsun Kilic, Mehtap 01 December 2009 (has links) (PDF)
Mineral treatment processes generally produce wastewaters containing ultrafine and colloidal particles that cause pollution upon their discharge into environment. It is essential that they should be removed from the wastewater before discharge. This study was undertaken by using synthetic turbid systems containing kaolinite and quartz particles in water with the amount of 0.20 g/L and 0.32 g/L, respectively. Removal of the turbidity was tried in two ways / electrocoagulation with aluminum anode and conventional coagulation with aluminum sulfate. Several key parameters affecting the efficiency of electrocoagulation and coagulation were investigated with laboratory scale experiments in search of optimal parameter values. Optimal values of the parameters were determined on the basis of the efficiency of turbidity removal from ultrafine suspensions. The parameters investigated in the study were suspension pH, electrical potential, current density, electrocoagulation time, and aluminum dosage. This study was also performed to compare electrocoagulation and conventional coagulation regarding the pH ranges under investigation and coagulant dosages applied. A comparison between electrocoagulation and coagulation was made on the basis of total dissolved aluminum, revealing that electrocoagulation and coagulation were equally effective at the same aluminum dosage for the removal of ultrafine particles from suspensions. Coagulation was more effective in a wider pH range (pH 5-8) than electrocoagulation, which yielded optimum effectiveness in a relatively narrower pH range around 9. In both methods, these pH values corresponded to near-zero zeta potentials of coagulated kaolinite and quartz particles. The mechanism for both coagulation methods was aggregation through charge neutralization and/or enmeshment in aluminum hydroxide precipitates. Furthermore, the experimental results confirmed that electrocoagulation could display some pH buffering capacity. The kinetics of electrocoagulation was very fast (&lt / 10 min) in approaching a residual turbidity, which could be modeled with a second-order rate equation.
37

Preparation of a Novel Tubular Carbon/Ceramic Composite Membrane and Its Applications in Treating Chemical Mechanical Polishing Wastewaters by Coupling with a Simultaneous Electrocoagulation and Electrofiltration Process

Tsai, Chi-Ming 27 August 2008 (has links)
This study addresses three major parts: (1) to establish the technology for the preparation of tubular ceramic membrane substrates; (2) to establish the technology for the preparation of tubular carbon/ceramic membranes; and (3) to reclaim water from chemical mechanical polishing (CMP) wastewaters by a combined treatment system of a novel simultaneous electrocoagulation/electrofiltration (EC/EF) process coupled with laboratory-prepared tubular composite membranes (TCMs) and evaluate its feasibility of water recycling and operating cost. First, in this work the green substrates of tubular porous ceramic membranes consisting of corn starch were prepared using the extrusion method, followed by curing, drying, and sintering processes. Experimental results have demonstrated that an addition of starch granules to the raw materials would increase the porosity, pore size, and permeability of the sintered matrices but accompanied by a decrease of the compressive strength. It revealed that the membrane substrates with desired pore sizes and permeability could be obtained by adding a proper amount of corn starch. The nominal pore sizes of the prepared membrane substrates were ranging from 1 to 2 £gm. The membrane substrates thus obtained are suitable for crossflow microfiltration applications. Second, the carbon/alumina TCMs and carbon fibers/carbon/alumina TCMs were obtained by the chemical vapor deposition (CVD) method resulting in a pore size distribution of 2 to 20 nm and a nominal pore size ranging from 3 to 4 nm. Besides, during the CVD process the reaction temperature was found to be the main factor for influencing the pore size of carbon fibers/carbon/alumina TCMs and the type of carbon fibers. When the reaction temperature was above or equal to 1000 ¢J, the pore size of TCMs increased due to the pyrolysis of thin carbon layers. The ¡§Tip-Growth¡¨ mechanism was found for tubular carbon fibers formation under such conditions. On the other hand, ¡§Base-Growth¡¨ (also known as ¡§Root-Growth¡¨) mechanism was found for curved and irregular carbon fibers formation when reaction temperature was under or equal to 950 ¢J. Third, for reclaiming water from CMP wastewaters, experimental results of laboratory-prepared carbon/alumina TCMs incorporated into the custom-made EC/EF treatment module used was found to be capable of treating oxide-CMP wastewater in a proper manner. Permeate thus obtained had a turbidity of below 0.5 NTU and the removal efficiencies of TS (total solids content) and Si were 80% and 93 %, respectively. Further, for understanding the applicability of fractional factorial design and Taguchi experimental design, two laboratory-prepared carbon fibers/carbon/alumina TCMs (i.e., Tube B and Tube E obtained from two different preparation conditions) incorporated into the EC/EF treatment module were chosen for evaluating the performance of CMP wastewaters treatment. Permeate obtained based on the fractional factorial design of experiments had a turbidity of below 1.0 NTU and the removal efficiencies of TOC (total organic carbon), Cu and Si were all above 80 % except for the TS (i.e., ranging from 72 to 74%). Permeate obtained based on the Taguchi experimental design had a turbidity of below 0.3 NTU and the removal efficiencies of TS, TOC, Cu and Si were ranging from 82 to 91%. Apparently, similar optimum operating conditions were obtained from the fractional factorial design and Taguchi experimental design. Permeate thus obtained could be reused as the make-up water of cooling towers. The operating cost of Cu-CMP wastewater treatment based on a total water reclaim of 600 m3 per day was determined to be NT$ 98 (i.e., US$ 3.22) and NT$ 35 (i.e., US$ 1.05) per m3 of permeate for Case 1 (i.e., the filtration area of 0.0189 m2 in one EC/EF module) and Case 2 (i.e., the filtration area of 0.0801 m2 in one EC/EF module), respectively.
38

Colloidal and Electrochemical Aspects of Copper-CMP

Sun, Yuxia January 2007 (has links)
Copper based interconnects with low dielectric constant layers are currently used to increase interconnect densities and reduce interconnect time delays in integrated circuits. The technology used to develop copper interconnects involves Chemical Mechanical Planarization (CMP) of copper films deposited on low-k layers (silica or silica based films), which is carried out using slurries containing abrasive particles. One issue using such a structure is copper contamination over dielectric layers (SiO2 film), if not reduced, this contamination will cause current leakage. In this study, the conditions conducive to copper contamination onto SiO2 films during Cu-CMP process were studied, and a post-CMP cleaning technique was discussed based on experimental results. It was found that the adsorption of copper onto a silica surface is kinetically fast (< 0.5 minute). The amount of copper absorbed is pH and concentration dependent and affected by presence of H2O2, complexing agents, and copper corrosion inhibitor Benzotrazole. Based on de-sorption results, DI water alone was unable to reduce adsorbed copper to an acceptable level, especially for adsorption that takes place at a higher pH condition. The addition of complex agent, citric acid, proved effective in suppressing copper adsorption onto oxide silica during polishing or post-CMP cleaning by forming stable copper-CA complexes. Surface Complexation Modeling was used to simulate copper adsorption isotherms and predict the copper contamination levels on SiO2 surfaces.Another issue with the application of copper CMP is its environmental impact. CMP is a costly process due to its huge consumption of pure water and slurry. Additionally, Cu-CMP processing generates a waste stream containing certain amounts of copper and abrasive slurry particles. In this study, the separation technique electrocoagulation was investigated to remove both copper and abrasive slurry particles simultaneously. For effluent containing ~40 ppm dissolved copper, it was found that ~90% dissolved copper was removed from the waste streams through electroplating and in-situ chemical precipitation. The amount of copper removed through plating is impacted by membrane surface charge, type/amount of complexing agents, and solid content in the slurry suspension. The slurry particles can be removed ~90% within 2 hours of EC through multiple mechanisms.
39

Reduction of Pollutants in Stormwaterand Processwater from the WoodIndustry by Electrocoagulation

Hansson, Henrik January 2010 (has links)
Although wood floor production does not use water in the production process, water consumptionis related to cleaning and washing of floor and machineries in different steps of the process line,which generate a number of small flows that are highly polluted.Besides this, the industry has a need to store large amounts of wood outside to be able to havecontinuity in the production. This takes up a lot of space outdoors and once it rains the water thathas been in contact with wood, oil and metals forms stormwater, which transports pollutants.Stormwater has for a long time not been seen as a problem and has often been discharged intorecipient water bodies without any treatment. During cold seasons, this also involves snowmelt thatcan transport high concentrations of different pollutants.This report describes the composition of process- and stormwater from a wood floor industry inNybro, Sweden regarding parameters such as COD, phenol, tannin and lignin. The concentrationsof phenols in the stormwater were found in a range considered toxic to marine life.Regarding the process water, high values was found for COD (Chemical Oxygen Demand) and forother substances and elements potentially toxic (e.g. formaldehyde, wood resins, detergents andmetals). If these waters are directly released to a sewage treatment plant without any pre-treatmentprocess it can disturb the plant treatment efficiency; if released to a recipient water body, it cancause oxygen deficiency and consequently, death to marine life.The possibility of reducing the levels of pollutants through the use of electrocoagulation has beenexamined in this study. This has been done both for process water and stormwater from the woodfloor industry. A 250 ml batch unit for electrocoagulation EC was setup with iron (Fe) andaluminium (Al) electrodes for treating process water and stormwater. The results show that the ECprocess can reduce COD concentration from stormwater at least 70%. On the other hand, lessefficiency of EC for treating process water was observed.A method for simulating a snowmelt period in lab scale was also developed. Snow collected from awood floor industry was melted according to real temperature and the quality of these samples hasthen been compared to on-site samples of stormwater / Development of an integrated approach for industrial wastewater and stormwater management in the wood-industry sector
40

Reduction of Pollutants in Stormwaterand Processwater from the WoodIndustry by Electrocoagulation

Hansson, Henrik January 2010 (has links)
<p>Although wood floor production does not use water in the production process, water consumptionis related to cleaning and washing of floor and machineries in different steps of the process line,which generate a number of small flows that are highly polluted.Besides this, the industry has a need to store large amounts of wood outside to be able to havecontinuity in the production. This takes up a lot of space outdoors and once it rains the water thathas been in contact with wood, oil and metals forms stormwater, which transports pollutants.Stormwater has for a long time not been seen as a problem and has often been discharged intorecipient water bodies without any treatment. During cold seasons, this also involves snowmelt thatcan transport high concentrations of different pollutants.This report describes the composition of process- and stormwater from a wood floor industry inNybro, Sweden regarding parameters such as COD, phenol, tannin and lignin. The concentrationsof phenols in the stormwater were found in a range considered toxic to marine life.Regarding the process water, high values was found for COD (Chemical Oxygen Demand) and forother substances and elements potentially toxic (e.g. formaldehyde, wood resins, detergents andmetals). If these waters are directly released to a sewage treatment plant without any pre-treatmentprocess it can disturb the plant treatment efficiency; if released to a recipient water body, it cancause oxygen deficiency and consequently, death to marine life.The possibility of reducing the levels of pollutants through the use of electrocoagulation has beenexamined in this study. This has been done both for process water and stormwater from the woodfloor industry. A 250 ml batch unit for electrocoagulation EC was setup with iron (Fe) andaluminium (Al) electrodes for treating process water and stormwater. The results show that the ECprocess can reduce COD concentration from stormwater at least 70%. On the other hand, lessefficiency of EC for treating process water was observed.A method for simulating a snowmelt period in lab scale was also developed. Snow collected from awood floor industry was melted according to real temperature and the quality of these samples hasthen been compared to on-site samples of stormwater</p> / Development of an integrated approach for industrial wastewater and stormwater management in the wood-industry sector

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