Spelling suggestions: "subject:"advanced treatment"" "subject:"dvanced treatment""
1 |
Comparação do desempenho de carvão ativado produzido a partir de diferentes matrizes para remoção de microcistina-LR de águas de abastecimento / Comparison of the performance of activated carbon produced from different raw materials for microcystin-LR removal from water supplyAraújo, Larissa Sene 07 March 2017 (has links)
A expansão agrícola e a urbanização têm agravado a eutrofização artificial dos mananciais superficiais, devido ao aumento de seus níveis de nutrientes, como nitrogênio e fósforo. Nesses episódios, o crescimento excessivo de cianobactérias de elevada capacidade adaptativa e potencial de produção de cianotoxinas pode prejudicar homens e animais. As microcistinas estão entre as cianotoxinas mais encontradas em florações de cianobactérias tóxicas, de difícil remoção pelas tecnologias convencionais de Estações de Tratamento de Água (ETA). Como barreira adicional no tratamento avançado de águas de abastecimento, destaca-se o processo de adsorção com carvão ativado pulverizado (CAP) ou granular (CAG). Esta pesquisa avaliou a eficiência de remoção de microcistina-LR (MC-LR) por oito carvões ativados (7 CAGs e 1 CAP) produzidos a partir de matérias-primas diversificadas. Os carvões foram caracterizados quanto a umidade, teor de cinzas, pH, massa específica aparente, número de iodo, índice de azul de Metileno, coeficiente de desuniformidade, área superficial específica, volume de micro e mesoporos, análise elementar por Espectroscopia de Energia Dispersiva e fotomicrografia por Microscopia Eletrônica de Varredura. Avaliou-se a capacidade adsortiva dos carvões sobre a MC-LR por isotermas descritas pelos modelos matemáticos de Langmuir e Freundlich. Para tais ensaios, foram utilizadas amostras trituradas de carvão. Além disso, foram operadas quatorze colunas CAG em escala de bancada, de modo intermitente, com concentração inicial (Co) de MC-LR na faixa de 69 a 137 µg/L. A concentração de toxina foi estimada pelo método ELISA (Ensaio de Imunoadsorção Enzimática). Os resultados indicaram que as propriedades do CA são influenciadas por seu material de origem e também pelo seu modo de produção, e que tais propriedades têm reflexo direto sobre a eficiência de remoção de MC-LR. Nos ensaios de adsorção de MC-LR com as amostras trituradas, os dados se ajustaram melhor ao modelo de Langmuir. O carvão à base de linhito (CGLIN), em dosagem de 100,0 mg/L e com 4h de tempo de contato, apresentou a maior capacidade de remoção (97,2%) de MC-LR (Co: 115,1 µg/L), com qe,máx de 10,6 mg/g. O bom desempenho do CGLIN foi associado ao seu maior volume de mesoporos (0,53 cm3/g). Correlação significativa foi observada entre volume de mesoporos e qe,máx (r = 0,98, Pearson), o que foi corroborado pela Análise de Componentes Principais. Nos ensaios nas colunas de CAG, o carvão de hulha, CGHU (Co: 85 g/L) apresentou o melhor desempenho, seguido pelo carvão de casca de coco, CGCO4 (Co: 137 µg/L), ambos com remoção média de MC-LR de 99,5%. Nos ensaios com as amostras trituradas, nenhuma das dosagens removeu MC-LR a concentrações menores que 1,0 µg/L – valor máximo permitido pela Portaria MS nº 2.914/11 para água potável – enquanto que no início do tratamento com as colunas de CAG, com exceção do carvão de coco CGCO1, o efluente das demais amostras foi compatível com este limite. A divergência de resultados entre os dois tipos de ensaios indica que os experimentos com amostras de CAG trituradas podem alterar sua capacidade adsortiva e induzir a uma escolha incorreta do carvão mais adequado. Com isso, os resultados oferecem subsídios para o entendimento do desempenho das CAs sobre a remoção de cianotoxinas, amparando a aplicação do processo de adsorção em ETAs para minimização da incidência de intoxicações por água contaminada. / The agricultural expansion and urbanization has aggravated the artificial eutrophication of surface water sources, due to the increase of nutrient levels, such as nitrogen and phosphorus. In these episodes, the excessive growth of cyanobacteria of high adaptive capacity and potential to produce cyanotoxins can harm humans and animals. Microcystins are among the cyanotoxins most found in toxic cyanobacteria blooms, difficult to remove by conventional technologies of Water Treatment Plants (WTP). As an additional barrier in the advanced water treatment, the adsorption process with pulverized (PAC) or granular activated carbon (GAC) is highlighted. This research evaluated the efficiency of microcystin-LR (MC-LR) removal by eight activated carbons (7 GACs and 1 PAC) produced from diversified raw materials. The carbons were characterized by moisture, ash content, pH, bulk density, iodine number, Methylene blue index, desuniformity coefficient, specific surface area, micro and mesopore volume, elemental analysis by Energy Dispersive X-Ray Detector and photomicrography by Scanning Electron Microscopy. The MC-LR adsorptive capacity of the carbons was evaluated by isotherms that follow the mathematical models of Langmuir and Freundlich. For these tests, carbon crushed samples were used. Besides that, fourteen GAC columns were operated on bench scale, intermittently, with initial concentration (Co) of MC-LR in the range of 69 to 137 µg/L. The toxin concentration was measured by ELISA (Enzyme-Linked Immunosorbent Assay). The results indicate that the AC properties are influenced by their source material and also by their production mode, and these properties have a direct effect on the efficiency of MC-LR removal. In the adsorption tests of MC-LR with the AC crushed samples, the data were better fitted to the Langmuir model. The lignite-based carbon (CGLIN), at a dosage of 100.0 mg/L and 4h of contact time, presented the highest MC-LR (Co: 115.1 µg/L) removal capacity (97.2%), with a qe,máx of 10.6 mg/g. The good performance of CGLIN was associated with its higher volume of mesopores (0.53 cm3/g). Significant correlation was observed between volume of mesopores and qe,max (r = 0.98, Pearson), which was corroborated by Principal Component Analysis. In the GAC columns tests, the coal CGHU (Co: 85 µg/L) presented the best performance, followed by the coconut carbon CGCO4 (Co: 137 µg/L), both with MC-LR average removal from 99.5%. In the trials with the crushed samples, none of the dosages removed MC-LR at values less than 1.0 µg/L – maximum permitted value by Portaria MS nº 2.914/11 for drinking water – while at the beginning of the treatment in the GAC columns, with the exception of the coconut carbon CGCO1, the effluent of the other samples was compatible with this limit. The divergence of results between these two types of assays indicates that the experiments with crushed samples may changes their adsorptive capacity and induce an incorrect choice of the most suitable AC. With this, the results provide support to understand the ACs performance on the cyanotoxins removal, supporting the application of the adsorption process in WTPs to minimize the incidence of poisoning by contaminated water.
|
2 |
Comparação do desempenho de carvão ativado produzido a partir de diferentes matrizes para remoção de microcistina-LR de águas de abastecimento / Comparison of the performance of activated carbon produced from different raw materials for microcystin-LR removal from water supplyLarissa Sene Araújo 07 March 2017 (has links)
A expansão agrícola e a urbanização têm agravado a eutrofização artificial dos mananciais superficiais, devido ao aumento de seus níveis de nutrientes, como nitrogênio e fósforo. Nesses episódios, o crescimento excessivo de cianobactérias de elevada capacidade adaptativa e potencial de produção de cianotoxinas pode prejudicar homens e animais. As microcistinas estão entre as cianotoxinas mais encontradas em florações de cianobactérias tóxicas, de difícil remoção pelas tecnologias convencionais de Estações de Tratamento de Água (ETA). Como barreira adicional no tratamento avançado de águas de abastecimento, destaca-se o processo de adsorção com carvão ativado pulverizado (CAP) ou granular (CAG). Esta pesquisa avaliou a eficiência de remoção de microcistina-LR (MC-LR) por oito carvões ativados (7 CAGs e 1 CAP) produzidos a partir de matérias-primas diversificadas. Os carvões foram caracterizados quanto a umidade, teor de cinzas, pH, massa específica aparente, número de iodo, índice de azul de Metileno, coeficiente de desuniformidade, área superficial específica, volume de micro e mesoporos, análise elementar por Espectroscopia de Energia Dispersiva e fotomicrografia por Microscopia Eletrônica de Varredura. Avaliou-se a capacidade adsortiva dos carvões sobre a MC-LR por isotermas descritas pelos modelos matemáticos de Langmuir e Freundlich. Para tais ensaios, foram utilizadas amostras trituradas de carvão. Além disso, foram operadas quatorze colunas CAG em escala de bancada, de modo intermitente, com concentração inicial (Co) de MC-LR na faixa de 69 a 137 µg/L. A concentração de toxina foi estimada pelo método ELISA (Ensaio de Imunoadsorção Enzimática). Os resultados indicaram que as propriedades do CA são influenciadas por seu material de origem e também pelo seu modo de produção, e que tais propriedades têm reflexo direto sobre a eficiência de remoção de MC-LR. Nos ensaios de adsorção de MC-LR com as amostras trituradas, os dados se ajustaram melhor ao modelo de Langmuir. O carvão à base de linhito (CGLIN), em dosagem de 100,0 mg/L e com 4h de tempo de contato, apresentou a maior capacidade de remoção (97,2%) de MC-LR (Co: 115,1 µg/L), com qe,máx de 10,6 mg/g. O bom desempenho do CGLIN foi associado ao seu maior volume de mesoporos (0,53 cm3/g). Correlação significativa foi observada entre volume de mesoporos e qe,máx (r = 0,98, Pearson), o que foi corroborado pela Análise de Componentes Principais. Nos ensaios nas colunas de CAG, o carvão de hulha, CGHU (Co: 85 g/L) apresentou o melhor desempenho, seguido pelo carvão de casca de coco, CGCO4 (Co: 137 µg/L), ambos com remoção média de MC-LR de 99,5%. Nos ensaios com as amostras trituradas, nenhuma das dosagens removeu MC-LR a concentrações menores que 1,0 µg/L – valor máximo permitido pela Portaria MS nº 2.914/11 para água potável – enquanto que no início do tratamento com as colunas de CAG, com exceção do carvão de coco CGCO1, o efluente das demais amostras foi compatível com este limite. A divergência de resultados entre os dois tipos de ensaios indica que os experimentos com amostras de CAG trituradas podem alterar sua capacidade adsortiva e induzir a uma escolha incorreta do carvão mais adequado. Com isso, os resultados oferecem subsídios para o entendimento do desempenho das CAs sobre a remoção de cianotoxinas, amparando a aplicação do processo de adsorção em ETAs para minimização da incidência de intoxicações por água contaminada. / The agricultural expansion and urbanization has aggravated the artificial eutrophication of surface water sources, due to the increase of nutrient levels, such as nitrogen and phosphorus. In these episodes, the excessive growth of cyanobacteria of high adaptive capacity and potential to produce cyanotoxins can harm humans and animals. Microcystins are among the cyanotoxins most found in toxic cyanobacteria blooms, difficult to remove by conventional technologies of Water Treatment Plants (WTP). As an additional barrier in the advanced water treatment, the adsorption process with pulverized (PAC) or granular activated carbon (GAC) is highlighted. This research evaluated the efficiency of microcystin-LR (MC-LR) removal by eight activated carbons (7 GACs and 1 PAC) produced from diversified raw materials. The carbons were characterized by moisture, ash content, pH, bulk density, iodine number, Methylene blue index, desuniformity coefficient, specific surface area, micro and mesopore volume, elemental analysis by Energy Dispersive X-Ray Detector and photomicrography by Scanning Electron Microscopy. The MC-LR adsorptive capacity of the carbons was evaluated by isotherms that follow the mathematical models of Langmuir and Freundlich. For these tests, carbon crushed samples were used. Besides that, fourteen GAC columns were operated on bench scale, intermittently, with initial concentration (Co) of MC-LR in the range of 69 to 137 µg/L. The toxin concentration was measured by ELISA (Enzyme-Linked Immunosorbent Assay). The results indicate that the AC properties are influenced by their source material and also by their production mode, and these properties have a direct effect on the efficiency of MC-LR removal. In the adsorption tests of MC-LR with the AC crushed samples, the data were better fitted to the Langmuir model. The lignite-based carbon (CGLIN), at a dosage of 100.0 mg/L and 4h of contact time, presented the highest MC-LR (Co: 115.1 µg/L) removal capacity (97.2%), with a qe,máx of 10.6 mg/g. The good performance of CGLIN was associated with its higher volume of mesopores (0.53 cm3/g). Significant correlation was observed between volume of mesopores and qe,max (r = 0.98, Pearson), which was corroborated by Principal Component Analysis. In the GAC columns tests, the coal CGHU (Co: 85 µg/L) presented the best performance, followed by the coconut carbon CGCO4 (Co: 137 µg/L), both with MC-LR average removal from 99.5%. In the trials with the crushed samples, none of the dosages removed MC-LR at values less than 1.0 µg/L – maximum permitted value by Portaria MS nº 2.914/11 for drinking water – while at the beginning of the treatment in the GAC columns, with the exception of the coconut carbon CGCO1, the effluent of the other samples was compatible with this limit. The divergence of results between these two types of assays indicates that the experiments with crushed samples may changes their adsorptive capacity and induce an incorrect choice of the most suitable AC. With this, the results provide support to understand the ACs performance on the cyanotoxins removal, supporting the application of the adsorption process in WTPs to minimize the incidence of poisoning by contaminated water.
|
3 |
ELIMINATION OF ANTIBIOTIC RESISTANCE GENES FROM WATER MATRICES USING CONVENTIONAL AND ADVANCED TREATMENT PROCESSESDas, Dabojani, 0009-0004-1997-0960 05 1900 (has links)
The overuse and misuse of antibiotics to treat bacterial infections, the release of unmetabolized residuals into the sewer system, and the incomplete removal antibiotic residues by wastewater treatment plants (WWTPs) pose a severe threat to human health. The accumulation of antibiotic residue induces selective pressure on the bacterial population, resulting in the spread of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) in water.
This study investigated the degradation of different types of ARGs in water matrices using a wide variety of treatment technologies. Real wastewater samples were collected from a WWTP in urban Philadelphia and the presence of single and multidrug-resistant bacteria and resistance genes were investigated using molecular-based techniques. Subsequently, an analytical method was developed and validated for the detection and quantification of the ARGs against a range of antibiotics, such as tetracycline (TCN), ciprofloxacin (CIP), and levofloxacin (LVX). Finally, to remove the ARGs from water matrices, different conventional and advanced oxidation processes were applied.
At the very onset, conventional treatment processes such as chlorine treatment was used to inactivate the E.coli resistant strains. It was observed that chlorination can potentially deactivate the ARBs by applying a lower dose and contact time. However, the effectiveness of chlorine treatment in removing all types of ARGs from water matrices was limited. For instance, no significant degradation of extracellular ARGs (e-ARGs) was observed in DI water during chlorine treatment. Subsequently, a peracetic acid (PAA) based treatment process was used to degrade the genomic and plasmid-encoded ARGs from the water matrices. Similar to chlorine treatment, no significant changes were observed in the degradation of extracellular ARGs (e-ARGs) in DI and WW.
Then, the degradation kinetics of ARGs across different types (gyrAR, tetAR, qnrSR) and forms (chromosomal, plasmids) were evaluated using the Ultraviolet (UV) disinfection process. Compared to chlorination and PAA, UV treatment showed better removal efficiencies for the degradation of different types of e-ARGs in DI water. The degradation profile of e-ARGs showed 1-4 log reductions at a UV fluence of 900 mj/cm2. The i-ARGs showed similar degradation rates as compared to e-ARGs in phosphate buffer saline (PBS) at the same UV dosage. On the other hand, the regrowth potential of ARBs at low UV dosage (60–180 mJ/cm2) showed the evidence of damage repairment after several hours of exposure to light (photoreactivation) and dark conditions, making it susceptible again to the resistance spread. To resolve this issue, process parameters were optimized, and no regrowth of the ARBs were found from the higher fluence from 300 to 600 mJ/ cm2.
Later, UV/ H2O2 based AOP was applied to evaluate the degradation and deactivation of the same resistant genes. The addition of H2O2 during the UV treatment produces strongly reactive •OH radicals during the treatment and showed considerable improvements in e-ARGs degradation (1.2-5 logs) compared to UV treatment alone. However, this AOP showed minimal contribution to i-ARG degradation (1-2.4 logs), possibly due to the scavenging of •OH radicals by the cellular components in PBS. In contrast to PBS, the wastewater matrix moderately enhanced the gene degradation during the treatment. In terms of plasmid degradation, the conformational differences of the supercoiled structures showed 1.2-2.8 times slower degradation rates than chromosomal ARGs. In addition, the degradation kinetics of the free residual ARGs (f-ARGs) were assessed during the treatment to reduce the AMR dissemination risk from the treated sample.
This study also examined the potential of ozone (O3) based oxidation process to degrade and deactivate the extracellular and intracellular ARGs, and MGE (plasmid, intl-1) from E.coli ARBs. The degradation kinetics of the ARGs across different sizes (118-454 bps) and types were evaluated in different water matrices (DI water, PBS, and WW), and showed a significantly higher removal for chromosomal, and plasmid encoded ARGs than other treatment technologies. For the e-ARGs in DI water, 3.8-5.2 logs removal was observed at ozone dosage of 2.0 × 10-2 M.s. i-ARGs in PBS and wastewater showed nearly similar degradation (3.8-5 logs) during O3, indicating the elimination of i-ARGs was not dependent on the cellular components and effluent organic matter.
Moreover, an analysis of environmental DNA (eDNA) from wastewater was conducted to examine the degradation of DNA and ARGs for different storage periods and temperatures (-20°C, 0°C, 4°C, 22±0.87°C). Result indicated that water samples kept at -20°C and 0°C showed the best performance in preventing the DNA concentration and gene degradation over time. Additionally, the effectiveness of different preservatives (Longmire buffers: LB1 and LB2, benzalkonium chloride at 0.1%, 0.01%) were investigated in preserving the DNA integrity and the gene degradation at an ambient temperature. It was found that the Longmire buffer (LB1) exhibited lowest gene degradation during the three-week storage period.
In summary, this research provided a comprehensive assessment on the degradation of e-ARGs, i-ARGs, and free ARGs from water using different treatment technologies (i.e., UV, UV/H2O2, O3, PAA, chlorine). Additionally, this study suggested valuable information on optimizing the process parameters of the selected methods and developed a comparative assessment of removing the ARGs from the water matrix (DI/PBS, WW). The estimation of Electrical Energy per Order (EEO, kWh/m3) during UV and ozone treatments provided a comparison of the energy consumption for ARGs degradation in the water. Overall, the findings of this study can be useful for evaluating different types and forms (chromosomal, plasmid) of ARG degradation from water matrices and can help to reduce the risk of AMR dissemination in the environment. / Civil Engineering
|
4 |
Estudo de t?cnicas para o tratamento alternativo de efluentes oleosos oriundos da industrializa??o da castanha de cajuJer?nimo, Carlos Enrique de Medeiros 24 May 2010 (has links)
Made available in DSpace on 2014-12-17T15:01:50Z (GMT). No. of bitstreams: 1
CarlosEMJ_TESE.pdf: 1404904 bytes, checksum: 3029c558b265d6dfdac69a6fac1ef20c (MD5)
Previous issue date: 2010-05-24 / An evaluation project was conducted on the technique of treatment for effluent
oil which is the deriving process to improve cashews. During the evaluation the following
techniques were developed: advanced processes of humid oxidation, oxidative processes,
processes of biological treatment and processes of adsorption. The assays had been carried
through in kinetic models, with an evaluation of the quality of the process by means of
determining the chemical demand of oxygen (defined as a technique of control by means of
comparative study between the available techniques). The results demonstrated that the
natural biodegradation of the effluent ones is limited, as result using the present natural flora
in the effluent one revealed impracticable for an application in the industrial systems,
independent of the evaluation environment (with or without the oxygen presence). The job of
specific microorganisms for the oily composite degradation developed the viability technique
of this route, the acceptable levels of inclusion in effluent system of treatment of the
improvement of the cashew being highly good with reasonable levels of removal of CDO.
However, the use combined with other techniques of daily pay-treatment for these effluent
ones revealed to still be more efficient for the context of the treatment of effluent and
discarding in receiving bodies in acceptable standards for resolution CONAMA 357/2005.
While the significant generation of solid residues the process of adsorption with agroindustrial
residues (in special the chitosan) is a technical viable alternative, however, when
applied only for the treatment of the effluent ones for discarding in bodies of water, the
economic viability is harmed and minimized ambient profits. Though, it was proven that if
used for ends of I reuse, the viability is equalized and justifies the investments. There was a
study of the photochemistry process which have are applicable to the treatment of the effluent
ones, having resulted more satisfactory than those gotten for the UV-Peroxide techniques.
There was different result on the one waited for the use of catalyses used in the process of
Photo. The catalyses contained the mixing oxide base of Cerium and Manganese,
incorporated of Potassium promoters this had presented the best results in the decomposition
of the involved pollutants. Having itself an agreed form the gotten photochemistry daily paytreatment
resulted, then after disinfection with chlorine the characteristics next the portability
to the water were guarantee. The job of the humid oxidation presented significant results in
the removal of pollutants; however, its high cost alone is made possible for job in projects of
reuses, areas of low scarcity and of raised costs with the capitation/acquisition of the water, in
special, for use for industrial and potable use. The route with better economic conditions and
techniques for the job in the treatment of the effluent ones of the improvement of the cashew
possesses the sequence to follow: conventional process of separation water-oil,
photochemistry process and finally, the complementary biological treatment / Neste trabalho foram avaliadas t?cnicas de tratamento para os efluentes oleosos
oriundos do processo de beneficiamento da castanha de caju. As t?cnicas avaliadas foram:
processos de oxida??o ?mida, processos oxidativos avan?ados, processos de tratamento
biol?gico e processos de adsor??o. Os ensaios foram realizados com propostas de modelos
cin?ticos, com monitoramento da qualidade dos processos por meio da determina??o da
demanda qu?mica de oxig?nio (definida como t?cnica de controle por meio de estudo
comparativo entre as t?cnicas dispon?veis). Os resultados demonstram que a biodegrada??o
natural dos efluentes ? limitada, e os resultados utilizando da flora natural presente no efluente
mostrou-se invi?vel para aplica??o em sistemas industriais, independente do ambiente de
avalia??o (com ou sem a presen?a de oxig?nio). O emprego de microorganismos espec?ficos
para a degrada??o de compostos oleosos incrementou a viabilidade t?cnica dessa rota,em
n?veis adequados para aplica??o em sistemas de tratamento de efluentes do beneficiamento da
castanha, tendo-se uma boa expressividade, com remo??o da DQO. Por?m, o uso combinado
com outras t?cnicas de pr?-tratamento para esses efluentes mostrou-se ainda mais eficiente
para o contexto do tratamento de efluentes e descarte em corpos receptores dentro dos padr?es
preconizados pela resolu??o CONAMA 357/2005. Apesar da gera??o significativa de
res?duos s?lidos, o emprego do processo de adsor??o com res?duos agroindustriais (em
especial a quitosana) ? uma alternativa tecnicamente vi?vel, por?m, quando aplicada apenas
para o tratamento dos efluentes para o descarte em corpos d ?gua, a viabilidade econ?mica ?
prejudicada e os ganhos ambientais minimizados. Por?m, foi comprovado que se utilizado
para fins de reuso, a viabilidade ? equiparada e justifica os investimentos. Os processos
fotoqu?micos s?o aplic?veis ao tratamento dos efluentes estudados, tendo-se como resultados
mais satisfat?rios aqueles obtidos para as t?cnicas de UV-Per?xido. Sendo o resultado
diferente do esperado pela utiliza??o de catalisadores usados no processo de Foto-Fenton. Os
catalisadores a base de ?xido misto de C?rio e Mangan?s, incorporado de promotores de
Pot?ssio, apresentaram os melhores resultados na decomposi??o dos poluentes envolvidos. Os
resultados obtidos de forma combinada ao pr?-tratamento fotoqu?mico, ap?s desinfec??o com
cloro, garantem caracter?sticas pr?ximas a potabilidade da ?gua. O emprego da oxida??o
?mida apresenta resultados muito significativos na remo??o de poluentes, entretanto, o seu
alto custo s? ? viabilizado para emprego em projetos de reuso, em ?reas de baixa escassez e
de elevados custos com a capta??o/aquisi??o da ?gua, em especial, para utiliza??o para uso
industrial e pot?vel. A rota com melhores condi??es econ?micas e t?cnicas para o emprego no
tratamento dos efluentes do beneficiamento da castanha de caju, possui a seq??ncia a seguir:
processo convencional de separa??o ?gua-?leo, processo fotoqu?mico e por fim, o tratamento
biol?gico complementar
|
5 |
Utvärdering av effektivitet för aktivt kol och anjonbytare vid reduktion av per- och polyfluorerade alkylsubstanser (PFAS) samt läkemedelssubstanser i avloppsvattenKalecinska, Monika January 2021 (has links)
Avloppsreningsverk (ARV) utgör en viktig del som spridningsväg för utsläpp av organiska mikroföroreningar, som per- och polyfluorerade alkylsubstanser (PFAS) och läkemedelssubstanser, från samhället till den akvatiska miljön. Befintliga reningssteg vid ARV reducerar mikroföroreningar dåligt varav denna studie syftade till att jämföra reduktionseffektiviteten av 5 olika granulära aktiva kol (GAK) och en anjonbytare (AIX) för att välja ut det material som är mest lämpat för vidare undersökningar i pilotskala inför installation ett avancerat reningssteg i Kungsängsverkets ARV i Uppsala. GAK (Filtrasorb 400, Cyclecarb 401, Brennsorb 1240, Aquasorb 5000 och Aquasorb 2000) utvärderades för avskiljning av 13 PFAS-ämnen i ett inledande bägarförsök genom placering i avloppsvatten från Kungsängsverket i 8 h. Cyclecarb 401 var mest effektivt vid avskiljning av PFAS där reduktionsgraden för PFAS-11 (85 %) och PFOS (90 %) var 35 % och 40 % högre än för det minst effektiva GAK Brennsorb 1240. Cyclecarb 401, Brennsorb 1240 och AIX Purolite 694E undersöktes i ett andra bägarförsök enligt en liknande metod, men utvärderades med avseende på avskiljning av 12 PFAS och 18 läkemedelssubstanser över 48 h. Resultatet för PFAS var likvärdigt för GAK, men AIX visades nå samma reduktionsgrad av PFAS som Cyclecarb 401 och detta skedde snabbare. Efter 48 h var reduktionen med GAK högst för läkemedelssubstanser (91-99 %) och med AIX för PFAS (78 %). Samtliga adsorbenter tillfördes även till kolonner, där Purolite 694E även seriekopplades efter Cyclecarb 401, med ett kontinuerligt flöde av avloppsvatten motsvarande 5 min kontakttid (EBCT). Även om duplikatprover togs varje vecka genomfördes inom ramen för detta examensarbete analyser för de prover tagna en timme (12 bäddvolymer), 2 veckor (4000 bäddvolymer) och 7 veckor (14 000 bäddvolymer) efter start för 12 PFAS och 18 läkemedelssubstanser. Purolite 694E reducerade PFAS bäst, 40-50 % bättre än GAK, följt av negativt laddade läkemedelssubstanser och adsorptionen för dessa ämnen var bättre över tid än för GAK. Seriekoppling av AIX efter GAK förbättrade reduktionsgraden över tid för främst PFAS (30 % ökning vid 14 000 bäddvolymer). Även för läkemedelssubstanser med negativ laddning som adsorberades väl av AIX. Adsorptionen till AIX gynnades mest av substanser med negativa laddning. Adsorptionen till samtliga adsorbenter gynnades av PFAS med en sulfonatgrupp, en lägre syrakonstant, en högre fördelningskonstant mellan oktanol och vatten samt en längre kolkedja. En seriekoppling av AIX efter GAK är främst intressant för förbättrad avkiljning av diklofenak och PFOS vid Kungsängsverket, men även avskiljning av andra PFAS och negativt laddade läkemedelssubstanser kan förbättras. Andra ämnen adsorberades väl av GAK där Cyclecarb 401 i samtliga försök visats mest effektiv. De analyserade provpunkterna för kolonnförsöket var för få varav en kommande noggrannare undersökning över hela försökets genomförande kommer påvisa livslängderna för varje adsorbent vid EBCT 5 min. EBCT var kort varav efterföljande försök bör undersöka avskiljningens effektivitet för Kungsängsverket vid längre EBCT. / Waste water treatment plants (WWTPs) constitute an important role in releasing organic micropollutants, such as per- and polyfluoroalkyl substances (PFAS) and pharmaceuticals, from the society into the aquatic environment. Reduction of them in existing treatment methods in WWTPs is insufficient which is why the aim of this study was to examine the reduction efficiency for 5 granular activated carbons (GAC) and an anion exchange resin (AIX) and choose the adsorbent most suited for further studies in pilot scale before an advanced treatment step is built to Kungsängsverket WWTP in Uppsala. GAC (Filtrasorb 400, Cyclecarb 401, Brennsorb 1240, Aquasorb 5000 and Aquasorb 2000) were evaluated for 13 PFAS compounds in an initial batch experiment using wastewater from Kungsängsverket during 8 h. Cyclecarb 401 had the highest removal efficiency for PFAS where the reduction grade for PFAS-11 (85 %) and PFOS (90 %) was 35 % and 40 % higher than for the least efficient GAC Brennsorb 1240. Cyclecarb 401, Brennsorb 1240 and the AIX Purolite 694E were evaluated in a second batch experiment through a similar method, analyzed for 12 PFAS and 18 pharmaceuticals over 48 h. The results for PFAS were similar for GAC, but AIX reached the same reduction grade for PFAS as Cyclecarb 401 which also happened faster. After 48 h reduction with GAC was best for pharmaceuticals (91-99 %) and with AIX for PFAS (78 %). Finally, these adsorbents were placed in individual columns, where Cyclecarb 401 was connected to an additional column with Purolite 694E, with a continuous flow of wastewater with an empty bed contact time (EBCT) of 5 min. Even though duplicate samples were taken each week analysis was performed for samples taken an hour (12 bed volumes), 2 weeks (4000 bed volumes) and 7 weeks after start (14 000 bed volumes) for 12 PFAS and 18 pharmaceuticals. Purolite 694E reduced PFAS the best, 40-50 % better than GAC, followed by negatively charged pharmaceuticals and adsorption for these compounds was better over time than with GAC. AIX after GAC increased reduction grade over time primarily for PFAS (30 % improvement after 14 000 bed volumes) but also for pharmaceuticals well adsorbed by AIX. Adsorption to AIX was mainly improved with a negative charge of the compound. Adsorption to adsorbents was favored for PFAS containing a sulfonate group, compounds with a lower acid dissociation constant, a higher octanol-water partition coefficient and a longer carbon chain. Implementation of AIX after GAC would be of interest for Kungsängsverket mainly due to the improved removal of diclofenac and PFOS, but also if removal of other PFAS and pharmaceuticals will become prioritized. Other compounds were removed by GAC well where Cyclecarb 401 was most effective in all experiments. The analyzed samples for the column experiment were too few which is why a more comprehensive study of all samples over the whole experiment period will be able to determine the life length of each adsorbent for EBCT 5 min. EBCT was short which is why further experiments need to examine the reduction efficiency for Kungsängsverket at a longer EBCT.
|
6 |
Utvärdering av långtidstester med aktivt kol och anjonbytare för avskiljning av läkemedelsrester och PFAS från kommunalt avloppsvatten : Reningseffektivitet, kostnad och klimatpåverkan / Evaluation of long-term tests with activated carbon and anion exchange resins for removal of pharmaceuticals and PFASs from municipal wastewater : Treatment efficiency, cost and climate impactOlsson, Sofia January 2023 (has links)
Avloppsreningsverk utgör en viktig spridningsväg för läkemedelsrester till den akvatiska miljön. Även per- och polyfluorerade alkylsubstanser (PFAS) har påvisats i utgående vatten från avloppsreningsverk. För att minska utsläpp av dessa krävs ett kompletterande reningssteg. Syftet med denna studie var att utvärdera utökad rening av avloppsvatten med granulerat aktivt kol (GAK) och anjonbytare (AIX, Anion exchange resin). Underlag för utvärdering utgjordes av resultat från pågående pilotstudie vid Kungsängsverket i Uppsala, vilken består av kolonnförsök samt pilotförsök i större skala. I kolonnförsöken testas kombinationen GAK (Cyclecarb 401 eller Filtrasorb 400) i fixerade bäddar, följt av AIX (Purolite 694E) i fixerade samt fluidiserade bäddar i olika driftlinjer. Kontakttiden (EBCT, Empty Bed Contact Time) var cirka 15 minuter för GAK respektive 5 minuter för AIX. I pilotförsöken inkluderas även tvåstegsdrift av GAK med EBCT på cirka 14 minuter per filter. Vid slutet av denna studie hade cirka 36 000 till 37 000 bäddvolymer (BV) behandlats med GAK, respektive 98 000 till 116 000 BV med AIX i kolonnförsöken. I pilotförsöken hade cirka 5 000 till 10 000 BV behandlats med GAK samt cirka 8 000 till 31 000 BV med AIX. Reningseffektivitet utvärderades avseende avskiljning av diklofenak, oxazepam, metoprolol, citalopram samt PFOS eftersom dessa i tidigare studie pekats ut som mest utmanande för mottagande vattenmiljö. En högre avskiljning av oxazepam, metoprolol och citalopram uppnåddes med GAK än med AIX, där Cyclecarb 401 uppvisat högst reduktion. För diklofenak och PFOS uppnåddes en högre avskiljning med kombinationen GAK följt av AIX än med enbart GAK. Driftkostnad och klimatpåverkan utvärderades för samtliga adsorbenter samt för specifika scenarion vid Kungsängsverket. Scenarierna inkluderar olika reningsmål för avancerad rening med singel- respektive tvåstegsdrift av GAK samt GAK följt av AIX. Reningsmålen avser en 80 procentig genomsnittlig reduktion över tid av diklofenak, oxazepam, PFOS eller en kombination av dessa. Vid ekvivalent dos av adsorbenterna resulterade Cyclecarb 401 i den lägsta driftkostnaden och klimatpåverkan. Lägst driftkostnad för samtliga reningsmål erhölls med tvåstegsdrift av GAK. För avskiljning av PFOS eller PFOS och diklofenak erhölls lägst klimatpåverkan med kombinationen GAK följt av AIX. För resterande reningsmål erhölls lägst klimatpåverkan med tvåstegsdrift av GAK. I tillägg utfördes en regressionsanalys för att undersöka om enkla mätningar av löst organiskt kol (DOC) eller ultraviolett absorbans (UVA) kan användas som uppföljningsmetod för reningseffektiviteten. Ingen korrelation kunde dock fastställas mellan skillnaden i ingående och utgående koncentration eller absorbans av DOC, UVA och diklofenak, oxazepam eller PFOS. / Wastewater treatment plants are an important source for the spread of pharmaceuticals to the aquatic environment. Per- and polyfluorinated alkyl substances (PFASs) have also been detected in outgoing wastewater. To reduce emissions of these micropollutants, an advanced treatment process is required. This study aimed to evaluate advanced treatment with granular activated carbon (GAC) and anion exchange resin (AIX), using results from an ongoing pilot study at the wastewater treatment plant Kungsängsverket in Uppsala, Sweden. The pilot study consists of column tests and pilot tests in larger scale. The column tests consist of the combination of GAC (Cyclecarb 401 or Filtrasorb 400) in fixed beds, followed by AIX (Purolite 694E) in fixed or fluidized beds in different operating lines. Contact time (EBCT, Empty Bed Contact Time) was 15 minutes for GAC and 5 minutes for AIX. The pilot tests include two-stage operation of GAC with EBCT of 14 minutes per filter. At the end of this study, in the column tests, approximately 36 000 bed volumes (BV) had been treated with GAC and 98 000 to 116 000 BV with AIX. In the pilot tests, 5 000 to 10 000 BV had been treated with GAC and 8 000 to 31 000 BV with AIX. Treatment efficiency was evaluated for diclofenac, oxazepam, metoprolol, citalopram and PFOS, since these were identified as prioritized substances in a previous study. A higher reduction of oxazepam, metoprolol and citalopram were obtained using GAC compared to AIX, where Cyclecarb 401 showed the highest reduction. For diclofenac and PFOS, a higher reduction was achieved for the combination of GAC followed by AIX compared to GAC alone. Operating cost and climate impact were evaluated for the adsorbents as well as for specific scenarios at Kungsängsverket, that includes different treatment goals for single stage and two-stage operation of GAC, and GAC followed by AIX. Treatment goals consists of an 80 percent average reduction over time of diclofenac, oxazepam, PFOS, or a combination of these. For an equivalent dose of adsorbent, the lowest operating cost and climate impact was obtained with Cyclecarb 401. The lowest operating cost for all the treatment goals was obtained with two-stage operation of GAC. For reduction of PFOS or PFOS and diclofenac, the lowest climate impact was obtained with the combination of GAC followed by AIX. For the remaining treatment goals, the lowest climate impact was obtained with two-stage operation of GAC. In addition, a regression analysis was preformed to evaluate whether measurements of dissolved organic carbon (DOC) or ultraviolet absorbance (UVA) could serve as a prediction method for the treatment efficiency of organic micropollutants. However, the regression analysis showed no correlation between the reduction of DOC, UVA, and diclofenac, oxazepam or PFOS.
|
Page generated in 0.0853 seconds