Fertilizer phosphorus (P) can become unavailable to crops due to immobilization of P in acidic soils through forming chemical bonds with iron (Fe) and aluminum (Al) amorphous oxides.  Organic chelating agents form strong bonds with metals in soil and may reduce P binding with Fe and Al.  Ethylenediamine tetraacetic acid (EDTA), hydroxyethyl ethylenediamine triacetic acid (HEEDTA), gluconic acid (GA), and citric acid (CA) were tested to determine their influence on water-soluble P (WSP), Mehlich-1 P and Mehlich-3 P in Loam and Sand soils fertilized with P and incubated for 49 days.  Soil P sorption capacity (PSC) was estimated from an oxalate extraction of Fe and Al, and chelates were applied at rates of 90 percent of the PSC.  The EDTA, HEEDTA, and CA significantly (P<0.05) reduced P sorption in the Loam and Sand when measured by WSP.  In soils without P fertilizer added, EDTA and HEEDTA significantly increased WSP, Mehlich-1, and Mehlich-3 P concentrations.  EDTA and HEEDTA were also applied at 0, 30, 60, 90, 120, and 150 percent PSC to produce a rate response curve for WSP in a second soil incubation.  With increasing chelating rate, there was a linear increase in WSP for both soils, thus indicating higher rates of chelating agents were most efficient at decreasing P sorption. EDTA and HEEDTA were also tested in a 4-week greenhouse study for efficiency at increasing plant available P to corn (Zea mays L.) in two soils.  Phosphorus was added with and without the addition of chelating agents to the center of the pot, simulating a starter band of P.  After 4weeks, soils were analyzed for WSP, Mehlich-1, and Mehlich-3 P and corn above- and below-ground biomass was quantified and analyzed for total P concentration.  Without the presence of chelating agents, concentrations of WSP, Mehlich-1 P, Mehlich-3 P, above- and below-ground biomass, and TKP increased linearly as P fertilizer rates increased at 0, 9.6, 19.3, 28.9, and 38.5 kg P ha-1.  Decreased P sorption using chelating agents was not observed in this experiment.  However, with the results from the soil incubation, chelating agents do show potential for increasing plant available P, but the application and incorporation method needs to be further studied. / Master of Science

Thesis (Ph. D.)--University of Missouri--Columbia, 1998. / "December 1998." Typescript. Vita. Includes bibliographical references (leaves 157-166). Also available on the Internet.

Este estudo teve como objetivo avaliar a capacidade de remoção da smear layer das paredes de canais radiculares instrumentados pelas soluções de soro fisiológico, EDTA a 17%, vinagre de maçã e SmearClear®, nos três níveis radiculares, associadas ou não ao ultra-som. Para tal propósito, foram utilizados 70 dentes caninos humanos superiores e inferiores extraídos os quais tiveram suas coroas removidas. O comprimento de trabalho foi determinado pela visualização da ponta de uma lima tipo K com diâmetro 10 no forame apical, subtraindo-se 1 milímetro dessa medida. Para o preparo biomecânico, instrumentou-se os dentes com o sistema rotatório ProTaper®, pela técnica coroa-ápice, até o instrumento F5, irrigando os canais com hipoclorito de sódio a 2,5% a cada troca de instrumento. Os dentes foram divididos aleatoriamente em 6 grupos de 10 dentes e 2 grupos controle de 5 dentes de acordo com o método de irrigação final a serem testados: Grupo 1 (controle) Soro fisiológico por 3 minutos sem ultra-som; Grupo 2 - (controle) Soro fisiológico por 3 minutos, sendo o primeiro minuto ativado pelo ultra-som; Grupo 3 - EDTA a 17% por 3 minutos sem ultra-som; Grupo 4 - EDTA a 17% por 3 minutos, sendo o primeiro minuto ativado pelo ultra-som; Grupo 5 - Vinagre de maçã por 3 minutos sem ultra-som; Grupo 6 - Vinagre de maçã por 3 minutos, sendo o primeiro minuto ativado pelo ultra-som; Grupo 7 - SmearClear® por 1 minuto sem ultra-som; Grupo 8 - SmearClear® por 1 minuto ativado pelo ultra-som. Em seguida, os dentes foram irrigados com hipoclorito de sódio a 2,5% e soro fisiológico e secos com cones de papel absorvente. As raízes foram seccionadas longitudinalmente e preparadas para a microscopia eletrônica de varredura com o aumento de 750 vezes. Fotomicrografias foram obtidas dos terços cervical, médio e apical e analisadas por três examinadores para a atribuição de escores para posterior análise estatística. Concluiu-se que as soluções de EDTA e SmearClear® foram efetivas na remoção da smear layer do canal radicular, com pequena vantagem numérica do EDTA, entretanto, sem diferença estatisticamente significante entre elas. O soro fisiológico apresentou resultado significativamente inferior comparado às demais soluções irrigadoras. O vinagre de maçã se mostrou ligeiramente inferior ao SmearClear® e ao EDTA, apresentando diferença estatisticamente significante ao EDTA no terço cervical. O uso do ultra-som não promoveu uma melhora significante na capacidade de limpeza de todas as soluções irrigadoras testadas. Em todos os grupos, o resultado menos favorável em relação à remoção da camada de smear layer foi observado no terço apical do canal radicular, com diferença estatisticamente significante em relação ao terço cervical. / The aim of this study was to evaluate the smear layer removal from instrumented root canal walls by saline solution, 17% EDTA, apple vinegar and SmearClear®, at three radicular levels, with or without ultrasonics. For that purpose, 70 upper and lower human canines were used, which had their crowns removed. The working length was established by visualizing the tip of a 10 K-type file at the apical foramen, by reducing 1 mm from this measurement. For preparation of root canal, the teeth were instrumented with rotatory files ProTaper®, using the crown-down technique, up to F5 instrument, irrigating with 2,5% sodium hypochlorite between each instrument change. The teeth were randomly divided into 6 groups of 10 teeth each and 2 control groups of 5 teeth according to the final irrigation protocol: Group 1 (control) Saline solution for 3 minutes without ultrasonics; Group 2 (control) Saline solution for 3 minutes, with ultrasonic activation for the first minute; Group 3 17% EDTA for 3 minutes without ultrasonics; Group 4 17% EDTA for 3 minutes, with ultrasonic activation for the first minute; Group 5 Apple vinegar for 3 minutes without ultrasonics; Group 6 Apple vinegar for 3 minutes, with ultrasonic activation for the first minute; Group 7 - SmearClear® for 1 minute without ultrasonics; Group 8 - SmearClear® for 1 minute with ultrasonic activation. Subsequently, the teeth were irrigated with 2,5% sodium hypochlorite and dried with paper points. The teeth were split open longitudinally and prepared for scanning electron microscopy at magnification of 750X. Photomicrographs were taken from coronal, middle and apical thirds and analyzed by three examiners for scores attribution for statistical analysis. It was concluded that EDTA and SmearClear® were efficient for smear layer removal from root canals, with a discrete superiority of EDTA, however, without statistical significance. The saline solution showed significant inferior results compared with the others solutions. Apple vinegar was slightly inferior to SmearClear® and EDTA, with statistical difference observed between apple vinegar and EDTA in coronal third. The ultrasonics did not enhance the cleaning ability of all the irrigating solutions tested. In all cases, the least favorable result regarding smear layer removal was observed in the apical third of the root canal, with statistically significant differences in the coronal third.

No description available.

O presente estudo teve como objetivo avaliar a ação das soluções de quitosana, EDTA e ácido cítrico sobre a microdureza da dentina radicular. Utilizaram-se 10 incisivos centrais superiores humanos, os quais tiveram suas coroas seccionadas transversalmente e desprezadas. As raízes foram incluídas em resina acrílica de rápida polimerização e o bloco formado raiz/resina adaptado a máquina de corte. Desprezou-se o primeiro corte transversal da porção cervical e dividiu-se o segundo, em quatro quadrantes. Cada quarto foi destinado à confecção do corpo de prova obtendo-se 4 espécimes para cada raiz, um para cada solução (n=10): G1- EDTA 15%; G2- ácido cítrico; G3- quitosana 0,2% e G4- controle. Os espécimes receberam 50 &mu;L da solução por 5 minutos, sendo em seguida, lavados com água deionizada. Utilizou-se um microdurômetro (dureza Knoop) com carga de 10 g durante 15 segundos. Os resultados mostraram que todas as soluções avaliadas apresentaram capacidade de reduzir a microdureza da dentina radicular de forma semelhante entre si e estatisticamente diferente a do grupo controle (p<0,01). Concluiu-se as soluções de quitosana 0,2%, EDTA 15% e ácido cítrico 10% apresentam efeito semelhante na redução da microdureza dentinária. / The aim of this study was to evaluate the action of solutions: chitosan, EDTA and citric acid on the microhardness of the root dentin. There were used 10 human maxillary central incisors which ones had their crown cross-sectioned and discarded. The roots were embedded in acrylic resin of rapid polymerization and the block formed root/resin suitable by cutting machine. Neglecting the first cross-section of the cervical portion and the second was divided in four quadrants. Each quarter was destined to the confection of the specimen and it was got 4 specimen to each root, one for each solution (n=10): G1- EDTA 15%; G2- citric acid;G3- chitosan 0,2 % and G4- control. The specimen received 50 &mu;L of the solution for 5 minutes, and following up they were washed by deionized water. It was used a microhardness (Knoop hardness) with a load of 10g during 15 seconds. The results showed that all the solutions evaluated presented a capacity to reduce the microhardness of the root dentin in a similar way between them, and statically differ from the control group (p<0,01). It was concluded that chitosan 0,2% EDTA 15% and the citric acid 10% presented a similar effect in the reduction of the dentin microhardness.

<p>Skoghalls Bruk fick i juni 2005 tillstånd av miljödomstolen att öka kartongproduktionen från 665 000 till 800 000 ton kartong per år. Villkoren för tillståndet var att under en prövotidsperiod bl.a. utreda möjligheten att minska utsläpp till omkringliggande vatten.</p><p>Syftet med examensarbetet var att kartlägga Skoghalls Bruks avloppssystem med avseende på komplexbildarna EDTA (etylendiamintetraättiksyra) och DTPA (dietylentriaminpentaättiksyra), kväve samt fosfor.</p><p>Dessutom genomfördes nedbrytningsförsök i luftade dammar i laboratorieskala.</p><p>För att få en klarare bild av nedbrytningen i Skoghalls Bruks luftade damm gjordes även en molekylviktsfraktionering på inkommande och utgående avloppsvatten.</p><p>Komplexbildare används inom pappers- och massaindustrin för sin förmåga att binda till sig metalljoner som kan vara skadliga i processen. Metalljoner katalyserar nedbrytningen av väteperoxid i blekningen och påskyndar bildandet av aldehyder i kartongen vilket kan leda till lukt- och smakpåverkan.</p><p>EDTA och DTPA anses vara stabila ämnen, vilket innebär att de är biologiskt svårnedbrytbara. Under den litteraturstudie som genomfördes fanns motsägande uppgifter angående nedbrytningen av komplexbildare, där vissa menade att de genomgår biologisk nedbrytning, men att det sker mycket långsamt. Andra påstod att komplexbildare inte bryts ner överhuvudtaget.</p><p>Komplexbildare kan elimineras genom fotokemisk oxidativ nedbrytning. Då EDTA och DTPA bildar komplex med Fe3+ blir de fotokemiskt labila och oxideras till mindre föreningar vid belysning med ultraviolett ljus. Sammanfattningsvis gav litteraturstudien att det mest effektiva sättet att minska komplexbildare i avloppsvatten innan det släpps till recipienten är att UV-bestråla vid optimala förhållanden, dvs. rätt pH och eventuellt tillsats av Fe3+ om det behövs.</p><p>Provtagning av avloppsvatten i Skoghalls Bruks reningsanläggning gjordes under 6 veckor för att kartlägga utsläppen och de olika delströmmarnas bidrag.</p><p>Nedbrytningsförsök genomfördes i två luftade dammar i laboratorieskala. För att studera temperaturens inverkan konstruerades en sommar- och en vinterdamm med temperaturerna 27 respektive 16°C. Efter referensförsöket, som gjordes för att se eventuella skillnader mellan försöken, undersöktes inverkan av ultraviolett ljus på nedbrytningen av komplexbildare. Sedan tillsattes Fe3+ i form av järnklorid i ett försök att öka den fotokemiska nedbrytningen. Alla försök pågick under två veckor vardera.</p><p>I syfte att undersöka partikelstorleksfördelningen före och efter nedbrytning i Skoghalls Bruks luftade damm gjordes en molekylviktsfraktionering. Inkommande och utgående avloppsvatten från dammen ultrafiltrerades och analyserades med avseende på COD (Chemical Oxygen Demand), komplexbildare, kväve och fosfor.</p><p>Kartläggningen visade att EDTA bröts ner effektivt i reningsanläggningen medan nedbrytningen av DTPA var obetydlig. EDTA reducerades med 88 % över den luftade dammen.</p><p>Avlopp från kartongmaskinerna samt CTMP-fabriken var de avlopp som innehöll mest EDTA. Största mängden DTPA återfanns i blekerifiltratet och i KM 8:s avlopp.</p><p>Skoghalls Bruk släppte ut komplexbildare motsvarande 0,188 kg/ton kartong, i form av 100 % syra i obunden form, under karteringsperioden vilket var klart lägre än gränsvärdet som är 1,6 kg 100 % syra/ton kartong.</p><p>Kväve reducerades med 67 % över den luftade dammen. Det nuvarande gränsvärdet för kväveutsläpp till recipient är 500 kg/dygn, men ett av målen med prövotidsutredningen är att minska utsläppen till 300 kg/dygn. Enligt resultaten från karteringsperioden var kväveutsläppet 204 kg/dygn vilket uppfyller målet för prövotidsutredningen. Av det totala kväveutsläppet kom 39 kg/dygn från komplexbildare. Utsläppet av kväve från mixeriavloppet var 56 kg/dygn till recipient vilket var klart högre än förväntat.</p><p>Den totala fosforreduceringen över reningsanläggningen var 78 %. Utsläppet av fosfor till recipient var 19 kg/dygn vilket är klart lägre än gränsvärdet som är 50 kg/dygn.</p><p>På grund av komplexbildaranalysens mätosäkerhet var det svårt att få entydiga resultat från laboratorieförsöken. Det fastställdes dock att DTPA var svårare att bryta ner än EDTA och att järntillsats i kombination med ultraviolett ljus gav en positiv effekt på nedbrytningen av båda komplexbildarna. Även nedbrytningen av COD, kväve och fosfor ökade vid järntillsats.</p><p>Att DTPA är svårare att bryta ner än EDTA framkom även av resultaten från molekylviktsfraktioneringen. Det visade sig också att EDTA och DTPA inte är helt vattenlösliga utan kan binda till fast material. Största delen av komplexbildarna fanns dock i fraktionen med partiklar med molekylvikt mindre än 1 kDa. Kväve och fosfor fanns i de låg- och högmolekylära fraktionerna.</p> / <p>In June of 2005 Skoghall Mill got permission from the Environmental Court to increase their production of board from 665 000 tons to 800 000 tons per year. The condition for the permission was to, during a trial period, investigate the possibility to decrease the emissions to the surrounding water. The purpose of this master thesis is to do a mapping of Skoghall Mill’s waste water treatment system regarding the chelating agents EDTA (ethylenediaminetetraacetic acid) and DTPA (diethylenetriaminepentaacetic acid), nitrogen and phosphor.</p><p>Also degradation-trials were made with aerated lagoons in laboratory-scale.</p><p>To get a more complete view of the degradation in Skoghalls Mills aerated lagoon a molecular weight fractionation of the incoming and the outgoing water was made.</p><p>Chelating agents are used in the pulp- and paper industry due to its ability to bind metal-ions which are hazardous for the process. The metal-ions catalyze the decomposition of hydrogen peroxide in the bleaching process and the forming of aldehydes in the board which can lead to problems with taste and odour.</p><p>EDTA and DTPA are regarded to be very stable, which means that they are hard to degrade biologically. There was contradictory information about the degradation of chelating agents during the literature survey. Some say that chelating agents are degraded biologically but very slowly. Others say that they don’t degrade at all.</p><p>Chelating agents can be eliminated through photochemical oxidative degradation. When EDTA and DTPA form complexes with Fe3+ they become photolabile and oxidize to smaller compounds at illumination with ultraviolet light. To sum up the literature survey, the most efficient way to reduce chelating agents in sewage water before discharge to receiving waters, is UV treatment at optimal conditions i.e., at the right pH and with addition of Fe3+ if necessary.</p><p>The sampling of the waste water in Skoghalls waste water treatment plant was made during 6 weeks to map the emissions and the contribution of the different sub-streams.</p><p>The degradation-trials were made in two aerated lagoons in laboratory-scale. To study the influence of temperature a summer- and a winter-lagoon were made and the temperatures were sat to, respectively, 27 and 16°C. After the reference-trial, which was made to determine possible differences between the trials, the influence of ultraviolet light on degradation of chelating agents were investigated. In an attempt to enhance the photochemical degradation, Fe3+ in the form of ferric chloride was then added. All trials went on for two weeks each.</p><p>In order to investigate the particle size distribution, before and after degradation in Skoghall Mill’s aerated lagoon, a molecule weight fractionation was made. Incoming and outgoing sewage water from the lagoon was ultra-filtrated and analyzed regarding COD (Chemical Oxygen Demand), chelating agents, nitrogen and phosphor.</p><p>The mapping showed that EDTA was efficiently degraded in the waste water treatment plant, while degradation of DTPA was insignificant. EDTA was reduced by 88 % trough the aerated lagoon.</p><p>Waste water from the board machines and the CTMP-plant contained the largest amount EDTA. DTPA was recovered mostly in the bleaching filtrate and KM 8’s waste water.</p><p>The emission of chelating agents, counted as acid, from Skoghall Mill during the period of the mapping was 0,188 kg/ton board which is well below the emission limit value of 1,6 kg/ton board.</p><p>Nitrogen was reduced by 67 % through the aerated lagoon. The present emission limit value for nitrogen is 500 kg/day. According to the results from the period of the mapping the emission of nitrogen was 204 kg/day which is well below the emission limit value. The contribution of chelating agents to the nitrogen emission was 39 kg/day. 56 kg nitrogen /day were recovered in the waste water from the causticizing area, which is remarkably higher than expected.</p><p>The total reduction of phosphor through the waste water treatment plant was 78 %. The emission of phosphor to receiving waters was 19 kg/day which is well below the emission limit value of 50 kg/day.</p><p>Due to the insecurity in measurement of chelating agents, it was difficult to retain unambiguous results from the laboratory-trials. However it was determined that DTPA was more difficult to degrade than EDTA and that a combination of ultraviolet light and addition of ferric iron had a favourable effect on the degradation of both chelating agents. Also the degradation of COD, nitrogen and phosphor increased when ferric iron was added.</p><p>The fact that DTPA are more difficult to degrade than EDTA was also stated in molecular weight fractionation. It was also shown that EDTA and DTPA weren’t totally water-soluble but can bind to solid material. The largest amount of chelating agents was recovered in the fraction with particles whose molecular weight is less than 1 kDa. Nitrogen and phosphor were recovered in the low- and high-molecular fractions.</p>

Skoghalls Bruk fick i juni 2005 tillstånd av miljödomstolen att öka kartongproduktionen från 665 000 till 800 000 ton kartong per år. Villkoren för tillståndet var att under en prövotidsperiod bl.a. utreda möjligheten att minska utsläpp till omkringliggande vatten. Syftet med examensarbetet var att kartlägga Skoghalls Bruks avloppssystem med avseende på komplexbildarna EDTA (etylendiamintetraättiksyra) och DTPA (dietylentriaminpentaättiksyra), kväve samt fosfor. Dessutom genomfördes nedbrytningsförsök i luftade dammar i laboratorieskala. För att få en klarare bild av nedbrytningen i Skoghalls Bruks luftade damm gjordes även en molekylviktsfraktionering på inkommande och utgående avloppsvatten. Komplexbildare används inom pappers- och massaindustrin för sin förmåga att binda till sig metalljoner som kan vara skadliga i processen. Metalljoner katalyserar nedbrytningen av väteperoxid i blekningen och påskyndar bildandet av aldehyder i kartongen vilket kan leda till lukt- och smakpåverkan. EDTA och DTPA anses vara stabila ämnen, vilket innebär att de är biologiskt svårnedbrytbara. Under den litteraturstudie som genomfördes fanns motsägande uppgifter angående nedbrytningen av komplexbildare, där vissa menade att de genomgår biologisk nedbrytning, men att det sker mycket långsamt. Andra påstod att komplexbildare inte bryts ner överhuvudtaget. Komplexbildare kan elimineras genom fotokemisk oxidativ nedbrytning. Då EDTA och DTPA bildar komplex med Fe3+ blir de fotokemiskt labila och oxideras till mindre föreningar vid belysning med ultraviolett ljus. Sammanfattningsvis gav litteraturstudien att det mest effektiva sättet att minska komplexbildare i avloppsvatten innan det släpps till recipienten är att UV-bestråla vid optimala förhållanden, dvs. rätt pH och eventuellt tillsats av Fe3+ om det behövs. Provtagning av avloppsvatten i Skoghalls Bruks reningsanläggning gjordes under 6 veckor för att kartlägga utsläppen och de olika delströmmarnas bidrag. Nedbrytningsförsök genomfördes i två luftade dammar i laboratorieskala. För att studera temperaturens inverkan konstruerades en sommar- och en vinterdamm med temperaturerna 27 respektive 16°C. Efter referensförsöket, som gjordes för att se eventuella skillnader mellan försöken, undersöktes inverkan av ultraviolett ljus på nedbrytningen av komplexbildare. Sedan tillsattes Fe3+ i form av järnklorid i ett försök att öka den fotokemiska nedbrytningen. Alla försök pågick under två veckor vardera. I syfte att undersöka partikelstorleksfördelningen före och efter nedbrytning i Skoghalls Bruks luftade damm gjordes en molekylviktsfraktionering. Inkommande och utgående avloppsvatten från dammen ultrafiltrerades och analyserades med avseende på COD (Chemical Oxygen Demand), komplexbildare, kväve och fosfor. Kartläggningen visade att EDTA bröts ner effektivt i reningsanläggningen medan nedbrytningen av DTPA var obetydlig. EDTA reducerades med 88 % över den luftade dammen. Avlopp från kartongmaskinerna samt CTMP-fabriken var de avlopp som innehöll mest EDTA. Största mängden DTPA återfanns i blekerifiltratet och i KM 8:s avlopp. Skoghalls Bruk släppte ut komplexbildare motsvarande 0,188 kg/ton kartong, i form av 100 % syra i obunden form, under karteringsperioden vilket var klart lägre än gränsvärdet som är 1,6 kg 100 % syra/ton kartong. Kväve reducerades med 67 % över den luftade dammen. Det nuvarande gränsvärdet för kväveutsläpp till recipient är 500 kg/dygn, men ett av målen med prövotidsutredningen är att minska utsläppen till 300 kg/dygn. Enligt resultaten från karteringsperioden var kväveutsläppet 204 kg/dygn vilket uppfyller målet för prövotidsutredningen. Av det totala kväveutsläppet kom 39 kg/dygn från komplexbildare. Utsläppet av kväve från mixeriavloppet var 56 kg/dygn till recipient vilket var klart högre än förväntat. Den totala fosforreduceringen över reningsanläggningen var 78 %. Utsläppet av fosfor till recipient var 19 kg/dygn vilket är klart lägre än gränsvärdet som är 50 kg/dygn. På grund av komplexbildaranalysens mätosäkerhet var det svårt att få entydiga resultat från laboratorieförsöken. Det fastställdes dock att DTPA var svårare att bryta ner än EDTA och att järntillsats i kombination med ultraviolett ljus gav en positiv effekt på nedbrytningen av båda komplexbildarna. Även nedbrytningen av COD, kväve och fosfor ökade vid järntillsats. Att DTPA är svårare att bryta ner än EDTA framkom även av resultaten från molekylviktsfraktioneringen. Det visade sig också att EDTA och DTPA inte är helt vattenlösliga utan kan binda till fast material. Största delen av komplexbildarna fanns dock i fraktionen med partiklar med molekylvikt mindre än 1 kDa. Kväve och fosfor fanns i de låg- och högmolekylära fraktionerna. / In June of 2005 Skoghall Mill got permission from the Environmental Court to increase their production of board from 665 000 tons to 800 000 tons per year. The condition for the permission was to, during a trial period, investigate the possibility to decrease the emissions to the surrounding water. The purpose of this master thesis is to do a mapping of Skoghall Mill’s waste water treatment system regarding the chelating agents EDTA (ethylenediaminetetraacetic acid) and DTPA (diethylenetriaminepentaacetic acid), nitrogen and phosphor. Also degradation-trials were made with aerated lagoons in laboratory-scale. To get a more complete view of the degradation in Skoghalls Mills aerated lagoon a molecular weight fractionation of the incoming and the outgoing water was made. Chelating agents are used in the pulp- and paper industry due to its ability to bind metal-ions which are hazardous for the process. The metal-ions catalyze the decomposition of hydrogen peroxide in the bleaching process and the forming of aldehydes in the board which can lead to problems with taste and odour. EDTA and DTPA are regarded to be very stable, which means that they are hard to degrade biologically. There was contradictory information about the degradation of chelating agents during the literature survey. Some say that chelating agents are degraded biologically but very slowly. Others say that they don’t degrade at all. Chelating agents can be eliminated through photochemical oxidative degradation. When EDTA and DTPA form complexes with Fe3+ they become photolabile and oxidize to smaller compounds at illumination with ultraviolet light. To sum up the literature survey, the most efficient way to reduce chelating agents in sewage water before discharge to receiving waters, is UV treatment at optimal conditions i.e., at the right pH and with addition of Fe3+ if necessary. The sampling of the waste water in Skoghalls waste water treatment plant was made during 6 weeks to map the emissions and the contribution of the different sub-streams. The degradation-trials were made in two aerated lagoons in laboratory-scale. To study the influence of temperature a summer- and a winter-lagoon were made and the temperatures were sat to, respectively, 27 and 16°C. After the reference-trial, which was made to determine possible differences between the trials, the influence of ultraviolet light on degradation of chelating agents were investigated. In an attempt to enhance the photochemical degradation, Fe3+ in the form of ferric chloride was then added. All trials went on for two weeks each. In order to investigate the particle size distribution, before and after degradation in Skoghall Mill’s aerated lagoon, a molecule weight fractionation was made. Incoming and outgoing sewage water from the lagoon was ultra-filtrated and analyzed regarding COD (Chemical Oxygen Demand), chelating agents, nitrogen and phosphor. The mapping showed that EDTA was efficiently degraded in the waste water treatment plant, while degradation of DTPA was insignificant. EDTA was reduced by 88 % trough the aerated lagoon. Waste water from the board machines and the CTMP-plant contained the largest amount EDTA. DTPA was recovered mostly in the bleaching filtrate and KM 8’s waste water. The emission of chelating agents, counted as acid, from Skoghall Mill during the period of the mapping was 0,188 kg/ton board which is well below the emission limit value of 1,6 kg/ton board. Nitrogen was reduced by 67 % through the aerated lagoon. The present emission limit value for nitrogen is 500 kg/day. According to the results from the period of the mapping the emission of nitrogen was 204 kg/day which is well below the emission limit value. The contribution of chelating agents to the nitrogen emission was 39 kg/day. 56 kg nitrogen /day were recovered in the waste water from the causticizing area, which is remarkably higher than expected. The total reduction of phosphor through the waste water treatment plant was 78 %. The emission of phosphor to receiving waters was 19 kg/day which is well below the emission limit value of 50 kg/day. Due to the insecurity in measurement of chelating agents, it was difficult to retain unambiguous results from the laboratory-trials. However it was determined that DTPA was more difficult to degrade than EDTA and that a combination of ultraviolet light and addition of ferric iron had a favourable effect on the degradation of both chelating agents. Also the degradation of COD, nitrogen and phosphor increased when ferric iron was added. The fact that DTPA are more difficult to degrade than EDTA was also stated in molecular weight fractionation. It was also shown that EDTA and DTPA weren’t totally water-soluble but can bind to solid material. The largest amount of chelating agents was recovered in the fraction with particles whose molecular weight is less than 1 kDa. Nitrogen and phosphor were recovered in the low- and high-molecular fractions.

Diss. (sammanfattning) Linköping : Univ., 2003. / Härtill 5 uppsatser.

Thesis (Ph. D.)--University of Missouri--Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves: 157-166). Also available on the Internet.

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