Στην παρούσα εργασία μελετήθηκαν οι μεταβολές του ολικού φωσφόρου σε φυτά γλυκού σόργου (Sorghum bicolor (L) Moench) ποικιλίας Keller και του διαθέσιμου φωσφόρου στο έδαφος. Ακολουθήθηκαν δύο χειρισμοί διαχείρισης, ο βιολογικός και ο συμβατικός. Σκοπός της εργασίας ήταν να διαπιστωθεί εάν οι πρακτικές βιολογικής διαχείρισης της γονιμότητας του εδάφους που εφαρμόστηκαν ήταν επαρκείς για την κάλυψη των αναγκών του γλυκού σόργου σε φώσφορο, προκειμένου να επιτευχθούν αποδόσεις που να προσεγγίζουν τις αποδόσεις του συμβατικού τρόπου καλλιέργειας. Τα πειράματα πεδίου πραγματοποιήθηκαν σε αγρόκτημα στο χώρο του Πανεπιστημίου Πατρών (θέση: ΓΠ: 38° 25΄ Β, ΓΜ: 21° 8΄ Α) την περίοδο 2003-2004. Η συσσώρευση φωσφόρου από τα φυτά του γλυκού σόργου ακολούθησε σιγμοειδή μεταβολή με το χρόνο και στους δυο χειρισμούς όπως αναφέρεται στη βιβλιογραφία. Με τα φυτά του συμβατικού να προσλαμβάνουν λίγο περισσότερο φώσφορο. Η αύξηση της ξηρής βιομάζας ήταν επίσης σιγμοειδής μεταβολή με το χρόνο και στους δύο χειρισμούς, σύμφωνα με τη βιβλιογραφία. Οι τελικές αποδόσεις ήταν της τάξεως των 24,47 t/ha για το βιολογικό χειρισμό και 23,42 t/ha για το συμβατικό. Τιμές που βρίσκονται στα επίπεδα που αναφέρονται στη βιβλιογραφία για τη συμβατική καλλιέργεια του γλυκού σόργου στη νότια Ευρώπη. Επομένως ο τρόπος διαχείρισης του εδαφικού φωσφόρου δεν επηρέασε τις τελικές αποδόσεις σε ξηρή υπέργεια βιομάζα στην καλλιέργεια του γλυκού σόργου. Η βιολογική διαχείριση του φωσφόρου στην καλλιέργεια του γλυκού σόργου, σε έδαφος με επάρκεια φωσφόρου έδωσε ικανοποιητικές τελικές αποδόσεις βιομάζας. Ενώ οι επιπλέον προσθήκες φωσφορικών λιπασμάτων στη συμβατική διαχείριση πιθανόν να ήταν πλεονασματικές και να επιβάρυναν το περιβάλλον. / In the present work was studied the total phosphorus fluctuation of sweet sorghum plants (Sorghum bicolor (L) Moench, variety Keller) and the available phosphorus in the soil. Two treatment practices were followed, the biological and the conventional one. Aim of the study was to ascertain whether the applied soil fertility practices of the biological management were sufficient in terms of the crop’s phosphorus nutrition, in order to achieve yields approaching those of the conventional one. Field experiments were conducted at the Patras’ University farm (lat. 38o 25׳ B, long. 21o 8׳A) during the period 2003-2004. The phosphorus uptake of sweet sorghum plants followed a sigmoid variation with time at both treatments as mentioned in literature with plants under conventional treatment taking up slightly higher amounts of phosphorus. Dry matter growth followed the same sigmoid variation in time at both treatments, according to literature. The total yields reached 24.47 t/ha for the biological treatment and 23.42 t/ha for the conventional one. These values were within the levels reported in literature for conventional treatment of sweet sorghum in southern Europe. Thus, soil phosphorus management practices had no effect on total above the ground dry matter yields of sweet sorghum. Biological management of phosphorus in the cultivation of sweet sorghum in a soil sufficient in phosphorus gave satisfactory total dry matter yields. Further addition of phosphates during conventional treatment was possibly excessive and may have harmed the environment.

A eutrofização acelerada dos mananciais superficiais, devido aos despejos de águas residuárias não tratadas, vem comprometendo a qualidade das águas utilizadas no abastecimento público. Como conseqüência desse processo, inúmeros registros de florações de cianobactérias são relatados em todo o mundo. Esses microrganismos são potenciais produtores de toxinas, as quais, presentes na água bruta que abastece uma Estação de Tratamento de Água (ETA), precisam ser removidas. As toxinas podem ter efeitos adversos à saúde, podendo causar danos hepatotóxicos, neurotóxicos e dermatotóxicos. A maioria das ETAs brasileiras tratam a água através do processo convencional de tratamento, compreendendo as etapas de coagulação, floculação, sedimentação, filtração e cloração. Esse tratamento é considerado eficiente para remover células de microrganismos, incluindo as cianobactérias. No entanto, suas toxinas não são afetadas, permanecendo na água tratada. Em função disso, alternativas de tratamento devem ser incorporadas ao tratamento convencional, visando remover a hepatotoxina microcistina a concentrações menores ou iguais a 1 μg.L-1, pois esse é o valor máximo permitido (VMP) pela Portaria nº 518/2004, do Ministério da Saúde, a qual define as diretrizes relativas ao controle e vigilância da qualidade da água para consumo humano. Nesse contexto, o objetivo do trabalho foi avaliar a eficiência do carvão ativado pulverizado (CAP), na remoção da cianotoxina microcistina presente na água utilizada para abastecimento público. Cinco amostras de CAP, produzidas a partir de madeira, osso, antracito e coco, foram caracterizadas e, para cada uma, determinadas as Isotermas de Freundlich. As Isotermas mostraram que os CAPs produzidos a partir da madeira apresentaram maior capacidade de remover microcistina. Os residuais de microcistina obtidos nestes ensaios foram ajustados ao modelo de decaimento logarítmico. Assim, para cada CAP, foi estabelecida uma equação geral do processo adsortivo, com a qual foi possível estabelecer dosagens de CAP, variando a concentração de microcistina inicial, para atingir uma concentração residual de 1 μg.L-1. A aplicabilidade da equação foi testada para uma amostra de CAP, em água natural, utilizando o coagulante policloreto de alumínio e concentrações iniciais de microcistina de 1, 10 e 100 μg.L-1. Os resultados mostraram que as dosagens de CAP calculadas foram suficientes para atingir o residual desejado. Além disso, através de ensaios de adsorção, em equipamento de jarros, foram simuladas as etapas de coagulação (utilizando coagulantes sulfato de alumínio e cloreto férrico), floculação, sedimentação e filtração do tratamento convencional para água natural acrescida de 100 μg.L-1 de microcistina. A aplicação do CAP foi realizada em dois pontos do tratamento (1) entrada da água bruta e (2) antes da aplicação do coagulante. A aplicação na entrada da água bruta possibilitou remoção da toxina abaixo do VMP, correspondendo à redução de, aproximadamente, 99% da concentração inicial de toxina. Já no ponto de aplicação antes do coagulante, não foi atingido o VMP. A partir dos estudos aqui realizados, concluiu-se que a melhor maneira de escolher o CAP para remoção de microcistina é a realização de ensaios específicos, como a Isoterma de Freundlich. Para uma remoção eficiente da toxina, o tratamento convencional mostra-se eficaz, desde que a etapa de adsorção seja incorporada ao tratamento. / The accelerated surface waters eutrophication, due to non treated residual waters discharges, has been harming the water quality utilized in the public supply. As a consequence of this process, countless records of cyanobacterias’ bloom are reported all over the world. These microorganisms potentially producers of toxins, which, when presented in the raw water that supplies the Water Treatment Plant (WTP), needs to be removed. The toxins can have harmfull effects to the health causing hepatotoxic, neurotoxic and dermatotoxic damage. Most of the Brazilian WTPs treat the water through the conventional water treatment process, covering the stages of coagulation, flocculation, sedimentation, filtering and chlorination. This treatment is considered efficient to remove microorganisms’ cells, including cyanobacterias. However its toxins are not affected, remaining in the treated water. Due to this fact, alternative treatment must be incorporated to the conventional one, trying to remove the microcystin hepatotoxin to concentrations lower or equal to 1 μg.L-1, the maximum allowed value (MAV) according to the Brazilian Ministry of Health Administrative Ruling 518/2004, which defines the rules related to the control and vigilance of the water quality for human consumption. In this context, the objective of the present work was to evaluate the efficiency of the powdered activated carbon’s (PAC), in the removal of the microcystin cyanotoxin present in the water for public supply. Five samples of PAC, made of wood, bone, antracite and coconut, were characterized and, for each one, were determined Freundlich adsorption isotherm . The isotherm showed that the PACs produced from wood presented the highest capacity of microcystin removal. The residuals of microcystin obtained in these tests were adjusted to the logarithmic decay model. Thus, for each PAC, it was established a general equation of the adsorptive process, in order to establish PAC dosages, varying the initial microcystin concentration, to achieve the residual concentration of 1 μg.L-1. The usage of this equation was tested for one sample of PAC, in natural water, using poly-aluminum chloride as a coagulant and the initial concentrations of microcystins of 1, 10 and 100 μg.L-1. The results showed that the dosage of PAC calculated was enough to achieve the desired residual. Besides this, through adsorptive tests, using jar’s equipments, were simulated the stages of coagulation (using alum sulphate and ferric chloride as coagulants), flocculation, sedimentation and filtering of the conventional treatment for natural water and with 100 μg.L-1 of microcystin added. The application of the PAC was performed in two points of the treatment: (1) entrance of the raw water and; (2) before the application of the coagulant. The application in the entrance of the raw water made possible the removal of the toxin under MAV, corresponding to a reduction of, approximately, 99% of the initial concentration of the toxin. Nevertheless, in the point of application before the coagulant, the MAV was not achieved. According to these studies, it was concluded that the best manner of choosing the PAC for microcystin removal is the realization of specific tests like a Freundlich isotherm. For an efficient removal of the toxin, the conventional treatment is efficient, once the adsorption stage is incorporated to the treatment.

A eutrofização acelerada dos mananciais superficiais, devido aos despejos de águas residuárias não tratadas, vem comprometendo a qualidade das águas utilizadas no abastecimento público. Como conseqüência desse processo, inúmeros registros de florações de cianobactérias são relatados em todo o mundo. Esses microrganismos são potenciais produtores de toxinas, as quais, presentes na água bruta que abastece uma Estação de Tratamento de Água (ETA), precisam ser removidas. As toxinas podem ter efeitos adversos à saúde, podendo causar danos hepatotóxicos, neurotóxicos e dermatotóxicos. A maioria das ETAs brasileiras tratam a água através do processo convencional de tratamento, compreendendo as etapas de coagulação, floculação, sedimentação, filtração e cloração. Esse tratamento é considerado eficiente para remover células de microrganismos, incluindo as cianobactérias. No entanto, suas toxinas não são afetadas, permanecendo na água tratada. Em função disso, alternativas de tratamento devem ser incorporadas ao tratamento convencional, visando remover a hepatotoxina microcistina a concentrações menores ou iguais a 1 μg.L-1, pois esse é o valor máximo permitido (VMP) pela Portaria nº 518/2004, do Ministério da Saúde, a qual define as diretrizes relativas ao controle e vigilância da qualidade da água para consumo humano. Nesse contexto, o objetivo do trabalho foi avaliar a eficiência do carvão ativado pulverizado (CAP), na remoção da cianotoxina microcistina presente na água utilizada para abastecimento público. Cinco amostras de CAP, produzidas a partir de madeira, osso, antracito e coco, foram caracterizadas e, para cada uma, determinadas as Isotermas de Freundlich. As Isotermas mostraram que os CAPs produzidos a partir da madeira apresentaram maior capacidade de remover microcistina. Os residuais de microcistina obtidos nestes ensaios foram ajustados ao modelo de decaimento logarítmico. Assim, para cada CAP, foi estabelecida uma equação geral do processo adsortivo, com a qual foi possível estabelecer dosagens de CAP, variando a concentração de microcistina inicial, para atingir uma concentração residual de 1 μg.L-1. A aplicabilidade da equação foi testada para uma amostra de CAP, em água natural, utilizando o coagulante policloreto de alumínio e concentrações iniciais de microcistina de 1, 10 e 100 μg.L-1. Os resultados mostraram que as dosagens de CAP calculadas foram suficientes para atingir o residual desejado. Além disso, através de ensaios de adsorção, em equipamento de jarros, foram simuladas as etapas de coagulação (utilizando coagulantes sulfato de alumínio e cloreto férrico), floculação, sedimentação e filtração do tratamento convencional para água natural acrescida de 100 μg.L-1 de microcistina. A aplicação do CAP foi realizada em dois pontos do tratamento (1) entrada da água bruta e (2) antes da aplicação do coagulante. A aplicação na entrada da água bruta possibilitou remoção da toxina abaixo do VMP, correspondendo à redução de, aproximadamente, 99% da concentração inicial de toxina. Já no ponto de aplicação antes do coagulante, não foi atingido o VMP. A partir dos estudos aqui realizados, concluiu-se que a melhor maneira de escolher o CAP para remoção de microcistina é a realização de ensaios específicos, como a Isoterma de Freundlich. Para uma remoção eficiente da toxina, o tratamento convencional mostra-se eficaz, desde que a etapa de adsorção seja incorporada ao tratamento. / The accelerated surface waters eutrophication, due to non treated residual waters discharges, has been harming the water quality utilized in the public supply. As a consequence of this process, countless records of cyanobacterias’ bloom are reported all over the world. These microorganisms potentially producers of toxins, which, when presented in the raw water that supplies the Water Treatment Plant (WTP), needs to be removed. The toxins can have harmfull effects to the health causing hepatotoxic, neurotoxic and dermatotoxic damage. Most of the Brazilian WTPs treat the water through the conventional water treatment process, covering the stages of coagulation, flocculation, sedimentation, filtering and chlorination. This treatment is considered efficient to remove microorganisms’ cells, including cyanobacterias. However its toxins are not affected, remaining in the treated water. Due to this fact, alternative treatment must be incorporated to the conventional one, trying to remove the microcystin hepatotoxin to concentrations lower or equal to 1 μg.L-1, the maximum allowed value (MAV) according to the Brazilian Ministry of Health Administrative Ruling 518/2004, which defines the rules related to the control and vigilance of the water quality for human consumption. In this context, the objective of the present work was to evaluate the efficiency of the powdered activated carbon’s (PAC), in the removal of the microcystin cyanotoxin present in the water for public supply. Five samples of PAC, made of wood, bone, antracite and coconut, were characterized and, for each one, were determined Freundlich adsorption isotherm . The isotherm showed that the PACs produced from wood presented the highest capacity of microcystin removal. The residuals of microcystin obtained in these tests were adjusted to the logarithmic decay model. Thus, for each PAC, it was established a general equation of the adsorptive process, in order to establish PAC dosages, varying the initial microcystin concentration, to achieve the residual concentration of 1 μg.L-1. The usage of this equation was tested for one sample of PAC, in natural water, using poly-aluminum chloride as a coagulant and the initial concentrations of microcystins of 1, 10 and 100 μg.L-1. The results showed that the dosage of PAC calculated was enough to achieve the desired residual. Besides this, through adsorptive tests, using jar’s equipments, were simulated the stages of coagulation (using alum sulphate and ferric chloride as coagulants), flocculation, sedimentation and filtering of the conventional treatment for natural water and with 100 μg.L-1 of microcystin added. The application of the PAC was performed in two points of the treatment: (1) entrance of the raw water and; (2) before the application of the coagulant. The application in the entrance of the raw water made possible the removal of the toxin under MAV, corresponding to a reduction of, approximately, 99% of the initial concentration of the toxin. Nevertheless, in the point of application before the coagulant, the MAV was not achieved. According to these studies, it was concluded that the best manner of choosing the PAC for microcystin removal is the realization of specific tests like a Freundlich isotherm. For an efficient removal of the toxin, the conventional treatment is efficient, once the adsorption stage is incorporated to the treatment.

A eutrofização acelerada dos mananciais superficiais, devido aos despejos de águas residuárias não tratadas, vem comprometendo a qualidade das águas utilizadas no abastecimento público. Como conseqüência desse processo, inúmeros registros de florações de cianobactérias são relatados em todo o mundo. Esses microrganismos são potenciais produtores de toxinas, as quais, presentes na água bruta que abastece uma Estação de Tratamento de Água (ETA), precisam ser removidas. As toxinas podem ter efeitos adversos à saúde, podendo causar danos hepatotóxicos, neurotóxicos e dermatotóxicos. A maioria das ETAs brasileiras tratam a água através do processo convencional de tratamento, compreendendo as etapas de coagulação, floculação, sedimentação, filtração e cloração. Esse tratamento é considerado eficiente para remover células de microrganismos, incluindo as cianobactérias. No entanto, suas toxinas não são afetadas, permanecendo na água tratada. Em função disso, alternativas de tratamento devem ser incorporadas ao tratamento convencional, visando remover a hepatotoxina microcistina a concentrações menores ou iguais a 1 μg.L-1, pois esse é o valor máximo permitido (VMP) pela Portaria nº 518/2004, do Ministério da Saúde, a qual define as diretrizes relativas ao controle e vigilância da qualidade da água para consumo humano. Nesse contexto, o objetivo do trabalho foi avaliar a eficiência do carvão ativado pulverizado (CAP), na remoção da cianotoxina microcistina presente na água utilizada para abastecimento público. Cinco amostras de CAP, produzidas a partir de madeira, osso, antracito e coco, foram caracterizadas e, para cada uma, determinadas as Isotermas de Freundlich. As Isotermas mostraram que os CAPs produzidos a partir da madeira apresentaram maior capacidade de remover microcistina. Os residuais de microcistina obtidos nestes ensaios foram ajustados ao modelo de decaimento logarítmico. Assim, para cada CAP, foi estabelecida uma equação geral do processo adsortivo, com a qual foi possível estabelecer dosagens de CAP, variando a concentração de microcistina inicial, para atingir uma concentração residual de 1 μg.L-1. A aplicabilidade da equação foi testada para uma amostra de CAP, em água natural, utilizando o coagulante policloreto de alumínio e concentrações iniciais de microcistina de 1, 10 e 100 μg.L-1. Os resultados mostraram que as dosagens de CAP calculadas foram suficientes para atingir o residual desejado. Além disso, através de ensaios de adsorção, em equipamento de jarros, foram simuladas as etapas de coagulação (utilizando coagulantes sulfato de alumínio e cloreto férrico), floculação, sedimentação e filtração do tratamento convencional para água natural acrescida de 100 μg.L-1 de microcistina. A aplicação do CAP foi realizada em dois pontos do tratamento (1) entrada da água bruta e (2) antes da aplicação do coagulante. A aplicação na entrada da água bruta possibilitou remoção da toxina abaixo do VMP, correspondendo à redução de, aproximadamente, 99% da concentração inicial de toxina. Já no ponto de aplicação antes do coagulante, não foi atingido o VMP. A partir dos estudos aqui realizados, concluiu-se que a melhor maneira de escolher o CAP para remoção de microcistina é a realização de ensaios específicos, como a Isoterma de Freundlich. Para uma remoção eficiente da toxina, o tratamento convencional mostra-se eficaz, desde que a etapa de adsorção seja incorporada ao tratamento. / The accelerated surface waters eutrophication, due to non treated residual waters discharges, has been harming the water quality utilized in the public supply. As a consequence of this process, countless records of cyanobacterias’ bloom are reported all over the world. These microorganisms potentially producers of toxins, which, when presented in the raw water that supplies the Water Treatment Plant (WTP), needs to be removed. The toxins can have harmfull effects to the health causing hepatotoxic, neurotoxic and dermatotoxic damage. Most of the Brazilian WTPs treat the water through the conventional water treatment process, covering the stages of coagulation, flocculation, sedimentation, filtering and chlorination. This treatment is considered efficient to remove microorganisms’ cells, including cyanobacterias. However its toxins are not affected, remaining in the treated water. Due to this fact, alternative treatment must be incorporated to the conventional one, trying to remove the microcystin hepatotoxin to concentrations lower or equal to 1 μg.L-1, the maximum allowed value (MAV) according to the Brazilian Ministry of Health Administrative Ruling 518/2004, which defines the rules related to the control and vigilance of the water quality for human consumption. In this context, the objective of the present work was to evaluate the efficiency of the powdered activated carbon’s (PAC), in the removal of the microcystin cyanotoxin present in the water for public supply. Five samples of PAC, made of wood, bone, antracite and coconut, were characterized and, for each one, were determined Freundlich adsorption isotherm . The isotherm showed that the PACs produced from wood presented the highest capacity of microcystin removal. The residuals of microcystin obtained in these tests were adjusted to the logarithmic decay model. Thus, for each PAC, it was established a general equation of the adsorptive process, in order to establish PAC dosages, varying the initial microcystin concentration, to achieve the residual concentration of 1 μg.L-1. The usage of this equation was tested for one sample of PAC, in natural water, using poly-aluminum chloride as a coagulant and the initial concentrations of microcystins of 1, 10 and 100 μg.L-1. The results showed that the dosage of PAC calculated was enough to achieve the desired residual. Besides this, through adsorptive tests, using jar’s equipments, were simulated the stages of coagulation (using alum sulphate and ferric chloride as coagulants), flocculation, sedimentation and filtering of the conventional treatment for natural water and with 100 μg.L-1 of microcystin added. The application of the PAC was performed in two points of the treatment: (1) entrance of the raw water and; (2) before the application of the coagulant. The application in the entrance of the raw water made possible the removal of the toxin under MAV, corresponding to a reduction of, approximately, 99% of the initial concentration of the toxin. Nevertheless, in the point of application before the coagulant, the MAV was not achieved. According to these studies, it was concluded that the best manner of choosing the PAC for microcystin removal is the realization of specific tests like a Freundlich isotherm. For an efficient removal of the toxin, the conventional treatment is efficient, once the adsorption stage is incorporated to the treatment.

Three oxidants have been evaluated for use as alternative chemical pretreatments for Fena Lake, a surface water that supplies the U.S. Navy's Public Water System (PWS) on the volcanic island of Guam. The study consisted of two investigative components. The first and primary component included a bench-scale evaluation to study the effects of different pre-oxidant chemicals on the formation of chlorinated disinfection by-products (DBPs). The second and ancillary component included a series of water treatment and distribution system management studies that analyzed DBP formation within the treatment plant and water distribution system. The goal of this research was to reduce total trihalomethane (TTHM) and the five haloacetic acid (HAA5) formations in the PWS. In the primary component of the research, raw surface water from Fena Lake was collected by U.S. Navy personnel and shipped to University of Central Florida (UCF) laboratories for experimentation. Bench-scale tests that simulated the coagulation, flocculation, sedimentation and filtration (CSF) that comprises the Navy Water Treatment Plant (NWTP) were used to evaluate the use of two alternative pre-oxidants, potassium permanganate (KMnO4) and chlorine dioxide (ClO2) in lieu of gaseous chlorine (Cl2). The research assessed DBP formation by comparing several pretreatment scenarios, namely: (1) no pretreatment, (2) chlorine pretreatment, and (3) alternative oxidant pretreatment. KMnO4 pretreatment resulted in the lowest percent reduction of TTHMs and HAA5 relative to chlorine pretreatment, at 5.7% and 22.7%, respectively; however, this amount was still a reduction from the results demonstrated for the chlorine pretreatment condition. Without using a pre-oxidant, TTHM and HAA5 formation were reduced by 22.8% and 37.3%, respectively, relative to chlorine pretreatment. Chlorine dioxide demonstrated the greatest TTHM and HAA5 reduction relative to chlorine pretreatment at 34.4% and 53.3%, respectively. The second component of research consisted of a series of studies that evaluated distribution system operations and management alternatives to identify opportunities that could achieve DBP reduction within the PWS. Three concerns that were addressed were the NWTP's compliance with the U.S. Environmental Protection Agency's (USEPA's) Stage 2 Disinfectants/Disinfection By-Products (D/DBP) Rule, variable hydraulic detention times within a small subdivision in the distribution system, and severe weather. It was determined that: (1) A decision based on in-plant studies to cease prechlorination at the NWTP resulted in a decrease in TTHMs and HAA5s throughout the distribution system by 62% and 75%, respectively; (2) A fluoride tracer study led to the discovery of a valved pipeline responsible for elevated DBPs because of excessive water age that when exercised and managed resolved intermittent DBP spikes in the PWS; and (3) when the NWTP's ballasted floc clarifier (BFC) was operated in-series prior to the conventional CSF process during severe weather conditions the TTHM and HAA5 were below 39 ug/L and 29 ug/L, respectively, proving BFC in-series is a practical option for the plant during severe weather.

Στην παρούσα εργασία μελετήθηκαν οι μεταβολές του ολικού αζώτου σε φυτά γλυκού σόργου (Sorghum bicolor (L) Moench) ποικιλίας Keller που καλλιεργήθηκαν με δύο τρό-πους διαχείρισης, το βιολογικό και το συμβατικό. Σκοπός της εργασίας ήταν να διαπιστωθεί εάν οι πρακτικές βιολογικής διαχείρισης της γονιμότητας του εδάφους που εφαρμόστηκαν ήταν επαρκείς για την κάλυψη των αναγκών του γλυκού σόργου σε άζωτο, προκειμένου να επιτευχθούν αποδόσεις που να προσεγγίζουν τις αποδόσεις του συμβατικού τρόπου καλλιέρ-γειας. Τα πειράματα πεδίου πραγματοποιήθηκαν σε αγρόκτημα στο χώρο του Πανεπιστημί-ου Πατρών (θέση: ΓΠ: 38° 25΄ Β, ΓΜ: 21° 8΄ Α) την περίοδο 2003-2004. Η αύξηση της ξηρής βιομάζας ακολούθησε την ίδια πορεία και στους δύο χειρισμούς, δείχνοντας σιγμοειδή μεταβολή με το χρόνο. Ο τρόπος διαχείρισης του εδαφικού αζώτου δεν επηρέασε τις αποδόσεις σε ξηρή βιομάζα, οι οποίες ήταν της τάξεως των 24,47 t ha-1 (σε φύλλα και βλαστό), εκ των οποίων το 86,5 % αφορούσε στους βλαστούς. Θεωρήθηκαν δε ικανοποιητικές, καθώς βρίσκονται στα επίπεδα που αναφέρονται στη βιβλιογραφία για τη συμβατική καλλιέργεια του γλυκού σόργου. Η συγκέντρωση του αζώτου σε ολόκληρα τα φυτά και τα επιμέρους όργανα έδειξε ανα-μενόμενη διακύμανση κατά τη διάρκεια της καλλιεργητικής περιόδου, ενώ δε διαπιστώθη-καν σημαντικές διαφορές ανάμεσα στους δύο χειρισμούς. Η πρόσληψη αζώτου από τα φυτά ακολούθησε διαφορετικά πρότυπα στους δύο χειρισμούς, με τα φυτά του βιολογικού χειρι-σμού να προσλαμβάνουν σημαντικά μεγαλύτερα ποσά στα πρώτα στάδια αύξησης, που είναι και τα πιο καθοριστικά για τη θρέψη των φυτών. Αν και το ολικό ποσό αζώτου που προσέ-λαβαν τα φυτά του βιολογικού χειρισμού σε όλη την καλλιεργητική περίοδο (10,39 g N m-2) ήταν μικρότερο από αυτό του συμβατικού χειρισμού (14,23 g N m-2), κυμάνθηκε στα επίπε-δα που δίνονται στη βιβλιογραφία. Οι αναλύσεις εδάφους έδειξαν ότι το μεγαλύτερο μέρος του ανόργανου αζώτου που προ-σέλαβαν τα φυτά προήλθε από το νιτρικό άζωτο. Οι πρακτικές διαχείρισης του εδαφικού αζώτου ευνόησαν τα φυτά του βιολογικού χειρισμού, τα οποία εντοπίσαμε ότι είχαν μία σημαντικά μεγαλύτερη ποσότητα διαθέσιμου ανόργανου αζώτου σε όλη τη διάρκεια της καλλιεργητικής περιόδου. Τέλος, οι δείκτες αζωτούχου θρέψης μας βοήθησαν να επιβεβαιώ-σουμε κάποια προηγούμενα συμπεράσματα, θεωρούμε, όμως, ότι απέτυχαν στο να αποδώ-σουν την πραγματική θρεπτική κατάσταση των φυτών. / In the present work we studied the tissue total nitrogen fluctuation of sweet sorghum plants (Sorghum bicolor (L) Moench, variety Keller), having been cultivated under conventional and alternative nutrient management strategies. Aim of the study was to ascertain whether the applied soil fertility practices of the biological management were sufficient in terms of the crop’s nitrogen nutrition, in order to achieve yields approaching those of the conventional one. Field experiments were conducted at the Patras’ University farm (lat. 38° 25΄ Β, long. 21° 8΄ Α) during the period 2003-2004. Dry matter growth followed the same pattern at both treatments, showing a sigmoid variation with time. Treatment had no effect on dry matter yields, which reached the 24,47 t ha-1 (leaves and stems), with stems accounting for 86,5 % of total dry matter yield. Dry matter yields were considered to be satisfying, as they matched the ones reported in literature for conventional management. The plant tissue nitrogen content exhibited an expected fluctuation during crop growth, while treatment had no major effect. Crop nitrogen uptake showed different patterns, with the biologically grown plants having acquired greater amounts during the early stages of development, which are considered to be the most determinative for plant nutrition. Despite the fact that the total amount of nitrogen uptaken by the plants of the biological treatment (10,39 g N m-2) was less than that of the conventional one (14,23 g N m-2), still the values were higher than those encountered in literature. Soil analysis suggested that the greater part of nitrogen acquired by the crop derived from nitrate nitrogen. Soil nitrogen management favoured the biologically treated plants, having at their disposal a significantly greater amount of available inorganic nitrogen throughout the growing season. Lastly, although nitrogen nutrition indices helped us to confirm some of the preceding outcomes, it is considered that they failed to reveal the actual nutritional state of the crop.

In this research, five different coagulants were evaluated to determine their effectiveness at removing turbidity, color and dissolved organic carbon (DOC) from a surface water in Sarasota County, Florida. Bench-scale jar tests that simulated conventional coagulation, flocculation, and sedimentation processes were used. Iron-based coagulants (ferric chloride and ferric sulfate) and aluminum-based coagulants (aluminum sulfate, polyaluminum chloride (PACl) and aluminum chlorohydrate (ACH)) were used to treat a highly organic surface water supply (DOC ranging between 10 and 30 mg/L), known as the Cow Pen Slough, located within central Sarasota County, Florida. Isopleths depicting DOC and color removal efficiencies as a function of both pH and coagulant dose were developed and evaluated. Ferric chloride and ACH were observed to obtain the highest DOC (85% and 70%, respectively) and color (98% and 97%, respectively) removals at the lowest dose concentrations (120 mg/L and 100 mg/L, respectively). Ferric sulfate was effective at DOC removal but required a higher concentration of coagulant and was the least effective coagulant at removing color. The traditional iron-based coagulants and alum had low turbidity removals and they were often observed to add turbidity to the water. PACl and ACH had similar percent removals for color and turbidity achieving consistent percent removals of 95% and 45%, respectively, but PACl was less effective than ACH at removing organics. Sludge settling curves, dose-sludge production ratios, and settling velocities were determined at optimum DOC removal conditions for each coagulant. Ferric chloride was found to have the highest sludge settling rate but also produced the largest sludge quantities. Total trihalomethane formation potential (THMFP) was measured iv for the water treated with ferric chloride and ACH. As with DOC removal, ferric chloride yielded a higher percent reduction with respect to THMFP.