South Africa is on a path of dramatically increasing its energy supplying capabilties. Eskom (the main utility supplying electricity to the national grid) recently announced that future power station technologies will focus on renewable energy and nuclear power. This is done in an effort to reduce South Africa’s dependance on burning fossil-fuels and thereby decreasing CO2 emissions and other harmful gases. This, together with the fact that there are a lot of fresh water scarce areas especially along the Eastern Cape coast of South Africa, is what inspired this study. This study investigates the use of a 200 MWth High Temperature Reactor (HTR) for cogeneration purposes. Heat from the reactor is utilised for electricity generation (Rankine cycle) and process heat (desalination). Two desalination concepts were evaluated thermodynamically and economically, namely Multi-Effect Distillation (MED) and Reverse Osmosis (RO). Computer software, Engineering Equation Solver (EES), was used to simulate different cycle configurations, where the heat available in the condenser was increased successively. The coupling of the two desalination technologies with a HTR was compared and it was found that a RO plant produces nearly twice as much water while sending the same amount of electricity to the grid (compared to coupling with MED). Coupling options were investigated and each simulation model was optimised to deliver maximum output (power and water). The best configuration was found to be the coupling of a HTR with a RO plant producing 86.56 MW generator power. This is equal to 2077 MWh/day. Using 332 MWh/day for desalination through RO, delivers 73 833 m3/day fresh water and results in 1745 MWh/day sent to the grid. This scenario is the best option from a thermodynamic and economic point of view. From an investment point of view, it will produce an Internal Rate of Return (IRR) of 10.9 percent and the Net Present Value (NPV) is calculated to be R 2,486,958,689. The results and analysis for the different cycle configurations are presented in such a way that an easy comparison can be made. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2011

Les déchets liés à l'élevage intensif ont un impact environnemental reconnu du fait de leur composition riche en en matière organique et minérale. Il apparait opportun de promouvoir des procédés de traitement permettant de maitriser l'impact environnemental de ce retour au sol, voire d'ouvrir de nouvelles valorisations au travers de la récupération d'énergie ou de l'exportation de co-produits (azotés et phosphatés notamment). Ce travail entre dans cette démarche en proposant de compléter les étapes de digestion anaérobie de ces déchets par des étapes de séparation sur membranes perm-sélectives. Les essais ont été réalisés sur unités pilotes de laboratoire en utilisant des digestats réels de diverses origines prélevés sur sites. Pour l'étape de clarification par ultrafiltration, la conduite d'une séparation en mode tangentiel est obligatoire au regard de la concentration des suspensions à traiter. La viscosité des suspensions, d'autant plus importante que la suspension est concentrée, apparait comme un paramètre déterminant pour le choix du protocole opératoire. Dans tous les cas, l'opération d'ultra-filtration (UF) permet une rétention conséquente (de 80 à 90%) de la fraction organique encore présente dans les digestats, à l'inverse, la rétention de la fraction minérale soluble est restée négligeable comme attendu. Le seuil de coupure de la membrane d'UF n'est pas apparu déterminant sur cette rétention. Malgré le mode tangentiel de séparation, l'opération de filtration induit une accumulation de composés au voisinage de la membrane qui diminue significativement la perméabilité du milieu filtrant. Cette chute de perméabilité apparaît d'autant plus importante que la suspension présente une concentration en demande chimique en oxygène (DCO) élevée. Ce critère apparaît alors comme le facteur limitant pour atteindre un facteur de concentration volumique (FCV) élevé (réduction des volumes). La surface membranaire à développer est directement liée à la perméabilité membranaire, elle-même dépendante de la concentration de la suspension à traiter donc de la nature du digestat et du FCV à atteindre. Le coût opérationnel de l'opération apparaît directement lié à l'énergie nécessaire pour assurer le mode tangentiel de filtration. Pour l'étape de concentration des sels d'intérêts, la rétention des composés minéraux solubles par osmose inverse haute pression dépasse 90% quels que soient les ions ciblés ou l'origine du digestat. A l'inverse, cette rétention est dépendante de l'ion ciblé et de l'origine du digestat pour les opérations de nano-filtration et d'osmose inverse basse pression. Dans tous les cas, la rétention de la fraction organique résiduelle est importante (>90%) permettant une décoloration du perméat très poussée (elle dépend toutefois du seuil de coupure de la membrane et du FCV choisi). La perméabilité membranaire diminue d'autant plus que la conductivité électrique (CE) de la solution à traiter est importante du fait de la pression osmotique et de l'accumulation de composés solubles au voisinage de la barrière membranaire. Cette conductivité, dépendante du digestat initial et du FCV choisi, apparaît alors comme le paramètre déterminant pour le dimensionnement de l'unité. Sur le plan énergétique, l'énergie liée à la mise sous pression des unités NF/OI est dominante par rapport à la circulation tangentielle du rétentat. Ce travail a permis de confirmer l'intérêt des séparations membranaires pour le traitement des digestats, afin d'une part, d'obtenir une eau de qualité permettant sa réutilisation ou son rejet dans le milieu naturel et d'autre part de récupérer et de concentrer des composés d'intérêt dans les différents rétentats. Ce travail a fait l'objet d'un soutien financier de l'ANR dans le cadre du programme BIOENERGIE 2010 (projet DIVA). / Intense spreading of livestock wastes are recognized to be detrimental to the environment due to their content of organic matter and mineral fraction. Then, it would appear to be necessary to promote greens treatments processes. In fact, anaerobic digestion allows the production of biogas (extremely useful source of renewable energy), whilst digestate should be a highly valuable biofertilizer This work enters in this approach by proposing to complete anaerobic digestion steps by the use of perm-selective membrane separation process. The first step is a clarification step by ultrafiltration, following by a soluble mineral concentration step by nanofiltration, low pressure and/or high pressure reverse osmosis (LPRO, HPRO). The tests were performed in a laboratory-scale pilot unit using real digestates. For clarification step, a cross-flow mode separation is obligate in view of suspended solid concentrations and viscosity which appeared as a determining factor for the choice of operative protocol. In any case, the ultra-filtration operation allows a high organic retention rate (of 80 to 90%). Conversely, soluble mineral retention remained at negligible as expected. The cut-off of ultrafiltration membrane is not a determining factor for this retention. Despite the cross-flow mode separation filtration induces a compound accumulation on the membrane which decreases significantly the permeability of filtering media. This permeability drop appears greater when suspension presents a high COD concentration. This criterion appears as a limiting factor to achieve a high volumic concentration factor (VCF). Membrane surface to develop is then directly related to the membrane permeability which depends on the digestate origin and VCF. The operational cost is linked directly to the energy required to ensure cross-flow mode. The retention of soluble mineral compounds by HPRO exceeds 90% whatever the target ions or the origine of digestate are. However, for NF and LPRO steps, this rejection depends on the target ions or the origine of digestate. In any case, organic retention is important (more than 90%) which allows significant discoloration of permeate. The, the more the electronic conductivity (EC) is, the more permeability decreases of suspension is important, due to an osmotic pressure and soluble compound accumulation on the membrane that increases with EC. This conductivity depends on initial digestate and, of course, of the chosen VCF target, which appears as decisive parameter for unit dimensioning. On the efficient energy, energy linked to separation step chosen is dominant in the absence of cross-flow mode of retentate. This work has allowed to confirm the potential interest of membrane separation to (i) obtain a final effluent: named fresh or new water and (ii) and (ii) to allow the production of liquid fertilizers.This work is financially supported by the National French Agency (Bio-Energy Program 2010, DIVA Project) and by TRIMATEC competitiveness cluster.

<div>Polyamide based reverse osmosis (PA-RO) membranes are applied for the desalination of halide-containing waters such as seawater and brackish groundwater. They are the industry standard because of their high selectivity and ability to withstand a wide range of pH. However, one of their pitfalls is their propensity to undergo biofouling, which is deterioration due to biological growth. Biofouling is known to dramatically decrease membrane performance and increase energy consumption. In order to overcome biofouling, a disinfectant, typically free chlorine, is applied; however, free chlorine is known to react with the polyamide layer and result in further membrane deterioration and performance loss.<br></div><div>One topic that has garnered less attention is the application of chloramines and their interactions with the PA-RO membrane when applied as a biofouling control. Furthermore, the role of halides (e.g. chloride, bromide, and iodide) in the presence of chloramines must be further explored because they are known to react to form secondary species which are reactive toward PA-RO membranes. In Chapter 2, the PA based monomers benzanilide (BA) and N-Methyl-N-phenylbenzamide (N-CH₃-BA) were used to model the PA layer. Monomers were exposed to halide containing waters and chloraminated with pre-formed NH₂Cl over a wide range of pH. The decay and by-product formation after exposure were evaluated using HPLC-DAD, LC/MS, and/or GC/MS. Results indicated that pH of the system and bromide concentration controlled parent compound decay and brominated by-product formation, where low pH and high bromide concentrations led to the highest formation of brominated by-products.</div><div>In Chapter 3, commercially made PA-RO membranes (SWC4-LD) were chloraminated or chlorinated with and without halides over a wide pH range. Their performance was evaluated after exposure through flux experiments using a dead-end flow cell. Results indicated that exposure to free chlorine led to the greatest change in flux and monochloramine resulted in the smallest change in flux. During chloramination of the membranes, the reactors containing bromide led to further change in flux than the chloramine only conditions. This was likely due to formation of secondary species that were reactive toward the PA membrane. Furthermore, Chapter 4 summarizes overall research contributions from this work and proposes future work pertaining to this topic.</div>

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2015 / The scarcity of water and strict environmental regulations have made sustainable engineering a prime concern in the process and manufacturing industries. Water minimisation involves the reduction of freshwater use and effluent discharge in chemical plants. This is achieved through water reuse, water recycle and water regeneration. Optimisation of the water network (WN) superstructure considers all possible interconnections between water sources, water sinks and regenerator units (membrane systems). In most published works, membrane systems have been represented using the “black-box” approach, which uses a simplified linear model to represent the membrane systems. This approach does not give an accurate representation of the energy consumption and associated costs of the membrane systems. The work presented in this dissertation therefore looks at the incorporation of a detailed reverse osmosis network (RON) superstructure within a water network superstructure in order to simultaneously minimise water, energy, operating and capital costs. The WN consists of water sources, water sinks and reverse osmosis (RO) units for the partial treatment of the contaminated water. An overall mixed-integer nonlinear programming (MINLP) framework is developed, that simultaneously evaluates both water recycle/reuse and regeneration reuse/recycle opportunities. The solution obtained from optimisation provides the optimal connections between various units in the network arrangement, size and number of RO units, booster pumps as well as energy recovery turbines. The work looks at four cases in order to highlight the importance of including a detailed regeneration network within the water network instead of the traditional “black-box’’ model. The importance of using a variable removal ratio in the model is also highlighted by applying the work to a literature case study, which leads to a 28% reduction in freshwater consumption and 80% reduction in wastewater generation. / GR2016

Grande parte da população rural do Semiárido brasileiro sofre com problemas de acesso à água de qualidade. A exploração da água subterrânea representa uma das principais alternativas para o abastecimento dessa parcela da população, mas muitas vezes os poços perfurados encontram-se longe da rede elétrica. A região apresenta abundante recurso solar e, assim, essa dificuldade poderia ser contornada com a utilização de sistemas fotovoltaicos de bombeamento. Mas, além da questão da energia para o funcionamento dos sistemas de bombeamento, pelo fato da maior parte do Semiárido estar localizada sobre escudo cristalino, muitos poços apresentam água com altos níveis de salinidade, o que inviabiliza a utilização desses mananciais para o fornecimento de água potável ou faz com que a população rejeite seu consumo, por conta do gosto. O presente trabalho tem como objetivo verificar se a adaptação de sistemas de dessalinização de pequeno porte disponíveis comercialmente a sistemas fotovoltaicos domiciliares pode potencializar a difusão dos sistemas fotovoltaicos de bombeamento em poços de água com alto teor de sais dissolvidos e se essa opção pode representar uma alternativa de fornecimento de água para a população rural de áreas com problemas de salinização dos mananciais de abastecimento. A opção analisada consiste em um sistema duplo de fornecimento de água, com tratamento do tipo ponto de uso da água para consumo humano. Foi verificado que os sistemas de dessalinização atualmente disponíveis no mercado podem funcionar acoplados a geradores fotovoltaicos e utilizados para fornecimento de água potável a partir de água salobra. / Much of the rural population of the Brazilian Semiarid region suffers from problems related to access of improved water quality. The exploitation of ground water is the main alternative for water supply solutions regarding this population, but often the boreholes are away from power lines. The region has abundant solar source and therefore this problem could be overcome with the use of photovoltaic pumping systems. Beyond the issue of energy for operation of the borehole systems, considering that most of the semiarid region is located on crystalline shield, many boreholes have water with high level of salinity, which hinder their use for drinking water supply solutions, as the population rejects the water because of its taste. This study aims to determine whether the adaptation of commercially available small household desalinization systems adapted to photovoltaic systems can enhance the diffusion of photovoltaic pumping systems of boreholes with high concentrations of dissolved salt, by proposing this water supply solution as an alternative for water supply systems in rural areas with problems of salinization of the main water sources. The proposed technical solution consists of a dual water supply system with the use a point of use water treatment for human consumption. It was found that desalination systems available on the market can operate coupled to photovoltaic generators and used to supply drinking water from brackish water.

Sistemas de membranas filtrantes, principalmente os de osmose reversa, estão sendo cada vez mais utilizados em diversos seguimentos de empresas (farmacêutica, tratamento de água, alimentícia e química), devido à diminuição do preço dos elementos filtrantes e da alta qualidade do produto obtido. O biofouling corresponde a um tipo de fouling inevitável, caracterizado pelo crescimento de microrganismos na superfície das membranas e liberação de EPS pelos mesmos; por isso, um melhor conhecimento sobre estas estruturas é necessário. O presente trabalho teve como objetivo caracterizar o biofouling em diferentes membranas de osmose reversa colmatadas de diferentes indústrias pela técnica da autópsia e comparar com resultados obtidos com biofilmes de cultura pura formados em membranas de osmose reversa; além de verificar a influência de biofilmes na deposição de sais e ação de compostos químicos utilizados na limpeza química de membranas nos mesmos. A autópsia dos elementos colmatados mostrou uma grande quantidade de células viáveis porém, com concentrações de carboidratos muito baixas; diferentemente do que ocorreu quando biofilmes de cultura pura isolados destas membranas foram analisados, apresentando correlações fortes entre quantidade de células viáveis e macromoléculas como proteínas e, principalmente, carboidratos. Com relação à influência dos biofilmes na deposição de sais, dois dos quatro biofilmes de cultura pura apresentaram incorporação de bário em sua estrutura (revelado por análises de fluorescência de raios X), esta incorporação, provavelmente, ocorreu por troca iônica e não pela deposição de sulfato de bário. Compostos como hidróxido de sódio (pH = 12) e ácido clorídrico (pH = 2) apresentaram bons resultados na diminuição de células viáveis porém, a recuperação dos microrganismos foi menor com a utilização do ácido. Os compostos EDTA e SDS não foram eficazes na diminuição de viáveis. / Systems of filter membranes, especially reverse osmosis, are being increasingly used in various segments of companies (pharmaceutical, water treatment, food and chemical industries) due to the decrease in the price of the filter elements and high quality of the product. The biofouling corresponds to a type of inevitable fouling characterized by growth of microorganisms on the surface of the membrane and release of EPS by them; so a better understanding of these structures is necessary. This study aimed to characterize the biofouling in different reverse osmosis membranes addressed from different industries by the technique of autopsy and compared with results obtained with pure culture biofilms in reverse osmosis membranes; and to verify the influence of biofilms in the deposition of salts and action of chemical compounds used in chemical cleaning of membranes in them. The autopsy of clogged elements showed a lot of viable cells but with very low carbohydrate concentrations; unlike what occurred when biofilms isolated pure culture of these membranes were analyzed, showing strong correlation between number of viable cells and macromolecules such as proteins and especially carbohydrates. Regarding the influence of biofilms in the deposition of salts, two of the four pure culture biofilms showed barium incorporation in its structure (revealed by fluorescence analysis X-ray), this merger probably occurred by ion exchange and not by deposition barium sulfate. Compounds such as sodium hydroxide (pH = 12) and hydrochloric acid (pH = 2) showed good results in the decrease of viable cells however, the recovery of microorganisms was lower with use of the acid. EDTA and SDS compounds were not effective in reducing viable.

O presente trabalho avaliou o desempenho de um sistema de pré-tratamento para água do mar constituído por um filtro lento de areia, com uma etapa prévia de filtração por um filtro de discos. O sistema demonstrou eficiência na remoção de fatores causadores de fouling em membranas de osmose reversa, removendo aproximadamente 97% dos sólidos suspensos totais presentes na água bruta, e gerando um filtrado com turbidez entre 0.1 e 0.2 UNT. As concentrações de microrganismos e AOC, principais fatores causadores da formação de biofouling, foram ambas reduzidas em cerca de 90%. Em sistemas de dessalinização de água do mar por osmose reversa, o pré-tratamento da água de alimentação constitui a principal estratégia no controle da formação do biofouling, que é gerado pelo estabelecimento de biofilmes sobre a superfície da membrana. A formação de biofouling gera impacto no desempenho do processo de osmose reversa e nos custos de operação. / This study evaluated the performance of a pretreatment system for seawater comprising of a slow sand filter, with a preliminary stage of filtration by disc filtration system. The system proved to be efficient in removing factors causing fouling in reverse osmosis membranes removing around 97% of the total suspended solids present in the raw water, and yielding a filtrate with turbidity between 0.1 and 0.2 NTU. The bacterial concentrations and AOC, main factors causing biofouling formation, were both reduced by about 90%. In seawater reverse osmosis systems, pretreatment of the feeded water is the main strategy to control biofouling, which is formed by the establishment of biofilms on a membrane surface. The biofouling formation produces an impact in the performance of the reverse osmosis process and operating costs.

Une étude a été menée sur la faisabilité technique du traitement de potabilisation des eaux de forage contaminées à l’arsenic par procédé membranaire. Pour ce faire, l’efficacité de deux membranes commerciales (NF270 et TW30) vis-à-vis de la rétention des espèces d’arsenic, arsénite [As (III)] et arséniate [As (V)], a été d’abord comparée sous différentes conditions expérimentales. Ensuite, la contribution des différents mécanismes intervenant dans l’élimination des espèces d’arsenic a été identifiée. Enfin, la membrane la plus performante a été utilisée pour le traitement d’une eau souterraine naturellement riche en arsenic. Il ressort de cette étude que la pression opératoire et le pH sont les paramètres importants sur lesquels il faut agir pour améliorer l’efficacité du système membranaire pour le traitement de l’arsenic. L’As(V) est facilement éliminé par rapport à l’As (III) aussi bien avec la membrane de nanofiltration que d’osmose inverse. Toutefois, la membrane d’osmose inverse (TW30) permet une meilleure élimination des différentes espèces d’arsenic que la membrane NF270. Cela est dû au fait que la membrane TW30 est une membrane dense. L’application de cette membrane pour la production d’eau potable à partir d’une eau de forage contenant 413,74µg/L d’arsenic total dont 405,63µg/L d’As (V) et 8,11 µg/L d’As (III) a donné une concentration d’arsenic total dans l’eau traitée de 9,99 µg/L soit un taux de rétention de 97,6% et un volume d’eau traité correspondant à 70% du volume d’eau brute. Il est donc possible de mettre en place un procédé de traitement de ces eaux de forage à partir de la membrane TW30 afin de produire de l’eau potable pour les populations du nord du Burkina Faso. La performance de ce procédé peut être encore améliorée en oxydant l’As (III) en As (V) avant filtration. / In order to produce potable water for human consumption, a study was carried out on the technical feasibility of arsenic-rich borehole water treatment by membrane process. Firstly the efficiency of two commercial membranes (NF2Une étude a été menée sur la faisabilité technique du traitement de potabilisation des eaux de forage contaminées à l’arsenic par procédé membranaire. Pour ce faire, l’efficacité de deux membranes commerciales (NF270 et TW30) vis-à-vis de la rétention des espèces d’arsenic, arsénite [As (III)] et arséniate [As (V)], a été d’abord comparée sous différentes conditions expérimentales. Ensuite, la contribution des différents mécanismes intervenant dans l’élimination des espèces d’arsenic a été identifiée. Enfin, la membrane la plus performante a été utilisée pour le traitement d’une eau souterraine naturellement riche en arsenic. Il ressort de cette étude que la pression opératoire et le pH sont les paramètres importants sur lesquels il faut agir pour améliorer l’efficacité du système membranaire pour le traitement de l’arsenic. L’As(V) est facilement éliminé par rapport à l’As (III) aussi bien avec la membrane de nanofiltration que d’osmose inverse. Toutefois, la membrane d’osmose inverse (TW30) permet une meilleure élimination des différentes espèces d’arsenic que la membrane NF270. Cela est dû au fait que la membrane TW30 est une membrane dense. L’application de cette membrane pour la production d’eau potable à partir d’une eau de forage contenant 413,74µg/L d’arsenic total dont 405,63µg/L d’As (V) et 8,11 µg/L d’As (III) a donné une concentration d’arsenic total dans l’eau traitée de 9,99 µg/L soit un taux de rétention de 97,6% et un volume d’eau traité correspondant à 70% du volume d’eau brute. Il est donc possible de mettre en place un procédé de traitement de ces eaux de forage à partir de la membrane TW30 afin de produire de l’eau potable pour les populations du nord du Burkina Faso. La performance de ce procédé peut être encore améliorée en oxydant l’As (III) en As (V) avant filtration.70 and TW30) for different arsenic species removal, arsenite [As (III)] and arsenate [As (V)], was compared under various experimental conditions. Afterward, the contribution of mechanisms in As species removal was determined. Finally, the most efficient membrane was used for As-rich groundwater treatment. Results show that, applied pressure and feed pH are the important parameters which must be considered if As removal wants to be improved. As (V) is much easily removed than As (III) both NF270 and TW30 membranes. Nevertheless, TW30 membrane has a better removal of As species than NF270 membrane. It is due to the fact that TW30 membrane is a compact membrane. The application of this membrane for potable water production from naturally contaminated groundwater containing 413.74 µg/L of total arsenic (405.63 µg/L of As (V) and 8.11 µg/L of As (III)) gave a treated water of 9.99 µg/L (97.6% of rejection) of total As concentration and water produced volume equivalent to 70% of raw water volume. Therefore, it is possible to implement a treatment process with TW30 membrane to remove arsenic from naturally contaminated groundwater coming from the northern part of Burkina Faso. The efficiency of this process can be improved again by oxidizing As (III) in As (V) before filtration.

Sistemas de membranas filtrantes, principalmente os de osmose reversa, estão sendo cada vez mais utilizados em diversos seguimentos de empresas (farmacêutica, tratamento de água, alimentícia e química), devido à diminuição do preço dos elementos filtrantes e da alta qualidade do produto obtido. O biofouling corresponde a um tipo de fouling inevitável, caracterizado pelo crescimento de microrganismos na superfície das membranas e liberação de EPS pelos mesmos; por isso, um melhor conhecimento sobre estas estruturas é necessário. O presente trabalho teve como objetivo caracterizar o biofouling em diferentes membranas de osmose reversa colmatadas de diferentes indústrias pela técnica da autópsia e comparar com resultados obtidos com biofilmes de cultura pura formados em membranas de osmose reversa; além de verificar a influência de biofilmes na deposição de sais e ação de compostos químicos utilizados na limpeza química de membranas nos mesmos. A autópsia dos elementos colmatados mostrou uma grande quantidade de células viáveis porém, com concentrações de carboidratos muito baixas; diferentemente do que ocorreu quando biofilmes de cultura pura isolados destas membranas foram analisados, apresentando correlações fortes entre quantidade de células viáveis e macromoléculas como proteínas e, principalmente, carboidratos. Com relação à influência dos biofilmes na deposição de sais, dois dos quatro biofilmes de cultura pura apresentaram incorporação de bário em sua estrutura (revelado por análises de fluorescência de raios X), esta incorporação, provavelmente, ocorreu por troca iônica e não pela deposição de sulfato de bário. Compostos como hidróxido de sódio (pH = 12) e ácido clorídrico (pH = 2) apresentaram bons resultados na diminuição de células viáveis porém, a recuperação dos microrganismos foi menor com a utilização do ácido. Os compostos EDTA e SDS não foram eficazes na diminuição de viáveis. / Systems of filter membranes, especially reverse osmosis, are being increasingly used in various segments of companies (pharmaceutical, water treatment, food and chemical industries) due to the decrease in the price of the filter elements and high quality of the product. The biofouling corresponds to a type of inevitable fouling characterized by growth of microorganisms on the surface of the membrane and release of EPS by them; so a better understanding of these structures is necessary. This study aimed to characterize the biofouling in different reverse osmosis membranes addressed from different industries by the technique of autopsy and compared with results obtained with pure culture biofilms in reverse osmosis membranes; and to verify the influence of biofilms in the deposition of salts and action of chemical compounds used in chemical cleaning of membranes in them. The autopsy of clogged elements showed a lot of viable cells but with very low carbohydrate concentrations; unlike what occurred when biofilms isolated pure culture of these membranes were analyzed, showing strong correlation between number of viable cells and macromolecules such as proteins and especially carbohydrates. Regarding the influence of biofilms in the deposition of salts, two of the four pure culture biofilms showed barium incorporation in its structure (revealed by fluorescence analysis X-ray), this merger probably occurred by ion exchange and not by deposition barium sulfate. Compounds such as sodium hydroxide (pH = 12) and hydrochloric acid (pH = 2) showed good results in the decrease of viable cells however, the recovery of microorganisms was lower with use of the acid. EDTA and SDS compounds were not effective in reducing viable.

O objetivo deste trabalho foi investigar o desempenho de uma membrana comercial na remoção de um metal pesado (níquel) de efluentes sintéticos, por osmose inversa. Na primeira etapa foi realizada uma comparação com os resultados obtidos com soluções de alimentação contendo sais, como NaCl, NaNO3 e Ni(NO3)2.6 H2O, nas concentrações de 50, 100 e 200 ppm, e nas pressões de 10, 20 e 26 bar. Os resultados mostraram que a influência da concentração e da pressão aplicada ao sistema não afetaram as rejeições de forma significativa. Na segunda etapa, como os parâmetros não influíram significativamente na rejeição dos sais, optou-se, pela aplicação de uma pressão de operação de 10 bar, para avaliar a eficiência de remoção de níquel. A membrana utilizada, constituída de poliamida, modelo HR98PP e fornecida pela DOW/Filmtec, apresentou uma boa permeabilidade hidráulica. Os resultados mostraram que para todas as concentrações testadas, as rejeições de níquel ultrapassaram 96%, comprovando a boa seletividade deste tipo de membrana na rejeição do referido metal, com fluxos de permeado variando entre 4,78 e 5,55 L/h.m2 , sob pressão de operação de 10 bar. Para estudar o efeito do tamanho iônico na rejeição da membrana, o níquel foi complexado pela adição de um agente quelante na solução de alimentação. O agente escolhido foi o Na2EDTA, devido à formação de um complexo estável com o níquel e por ser um agente não prejudicial à saúde humana. Os resultados com adição de EDTA indicaram um aumento na rejeição de níquel, atingindo o índice máximo de 98,22 %, partindo-se de uma solução com 40,39 ppm de Ni2+, e confirmam que o processo de osmose inversa com a membrana HR98PP é altamente adequado para o tratamento de efluentes contendo níquel / The present work aim to investigate the performance of commercial membrane (HR98PP) at reverse osmosis process for nickel removal from synthetic effluents. The results was obtained by using salt solution of NaCl, NaNO3 and Ni(NO3)2.6 H2O at different feed concentration (50, 100 and 200 mg/L) and pressure (10, 20 and 26 bar), as drive-force of process. The membrane performance showed a good hydraulic permeability (Lp) and nickel removal at 10 bar. This condition was used to investigate the influence of EDTA, as chelate agent, on nickel rejection when a feed solution with lower Ni2+ concentration (&#8776; 40 mg/L) was prepared. The EDTA was chosen due to the stable complex formations and because this agent in not a prejucial element to human health and to environment. In this case, the HR98PP membrane was showed a high nickel rejection (&#8776; 98%), using feed solution containing 40,39 mg/L Ni2+. However, it is suitable for the wastewater nickel treatment