Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: When desalinating brackish water by reverse osmosis (RO) or other techniques, high overall water recoveries are essential to minimize brine production and the associated disposal costs thereof. As the overall water recovery increases, concentrations of sparingly soluble salts (e.g. barium sulphate, calcium sulphate) reach levels above saturation, especially near the membrane surface, drastically increasing the scaling propensity. Antiscalants are typically dosed into the feed water to prevent such scaling during RO desalination. However, the carry-over of antiscalant into the concentrate stream can complicate subsequent salt precipitation processes that may be used to increase overall water recovery. These precipitation techniques are sometimes used to reduce the levels of super-saturation in the RO concentrate prior to a subsequent RO desalination step. The purpose of this study was to assess the feasibility of reducing calcium sulphate scaling on RO membranes, by using periodic permeate flushing when feeding a lab-scale RO unit with a supersaturated calcium sulphate solution in the absence of anti-scalant. The overall water recovery was increased by recycling the concentrate, after an intermediate de-supersaturation step. This simulated a multiple-stage RO system, typical of processes used in high-recovery acid mine drainage (AMD) treatment plants. De-supersaturation of the concentrate intermediate was achieved with direct seeded gypsum precipitation, in the absence of any antiscalant. On the membrane surface inside the membrane unit, calcium sulphate concentrations greatly exceeded saturation levels – a combined consequence of the normal concentration process and the well-known surface-based concentration polarisation phenomenon. Therefore, periodic forward-flushing of the supersaturated solution from the membrane unit was performed with permeate. In theory, the periodic flushing removes the highly concentrated layer at the membrane surface during every flush, before scaling can occur. Various flushing regimes were evaluated to assess the effectiveness of the process. A lab-scale desalination unit with a 0.106 m2 flat sheet polyamide RO membrane was designed and constructed. The unit could operate at a feed rate of 12-14 L/h and at permeate fluxes of 12-24 LMH. Super-saturated feed solutions were prepared by mixing sodium sulphate and calcium chloride dihydrate salts with demineralised water, with an initial salinity of ± 5300 mg/L TDS, corresponding to a gypsum saturation index (SIg) of 1.2 for most experiments. The total production time, net permeate production and flux decline were used to compare the flushing efficiency in different experimental runs. Initial tests showed that scaling could be prevented (when operating the unit in full recycle mode, i.e. where both concentrate and permeate were recycled to feed), at flushing frequencies between 12 and 2.4 h-1, when the membrane feed and concentrate were slightly under-saturated (SIg = 0.9) and slightly super-saturated (SIg = 1.1) respectively. However, when switching the same system to non-flushing mode after 24 hours of operation, membrane scaling occurred within 2-3 hours, as indicated by a strong decline in flux. However, when operating the system in concentrate recycle mode (i.e. permeate is withdrawn) with super-saturated feed solutions (e.g. SIg = 1.2), and thus a notably more super-saturated solution in the membrane concentrate, scaling could not be prevented (albeit delayed for some time) with intermittent permeate flushing. A fractional 25-1 factorial design was used to determine which factors had the most significant effect on total production time and permeate production rate, testing five factors: 1) flushing frequency, 2) flushing volume, 3) permeate soak time, 4) permeate flux and 5) instantaneous recovery. The ANOVA analysis showed that total production times were, not surprisingly, primarily affected by the permeate flux, where operation at 24 LMH resulted in a lower net permeate production between 3.0 - 4.2 L, compared to 7.6 - 9.7 L at 12 LMH. Higher permeate fluxes clearly resulted in higher levels of concentration polarisation at the membrane surface, thus increasing the propensity for membrane scaling. Flushing frequency and instantaneous recovery also affected the net permeate production, where 6 h-1 and 10 % were the optimal values respectively within the range of test conditions. The lowest permeate production rate resulted in the highest net permeate volume production (i.e. also longest total production time), confirmed by a least squares regression. In summary: This study showed that periodic permeate flushing could delay the membrane scaling process. However, it failed to prevent membrane scaling completely when operating the system with supersaturated calcium sulphate solutions in the absence of antiscalants. The flushing technique effectively delayed the onset of precipitation, but scaling eventually occurred if the lab-scale RO system was operated in concentrate recycle mode with oversaturated feed solutions (SIg = 1.2). Additional experiments at different cross-flow velocities during permeate flushing, while using an optimised RO test cell flow channel design, are recommended for future studies. / AFRIKAANSE OPSOMMING: Gedurende die ontsouting van brakwater deur tegnieke soos tru-osmose (TO), is ʼn maksimum herwinning van water noodsaaklik om die produksie, en die gepaardgaande kostes van verwydering, van die sout/brak neweproduk te minimeer. Soos die herwinning van water verhoog, so ook verhoog die konsentrasie van moeilik-oplosbare soute (soos bariumsulfaat, kalsiumsulfaat) in die sout konsentraat stroom, totdat die soute uiteindelik superversadiging bereik. Hierdie superversadiging gebeur veral naby die membraanoppervlak, waar dit lei tot ʼn verhoogde kans van presipitasie en skaalvorming. Om dit te voorkom word die voerwater na ʼn TO stelsel tipies gedoseer met antiskaalmiddels. Hierdie antiskaalmiddels verlaat die stelsel saam met die konsentraat, waar hulle gevolglike die presipitasie van soute bemoeilik. Presipitasie van soute uit die konsentraat kan tipies gebruik word om die vlak van superversadiging in die konsentraat te verlaag, waarna verdere TO behandeling gebruik word om selfs ʼn hoër algehele waterherwinning te bewerkstellig. Die doel van hierdie studie was om die vatbaarheid van die vermindering van kalsiumsulfaat (gips) skaalvorming in die afwesigheid van antiskaalmiddels op TO membrane te toets. Dit is bewerkstellig deur ʼn laboratoriumskaal TO eenheid te voer met ʼn superversadigde kalsiumsulfaat oplossing en die membraan periodies met skoon produkwater (permeaat) te was. Die algehele waterherwinning is verhoog deur met ʼn tussenstap die versadigingsvlak van gips in die konsentraat te verlaag, waarna dit hersirkuleer is na die voertenk. Sodoende is ʼn multi-stadium TO stelsel nageboots, soos dit tipies in hoë herwinningsaanlegte, soos met die herwinning van suur mynwater (E: acid mine drainage, AMD), gebruik word. ʼn Verlaging in superversadiging van die konsentraat in die tussenstap is behaal deur die konsentraat direk aan gipskristalle bloot te stel om presipitasie te bewerkstellig in die afwesigheid van enige antiskaalmiddels. Gedurende eksperimente het die soutkonsentrasie op die membraanoppervlak in die TO eenheid superversadigingsvlakke vêr oorskry, as gevolg van die natuurlike konsentrasie proses en die bekende konsentrasie polarisasie oppervlaksverskynsel. Om hierdie superversadiging teen te werk is periodiese saamstroom spoeling van die membraan met skoon produkwater uitgevoer. In teorie het die periodiese spoeling die hoogs gekonsentreerde oplossing van die membraan oppervlak verwyder voor skaalvorming kan plaasvind. Verskillende spoelpatrone is ondersoek om die doeltreffendheid van die spoeling te bepaal. Om die eksperimente uit te voer is ʼn laboratoriumskaal ontsoutingsaanleg met ʼn maklik verwyderbare 0.106 m2 plat-vel poli-amied TO membraan ontwerp en gebou. Die aanleg kan vloeistof voertempo’s tussen 12-24 L/h hanteer en skoon produkwater teen 12-24 LHM lewer. Die superversadigde voer oplossings, soos gebruik in die meerderheid van die eksperimentes is voorberei deur natriumsulfaat en kalsiumchloried-dihidraat soute te meng in gedemineraliseerde water, tot ʼn soutgehalte van ± 5300 mg/L TDS bereik is. Hierdie soutgehalte stem ooreen met ʼn gips versadigingsindeks (E: gypsum saturation index, SIg) van 1.2. Die skoon produkwater totale produksietyd en netto produksie, asook die membraan vloed afname, is gebruik as veranderlikes om die spoel doeltreffendheid tussen eksperimentele lopies te vergelyk. Aanvanklike toetse het getoon dat skalering voorkom is by effens onderversadigde (SIg = 0.9) en effens superversadigde (SIg = 1.1) voer oplossings met die onderskeie spoel frekwensies van 12 en 2.4 h-1, (terwyl die aanleg in algehele hersirkulasie bedryf is, m.a.w. wanneer beide die konsentraat en produkwater gedurig na die voertenk hersirkuleer word). ʼn Effens-superversadigde eksperiment is ook sonder spoeling uitgevoer vir 24 uur. In hierdie geval het skaalvorming binne twee tot drie uur gebeur, soos bevestig deur ʼn skerp afname in die membraan vloed. Skaalvorming kon nie verhoed word terwyl die aanleg bedryf word met superversadigde (SIg = 1.2) voeroplossings en slegs konsentraat hersirkulasie nie (m.a.w. skoon produkwater word opgevang), alhoewel skaalvorming vertraag kon word. Hierdie operasie het tot beduidend meer gekonsentreerde oplossings in die membraan gelei. Om te bepaal watter faktore die grootste invloed op totale produksietyd en netto produksie van skoon produkwater het, is ʼn fraksionele faktoriaalontwerp van 25-1 uitgelê wat vyf faktore toets, naamlik: 1) spoel frekwensie, 2) spoel volume, 3) skoon produkwater weektyd, 4) membraanvloed en 5) oombliklike herwinning. ʼn AVOVA analise het getoon dat totale produksietyd hoofsaaklik deur membraanvloed beïnvloed is, soos verwag kan word. Dit word gestaaf deurdat die aanleg, bedryf teen 24 LMH, slegs 3 - 4.2 L netto produkwater gelewer het, teenoor 7.6 - 9.7 L by 12 LMH. Hoër membraan vloedtempo’s het tot hoër vlakke van konsentrasie polarisasie op die membraanoppervlak gelei, wat ʼn groter neiging tot skaalvorming tot gevolg gehad het. Spoelfrekwensie en oombliklike herwinning het ʼn invloed op die netto produksie van skoon produkwater gehad, met 6 h-1 en 10 % as die onderskeie optimale waardes. ʼn Kleinstekwadraat regressie het aangedui dat die laagste produksietempo van skoon produkwater die hoogste netto produksie van skoon produkwater gelewer het, (asook die langste produksietyd). In opsomming: Hierdie studie het getoon dat gereelde spoeling met skoon produkwater die membraan skaalproses kan vertraag. Gedurende bedryf met superversadigde kalsiumsulfaat oplossings sonder enige antiskaalmiddels is daar gevind dat skaalvorming nie geheel en al vermy kon word nie. Die spoeltegniek, soos gebruik in hierdie studie, het die aanvang van skaalvorming in die laboratorium skaal TO eenheid vertraag, maar bedryf met konsentraat hersirkulasie en superversadigde oplossings (SIg = 1.2) het steeds skaal gevorm. Bykomende eksperimente teen verskeie kruisvloei snelhede gedurende die spoel stap word aanbeveel vir toekomstige studies.

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. Apesar do preço dos elementos de osmose reversa terem caído nos últimos tempos, a substituição destes continua sendo o fator mais dispendioso de um sistema de osmose reversa. A autópsia de membranas é uma técnica utilizada para investigar a causa que levou à colmatação de um elemento, contribuindo no melhoramento do pré-tratamento da água de alimentação e consequentemente aumentando a vida útil dos elementos. O presente trabalho teve como objetivo incrementar a técnica de autópsia de membranas de osmose reversa através da análise da volatilização dos principais compostos inorgânicos presentes nestas membranas, modificação na metodologia de quantificação de açúcares e proteínas, comparação de diferentes técnicas de remoção do material depositado sobre as membranas e análise da distribuição de biofilmes sobre elementos colmatados de osmose reversa. A análise dos resultados mostrou que dentre os inorgânicos, ocorreu volatilização completa do cloreto de amônio e pequena variação no composto cloreto férrico; a quantificação de proteínas e açúcares, através da fortificação das amostras, apresentou valores diferentes quando comparados com os valores obtidos diretamente da curva padrão, devido à diferença de inclinação entre as retas de fortificação e padrão; os resultados também mostraram que a trituração foi mais eficiente na remoção do material aderido quando comparado com a raspagem e a sonicação e a distribuição de biofilmes se mostrou uniforme nos dois elementos analisados. / Filter membrane systems, especially reverse osmosis, are being increasingly used in various business segments (pharmaceutical, water treatment, food and chemical) due to decrease in the price of the filter elements and high quality product. Although the price of reverse osmosis elements have fallen in recent times, the replacement of the part remains more expensive a reverse osmosis system. The autopsy of membranes is a technique used to investigate the cause that led to clogging of one factor contributing to the improvement of pre-treatment of water feeding and consequently increasing the life of the elements. This study aimed to improve the technique of autopsy reverse osmosis membranes by examining the volatilization of major inorganic compounds present in these membranes, modification the methodology for quantification of sugars and proteins, comparison of different techniques for removal of material deposited on the membranes and distribution analysis of biofilms on elements obscured reverse osmosis. The results showed that among the Inorganic volatilization was full of ammonium chloride and small variation in the compound ferric chloride, the quantification of proteins and sugars, by fortifying the samples showed different values when compared with values obtained directly the standard curve due to the difference in slope between the lines of and fortification standard, the results also showed that the blending was more efficient in removing adhered material when compared with the scraping and sonication and distribution of biofilms showed uniform the two elements analyzed.

Securing water in the right quantities at the right quality for the right price is a major issue around the world. Membranes are making an increasingly important contribution to meeting this need; however their performance is limited by fouling. This thesis reports on an investigation into the fouling of systems related to water treatment using the Direct Observation Through the Membrane (DOTM). The investigation focused on the measurement of critical flux and observation of particle behaviour under a variety of conditions and for a number of different particles. The range of meanings attributed to critical flux in the literature was analysed and several proposals made for the improved use of the concept. In particular, critical flux determination techniques were classified by whether they measure resistance changes or particle deposition; leading to the definition of Critical Resistance and Critical Deposition Fluxes. In this thesis the deposition definition is used exclusively. The effect of Reynolds number and spacer orientation on critical flux was correlated for spacer-filled channels. The heterogeneous deposition patterns observed with regions of heavy deposition next to areas of little or no deposition. This pattern was related to the local hydrodynamics of spacer cells (a few mm2 in size). The correlations developed for critical flux in spacer-filled channels were adjusted for submicron particle size and incorporated into a SpiralWound Module (SWM) leaf model and then used to simulate the fouling of SWM leaves under a range of operating conditions and operating policies. The Mass Balance technique of critical flux determination was also briefly assessed. The applicability of critical flux criteria to SWM arrays was discussed. Fouling, particle behaviour and critical flux were also investigated in air-sparged systems. The post-cleaning water flux was found to be enhanced when the membrane is fouled in the presence of bubbles. The rate of flux decline was reduced by bubbles. Critical flux increased with air flowrate, and decreased with increased liquid flowrate and concentration. Bubbles caused particles to periodically deposit on the membrane. Particles were observed to stream past the membrane under the influence of back-diffusive forces. Video clips of particulate fouling are provided.

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. Apesar do preço dos elementos de osmose reversa terem caído nos últimos tempos, a substituição destes continua sendo o fator mais dispendioso de um sistema de osmose reversa. A autópsia de membranas é uma técnica utilizada para investigar a causa que levou à colmatação de um elemento, contribuindo no melhoramento do pré-tratamento da água de alimentação e consequentemente aumentando a vida útil dos elementos. O presente trabalho teve como objetivo incrementar a técnica de autópsia de membranas de osmose reversa através da análise da volatilização dos principais compostos inorgânicos presentes nestas membranas, modificação na metodologia de quantificação de açúcares e proteínas, comparação de diferentes técnicas de remoção do material depositado sobre as membranas e análise da distribuição de biofilmes sobre elementos colmatados de osmose reversa. A análise dos resultados mostrou que dentre os inorgânicos, ocorreu volatilização completa do cloreto de amônio e pequena variação no composto cloreto férrico; a quantificação de proteínas e açúcares, através da fortificação das amostras, apresentou valores diferentes quando comparados com os valores obtidos diretamente da curva padrão, devido à diferença de inclinação entre as retas de fortificação e padrão; os resultados também mostraram que a trituração foi mais eficiente na remoção do material aderido quando comparado com a raspagem e a sonicação e a distribuição de biofilmes se mostrou uniforme nos dois elementos analisados. / Filter membrane systems, especially reverse osmosis, are being increasingly used in various business segments (pharmaceutical, water treatment, food and chemical) due to decrease in the price of the filter elements and high quality product. Although the price of reverse osmosis elements have fallen in recent times, the replacement of the part remains more expensive a reverse osmosis system. The autopsy of membranes is a technique used to investigate the cause that led to clogging of one factor contributing to the improvement of pre-treatment of water feeding and consequently increasing the life of the elements. This study aimed to improve the technique of autopsy reverse osmosis membranes by examining the volatilization of major inorganic compounds present in these membranes, modification the methodology for quantification of sugars and proteins, comparison of different techniques for removal of material deposited on the membranes and distribution analysis of biofilms on elements obscured reverse osmosis. The results showed that among the Inorganic volatilization was full of ammonium chloride and small variation in the compound ferric chloride, the quantification of proteins and sugars, by fortifying the samples showed different values when compared with values obtained directly the standard curve due to the difference in slope between the lines of and fortification standard, the results also showed that the blending was more efficient in removing adhered material when compared with the scraping and sonication and distribution of biofilms showed uniform the two elements analyzed.

Hollow fiber membranes offer the opportunity to dramatically reduce the energy required to perform gas separations in the chemical industry. The membranes are fabricated from highly non-Newtonian precursor materials, including concentrated polymer solutions that sometimes also contain dispersed particles. These materials are susceptible to shear-induced microstructural changes during processing, which can affect the characteristics of the resulting membrane. This thesis explores several shear-related effects using materials and flow conditions that are relevant for fiber spinning. The findings are discussed as they relate to membrane processing, and also from the standpoint of enhancing our fundamental understanding of the underlying phenomena. First, the effect of shear on polymeric dope solutions was investigated. Shear-induced demixing—a phenomenon not previously studied in membrane materials—was found to occur in membrane dopes. Phase separation experiments also showed that shear-induced demixing promotes macrovoid formation. The demixing process was found to depend not only on the instantaneous shear conditions, but also on the shear history of the solution. This suggests that low-shear flow processes that occur in the upstream tubing and channels used for fiber spinning can affect macrovoid formation. The effect of viscoelastic media on dispersed particles was also explored. Shear-small-angle light scattering results showed that particles suspended in membrane dope solutions formed aggregated, vorticity-oriented structures when shear rates in the shear-thinning regime of the polymer solution were applied. Shear rates well below the shear-thinning regime did not produce any structure. In fact, the application of a Newtonian shear rate to a sample already containing the vorticity structure caused the sample to return to isotropy. Measurements using a highly elastic, constant-viscosity Boger fluid showed that strong normal forces alone are not sufficient to form the vorticity structures, but that shear thinning is also required. Lastly, a study was conducted examining cross-stream migration of particles dispersed in viscoelastic media. Fluids exhibiting varying degrees of shear thinning and normal forces were found to have different effects on the particle distribution along the shear gradient axis in Poiseuille flow. Shear thinning was found to promote migration toward the channel center, while normal stresses tended to cause migration toward the channel walls. In addition to hollow fiber spinning, many other industrially relevant applications involve polymer solutions and suspensions of particles in viscoelastic media. Often, the properties and performance of the material depend strongly on the internal microstructure. The results from the research described in this thesis can be used to guide the design of materials and processing conditions, so that the desired microstructural characteristics can be achieved.

Particles and macromolecular components, including biopolymers (protein and carbohydrate), are viewed as the main foulants in the complex feed submerged membrane filtration systems such as membrane bioreactor (MBR). This work focused on two aspects of fouling in complex fluids: 1- Assessing fouling propensity and mechanisms for various model solutions. 2- Using of two specific solutions modelling biomass found in MBR for a better understanding of the fouling mechanisms in submerged MBR processes. Filtrations were carried out with 0.22 ??m PVDF hollow fibre membrane. Alginate was used as a model for polysaccharide, bovine serum albumin (BSA) as a model for protein, (un)washed yeast and bentonite were representing suspended solid contents. According to the data obtained during this study the fouling propensity of each model solution was classified as follow in a decreasing order: Alginate &gt unwashed yeast &gt washed yeast &gt BSA &gt bentonite for one-component solutions; and Alginate-washed yeast &gt Alginate-BSA &gt Alginate-bentonite &gt Alginate-unwashed yeast for two-component solutions. Introducing the alginate increased the reversible fouling (except BSA). Passive adsorption had a significant effect on fouling of alginate even before the beginning of the filtration. Washed yeast and a mixture of washed yeast + BSA were then used as model solutions to simulate the activated sludge found in MBR. The concentration of washed yeast and BSA used in this study were calculated in order for the characterisations of the two model solution to match (in terms of biopolymer contents) those of MBR biomasses reported in the literature. By rinsing, backwashing and chemical cleaning of the membrane, three fouling layers of upper, intermediate and lower were defined respectively. Results obtained from the analysis of the biopolymers found in the cleaning solutions allow a better understanding of the fouling mechanisms occurring for the two model solutions used in this study: for washed yeast, the lower layer and for washed yeast + BSA , the upper and intermediate layers were found to have relatively high biopolymeric composition. This was explained by higher concentration of solids on the membrane surface and by higher biopolymer interactions when washed yeast was mixed with BSA.

Ceramic membrane processes are a rapidly emerging technology for water treatment, yet virtually no information on the performance and fouling mechanisms is available to the industry. Ceramic microfiltration of model feed solutions and a synthetic river water was examined, and a systematic comparison with polymeric counterpart was performed. The results suggested that the models which have been applied to polymeric membranes agreed well with the ceramic membrane filtration data. The fouling was characterized by the initial pore blocking mechanism and transition to the cake filtration mechanism at a later phase. Cake resistance was dominant and readily removable by physical cleaning. The effects of solution chemistry including ionic strength, divalent ion concentration and pH on the flux behavior were comparatively evaluated for ceramic and polymeric ultrafiltration of synthetic water containing model natural organic matter. Experimental evaluations further included resistance-in-series model analysis, organic matter fouling visualization using quantum dots, batch adsorption test, and contact angle measurement, and provided a quantitative a quantitative comparison of fouling characteristics between ceramic and polymeric membranes. The results collectively suggested that the effects of solution chemistry on the fouling behavior with ceramic membranes were mostly similar with polymeric membranes in terms of trends, while the extents varied depending on water quality parameters. Less fouling tendency and better cleaning efficiency were observed with the ceramic membranes, which was a promising finding for ceramic membrane application to surface water treatment. The study further examined a coagulation-ceramic membrane process as a robust option for surface water treatment. The performance of the hybrid system was evaluated using selected surface waters by varying coagulation conditions and types of coagulants. Results suggested that ceramic membranes experienced relatively less fouling and had better cleaning efficiency than polymeric counterpart. The results of this study provide critical information to guide the industry practitioners, consultants, and regulatory agents considering early adoption of this new technology as well as fundamental knowledge upon which further in-depth studies can be built.

Particles and macromolecular components, including biopolymers (protein and carbohydrate), are viewed as the main foulants in the complex feed submerged membrane filtration systems such as membrane bioreactor (MBR). This work focused on two aspects of fouling in complex fluids: 1- Assessing fouling propensity and mechanisms for various model solutions. 2- Using of two specific solutions modelling biomass found in MBR for a better understanding of the fouling mechanisms in submerged MBR processes. Filtrations were carried out with 0.22 ??m PVDF hollow fibre membrane. Alginate was used as a model for polysaccharide, bovine serum albumin (BSA) as a model for protein, (un)washed yeast and bentonite were representing suspended solid contents. According to the data obtained during this study the fouling propensity of each model solution was classified as follow in a decreasing order: Alginate &gt unwashed yeast &gt washed yeast &gt BSA &gt bentonite for one-component solutions; and Alginate-washed yeast &gt Alginate-BSA &gt Alginate-bentonite &gt Alginate-unwashed yeast for two-component solutions. Introducing the alginate increased the reversible fouling (except BSA). Passive adsorption had a significant effect on fouling of alginate even before the beginning of the filtration. Washed yeast and a mixture of washed yeast + BSA were then used as model solutions to simulate the activated sludge found in MBR. The concentration of washed yeast and BSA used in this study were calculated in order for the characterisations of the two model solution to match (in terms of biopolymer contents) those of MBR biomasses reported in the literature. By rinsing, backwashing and chemical cleaning of the membrane, three fouling layers of upper, intermediate and lower were defined respectively. Results obtained from the analysis of the biopolymers found in the cleaning solutions allow a better understanding of the fouling mechanisms occurring for the two model solutions used in this study: for washed yeast, the lower layer and for washed yeast + BSA , the upper and intermediate layers were found to have relatively high biopolymeric composition. This was explained by higher concentration of solids on the membrane surface and by higher biopolymer interactions when washed yeast was mixed with BSA.

Capes / A eutrofização atinge diversos reservatórios de abastecimento de água, causando problemas principalmente da ordem operacional e comprometimento da qualidade da água para a população. Algumas tecnologias de tratamento de água passam por um processo de aperfeiçoamento e outras surgem para melhorar a eficiência do tratamento. Este trabalho teve por objetivo avaliar a remoção de cianobactérias e cianotoxinas por meio de coagulação com Moringa oleifera, seguida de microfiltração e nanofiltração. Sendo assim a primeira etapa do trabalho foi o cultivo em laboratório da cianobactéria Microcystis aeruginosa e a determinação de curvas de crescimento deste microrganismo. Na seqüência foram realizados ensaios para verificar a as melhores condições de coagulação/floculação/sedimentação com a solução coagulante de M. oleifera (1%), como respostas foram utilizadas a remoção de células da M. aeruginosa e a redução da turbidez. Foram avaliadas as seguintes variáveis: tempo de coagulação; velocidade rápida, tempo de floculação, velocidade lenta, tempo de sedimentação, turbidez inicial, quantidade de solução coagulante. Em seguida o processo de coagulação/floculação/sedimentação foi associado à microfiltração, nesta etapa foi realizada com água do cultivo e água da Represa do Passaúna –PR contaminada com o cultivo da M. aeruginosa. Por fim, devido à M. aeruginosa cultivada ser tóxica e produtora de microcistina avaliou-se a coagulação/floculação/sedimentação associada à nanofiltração. Os resultados indicam que as melhores condições de coagulação e floculação foram com 2 minutos de coagulação a 80 rpm, e 18 minutos para floculação a 13 rpm tendo uma remoção de células de 95,6 % e uma redução da turbidez de 97,5%. Verificou-se que 60 minutos de sedimentação já foi suficiente para remoções acima de 90% da cianobactéria, e 95% de redução da turbidez. Com relação à quantidade de solução coagulante observou-se um aumento na eficiência dos processos com o aumento da quantidade da solução coagulante, porém em 70 mg essa remoção já não tem grandes variações. A associação da coagulação/floculação/sedimentação com a microfiltração foi positiva, pois após 60 minutos a turbidez chegou a 0 uT e a ausência de células de M. aeruginosa. A retenção da microcistina com a nanofiltração apresentou uma retenção de 87,3% no início, porém com o decorrer do tempo este valor apresentou uma queda para 58,0%. Em resumo, pode-se considerar a associação da o uso da M. oleifera como coagulante com a microfiltração como uma boa alternativa para redução de turbidez e remoção de cianobactérias, assim como o uso da nanofiltração para remoção de microcistina. / The eutrophication affects many reservoirs of water, causing problems, specially the commitment of operational and water quality for the population. Some water treatment technologies go through a process of improvement and others appear to improve treatment efficiency. This work aimed to evaluate the removal of cyanobacterial and cyanotoxins through coagulation with Moringa oleifera, followed by microfiltration and nanofiltration. Thus the first stage of work was growing in the laboratory of the cyanobacterial Microcystis aeruginosa and determination of growth curves of this microorganism. Following tests were conducted to verify the optimal conditions for coagulation/flocculation/sedimentation with coagulant solution of M. oleifera (1%) were used in response to removal of cells from M. aeruginosa and reduced turbidity. The following variables were evaluated: coagulation time, fast speed, time of flocculation, slow speed, time of sedimentation, turbidity initial amount of the coagulant solution. Then the process of coagulation/flocculation/ sedimentation was associated with microfiltration this step was carried out with water end crop water of Passaúna –PR contaminated with the cultivation of M. aeruginosa. Finally, due to M. aeruginosa grown to be toxic microcystin producing and evaluate produce the coagulation/flocculation/sedimentation associated with nanofiltration. The results indicate that optimum conditions for coagulation and flocculation were clotting with 2 minutes at 80 rpm, and 18 minutes for flocculation at 13 rpm with a removal of cells and a 95,6% reduction in turbidity of 97,5%. It was found that 60 minutes was enough sediment removal for over 90% of the cyanobacterial, and 95% reduction in turbidity. With respect to the amount of coagulant solution was observed an increase in process efficiency by increasing the amount of coagulant solution, but at 70 mg such removal no longer has large variations. The association of coagulation /flocculation/sedimentation with microfiltration was positive, because after 60 minutes reached the turbidity 0 uT and the absence of cells of M. aeruginosa. The retention of microcystin with nanofiltration showed a retention of 87,3% at the beginning, but with the passage of time this value showed a decrease to 58,0%. In summary, one can consider adding the use of M. oleifera as a coagulant with microfiltration as a good alternative to reduce turbidity and removal of cyanobacterial, as well as the use of nanofiltration removal of microcystin.

Capes / A eutrofização atinge diversos reservatórios de abastecimento de água, causando problemas principalmente da ordem operacional e comprometimento da qualidade da água para a população. Algumas tecnologias de tratamento de água passam por um processo de aperfeiçoamento e outras surgem para melhorar a eficiência do tratamento. Este trabalho teve por objetivo avaliar a remoção de cianobactérias e cianotoxinas por meio de coagulação com Moringa oleifera, seguida de microfiltração e nanofiltração. Sendo assim a primeira etapa do trabalho foi o cultivo em laboratório da cianobactéria Microcystis aeruginosa e a determinação de curvas de crescimento deste microrganismo. Na seqüência foram realizados ensaios para verificar a as melhores condições de coagulação/floculação/sedimentação com a solução coagulante de M. oleifera (1%), como respostas foram utilizadas a remoção de células da M. aeruginosa e a redução da turbidez. Foram avaliadas as seguintes variáveis: tempo de coagulação; velocidade rápida, tempo de floculação, velocidade lenta, tempo de sedimentação, turbidez inicial, quantidade de solução coagulante. Em seguida o processo de coagulação/floculação/sedimentação foi associado à microfiltração, nesta etapa foi realizada com água do cultivo e água da Represa do Passaúna –PR contaminada com o cultivo da M. aeruginosa. Por fim, devido à M. aeruginosa cultivada ser tóxica e produtora de microcistina avaliou-se a coagulação/floculação/sedimentação associada à nanofiltração. Os resultados indicam que as melhores condições de coagulação e floculação foram com 2 minutos de coagulação a 80 rpm, e 18 minutos para floculação a 13 rpm tendo uma remoção de células de 95,6 % e uma redução da turbidez de 97,5%. Verificou-se que 60 minutos de sedimentação já foi suficiente para remoções acima de 90% da cianobactéria, e 95% de redução da turbidez. Com relação à quantidade de solução coagulante observou-se um aumento na eficiência dos processos com o aumento da quantidade da solução coagulante, porém em 70 mg essa remoção já não tem grandes variações. A associação da coagulação/floculação/sedimentação com a microfiltração foi positiva, pois após 60 minutos a turbidez chegou a 0 uT e a ausência de células de M. aeruginosa. A retenção da microcistina com a nanofiltração apresentou uma retenção de 87,3% no início, porém com o decorrer do tempo este valor apresentou uma queda para 58,0%. Em resumo, pode-se considerar a associação da o uso da M. oleifera como coagulante com a microfiltração como uma boa alternativa para redução de turbidez e remoção de cianobactérias, assim como o uso da nanofiltração para remoção de microcistina. / The eutrophication affects many reservoirs of water, causing problems, specially the commitment of operational and water quality for the population. Some water treatment technologies go through a process of improvement and others appear to improve treatment efficiency. This work aimed to evaluate the removal of cyanobacterial and cyanotoxins through coagulation with Moringa oleifera, followed by microfiltration and nanofiltration. Thus the first stage of work was growing in the laboratory of the cyanobacterial Microcystis aeruginosa and determination of growth curves of this microorganism. Following tests were conducted to verify the optimal conditions for coagulation/flocculation/sedimentation with coagulant solution of M. oleifera (1%) were used in response to removal of cells from M. aeruginosa and reduced turbidity. The following variables were evaluated: coagulation time, fast speed, time of flocculation, slow speed, time of sedimentation, turbidity initial amount of the coagulant solution. Then the process of coagulation/flocculation/ sedimentation was associated with microfiltration this step was carried out with water end crop water of Passaúna –PR contaminated with the cultivation of M. aeruginosa. Finally, due to M. aeruginosa grown to be toxic microcystin producing and evaluate produce the coagulation/flocculation/sedimentation associated with nanofiltration. The results indicate that optimum conditions for coagulation and flocculation were clotting with 2 minutes at 80 rpm, and 18 minutes for flocculation at 13 rpm with a removal of cells and a 95,6% reduction in turbidity of 97,5%. It was found that 60 minutes was enough sediment removal for over 90% of the cyanobacterial, and 95% reduction in turbidity. With respect to the amount of coagulant solution was observed an increase in process efficiency by increasing the amount of coagulant solution, but at 70 mg such removal no longer has large variations. The association of coagulation /flocculation/sedimentation with microfiltration was positive, because after 60 minutes reached the turbidity 0 uT and the absence of cells of M. aeruginosa. The retention of microcystin with nanofiltration showed a retention of 87,3% at the beginning, but with the passage of time this value showed a decrease to 58,0%. In summary, one can consider adding the use of M. oleifera as a coagulant with microfiltration as a good alternative to reduce turbidity and removal of cyanobacterial, as well as the use of nanofiltration removal of microcystin.