Leveduras oleaginosas possuem a capacidade de sintetizar grande quantidade de lipídeos em suas células, gerando produtos de alto valor agregado através de um processo sustentável. Um perfil de ácidos graxos poli-insaturados é de grande interesse por parte das industrias alimentícia e farmacêutica e têm sido alvo de diversos estudos em relação à sua produção e efeitos benéficos à saúde. O presente trabalho teve como objetivo produzir ácidos graxos poli-insaturados pela levedura Meyerozyma guilliermondii BI281 utilizando glicose, glicerol residual e permeado de soro de queijo como fontes de carbono. Avaliou-se o metabolismo da levedura em meios de cultivo com diferentes composições (“meio A” e “base YM”) e comparou-se o seu desempenho em razões C/N 100: 1 e 50:1. A levedura foi capaz de metabolizar todos os substratos testados e o meio de cultivo “A” com glicerol residual e razão C/N 50:1 mostrou-se o mais adequado, obtendo valores de 5,67 g.L-1 de biomassa e 1,04 g.L-1 de lipídeos, representando aproximadamente 18 % do peso da massa seca de biomassa. Esta condição foi escalonada para biorreator de 2 L, onde condições de aeração e controle de pH puderam ser avaliadas, apresentando quantidade semelhante de lipídeos (1,08 g.L-1) e uma maior produção de biomassa (7,05 g.L-1). Os ácidos graxos sintetizados apresentaram em sua composição ácido láurico (C12:0), ácido mistírico (C14:0), ácido palmítico (C16:0), ácido pamitoleico (C16:1), ácido esteárico (C18:0), ácido oleico (C18:1 n-9), ácido linoleico (C18:2 n-6) e ácido linolênico (C18:3 n-3). / Oleaginous yeasts are able to synthesize high amounts of lipids in their cells, producing high added-value products through a sustainable process. Food and pharmaceutical companies have great interest in polyunsaturated fatty acids depending on their profiles and many studies related to their production and health benefits have been carried out. The aim of this study was to produce polyunsaturated fatty acids by the yeast Meyerozyma guilliermondii BI281A using glucose, crude glycerol, and cheese whey permeate as carbon sources. Yeast metabolism was evaluated in different compositions of culture media (“A” and “YM”) and at different C/N ratios (100:1 and 50:1). The yeast was able to assimilate all substrates tested, and medium “A” with crude glycerol as carbon source at a C/N ratio of 50:1 had the most efficient result with biomass production of 5.67 g.L-1 and lipid production of 1.08 g.L-1, which represented 18 % of dry cell weight. This composition was scaled-up to a 2 L bioreactor, where it was possible to measure pH and aeration conditions, and showed similar lipid production (1.08 g.L-1) and higher biomass production (7.05 g.L-1). Fatty acids profile obtained was composed by lauric acid (C12:0), myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16:1), stearic acid (C18:0), oleic acid(C18:1), linoleic acid (C18:2 n-6), and linolenic acid (C18:3 n-3).

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2017-09-18T17:36:34Z No. of bitstreams: 1 Jordana_D_dos_Santos_2016.pdf: 2287544 bytes, checksum: 3fbe2e0a3e10d36d5d3531c1abc806aa (MD5) / Made available in DSpace on 2017-09-18T17:36:34Z (GMT). No. of bitstreams: 1 Jordana_D_dos_Santos_2016.pdf: 2287544 bytes, checksum: 3fbe2e0a3e10d36d5d3531c1abc806aa (MD5) Previous issue date: 2016-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This research aimed to study the treatment of manipueira by combined process of coagulation/flocculation and membrane separation, targeting the non-potable reuse this water. For pretreatment of the effluent triage was performed using five natural coagulants (Acquapol WW, and S5T Tanfloc POP, ST, SG), a chemical (Al2SO4) and a cationic flocculant (Zetag ® 8185).Experimental designs Plackett & Burman (PB12) followed by a full factorial 2k was used in order to obtain the best experimental conditions in the process. The supernatant obtained in step of coagulation/flocculation under went a process of separation of micro-and ultrafiltration membranes varying pressures (0,6, 1 and 1,4 bar), permeate flows being analyzed, fouling and removal efficiency.The raw sewage and water resulting from treatment in the best conditions of coagulation/flocculation and filtration, under went a toxicity test using brine shrimp body. From the selected sorting the sedimentation time 15 minutes and Tanfloc POP among the natural coagulants.The best condition of operation of the coagulation/flocculation obtained through experimental planning was 1 min to 10 min, TMR TML, 180 rpm for VMR and 10 rpm of VML, pH of 8.5 and coagulant concentration of 440 mg L-1, with removals of 88,5% to turbidity and 78,9% color. The model adjusted to the data in the color parameter removal complete factorial planning using coagulant Tanfloc POP. The tests of filtration (MF and UF) presented on pressure of 1,4 bar, above 95% removal of colour and turbidity, and above 60% for nitrogen and COT, but with lower COD removal (less than 70%). The toxicityof that treated wastewater (66% and 100%) reported toxic to the test organism due to the presence of free cyanide. The permeated obtained (MF) could be used for less noble purposes among the classes (2, 3 and 4) suggested by the ABNT NBR 13,696/1997. The results obtained in this study demonstrate the potential of C/F, MF and UF, for treatment of manipueira. / Esta pesquisa teve como objetivo estudar o tratamento da manipueira por processo combinado de coagulação/floculação e separação por membranas, visando o reuso não potável desta água. Para o pré-tratamento do efluente foi realizada uma triagem utilizando cinco coagulantes naturais (Acquapol WW, S5T e Tanfloc POP, ST, SG), um químico (Al2SO4) e um floculante catiônico (Zetag 8185®). Planejamentos experimentais Plackett & Burman (PB12) seguido de um fatorial completo 2k foram utilizados a fim de obter as melhores condições experimentais no processo. O sobrenadante obtido na etapa de coagulação/floculação foi submetido a um processo de separação por membranas de micro e ultrafiltração variando-se as pressões (0,6, 1 e 1,4 bar), sendo analisados os fluxos de permeado, fouling e eficiência de remoção. O efluente bruto e a água resultante do tratamento nas melhores condições dos ensaios de coagulação/floculação e filtração, foram submetidos a um ensaio de toxicidade utilizando o organismo Artemia salina. A partir da triagem selecionou-se o tempo de sedimentação de 15 minutos e o Tanfloc POP dentre os coagulantes naturais. A melhor condição de operação da coagulação/floculação obtida através dos planejamentos experimentais foi de 1 min para TMR, 10 min de TML, 180 rpm para VMR e 10 rpm de VML, pH de 8,5 e concentração do coagulante de 440 mg L-1, com remoções de 88,5% para cor e 78,9% de turbidez. O modelo ajustou-se aos dados de remoção do parâmetro cor no planejamento fatorial completo utilizando o coagulante Tanfloc POP. Os ensaios de filtração (MF e UF) apresentaram na pressão de 1,4 bar, remoções acima de 95% de cor e turbidez, e acima de 60% para nitrogênio e TOC, porém com baixa remoção de DQO (menor que 70%). A toxicidade, do efluente mesmo tratado (66% e 100%) apresentou-se tóxico para o organismo teste devido à presença de cianeto livre. O permeado obtido (MF) poderia ser utilizado para fins menos nobres dentre as classes (2, 3 e 4) sugeridas pela ABNT NBR 13.969/1997. Os resultados obtidos neste estudo demonstram o potencial dos processos de C/F, MF e UF, para tratamento da manipueira.

La prédiction des performances des séparations membranaires barométriques, fortement affectées par la polarisation de concentration, serait une avancée importante pour le dimensionnement et l’optimisation des procédés. Dans ce contexte, les équations couplées de Navier-Stokes et de conservation du soluté adimensionnées sont résolues numériquement dans le cas d’un écoulement stationnaire laminaire en filtration tangentielle. Le canal plan bidimensionnel comporte des parois perméables soumises à des conditions aux limites du type solubilisation-diffusion. Le flux de perméat, le taux de rétention et le débit, la concentration et la chute de pression du rétentat sont déterminés localement. Les simulations soulignent l’influence des perméabilités membranaires au soluté et au solvant sur la polarisation de concentration et la dépendance non-asymptotique du taux de rétention avec la pression appliquée. Le modèle est validé pour des modules plans et spiralés d’osmose inverse et de nanofiltration dense en comparant les calculs à des résultats expérimentaux tirés de la littérature et de nos propres essais pilotes de dessalement. Aussi, une méthode à l’échelle de la paillasse permettant de déterminer les perméabilités au soluté et au solvant par des expériences d’osmose et diffusion est développée et appliquée à des membranes d’osmose inverse et de nanofiltration. La divergence des mécanismes de transfert engendrés sous l’influence de la pression ou sous l’influence d’un gradient osmotique est mise en évidence. Le modèle numérique et la méthode expérimentale sont des outils prometteurs d’applicabilité immédiate dans le domaine des membranes. / The prediction of the performance of pressure-driven membrane separations, deeply affected by concentration polarization, would be an important advance for process design and optimization. In this context, the dimensionless coupled Navier-Stokes and solute conservation equations are solved numerically for a steady laminar cross-flow filtration. The two-dimensional flat channel consists of permeable walls subject to solution-diffusion boundary conditions. The permeate flux, the rejection rate and the retentate’s flow rate, concentration and pressure drop are determined locally. The simulations highlight the influence of the membrane solute and solvent permeabilities on concentration polarization and the non-asymptotic dependence of the rejection rate on the applied pressure. The model is validated for reverse osmosis and tight-nanofiltration plate-and-frame and spiral-wound modules by comparison to experimental results from the literature and from our own pilot desalination tests. Furthermore, a bench-scale method enabling the determination of solute and solvent permeabilities from osmotic-diffusive experiments is developed and applied to reverse osmosis and nanofiltration membranes. The divergence between the transport mechanisms engendered by pressure and by an osmotic gradient is evidenced. The numerical model and the experimental method are new promising tools with immediate applicability in the membrane field.

Leveduras oleaginosas possuem a capacidade de sintetizar grande quantidade de lipídeos em suas células, gerando produtos de alto valor agregado através de um processo sustentável. Um perfil de ácidos graxos poli-insaturados é de grande interesse por parte das industrias alimentícia e farmacêutica e têm sido alvo de diversos estudos em relação à sua produção e efeitos benéficos à saúde. O presente trabalho teve como objetivo produzir ácidos graxos poli-insaturados pela levedura Meyerozyma guilliermondii BI281 utilizando glicose, glicerol residual e permeado de soro de queijo como fontes de carbono. Avaliou-se o metabolismo da levedura em meios de cultivo com diferentes composições (“meio A” e “base YM”) e comparou-se o seu desempenho em razões C/N 100: 1 e 50:1. A levedura foi capaz de metabolizar todos os substratos testados e o meio de cultivo “A” com glicerol residual e razão C/N 50:1 mostrou-se o mais adequado, obtendo valores de 5,67 g.L-1 de biomassa e 1,04 g.L-1 de lipídeos, representando aproximadamente 18 % do peso da massa seca de biomassa. Esta condição foi escalonada para biorreator de 2 L, onde condições de aeração e controle de pH puderam ser avaliadas, apresentando quantidade semelhante de lipídeos (1,08 g.L-1) e uma maior produção de biomassa (7,05 g.L-1). Os ácidos graxos sintetizados apresentaram em sua composição ácido láurico (C12:0), ácido mistírico (C14:0), ácido palmítico (C16:0), ácido pamitoleico (C16:1), ácido esteárico (C18:0), ácido oleico (C18:1 n-9), ácido linoleico (C18:2 n-6) e ácido linolênico (C18:3 n-3). / Oleaginous yeasts are able to synthesize high amounts of lipids in their cells, producing high added-value products through a sustainable process. Food and pharmaceutical companies have great interest in polyunsaturated fatty acids depending on their profiles and many studies related to their production and health benefits have been carried out. The aim of this study was to produce polyunsaturated fatty acids by the yeast Meyerozyma guilliermondii BI281A using glucose, crude glycerol, and cheese whey permeate as carbon sources. Yeast metabolism was evaluated in different compositions of culture media (“A” and “YM”) and at different C/N ratios (100:1 and 50:1). The yeast was able to assimilate all substrates tested, and medium “A” with crude glycerol as carbon source at a C/N ratio of 50:1 had the most efficient result with biomass production of 5.67 g.L-1 and lipid production of 1.08 g.L-1, which represented 18 % of dry cell weight. This composition was scaled-up to a 2 L bioreactor, where it was possible to measure pH and aeration conditions, and showed similar lipid production (1.08 g.L-1) and higher biomass production (7.05 g.L-1). Fatty acids profile obtained was composed by lauric acid (C12:0), myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16:1), stearic acid (C18:0), oleic acid(C18:1), linoleic acid (C18:2 n-6), and linolenic acid (C18:3 n-3).

No description available.

No description available.

No / Multi Effect Distillation (MED) and Reverse Osmosis (RO) processes have been extensively used to produce freshwater from seawater resources. amongst many performance indicators, energy consumption of different configuration of hybrid system of MED and RO processes have been analysed in the past. Hybrid MED-RO system is energy intensive and use of fossil fuel can significantly increase the carbon footprint, unless stable renewable energy sources are used. In this work specific energy consumption of a simple hybrid MED-RO system with permeate reprocessing is minimised while optimising a number of operating decision variables using model based optimisation technique. A detailed process model developed earlier by the authors is embedded in the optimisation framework resulting in a constrained Non-linear Programming (NLP) problem. The minimum specific energy consumption achieved in this work is about 18% lower than what is reported in the literature resulting in a significant energy saving and thus carbon footprint.

Yes / The removal of pollutants such as N-nitrosamine present in drinking and reuse water resources is of significant interest for health and safety professionals. Reverse osmosis (RO) is one of the most promising and efficient methodologies for removing such harmful organic compounds from wastewater. Having said this, the literature confirms that the multi-stage RO process with retentate reprocessing design has not yet achieved an effective removal of N-nitrosodimethylamine-D6 (NDMA) from wastewater. This research emphasizes on this particular challenge and aims to explore several conceptual designs of multi-stage RO processes for NDMA rejection considering model-based techniques and compute the total recovery rate and energy consumption for different configurations of retentate reprocessing techniques. In this research, the permeate reprocessing design methodology is proposed to increase the process efficiency. An extensive simulation analysis is carried out using high NDMA concentration to evaluate the performance of each configuration under similar operational conditions, thus providing a deep insight on the performance of the multi-stage RO permeate reprocessing predictive design. Furthermore, an optimisation analysis is carried out on the final design to optimise the process with a high NDMA rejection performance and the practical recovery rate by manipulating the operating conditions of the plant within specified constraints bounds. The results show a superior removal of NDMA from wastewater.

Yes / Reverse Osmosis (RO) is one of the most widely used technologies for wastewater treatment for the removal of toxic impurities, such as phenol and phenolic compounds from industrial effluents. In this research, performance of multi-stage RO wastewater treatment system is evaluated for the removal of chlorophenol from wastewater using model-based techniques. A number of alternative configurations with recycling of permeate, retentate, and permeate-retentate streams are considered. The performance is measured in terms of total recovery rate, permeate product concentration, overall chlorophenol rejection and energy consumption and the effect of a number of operating parameters on the overall performance of the alternative configurations are evaluated. The results clearly show that the permeate recycling scheme at fixed plant feed flow rate can remarkably improve the final chlorophenol concentration of the product despite a reduction in the total recovery rate.

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.