Efficiently combining water reuse and desalination through Forward Osmosis-Reverse Osmosis (FO-RO) hybrids: a critical review

Forward osmosis (FO) is a promising membrane technology to combine seawater desalination and water reuse. More specifically, in a FO-reverse osmosis (RO) hybrid process, high quality water recovered from the wastewater stream is used to dilute seawater before RO treatment. As such, lower desalination energy needs and/or water augmentation can be obtained while delivering safe water for direct potable reuse thanks to the double dense membrane barrier protection. Typically, FO-RO hybrid can be a credible alternative to new desalination facilities or to implementation of stand-alone water reuse schemes. However, apart from the societal (public perception of water reuse for potable application) and water management challenges (proximity of wastewater and desalination plants), FO-RO hybrid has to overcome technical limitation such as low FO permeation flux to become economically attractive. Recent developments (i.e., improved FO membranes, use of pressure assisted osmosis, PAO) demonstrated significant improvement in water flux. However, flux improvement is associated with drawbacks, such as increased fouling behaviour, lower rejection of trace organic compounds (TrOCs) in PAO operation, and limitation in FO membrane mechanical resistance, which need to be better considered. To support successful implementation of FO-RO hybrid in the industry, further work is required regarding up-scaling to apprehend full-scale challenges in term of mass transfer limitation, pressure drop, fouling and cleaning strategies on a module scale. In addition, refined economics assessment is expected to integrate fouling and other maintenance costs/savings of the FO/PAO-RO hybrid systems, as well as cost savings from any treatment step avoided in the water recycling

Consommation d'eau de la vigne en conditions hydriques non limitantes. Formulation simplifiée de la transpiration

La modélisation géometrique de la vigne, utilisée pour l'interception du rayonnement solaire (RIOU et al. 1989) est d'abord reprise pour évaluer les bilans radiatifs de la vigne et du sol intercalaire. La vérification expérimentale est satisfaisante. Après une période pluvieuse, les différents flux du bilan d'energie du vignoble sont ensuite mesurés, notamment grâce à la méthode des corrélations tourbillonnaires tandis que la transpiration de la vigne seule est obtenue par une mesure de flux de sève (VALANCOGNE et NASR 1993).Trois grandeurs concernant la vigne elle-même restent proches: le taux de transpiration par rapport à l'évaporation totale , le taux d' absorption du rayonnement net par rapport au bilan radiatif total et le taux d'absorption du rayonnement solaire par rapport au rayonnement global absorbé par le vignoble; une simulation montre que ces deux derniers taux restent voisins quand la distance entre rangs varie. L'évapotranspiration maximum étant finalement exprimée correctement par la formule de PENMAN (1948), ces résultats conduisent à proposer une formulation simple de la transpiration de la vigne en conditions hydriques non limitantes.Water use of grapevines well supplied with water. Simplified expression of transpirationA model of solar radiation interception by a vineyard canopy from simple geometrical assumptions (Riou et al. 1989) is first extended into a model of the whole radiative balance of the vine rows and of the intervening soil surface; experimental validation is excellent. After a rainy period, the various fluxes taking part in the energy balance of a vineyard canopy were measured, among which total evaportranspiration by an eddy correlation technique, and vine transpiration from a sap-flow estimation (Valancogne et Nasr 1993). Three partition rates quantifying the exchanges of the vines alone remain noticeably close to each other: those of transpiration over total evaportranspiration, of absorbed net radiation over overall radiative balance, and of intercepted global radiation over global radiation intercepted by the whole canopy. From a simulation, evidence is provided these two latter rates are still hardly distinguishable when the row spacing is changed. As maximum evapotranspiration is quite correctly expressed by the Penman formula, these results lead to the proposal of a simple method for estimating transpiration of grapevines well supplied with water

Practical considerations for operability of an 8″ spiral wound forward osmosis module: Hydrodynamics, fouling behaviour and cleaning strategy

© 2016 Elsevier B.V. A better understanding of large spiral wound forward osmosis (SW FO) module operation is needed to provide practical insight for a full-scale FO practical implementation desalination plant. Therefore, this study investigated two different 8″ SW FO modules (i.e. cellulose tri acetate, CTA and thin film composite, TFC) in terms of hydrodynamics, operating pressure, water and solute fluxes, fouling behaviour and cleaning strategy. For both modules, a significantly lower flow rate was required in the draw channel than in the feed channel due to important pressure-drop in the draw channel and was a particularly critical operating challenge in the CTA module when permeate spacers are used. Under FO and pressure assisted osmosis (PAO, up to 2.5 bar) operations, the TFC module featured higher water flux and lower reverse salt flux than the CTA module. For both modules, fouling tests demonstrated that feed inlet pressure was more sensitive to foulant deposition than the flux, thus confirming that FO fouling deposition occurs in the feed channel rather than on the membrane surface. Osmotic backwash combined with physical cleaning used in this study confirmed to be effective and adapted to large-scale FO module operation

Membrane autopsy of a 10year old hollow fibre membrane from Sydney Olympic Park water reclamation plant

Membrane autopsy was performed for a 10. year old polypropylene (PP) hollow fibre microfiltration membrane from Sydney Olympic Park water reclamation plant. The properties of the membrane were studied using scanning electron microscope (SEM) imaging, contact angle, bubble test, thermogravimetric analysis, tensile strength test and functional group. The old and fouled membrane exhibited a significant difference in surface properties and material strength in comparison to the virgin membrane. The old and fouled membrane surface is less hydrophilic and less negatively charged indicating that aged membrane is more vulnerable to fouling than virgin membrane. The fibre material of the old fouled membrane appears less flexible and brittle. Foulant analysis indicated that major components of the metallic elements were silicon and calcium. The dissolved organic matter was mainly composed of biopolymers (hydrophilic) and humic substances (hydrophobic). © 2011 Elsevier B.V

Looking beyond forest cover: an analysis of landscape-scale predictors of forest degradation in the Brazilian Amazon.

While forest degradation rates and extent exceed deforestation in the Brazilian Amazon, less attention is given to the factors controlling its spatial distribution. No quantified correlation exists between changes of forest structure due to anthropogenic disturbances and dynamics of land use and cover change occurring at broader spatial levels. This study examines the influence of multi-scale landscape structure factors (i.e. spatial composition, configuration and dynamic of land use/cover) on primary forest's aboveground biomass (AGB), spanning from low to highly degraded, in Paragominas municipality (Pará state). We used random forest models to identify the most important landscape predictors of degradation and clustering methods to analyze their distribution and interactions. We found that 58% of the variance of AGB could be explained by metrics reflecting land use practices and agricultural dynamics around primary forest patches and that their spatial patterns were not randomly distributed. Forest degradation is mainly driven by fragmentation effects resulting from old deforestation and colonization events linked with cropland expansion (e.g. soybean and maize) coupled with high accessibility to market. To a lesser extent, degradation is driven by recent and ongoing (1985?2015) deforestation and fragmentation in slash-and-burn agricultural areas, characterized by heterogeneous mosaics of pastures and fallow lands combined with high use of fire. Our findings highlight the potential of landscape-level framework and remotely sensed land cover data for a thorough understanding of the distribution of forest degradation across human-modified landscapes. Addressing these spatial determinants by looking at agricultural dynamics beyond forest cover is necessary to improve forest management which has major implications for biodiversity, carbon and other ecosystem services

Role of CAP350 in Centriolar Tubule Stability and Centriole Assembly

BACKGROUND: Centrioles are microtubule-based cylindrical structures composed of nine triplet tubules and are required for the formation of the centrosome, flagella and cilia. Despite theirs importance, centriole biogenesis is poorly understood. Centrosome duplication is initiated at the G1/S transition by the sequential recruitment of a set of conserved proteins under the control of the kinase Plk4. Subsequently, the procentriole is assembled by the polymerization of centriolar tubules via an unknown mechanism involving several tubulin paralogs. METHODOLOGY/PRINCIPAL FINDINGS: Here, we developed a cellular assay to study centrosome duplication and procentriole stability based on its sensitivity to the microtubule-depolymerizing drug nocodazole. By using RNA interference experiments, we show that the stability of growing procentrioles is regulated by the microtubule-stabilizing protein CAP350, independently of hSAS-6 and CPAP which initiate procentriole growth. Furthermore, our analysis reveals the critical role of centriolar tubule stability for an efficient procentriole growth. CONCLUSIONS/SIGNIFICANCE: CAP350 belongs to a new class of proteins which associate and stabilize centriolar tubules to control centriole duplication

A Large Gene Network in Immature Erythroid Cells Is Controlled by the Myeloid and B Cell Transcriptional Regulator PU.1

PU.1 is a hematopoietic transcription factor that is required for the development of myeloid and B cells. PU.1 is also expressed in erythroid progenitors, where it blocks erythroid differentiation by binding to and inhibiting the main erythroid promoting factor, GATA-1. However, other mechanisms by which PU.1 affects the fate of erythroid progenitors have not been thoroughly explored. Here, we used ChIP-Seq analysis for PU.1 and gene expression profiling in erythroid cells to show that PU.1 regulates an extensive network of genes that constitute major pathways for controlling growth and survival of immature erythroid cells. By analyzing fetal liver erythroid progenitors from mice with low PU.1 expression, we also show that the earliest erythroid committed cells are dramatically reduced in vivo. Furthermore, we find that PU.1 also regulates many of the same genes and pathways in other blood cells, leading us to propose that PU.1 is a multifaceted factor with overlapping, as well as distinct, functions in several hematopoietic lineages

Process configurations and fouling in membrane bio-reactors

MBR process consists of a suspended growth biological reactor combined with a membrane unit. The widespread of this system for waste water treatment is contained by membrane fouling, which is strongly influenced by three factors: biomass characteristics, operating conditions and membrane characteristics. Fouling control techniques mainly include low-flux operation (sub-critical flux operation) and/or high-shear slug flow aeration in submerged. configuration. Based on the concept of the critical flux (Jo), the flux-step method has been developed to more fully characterise transmembrane pressure (TMP) behaviour during constant-fluxoperation. A zero rate of TMP increase was never attained during the trial, such that no critical flux, in its strictest definition, could be defined in this study for a submerged MBRs challenged with real and simulant sewage. Under similar operating conditions, Jc was obtained around 18 and 10 L.m-2.h-1 for a submerged MBR fed by real and synthetic sewage respectively. Three TMP-based parameters have been defined, all indicating the same flux value at which fouling starts to be more significant (the weak form of Jo). Results from factorial experimental designs revealed the relative effect of MLSS levels, aeration rate and membrane pore size on J, The MLSS effect on Jc was generally around double that of the aeration effect. The calculation of mean sub-critical values for the different TMP-based parameters suggest lower short-term fouling resistance for large pore sized membranes. A direct comparison between the two MBR configurations revealed a greater J, for the submerged compared to the SS MBR (22 and 11 L.m-2.h-1 respectively) under similar hydraulic conditions. The fluid hydrodynamics has been studied for both configurations, leading to an accurate calculation of shear at the membrane surface in SS MBR and to the determination of the minimum gas velocity required for Taylor bubble formation in submerged MBR (around 0.1 m.s-1). Finally, the effect of operating conditions such as process configuration, feed nature, and aeration type on biomass characteristics has been assessed and link to membrane fouling. Key words: Fouling, MBR, critical flux, process configuration, biomass characterisation