Waterbody scale assessment using spatial models to identify suitable locations for cage aquaculture in large lake systems: A case study in Volta Lake, Ghana

Large lakes throughout the world offer development opportunities for cage aquaculture. However, due to their vast area, identifying the most suitable locations can be a challenge. This is also complicated as lake systems are often multi‐use environments, so a strategic approach to managing the resource is required. This study uses geographic information systems (GIS) to develop a broad‐scale approach that identifies potential areas that may be suitable for cage aquaculture development. Volta Lake, one the world's largest man‐made lakes, is used as a case study. The overall GIS model combines four sub‐models, bathymetry, hydrography, water quality and access, and a constraints layer, to identify the most suitable locations for tilapia production. Three different cage sizes are modelled: small, medium and large. The model outputs suggest that approximately 102 km2 (1.7%), 406 km2 (6.9%) and 407 km2 (6.9%) of Volta Lake can be categorized as highly suitable for development of small, medium and large cages respectively. A further 634 km2 (10.8%), 1264 km2 (21.4%) and 1055 km2 (17.9%) can be categorized as suitable for the same. The results can be used by stakeholders and decision makers to identify specific areas where aquaculture development for cage farming of tilapia could be prioritized

Isolation and screening of Bacillus subtilis MJ01 for MEOR application: biosurfactant characterization, production optimization and wetting effect on carbonate surfaces

Abstract The bacterial strain MJ01 was isolated from stock tank water of one of the Iranian south oil field production facilities. The 16S rRNA gene of isolate, MJ01, showed 99% similarity to Bacillus subtilis. The results revealed that biosurfactant produced by this strain was lipopeptide-like surfactin based on FTIR analysis. Critical micelle concentration of produced surfactin in distilled water was 0.06 g/l. Wettability study showed that at zero salinity surfactin can change original oil-wet state to water-wet state, but in seawater salinity it cannot modify the wettability significantly. To utilize this biosurfactant in ex situ MEOR process, economical and reservoir engineering technical parameters were considered to introduce a new optimization strategy using the response surface methodology. Comparing the result of this optimization strategy with the previous optimization research works was shown that significant save in use of nutrients is possible by using this medium. Furthermore, using this method leads to less formation damage due to the incompatibility of injecting fluid and formation brine, and less formation damage due to the bioplugging

Effect of Water-Soluble Drag-Reducing Polymer on Flow Patterns and Pressure Gradients of Oil/Water Flow in Horizontal and Upward-Inclined Pipes

Summary Experimental investigations of flow patterns and pressure gradients of oil/water flow with and without drag-reducing polymer (DRP) were carried out in horizontal and upward-inclined acrylic pipe of 30.6-mm inner diameter (ID). The oil/water flow conditions of 0.1- to 1.6-m/s mixture velocities and 0.05–0.9 input oil-volume fractions were used, and 2,000 ppm master solution of the water-soluble DRP was prepared and injected at controlled flow rates to provide 40 ppm of the DRP in the water phase at the test section. The flow patterns at the water-continuous flows were affected by the DRP, whereas there were no tangible effects of the DRP at the oil-continuous flow regions. The upward inclinations shifted the boundaries between stratified flows and dual continuous flows, and the boundaries between dual continuous flows and water-continuous flows to lower mixture velocities. This means that the inclinations increased the rate of dispersions. The frictional pressure gradients for both with and without DRP slightly decreased with inclinations especially at low mixture velocities, whereas the significant increases in the total pressure gradients with the inclinations were more pronounced at low mixture velocities. The inclinations did not have a major effect on the drag reductions by the DRP at the high mixture velocities and low-input oil-volume fractions where the highest drag reductions recorded were 64% at 0° inclination and 62% at both + 5° and +10° inclinations. However, the inclinations increased the drag reductions as the input oil-volume fractions were increased before phase-inversion points.</jats:p