Mapping groundwater recharge potential zones in arid region using GIS and Landsat approaches,southeast Tunisia

The rapid growth of population and agricultural and industrial activities has caused an increase in demand on the Jeffara aquifers of Gabes (southeast Tunisia). In fact, the over-pumping of this aquifer system has resulted in water-level declines ranging from 0.25 to 1 m/year during the past three decades. The aim of this study is to identify favourable artificial recharge sites of this aquifer system based on the combined use of remotely sensed data, a geographic information system (GIS), the Shuttle Radar Topography Mission (SRTM) product and a multiple criteria decision making (MCDM) technique. The delineation of artificial recharge zones shows high to moderate potential for groundwater recharge (40%) in the Gabes region, with high precision of good potential proposed sites. Recharge processes need to account for natural conditions and ecosystems.     

Modeling and simulation of hybrid anaerobic/aerobic wastewater treatment system

Modeling and simulation using GPS-X software for a packed bed up-flow anaerobic sludge blanket followed by a biological aerated filter were studied. Both treatment units were packed with a non-woven polyester fabric as a bio-bed. The system was operated at a hydraulic and organic loading rate of 9.65 m³/m²/d and 2.64 kg BOD₅/m³/day. Verification of the experimental results and calibration of the model were carried out prior simulation and modeling. Variables under consideration were HLR, OLR, and surface area of the packing material. HLR and OLR are increased incrementally until the break through point has been achieved. The results obtained from modeling indicated that the treatment system has great potential to be used as an ideal and efficient option for high hydraulic and organic loading rates up to 19.29 m³/m²/d and 4.48 kg BOD₅/m³/day. The model indicated that increasing the input HLR and OLR loads to the treatment system up to 50 % of the original values achieved removal efficiencies 98 % for TSS, 88 % for BOD₅, and 85 % for COD. Moreover, increasing the HLR to four times the original value (38.59 m³/m²/d) reduced the efficiency of the treatment system to 50 % for COD and BOD₅. However, the removal rates of TSS, TKN, and TP were not affected. Also, the modeling results indicated that increasing the surface area of the packing material increased the overall efficiency of the treatment system.     

Hydrothermal alteration of plagioclase in granitic rocks from Proterozoic basement of SE Sweden

Petrographic examinations and electron microprobe analyses of Proterozoic granitic rocks, SE Sweden aimed to characterize and unravel the mechanisms and conditions of plagioclase alterations. These alterations include saussuritization, albitization and replacement of plagioclase by K‐feldspar. The hydrothermal alterations, which are inferred to have occurred at ca. 250–400°C, resulted in concomitant formation of Al‐rich titanite, epidote, calcite, pumpellyite, prehnite and iron oxides. Replacement of plagioclase by K‐feldspar occurs in red‐stained zones, which have developed close to thin fractures owing to the precipitation of tiny Fe‐oxide pigment particles within the altered plagioclase, whereas saussuritized plagioclase has less systematic spatial relationships to these fractures. Albitization of plagioclase occurred in rocks that are poor in biotite compared to rocks that suffered extensive saussuritization. The chemical and textural characterization of various types of plagioclase alterations allows elucidation of the granitic hydrothermal systems. Features of feldspar alteration in the granitic rocks are similar to those encountered in feldspathic sandstones and should hence be considered in studies on diagenetic changes of siliciclastic successions during basin evolution. Copyright © 2009 John Wiley & Sons, Ltd.     

Analytical solution for distributed torsional low strain integrity test for pipe pile

Low strain integrity tests (LSITs) are the most popular non-destructive methods for pile testing. However, traditional LSITs have encountered unprecedented challenges as the need for long pile and existing pile testing keeps multiplying. Compared to traditional longitudinal excitations, the torsional wave is less influenced by the velocity attenuation effect and can be subjected at the pile shaft for existing piles. Distributed torsional LSIT is proposed in this article with the presentation of the corresponding analytical solutions that exhibiting the velocity responses along the pile shaft. The solution is verified with previous simplified theoretical and rigorous finite element method (FEM) answers. At the end, the application of this method is exhibited through the identification of necking and concrete segregation defects on pipe piles, which shows the advantage of this method on long pile testing.