Volume 16 [2014]

With the aggravation of the unprecedented greenhouse effect, the reduction of greenhouse gases which mainly consist of CO₂ has caught high attention by global scholars. The membrane absorption of CO₂ from the flue gas seems a promising alternative to conventional absorption methods like chemical absorption. In this article, the principles of the membrane absorption process were discussed. The research development and current status of CO₂ capture in flue gas using a hollow fiber membrane contactor were reviewed. The affecting factors included the membrane structure and material, module connection form, gas and liquid flow pattern and absorbent. Also, these factors that affected the separation performance of mass transfer processes, as well as the mass transfer coefficients and models for CO₂ absorption were critically discussed in the tube side, shell side and membrane. Also, an experiment system for CO₂ absorption in a membrane contactor was dipicted. The modeling works were validated with experimental results. Additionally, the deficiencies of present development in membrane gas absorption of acid gases and recommendations for future pilot-scale applications were proposed. 

The removal of mercury by adsorption process using fly ash was investigated in this study. Mercury removal capacity of fly ash was performed by batch mode adsorption experiment with the effect of various parameters i.e., contact time (0.5-3.5) h, pH of 2-10, concentration of adsorbate (1, 5 and 10)
mg l^-1, adsorbent dose (100-1000) mg per 100 ml solution and temperature (303, 313 and 323) K. Mercury concentration (10 mg l^-1) was chosen for all parameters except adsorbent dose. The experimental data were showed that the adsorbent dose of 200, 400 and 600 mg per 100 ml were sufficient to maximum removal of mercury (98 percent) from aqueous solution of mercury (1, 5 and 10) mg.L^-1 at equilibrium and 89 percent mercury was removed when concentration was 10 mg l^-1 at 303K temperature. Adsorbent dose of 100 mg per 100 ml solution showed 74 percent removal of mercury for 2 hours contact time and 90 percent removal at pH 10. The experimental data were fitted with pseudo first order and pseudo second order kinetics which was proposed by Lagergreen. The value of pseudo first order rate constant, k₁ is 0.697 h^-1 and pseudo second order rate constant k₂ is 0.135 l mg^-1 h^-1.

A method is presented and preliminarily applied to the optimization of the allocation of oil-slick combating coastal stations in a coastal basin. The decision support methodology is based on the annual simulation of the circulation in the basin according to climatologic data, on the oil spill simulation by the method of Lagrangian particles, on the analysis of the quantified stochastic environmental effects from a number of probable oil spill sources distributed over the basin and on the selection of the optimal coastal oil spill stations. The selection is based on a proposed metric for the operational effectiveness of each station. Using available data, a preliminary application is presented for the Azov Sea, where a number of coastal sites, protected by Ramsar convention, exist and an intensive maritime traffic is planned for the near future.

Extreme floods often demonstrate unanticipated characteristics that pose problems for management and response. The flood in the Stratoni region in February 2010 provided an example of such unexpected response. The aim of this paper is the quantification of the hydrologic response of the torrents that outfall in the area of Stratoni of the prefecture of Chalkidiki by means of the synthetic unit hydrograph method. For this purpose, the effective rainfall is estimated with a Curve Number of Soil Conservation Service (SCS) procedure. In addition, the flood hydrograph is estimated using the Sierra Nevada’s synthetic unit hydrograph procedure. The resulting maximum flood discharge was compared with the value obtained by the method of flood-water traces and found not to differ significantly. Understanding of the hydrological operation of floods in small watersheds helps towards the design of plans and constructions of the infrastructure against flood risk.