In recent years, the increasing threat to ground water quality due to human activities has become a matter of great con-cern. The ground water quality problems present today are caused by contamination and by over exploitation or by combination of both. Reverse osmosis (RO) desalination is one of the main technologies for producing fresh water from sea water and brackish ground water.
Algeria is one of the countries which suffer from the water shortage since many years, so desalination technology becomes inevitable solution to this matter.
In this study, a comparison is provided of results of reverse osmosis desalination for three different qualities of brack-ish water from the central-east region of Algeria (Bouira and Setif Prefectures), wherein they cannot use it as human drink-ing or in irrigation systems. The main objective of our study is to establish a comparison of the reverse osmosis membrane TW30-2540 performances in the term of (permeate flow, recovery rate, permeate total dissolved solids – TDS and salts re-jection) under different operation pressures (each one takes a time of 720 second for pilot scaling). In order to make an overview comparison between the experimental and the simulated results we used ROSA (Reverse Osmosis System Analy-sis) software.
At the end of this study we noted that, the simulated results are lower than the pilot scaling values and the most re-moved salts are the sodium chlorides with 99.05% of rejection rate.
The paper deals with linear circuits synthesis with periodic parameters. It was proved that the time-varying voltages and currents of inner branches of such circuits can be calculated using linear recursive equations with periodic coefficients if signals on port are given. The stability theorem of periodic solution was formulated. Hereby described the synthesis problems appear when compensation of power supply systems is considered.
Many of already existing roads cross wetland river valleys. Also the roads nowadays planned are cutting through valuable wetlands. It is necessary to evaluate the range of their impact on the natural environment. This paper focuses only on the analysis of the road crossing impact on the groundwater level. Two options of crossing the wetlands were analyzed, building the road on embankments and in the bridge. It was assumed that the valley is filled with organic material under laid by permeable sands. Calculation results showed that building a road in the valley affects groundwater level only to the slight extend. Water conditions in the valley may be affected only during the construction of the road. Calculation results were confirmed by field observations.
It should be stressed that the object of this paper is the evaluation of water conditions. Environment might be influenced by other factors.
The aim of this study was to assess the anisakid nematode distribution pattern in the fish collected from the South Shetland Islands . A total of 32 fish species were examined for the presence of nematodes in 1978, 1979, 1981 and 2007/2008. The fish were caught off the South Shetland Islands ( Elephant Island , Shishkov Island and in Admiralty Bay – King George Island ). Three genera of L3 larval nematodes were identified: Anisakis sp., Contracaecum spp. and Pseudoterranova decipiens. The infection level was higher on the shelf around the islands than in Admiralty Bay . This is explained by a higher abundance of the final hosts in the region. A comparison of the infection data from 1978/79 and 2007/2008 with data from 1994/96 (Palm et al. 1998, 2007) was done. The parameters of infection of Notothenia coriiceps and Lepidonotothen nudifrons by Pseudoterranova decipiens were decreasing within the 30 years period.