Zahia Tigrine

Wastewater from soap production often contains high levels of organic pollutants, exceeding regulatory discharge limits and posing significant environmental concerns. This study investigates a two-stage treatment approach integrating ferric chloride (FeCl₃)-based coagulation–flocculation with membrane filtration to enhance wastewater purification efficiency. This method is one of the appropriate treatment techniques to reduce water pollution. Thus, numerous Jar test trials have been carried out in order to determine the optimal conditions and parameters that make it possible to reduce suspended solids. Key water quality parameters, including chemical oxygen demand (COD), pH, and turbidity, were monitored to assess process performance. Optimization experiments identified optimal coagulation–flocculation conditions, achieving a substantial COD reduction from 9200 mg/L to 351 mg/L significantly improving water quality. However, the treated effluent still failed to meet reuse standards, necessitating further purification. A subsequent membrane filtration stage was implemented, achieving a significant decrease in turbidity to 0.85 Ntu and a turbidity removal efficiency of 99.97%, indicating high treatment efficiency. The final COD of the collected water was 58 mg/L, well below regulatory limits. This hybrid treatment approach offers a highly effective and sustainable solution for soap wastewater management, supporting environmental protection and resource recovery.

We present a numerical investigation of the three-dimensional geometry effect on liquid metal flows in a rectangular duct subject to a transverse magnetic field using miniature cylinders immersed in fluid. Simulations are performed by means of a numerical method based on the finite volume method. The considered liquid metal is the 17Li83Pb eutectic alloy evolving in a rectangular channel. The influence of forced convection and magnetic field is studied. Streamwise counter rotating vortices are created in a spanwise direction by small devices intended for controlling the secondary flow near the wall region. It is found that the mushroom structure dominates in the flow at a low Reynolds number Reh ≤ 272. With a large Reynolds number, the flow regime is unstable downstream the duct showing horseshoe vortex patterns. By increasing the aspect ratio of the rectangular duct, the onset of steady streaks is delayed. Key words: Magnetohydrodynamics, liquid metal, numerical simulations, aspect ratio. Tables 1, Figs 8, Refs 26.

This study aims to develop efficient desalination equipment that increases the distilled water production rate and enhances heat transfer in the evaporator. It focuses on the impact of equipment geometry and energy storage during the daytime and nocturnal period. In addition, the effects of the energy storage system, which is placed in two specific areas on the yield of the distillation process with and without energy storage, have been studied. The heat exchanger system provides the energy to the water to be treated in the daytime, while the concrete part provides the energy storage in the desalination evaporator at night time. The experimental test results showed that the increase of distilled water through the heating system is very important in comparison to the productivity of the conventional solar still. The obtained results indicate that the use of energy storage increases productivity by 50% in the nocturnal period. Indeed, the daily productivity of the concrete solar still, strongly affected by the heat transfer produced via concrete to the water evaporator, is presented in this study. It was found that the average daily distillate output of concrete solar still with energy storage is more significant than that of a solar still without energy storage.

The purpose of this study is to optimize the operating conditions in batch mode using Box‐Behnken Design (BBD), for the coagulation‐flocculation line sizing prior the sand filter in the pilot scale. Three coagulants were employed to achieve a high turbidity removal with a low concentration of residual metals. The results showed that the best turbidity removal was obtained with FeCl₃. Using BBD (15 experiments), the optimal parameters were: coagulant dose = 5.5 mg FeCl₃/L, slow stirring time = 33 min and slow stirring velocity = 45 rpm, in these conditions, the turbidity removal reached 94.89% and the residual iron concentration was 0.449 mg/L. Regarding the model fit, the obtained R² values were 99.67% for turbidity removal and 99.47% for residual iron concentration. The optimum conditions obtained from this study could be scaled up and applied to desalination plants. BBD approach is of great interest because it allows the prediction of the response value without performing experiments.

The management of concentrated brine waste is the main challenge of seawater desalination by reverse osmosis (RO) because of its negative impacts on the contamination of soil, ground water, and the marine eco-system. Consequently, it is necessary to develop alternative methods for brine treatment that allow the reducing of the negative effect on the marine environment. This paper investigates also diverse environmental impacts associated with brine and its disposal methods; it highlights also the desalination process in Algeria by presenting some statistics about RO brine. According to the experts, the desalination of seawater in Algeria passed from 2.26 million m ³ per day in 2011 to 2,580,000 in 2020, with the optimum recovery ratio of 45%, which indicate that the discharged brine quantity is important than the desalted water. In that sense and according to the brine management analyses, the brine recovering methods are depending to many parameters, which make the choice of such method as a big challenge in order to protect the marine environment.

The solar power potential of Algeria is huge and enormous. Solar energy is promising source for water desalination notably in the south regions of Algeria for fresh and drinking water providing. Solar thermal energy can be used to run thermal desalination plants such as multi-effect desalination processes (MED). In this work, solar collectors and Multi Effects desalination unit used to produce fresh water from brackish water have been proposed. Mathematic models based on energy and mass balances of various components of the MED plant (evaporator, condenser, flashing chamber) as well as for the parabolic trough collectors have been developed. The global model of the proposed system has been numerically solved and the results have been presented and analyzed. To validate the obtained simulations results, the plant performances are compared with the results available on the literature. The results show clearly that the solar MED technology may provide a key solution for freshwater deficit in the southern area of Algeria.

Algeria is located in a semi-arid region, suffering now more than ever from the problem of inadequate water resources. It is also characterized by irregular rainfall. Membrane sea water desalination technology has known in recent years remarkable progress. Reverse osmosis is the most widespread process to increase fresh water production for domestic, agriculture and industrial uses. Currently, renewable energies can provide a sustainable and alternative solution for generating reverse osmosis systems operating at high pressure. The production of fresh and potable water by solar water desalination remains a sustainable strategy and economic option to fill the water deficit in areas that do not have access to safe drinking water and electricity. For this, this principle is developed industrially for the desalination of the sea waters and the purification of the water. The main objective of the present work is the study of a small capacity (100 I/h) reverse osmosis plan intended for desalination and water treatment operation. We have especially worked on the effect of pressure and salinity on the production and quality of the water produced. The performed work is purely experimental and is part within the framework of improving the profitability of an RO device. Initiation of coupling of the reverse osmosis pilot to solar energy in order to reduce energy consumption (4 KW/ 1m3) is being investigated. During this period of experimentation a physicochemical and bacteriological analysis of the water before and after treatment were carried out.

In this paper, the effect of transverse magnetic field on a laminar liquid lead lithium flow in an insulating rectangular duct is numerically solved with three-dimensional (3D) simulations. Cases with and without buoyancy force are examined. The stability of the buoyant flow is studied for different values of the Hartmann number from 0 to 120. We focus on the combined influence of the Hartmann number and buoyancy on flow field, flow structure in the vicinity of walls and its stability. Velocity and temperature distributions are presented for different magnetic field strengths. It is shown that the magnetic field damps the velocity and leads to flow stabilization in the core fluid and generates magnetohydrodynamic (MHD) boundary layers at the walls, which become the main source of instabilities. The buoyant force is responsible of the generation of vortices and enhances the velocities in the core region. It can act together with the MHD forces to intensify the flow near the Hartmann layers. Two critical Hartmann numbers (Ha_c1 = 63, Ha_c2 = 120) are found. Ha_c1 is corresponding to the separation of two MHD regimes: the first one is characterized by a core flow maximum velocity, whereas the second regime is featured by a maximum layer velocity and a pronounced buoyancy effect. Ha_c2 is a threshold value of electromagnetic force indicating the onset of MHD instability through the generation of small vortices close to the side layers.