Salah Bouguecha | National Engineering School of Gabes (original) (raw)

Papers by Salah Bouguecha

Chemical Engineering & Technology

The performance of the direct-contact membrane distillation (DCMD) process in desalting Mediterra... more The performance of the direct-contact membrane distillation (DCMD) process in desalting Mediterranean seawater was investigated. Theoretical and experimental optimization of various operating parameters was conducted. The effects of temperature differences, feed velocity, and membrane characteristics were studied. When using commercial polyvinylidene fluoride membranes, the vapor transfer throughout the membrane pores is dominated by the Knudsen-molecular diffusion model. Maximum permeate flux was obtained when increasing temperature, feed velocity, membrane pore size, and porosity and decreasing membrane tortuosity and thickness. Thermal efficiency, gained output ratio, and specific thermal energy consumption were improved when increasing feed temperature. By application of the DCMD process to Mediterranean seawater, a high water quality was obtained.

Chemistry Africa

Forward osmosis (FO) is a membrane technology which has attracted attention for water treatment a... more Forward osmosis (FO) is a membrane technology which has attracted attention for water treatment and desalination. However, selecting an appropriate draw solute is vital to optimize its performance. This study seeks the efficiency of aluminum sulfate as an alternative draw solute in FO desalination with a cellulose triacetate (CTA) membrane. The effects of operating parameters on the performance of the FO were studied such as feed and draw temperatures, concentrations and flow. The experiments revealed that the permeate flux was improved by monitoring draw temperature, with a maximum of 2.5 L/m 2 h was obtained at 53 °C. Also, the permeate flux was found to decrease with feed concentration. A maximum permeate flux of 2 L/m 2 h was obtained at a draw flow rate of 35 L/h and draw concentration of 1 mol/L. On the other hand, using deionized water as feed solution yielded a reverse aluminum sulfate flux of 1.46 g/m 2 h. The plots of the experimental and the modeling water flux displayed analogous trends in all tests, but the results showed a large deviation which was attributed to reverse solute flux, internal polarization concentration (ICP), external polarization concentration (ECP) and membrane fouling. Precipitation reaction using calcium hydroxide served to recover product water from the diluted draw solution. This operation was carried out via a precipitation reaction of aluminum sulfate with calcium hydroxide to eliminate the soluble chemicals like insoluble aluminum hydroxide and calcium sulfate. Eventually, aluminum sulfate draw solution was recovered by the reaction of aluminum hydroxide with sulfuric acid.

Membranes

The membrane distillation (MD) process for water desalination is affected by temperature polariza... more The membrane distillation (MD) process for water desalination is affected by temperature polarization, which reduces the driving force and the efficiency of the process. To counteract this phenomenon, spacer-filled channels are used, which enhance mixing and heat transfer but also cause higher pressure drops. Therefore, in the design of MD modules, the choice of the spacer is crucial for process efficiency. In the present work, different overlapped spacers are investigated by computational fluid dynamics (CFD) and results are compared with experiments carried out with thermochromic liquid crystals (TLC). Results are reported for different flow attack angles and for Reynolds numbers (Re) ranging from ~200 to ~800. A good qualitative agreement between simulations and experiments can be observed for the areal distribution of the normalized heat transfer coefficient. Trends of the average heat transfer coefficient are reported as functions of Re for the geometries investigated, thus pro...

Desalination

The thermo-fluid dynamic behavior of spacer-filled channels for membrane distillation was investi... more The thermo-fluid dynamic behavior of spacer-filled channels for membrane distillation was investigated experimentally. Several different geometry were investigated thanks to customized reference spacers manufactured using a 3D printer. In particular, two sets of experiments were conducted: in the first set, cylindrical filaments were orthogonally arranged and the flow attack angle was made to vary from 0 o to 90 o ; in the second set, the flow attack angle was kept symmetrical and the filament angle was made to vary from 30° to 150°. Each spacer was tested for Reynolds numbers between 200 and 900 in the hot channel, while maintaining a constant temperature difference of 13 °C between the hot and the cold channels. Thermochromic Liquid Crystal (TLC) sheets were used for surface temperature measurements. Results showed that, for all spacers, the heat transfer coefficient increases with hot feed flow rate and that the combination of attack angle 45° and filament angle 90° gave the highest heat transfer. Pressure drop measurements showed that spacers could be categorized into two groups relevant to the values of the Darcy friction coefficients (f). One group, associated with spacer designs with filament angles greater than 90°, led to high f values, while the other, associated with filament angles less than 90°, led to moderate f values.

DESALINATION AND WATER TREATMENT

Water science and technology : a journal of the International Association on Water Pollution Research, 2016

Membrane distillation (MD) is considered as a relatively high-energy requirement. To overcome thi... more Membrane distillation (MD) is considered as a relatively high-energy requirement. To overcome this drawback, it is recommended to couple the MD process with solar energy as the renewable energy source in order to provide heat energy required to optimize its performance to produce permeate flux. In the present work, an original solar energy driven direct contact membrane distillation (DCMD) pilot plant was built and tested under actual weather conditions at Jeddah, KSA, in order to model and optimize permeate flux. The dependency of permeate flux on various operating parameters such as feed temperature (46.6-63.4°C), permeate temperature (6.6-23.4°C), feed flow rate (199-451L/h) and permeate flow rate (199-451L/h) was studied by response surface methodology based on central composite design approach. The analysis of variance (ANOVA) confirmed that all independent variables had significant influence on the model (where P-value <0.05). The high coefficient of determination (R(2) = 0...

Desalination, 2005

In Tunisia, water resources are very limited and have high salinities. Domestic water in rural co... more In Tunisia, water resources are very limited and have high salinities. Domestic water in rural communities has TDS reaching 2750 ppm. Inhabitants of these areas are scattered and lack proper infrastructure for the implementation of conventional desalination plants. However, these regions have an important potential of renewable energy (RE), especially solar energy where sunshine in southern regions can reach 2500 h per year. RE can be harnessed to power small-scale desalination plants in order to produce the fresh water necessary to cover the basic requirements (drinking and cooking). This paper aims to identify the potential of renewable energies, mainly solar and geothermal. It illustrates the quality of distributed water in rural communities. It presents several studies that were carried out, including solar multiple effects distillation, reverse osmosis driven by photovoltaic panels, and lately membrane distillation using a geothermal resource. The experimental results show technical promise. However, more investigations will need to optimise the operating parameters and improve economic feasibility.

Desalination, 2007

In the recent years, membrane processes have drawn more attention because of their strong separat... more In the recent years, membrane processes have drawn more attention because of their strong separation capabilities and exhibiting a great potential for the treatment of waters and wastewaters worldwide. However, these membrane separation processes have some problems due to the formation of polarisation films and by-products which may generate bacteria and fouling. These problems may be overcome by combining two or more processes in the desalination units of the treatment process. The specificity of each process makes their integration more efficient. In this work, we report on the concept and the realisation of an experimental pilot plant which is composed of the following compartments: nanofiltration (NF), reverse osmosis (RO), cartridges filter, pump and measuring instruments. Samples of brackish water were filtered through filtrate cartridges in order to get rid of the suspended matter. A pilot plant equipped with composite RO and NF membranes was operated at 6 bar, ambient temperature and neutral pH with relatively good water recovery. This pilot plant shows the ease with which the combination of both processes is carried out. The main objective is to evaluate the effect of NF and RO membranes as well as their coupling on water quality. The effects of divalent and monovalent cations on operating parameters were studied. The recovery (Y) in NF/RO coupling was improved compared to that obtained in RO alone. This may be explained by a decrease in the input osmotic pressure of the RO membrane. This coupling also improves salt rejection and thus leads to a decrease in the salinity of water product. The results show that the coupling is efficient as it highly reduces water salinity.

Desalination, Mar 1, 2008

Tunisia, located in a semi-arid zone, has limited water resources. The shortage of good water qua... more Tunisia, located in a semi-arid zone, has limited water resources. The shortage of good water quality in particular at the south regions required a brackish water desalination to supply these regions with potable water. Zarzis desalination plant, working since 1999, has revealed difficulties related to the loss of membrane performances. In the aim to determine the reason of membrane fouling, foulant layer were analysed. The membrane autopsy has achieved by different methods, such as TOC (total organic carbon) measurement, SEM (scanning electron microscopy), AFM (atomic force microscopy), FTIR (fourier transform infrared spectroscopy) analysis, diffraction by X-ray. Results show that the foulant layer composed mostly of SiO 2 , clay, organic matter (polysaccharide, protein), CaSiO 3 , Fe 3 O 4 , AlPO 4 , and CaSO 4. The characteristics bonds obtained by IR indicate the presence of polysaccharides and proteins that constitute a source for further microbiological growth; this is the problem of biofouling. The metallic elements results of corroded stainless steel and internal coating of cartridges filter that are damaged by the silica particle rejected by sand filters. The scale of CaSO 4 and CaSiO 3 deposition is owing to the bad antiscaling efficiency. The results are presented and discussed in the light of new trends in material.

DESCRIPTION Desalination by solar energy assisted Membrane Distillation Project No.: CEDT-30-201 ... more DESCRIPTION Desalination by solar energy assisted Membrane Distillation Project No.: CEDT-30-201 Forward: The material presented in this final report cover the approved proposal for the project titled “Desalination by solar energy assisted membrane distillation”, together with a summary of the progress reports 1, 2, and the complied reports # 3 and 4. This report comprises three chapters; the first chapter presents the experimental results obtained in aim to determine the more significant operating parameters (task#8). The second one handles the practical learned lessons. The third chapter describes the adopted configuration of the MD pilot plant, and gives a summary technical documentation. Key Words: Seawater Desalination; Membrane distillation; solar energy (PV, Solar Collectors); Solar driven DCMD; Performance evaluation; Thermal energy efficiency; Permeate flux; ANOVA analysis; Central composite design; Desirability function.

DESCRIPTION Desalination by solar energy assisted Membrane Distillation Project No.: CEDT-30-201 ... more DESCRIPTION Desalination by solar energy assisted Membrane Distillation Project No.: CEDT-30-201 20/08/2015 The material presented in this final report cover the approved proposal for the project titled “Desalination by solar energy assisted membrane distillation”, together with a summary of the progress reports 1, 2, and the complied reports # 3 and 4. This report comprises three chapters; the first chapter presents the experimental results obtained in aim to determine the more significant operating parameters (task#8). The second one handles the practical learned lessons. The third chapter describes the adopted configuration of the MD pilot plant, and gives a summary technical documentation.

The material presented in this final report cover the approved proposal for the project titled “D... more The material presented in this final report cover the approved proposal for the project titled “Desalination by solar energy assisted membrane distillation”, together with a summary of the progress reports 1, 2, and the complied reports # 3 and 4. This report comprises three chapters; the first chapter presents the experimental results obtained in aim to determine the more significant operating parameters (task#8). The second one handles the practical learned lessons. The third chapter describes the adopted configuration of the MD pilot plant, and gives a summary technical documentation.

DESCRIPTION Desalination by solar energy assisted Membrane Distillation Project No.: CEDT-30-201 ... more DESCRIPTION Desalination by solar energy assisted Membrane Distillation Project No.: CEDT-30-201 (20/08/2015) The material presented in this final report cover the approved proposal for the project titled “Desalination by solar energy assisted membrane distillation”, together with a summary of the progress reports 1, 2, and the complied reports # 3 and 4. This report comprises three chapters; the first chapter presents the experimental results obtained in aim to determine the more significant operating parameters (task#8). The second one handles the practical learned lessons. The third chapter describes the adopted configuration of the MD pilot plant, and gives a summary technical documentation.

DESCRIPTION High lights of the 1st progress report • The MD requires only a low grade of thermal ... more DESCRIPTION High lights of the 1st progress report • The MD requires only a low grade of thermal energy input. Therefore, the survey for available literature showed that there is a strong potential to drive the MD units cheaply by tapping the sources for various renewable energy forms whether it is solar, wind, geothermal or tidal energy. Concerning the possibility of utilizing the industrial waste heat, attention should be focused on low and medium temperature resources, which represent more than two thirds of the available waste heat. • The KSA has a great potential as far as renewable energy is concerned. Specifically due to geographical position on world map, it receives one of the highest solar flux intensities in the world, in addition to almost all the year round clear sky conditions. The mountains covered a small portion of the vast area, which would help in harvesting the wind energy on big scale. The geothermal energy is very much allocated in the western region of the KSA...

DESCRIPTION 2. High lights of the 2nd Progress report • Preliminary tests showed that the experim... more DESCRIPTION 2. High lights of the 2nd Progress report • Preliminary tests showed that the experimental setup is in good working conditions, • The PV power panel shows the expected trend of the performance with a reasonable time lag and response. • The solar collectors exhibit good performance up to a level about 90 C collector's outlet temperature. • Despite thermal insulation, the piping between the solar collectors in the 3rd floor level and the heat exchanger on the second floor level lose a significant part of the temperature gain at the collectors. However, it is still enough to drive the MD system. • Due to the high temperature of the local municipality water, and in order to achieve an acceptable level of the MD performance, it is necessary to shunt the MD loop to a proper sink, preferably, a sink powered by a vapor compression refrigeration cycle

Journal of Industrial and Engineering Chemistry, 2013

In this paper,we focused our work on the direct contact membrane distillation (DCMD) capability t... more In this paper,we focused our work on the direct contact membrane distillation (DCMD) capability to treat hyper-saline
solution. The governing operative model for mass transfer was investigated. The measured flux has been well predicted by the Knudsen-molecular mechanism model. The effects on the DCMD flux of polarization phenomena TP and CP were underlined. The optimum operating parameters were defined: the hot and cold stream temperatures were set, respectively at 59 and 20 °C, and the feed and permeate velocities were fixed both to 0.046 m s−1.With regard to membrane performance to treat the reverse osmosis brine, a long-term experiment
was carried out under the optimal experimental conditions. The increase in feed RO brine concentration provoked
a noticeably decrease in flux from 8.43 to 4.06 kg m−2 h−1. The RO brine experiments proved that the DCMD process was capable to concentrate the solution tell to reach concentration factor (CF) further than four times, which corresponded to the super-saturation of saline solution. Based on the characterization methods, the occurrence of the membrane wetting and scaling was shown and interpreted. These extreme phenomena promote the salt crystallization on the feed side of the membrane. The onset crystallization phenomenon starts
when the permeate decreases so fast. Their sudden decline was about 90% for a working period of 20 h.

Chemical Engineering & Technology

Chemistry Africa

Membranes

Desalination

DESALINATION AND WATER TREATMENT

Water science and technology : a journal of the International Association on Water Pollution Research, 2016

Desalination, 2005

Desalination, 2007

Desalination, Mar 1, 2008

DESCRIPTION Desalination by solar energy assisted Membrane Distillation Project No.: CEDT-30-201 ... more DESCRIPTION Desalination by solar energy assisted Membrane Distillation Project No.: CEDT-30-201 20/08/2015 The material presented in this final report cover the approved proposal for the project titled “Desalination by solar energy assisted membrane distillation”, together with a summary of the progress reports 1, 2, and the complied reports # 3 and 4. This report comprises three chapters; the first chapter presents the experimental results obtained in aim to determine the more significant operating parameters (task#8). The second one handles the practical learned lessons. The third chapter describes the adopted configuration of the MD pilot plant, and gives a summary technical documentation.

DESCRIPTION Desalination by solar energy assisted Membrane Distillation Project No.: CEDT-30-201 ... more DESCRIPTION Desalination by solar energy assisted Membrane Distillation Project No.: CEDT-30-201 (20/08/2015) The material presented in this final report cover the approved proposal for the project titled “Desalination by solar energy assisted membrane distillation”, together with a summary of the progress reports 1, 2, and the complied reports # 3 and 4. This report comprises three chapters; the first chapter presents the experimental results obtained in aim to determine the more significant operating parameters (task#8). The second one handles the practical learned lessons. The third chapter describes the adopted configuration of the MD pilot plant, and gives a summary technical documentation.

Journal of Industrial and Engineering Chemistry, 2013