Chemical Engineering

The development and application of a membrane bioreactor (MBR) for full-scale Municipal wastewater treatment is the most important recent technological advance in terms of biological wastewater treatment. The MBR is a suspended growth-activated sludge system which combines the use of biological processes and membrane technology to treat wastewater and provide organic and suspended solids removal instead of secondary clarifiers. Use of MBR offers the possibility to overcome a lot of problems in activated sludge processes which are mostly due to tertiary treatment. It represents a decisive step forward concerning effluent quality by delivering a hygienically pure effluent and by exhibiting a very high operational reliability. Advanced MBR wastewater treatment technology is being successfully applied at an ever-increasing number of locations around the world. This review article has covered several aspects of MBR. The membrane separation of microorganisms from the treated wastewater is discussed in detail. Problems of membrane fouling and membrane washing and regeneration, linked to activated sludge characteristics, are examined. Finally, advantages and disadvantages of MBR over conventional activated sludge are concerned.

A combination of semi-coking followed by wet high intensity magnetic separation has been used for the upgrading of El-Magara ultrafine Coal. The samples were semicoking at 550°C and then upgraded by the wet high intensity magnetic separator. Semi-coking of ultrafine coal decreases energy costs for its crushing and significantly increases magnetic properties of its mineral constituent. The factors effects on the processes were studied feeding rate, solid/liquid ratio and magnetic field intensity. The semi-coking coal in the size range of ?25?m with pyrite feed contains 2.1% was used for this study. At the end of this study the Sulphur decreased from 2.1 % to 0.45%.

The demand for feldspar as a raw material for various industrial applications is continuously increasing. It is a valuable raw material in the manufacture of glass, ceramic, fillers, enamel frits and welding electrodes. Feldspar is abundant in the earth’s crust and is generally associated with other silicate, titanium and iron oxide minerals. The present paper aimed to reduce the iron oxide content from feldspar ore of Libya, as well as, to obtain an optimal grade of feldspar concentrate for industrial applications. It should be mentioned that this is the first time that Libyan feldspar ores subjected to upgrading studies. Dry and wet magnetic separation techniques followed by leaching processes were carried out, in order to decrease the iron contamination and increase the feldspar content. From a feed containing 2.48% Fe2O3 a non-magnetic concentrate of 0.28 % Fe2O3 with feldspar yield of 84.5 % was obtained at size fraction – 0.032 mm. Such concentrate contains about 21.05% Al2O3% and Na2O, K2O of 18.24% in comparison to 12.18% in the feldspar ore. Leaching process successfully reduced the iron oxide content up to 0.07 %. At the same time, the total contents of Na2O + K2O increased to about 16.73% in comparison to 12.18% in the original feldspar ore.

Chromium has been widely used in various industries like textile, leather, chemical manufacture, metal finishing, paint industry and many other industries. Since hexavalent chromium is a priority toxic, mutagenic and carcinogenic chemical when present in excess, it is very much required to remove chromium from effluents before allowing it to enter any water system or on to land. In the present study, the removal of hexavalent chromium by adsorption on the Borasus flabellifer coir powder as adsorbent has been investigated in the batch experiments. The agitation time, the adsorbent size, adsorbent dosage, initial chromium concentration, temperature and the effect of solution pH are studied. Adsorption mechanism is found to follow Freundlich. The adsorption behavior is described by a second order kinetics. Percentage removal of chromium (VI) is found to be 97.16% at pH=2, w=0.5g, dp=63µm and temperature=303 K. The results obtained in this study illustrate that Borasus flabellifer coir powder is an effective and economically viable adsorbent for hexavalent chromium removal from industrial waste water.

PVA membrane and PVA-PES membrane were used for study of Pervaporation separation of IPA/water mixture. In present study experiments were carried out at different feed temperature (45-75 0C), feed concentration (6.28- 14.39 wt %.) and flow rates (6-18 LPH). The degree of swelling of the membranes studied at different concentration of water in feed. The experimental results of IPA/water system were presented and compared with regression analysis model data. It was observed that PVA-PES membrane has higher flux and lower separation factor than PVA membrane for separation of IPA/water mixture. The total permeation flux increased with increase in feed temperature and feed concentration. Increasing the feed flow rate had a positive effect on both permeation flux and selectivity due to elimination of concentration and temperature polarization. A permeation flux of 110.81 gm/m2.hr with separation factor 124.93 was achieved for PVA membrane and permeation flux of 158.44 gm/m2.hr with separation factor 25.24 was achieved for PVA-PES membrane. The Comparative results are presented in this work.

The Synthesis and functionalization of Zeolite A from Nigerian Ahoko Kaolin for adsorption studies of Methylene blue (MB) was studied in this paper. Zeolite A was successfully synthesised from metakaolin earlier developed from refined kaolin using conventional hydrothermal method. The synthesised zeolite A was thereafter functionalized using Hexamethyltetraamine (HMTA) and characterized. The effect of initial concentration, adsorbate dosage, pH, temperature and contact time were studied in a batch adsorption system for both unfunctionalized zeolite (UFZA) and functionalized zeolite A (FZA) under the following condition of initial concentration of 100 mg/l, temperature of 303 K, and pH of 7. The adsorption rate increases with increase pH, temperature, initial concentration but decrease with adsorbent dosage for both UFZA and FZA. Langmuir, Feundlich and temkim isothermal were also investigated and was found out that Langmuir isotherm is the most suitable. The pseudo–first order and pseudo-second order kinetic equation were evaluated and adsorption of MB onto UFZA and FZA followed the later. The thermodynamic studies indicate that adsorption of MB onto UFZA and FZA are spontaneous and endothermic reaction.

The potential use of custard apple peel powder for the removal of Cu (II) from waste water has been investigated in batch mode experiments. Influences of parameters like initial Cu (II) concentration (20-60 mg/l), pH (5-7), and biomass dosage (25-35 g/l) on Cu (II) adsorption were examined using response surface methodology. The Box-Behnken experimental design in response surface methodology was used for designing the experiments as well as for full response surface estimation and 15 trials as per the model were run. The optimum conditions for maximum removal of Cu (II) from an aqueous solution of 20 mg/l were as follows: adsorbent dosage (28.139 g/l), pH (6.40213) and initial Cu (II) concentration (17.6572 mg/l). The high correlation coefficient (R² =0.991) between the model and the experimental data showed that the model was able to predict the removal of Cu (II) from waste water using Custard apple peel powder efficiently.

The second generation bioethanol production (G2) is made from cellulose and hemicellulose. This research aim was to determine the concentration of 1-3% NaOH solution and the best immersion time in the pre-treatment process in the manufacture of bioethanol from lignocellulose raw materials of palm oil stems. NaOH concentration (1%, 2% and 3%) and immersion time of oil palm lignocellulose stem had no significant effect on bioethanol levels. The bioethanol levels produced were still very good. The best treatment was X4.

Biogas, a clean and renewable form of energy could very well substitute (especially in the rural sector) for conventional sources of energy (fossil fuels, oil, etc.) which are causing ecological–environmental problems and at the same time depleting at a faster rate. Despite its numerous advantages, the potential of biogas technology could not be fully harnessed or tapped as certain constraints are also associated with it. Most common among these are: the large hydraulic retention time of 30–50 days, low gas production in winter, etc. Therefore, efforts are needed to remove its various limitations so as to popularize this technology in the rural areas. Researchers have tried different techniques to enhance gas production. This paper reviews the various techniques, which could be used to enhance the gas production rate from solid substrates.

Free Fatty Acid (FFA) was removed from waste oil and favorably employed for the production of high quality biodiesel. FFA extraction minimizes the drawbacks encountered with alkaline catalysts in biodiesel production. Three combinations of reagents (methanol-benzene, methanol-toluene and methanol-xylene) were used for extraction purpose and a rapid extraction of FFA has been obtained. The composition of non-polar solvent (benzene, toluene and xylene) in each of the above mentioned reagents was varied from 1% to 10% by weight. An optimal ratio of (0.8:1) reagent and oil by weight was found to reduce the FFA concentration by 43.3% in single step. Equilibrium study for the extraction of FFA was also carried out. The experimental data obtained were presented on the basis of amount of FFA extracted, with respect to time required for extraction (25 to 300 min) and stirrer speed (50 to 300 rpm). The optimum value for the time required for extraction was obtained at 150 min. the optimum value for the stirrer speed required for the extraction of FFA was obtained at 150 rpm.