Aghareed M. Tayeb

Conditioning of aluminium-based water treatment sludge with Fenton's reagent: effectiveness and optimising study to improve dewaterability.

Alternative conditioning of aluminium-based drinking water treatment sludge using Fenton reagent (Fe2+/H2O2) was examined in this study. Focuses were placed on effectiveness and factors to affect such novel application of Fenton process. Experiments have demonstrated that considerable improvement of alum sludge dewaterability evaluated by capillary suction time (CST) can be obtained at the relative low concentrations of Fenton reagent. A Box-Behnken experimental design based on the response surface methodology was applied to evaluate the optimum of the influencing variables, i.e. iron concentration, hydrogen peroxide concentration and pH. The optimal values for Fe2+, H2O2, and pH are 21 mg g(-1)DS(-1)(dry solids), 105 mg g(-1)DS(-1) and 6, respectively, at which the CST reduction efficiency of 48+/-3% can be achieved, this agreed with that predicted by an established polynomial model in this study.

Photo-catalytic degradation of an oil-water emulsion using the photo-Fenton treatment process : effects and statistical optimization

Fruits of 63 accessions of Capsicum chinense Jacq. from the USDA/ARS Capsicum germplasm collection were analyzed for two major capsaicinoids, capsaicin and dihydrocapsaicin, using gas chromatography with nitrogen phosphorus detection (GC/NPD). The objectives of the present investigation were: (i) to quantify the major capsaicinoids (capsaicin and dihydrocapsaicin) in fruits of Capsicum chinense accessions and (ii) to identify accessions containing great concentrations of capsaicinoids among countries of hot pepper origin. Seeds of C. chinense accessions received from Belize, Brazil, Colombia, Ecuador, Mexico, Peru, Puerto Rico, and United States were field grown in a silty-loam soil. Mature fruits were analyzed for major capsaicinoids content. Capsaicin concentrations were generally greater than dihydrocapsaicin. Fruits of C. chinense accession PI640900 (USA) contained the greatest concentration of capsaicin (1.52 mg g(- 1) fruit) and dihydrocapsaicin (1.16 mg g(- 1) fruit), while total major capsaicinoids in the fruits of PI438648 (Mexico) averaged 2 mg g(- 1) fruit. These two accessions were identified as potential candidates for mass production of major capsaicinoids that have health-promoting properties and for use as a source of pest control agents in agricultural fields.The application of advanced oxidation processes (AOPs) to the treatment of an effluent contaminated with hydrocarbon oils was investigated. The AOPs conducted were Fe2 +/H2O2 (Fentons reagent), Fe2 +/H2O2/UV (Photo-Fentons reagent) and UV-photolysis. These technologies utilize the very strong oxidizing power of hydroxyl radicals to oxidize organic compounds to harmless end products such as CO2 and H2O. A synthetic wastewater generated by emulsifying diesel oil and water was used. This wastewater might simulate, for example, a waste resulting from a hydrocarbon oil spill, onto which detergent was sprayed. The experiments utilising the Photo-Fenton treatment method with an artificial UV source, coupled with Fentons reagent, suggest that the hydrocarbon oil is readily degradable, but that the emulsifying agent is much more resistant to degradation. The results showed that the COD (chemical oxygen demand) removal rate was affected by the Photo-Fenton parameters (Fe2+, H2O2 concentrations and the initial pH) of the aqueous solution. In addition, the applicability of the treatment method to a ‘real’ wastewater contaminated with hydrocarbon oil is demonstrated. The ‘real’ wastewater was sourced at a nearby car-wash facility located at a petroleum filling station and the experimental results demonstrate the effectiveness of the treatment method in this case. A statistical analysis of the experimental data using the Statistical Analysis System (SAS) and the response surface methodology (RSM) based on the experimental design was applied to optimize the Photo-Fenton parameters (concentrations of Fe2 +, H2O2 and initial pH) and to maximize the COD removal rate (more than 70%).

Exploitation of Fenton and Fenton-like reagents as alternative conditioners for alum sludge conditioning

The use of Fentons reagent (Fe2+/H2O2) and Fenton-like reagents containing transition metals of Cu(II), Zn(II), Co(II), and Mn(II) for an alum sludge conditioning to improve its dewaterability was investigated. The results obtained were compared with those obtained from conditioning the same alum sludge using cationic and anionic polymers. Experimental results show that Fentons reagent was the best among the Fenton and Fenton-like reagents for the alum sludge conditioning. A considerable effectiveness of capillary suction time (CST) reduction efficiency of 47% can be achieved under test conditions of Fe2+/H2O2 = 20/125 mg/g DS (dry solid) and pH 6.0. The observation of floc-like particles after Fentons reagent conditioning of alum sludge suggested that the mechanism of Fentons reagent conditioning was different from that of polymer conditioning. In spite of the lower efficiency in the CST reduction of Fentons reagent in alum sludge conditioning compared to that of polymer conditioning, Fentons reagent offers a more environmentally safe option. This study provided an example of proactive treatment engineering, which is aimed at seeking a safe alternative to the use of polymers in sludge conditioning towards achieving a more sustainable sludge management strategy.

Use of some industrial wastes as energy storage media

Solar energy is stored using different solid storage materials, both chemical and metallic industrial wastes. The materials tested in the present study are paraffin wax, copper slag, aluminium slag, iron slag, cast iron slag and copper chips. Solar energy is stored in these materials, and the energy is then recovered with a water stream at different flow rates, and the storage capacity and period for different materials were compared. The same set of experiments is run on solid metallic materials mixed with wax. The results indicated that iron slag has the highest storage capacity followed by cast iron slag then aluminium slag and copper chips and copper slag. It is also noted that the addition of paraffin wax to the solid metallic material greatly improves its storage capacity and duration. The storage efficiency of different units is calculated and compared.

A simulation model for a phase-change energy storage system: Experimental and verification

Abstract Glaubers salt is used as a phase-change energy storage material in a developed system. The salt is contained in 0.8 cm dia glass tubes fixed in two transparent shells. The two shells are connected in parallel through a 2-way valve and are used alternately. The system consists of two loops, namely the energy collecting loop (ECL) which collects the solar energy through the phase-change material and the energy load loop (ELL) which extracts the collected energy into the outlet streams. The primary objective of the process is to get a stream of hot water at constant temperature to be used for domestic purposes, and the secondary objective is to get a constant flow rate stream of hot air to be used for space heating. The system is numerically simulated and a model, which gives the optimum flow rate of the inlet water supply required to maintain the constant-temperature water outlet, is reached. Next, the model is validated through experimental simulation using a changeable watt heat lamp. The experimental results showed good agreement with the data obtained from the simulation model.

Performance study of some designs of solar stills

Abstract The efficiency of solar energy utilization and the performance of four different designs of basin-type stills is considered. The stills have the same area of evaporation but different shapes and, thus, different areas of condensation. The effect of these design factors, as well as the effects of materials of construction and some operating factors, such as basin temperature, cover temperature, ambient temperature and solar intensity, is examined and analyzed. The efficiency of the stills is also calculated. The results show that a higher ratio of condensation area ( A c ) to evaporation area ( A e ) leads to a higher productivity, if not contradicted by another effect such as shading. Basin temperature has a positive effect on productivity, but the effect of cover temperature is not so pronounced. The productivity is affected directly and positively by solar intensity. The efficiency of these different stills is calculated, and it was found to range from 14.9 to 21.8%.

Modification of urea–sodium acetate trihydrate mixture for solar energy storage

The system urea–sodium acetate trihydrate has been mentioned in the literature as an energy storage system. Due to its low melting point (30 °C), the system is not suitable for use in a hot climate. Modifying the system composition is shown in the present work through adding lead acetate trihydrate to the binary mixture in the ratio of 16.6% with the object of raising its melting point to a practical value. A melting point of 44.5 °C could be reached for the new system.

Organic-inorganic mixtures for solar energy storage systems

Abstract Mixtures of organic-inorganic substances are studied for their performance as energy storage media. Use is made of the fact that organic substances give higher amounts of energy but within a wide range of temperature on the one side and the fact that inorganic substance give lower amounts of energy at constant temperature on the other side. Mixtures of both types of substances, in different ratios, are investigated for the object of determining that optimum composition which stores a higher amount of energy and, meanwhile, releases it at a constant temperature or within a narrow range of temperature. The mixtures used are composed of Glaubers salt (Na 2 SO 4 .1OH 2 O) and stearic acid in different proportions. The effect of cooling fluid flow rate and ambient temperature as well as the effect of addition of a nucleating agent is studied. The results showed that the highest amount of energy stored could be obtained from a mixture containing 40% stearic acid and 60% Glaubers salt. The amounts of energy stored at a heat transfer fluid flow rate of 0.012 1/min are 1734, 1812 and 1978 cal for sample 1 (pure Glaubers salt), sample 2 (20% stearic acid and 80% Glaubers salt) and sample 3 (40% stearic acid and 60% Glaubers salt), respectively.

Modern solar grain dryer

Abstract A modern unit for drying grains after harvesting was investigated. The unit is simply a rotary dryer that uses solar energy as the heating source. The performance was tested and found statisfactory. Results of tests for drying corn and peanuts are given in the form of tables and curves. Peanuts were found to dry in 3 and corn in 5·5 h. Design steps of the unit are given in detail.

Solar-augmented foam-mat drying of fruits

The foam-mat drying technique is used to dry fruit syrups into powder. Literature has indicated that solar energy has not yet been used in this field. Thus, it is the object of the present work to dry the foamed syrups of different fruits in a solar energy augmented drying unit. This leads to a saving in both energy and environmental pollution. An auxiliary heater, along with a control unit, is used to ensure drying at constant temperature. Foaming is effected by suitable edible additives and in some cases a stabilizer is needed as well. New techniques concerning the concentration and neutralization of fruit syrup were reached. The drying experiments were run on orange, lemon, grapefruit, tomatoes, strawberry, guava and apple. The results showed that foaming decreased the time of drying by 30.8–41.5% in the case of direct sun drying and by 47.1–73.2% in the case of solar drying compared to the drying time of unfoamed syrup. The present study showed that the solar-augmented foam-mat drying technique proves to be of sufficient efficiency and acceptability to replace spray drying which is known to be a highly complicated and energy-consuming technique.