Maha A. Tony

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.

Oil refinery wastewater treatment using physicochemical, Fenton and Photo-Fenton oxidation processes

The objective of this study was to investigate the application of advanced oxidation processes (AOPs) to the treatment of wastewaters contaminated with hydrocarbon oil. Three different oil-contaminated wastewaters were examined and compared: (i) a ‘real’ hydrocarbon wastewater collected from an oil refinery (Conoco-Phillips Whitegate refinery, County Cork, Ireland); (ii) a ‘real’ hydrocarbon wastewater collected from a car-wash facility located at a petroleum filling station; and (iii) a ‘synthetic’ hydrocarbon wastewater generated by emulsifying diesel oil and water. The AOPs investigated were Fe2+/H2O2 (Fentons reagent), Fe2+/H2O2/UV (Photo-Fentons reagent) which may be used as an alternative to, or in conjunction with, conventional treatment techniques. Laboratory-scale batch and continuous-flow experiments were undertaken. The photo-Fenton parametric concentrations to maximize COD removal were optimized: pH = 3, H2O2 = 400 mg/L, and Fe2+ = 40 mg/L. In the case of the oil-refinery wastewater, photo-Fenton treatment achieved approximately 50% COD removal and, when preceded by physicochemical treatment, the percentage removal increased to approximately 75%.

Evaluating the photo-catalytic application of Fenton's reagent augmented with TiO2 and ZnO for the mineralization of an oil-water emulsion.

In the present study, homogenous (photo-Fenton) and heterogeneous photo-assisted systems (Fenton/TiO2/UV, Fenton/ZnO/UV and Fenton/TiO2/UV/Air) were investigated for the treatment of a diesel-oil wastewater emulsion. The augmentation of the photo-Fenton process by heterogeneous TiO2 increased the reaction rate, in terms of COD reduction efficiency from 61% to 71%. Furthermore, the COD removal efficiency was increased to 84% when air was bubbled through the reactants. However, if the Fenton/TiO2 /UV/Air process is to be utilized as a treatment for this wastewater, the separation of the TiO2 from the treated effluent would need further consideration.

Fenton and Fenton-like AOPs for alum sludge conditioning : effectiveness comparison with different Fe2+ and Fe3+ salts

Currently, organic polymers are adopted in alum sludge (aluminum-coagulated drinking water treatment sludge) conditioning. However, there are important concerns regarding the use of these polymers because of the unknown and long-term effects of the potential release of excess polymer to the surrounding environment when the sludge is landfilled. Therefore, as an initial action, this study aimed at investigating alternative chemical conditioning methods and focused mainly on exploiting Fenton (Fe2+/H2O2) and Fenton-like (Fe3+/H2O2) reagents as the conditioner. Experiments have been conducted to test the effectiveness of Fentons reagent (containing the ferrous salts of chloride, sulfate, or oxalate), Fenton-like reagent (containing ferric salts of chloride and sulfate), and the coagulation method using FeCl3 for alum sludge conditioning at constant hydrogen peroxide and iron salt concentrations of 125 and 20 mg/g DS (dry solids), respectively. The effectiveness on dewaterability of the alum sludge demonstrated that the maximum reduction (%) of SRF (specific resistance to filtration) and CST (capillary suction time) of 74% and 47%, respectively, can be obtained when Fentons reagent was adopted for sludge conditioning. Such reduction of 64% for SRF and 38% for CST can be achieved when Fenton-like reagents were applied.