Hatice Inan

Olive oil mill wastewater treatment by means of electro-coagulation

Abstract The removal of chemical oxygen demand (COD), color and suspended solid (SS) from olive oil mill wastewater (OMWW) was experimentally investigated by using electro-coagulation (EC). Aluminum and iron were used in the reactor simultaneously as materials for electrodes. The reactor voltage was 12 V, current density (CD) was changing between 10 and 40 mA cm −2 , pH was taken equal to 4, 6, 7, and 9 units, and duration varied in the limits of 2–30 min. Under the 30-min retention time, 52% COD was removed by the aluminum anode and 42% was removed by the iron anode. CD efficiency versus the percent of COD removal was examined at the 10-min retention time for pH 6.2±0.2. It appeared that with the CD increase, the percent of COD removal was increasing as well. The color removal yield was examined as the result of using different retention times, current densities, and iron and aluminum as materials for anodes. CD values in the range of 10–40 mA cm −2 were tested at the 10-min retention time each one; color removal was 90–97% by this. In this study the EC process was examined with the aim of determining the highest rate of SS removal from the OMWW as well.

WATER QUALITY FACTORS AFFECTING BROMATE REDUCTION IN BIOLOGICALLY ACTIVE CARBON FILTERS

Biological removal of the ozonation by-product, bromate, was demonstrated in biologically active carbon (BAC) filters. For example, with a 20-min EBCT, pH 7.5, and influent dissolved oxygen (DO) and nitrate concentrations 2.1 and 5.1 mg/l, respectively, 40% bromate removal was obtained with a 20 microg/l influent bromate concentration. In this study, DO, nitrate and sulfate concentrations, pH, and type of source water were evaluated for their effect on bromate removal in a BAC filter. Bromate removal decreased as the influent concentrations of DO and nitrate increased, but bromate removal was observed in the presence of measurable effluent concentrations of DO and nitrate. In contrast, bromate removal was not sensitive to the influent sulfate concentration, with only a slight reduction in bromate removal as the influent sulfate concentration was increased from 11.1 to 102.7 mg/l. Bromate reduction was better at lower pH values (6.8 and 7.2) than at higher pH values (7.5 and 8.2), suggesting that it may be possible to reduce bromate formation during ozonation and increase biological bromate reduction through pH control. Biological bromate removal in Lake Michigan water was very poor as compared to that in tapwater from a groundwater source. Bromate removal improved when sufficient organic electron donor was added to remove the nitrate and DO present in the Lake Michigan water, indicating that the poor biodegradability of the natural organic matter may have been limiting bromate removal in that water. Biological bromate removal was demonstrated to be a sustainable process under a variety of water quality conditions, and bromate removal can be improved by controlling key water quality parameters.

Phosphate and nitrogen removal by iron produced in electrocoagulation reactor

AbstractIn this study, concentrated iron solution generated by electrocoagulation (EC) process was used for the removal of nutrients from human urine (yellow water). Yellow water was prepared synthetically with major components: nitrogen and phosphorus. As a result of the pH adjustment, nitrogen and phosphorus, which are present in urine, react with electrochemically generated iron solution and then accumulate in the sludge by precipitation. All experiments were done under different pH values for the evaluation of this novel EC nutrient removal process. The effect of the EC treatment on the removal of nutrients was followed by total nitrogen and phosphate measurements and Fourier transform infrared spectroscopy (FTIR). The effects of treatment parameters (pH, iron/phosphate, iron/nitrogen, and iron/nutrient ratios) on the performance of the EC treatment were also examined for the evaluation of applicability of this novel EC method for the treatment of yellow waters. The results show that the pH increase i...

Experimental and theoretical study on catalytic ozonation of humic acid by ZnO catalyst

ABSTRACT Ozonation and catalytic ozonation of humic acid (HA) in the presence of ZnO were examined in a batch scale reactor. The degradation of HA by catalytic ozonation was found to be much more effective than ozonation alone. The quantum chemistry calculations showed that the reaction of the O3 disproportionation on the surface of ZnO corresponds to the barrierless mechanism. The activation energy of the transition state formation was −5.25 eV. The active oxygen atom formed on the surface of ZnO was found as interacting with both water molecules and dissolved organic molecules, which might lead to further oxidizing reactions.

Degradation of Toxic Indigo Carmine Dye by Electrosynthesized Ferrate (VI)

Response surface methodology was applied for optimizing indigo carmine (IC) dye removal by electrochemically produced ferrate (VI). Box-Behnken design was employed in this study, and design parameters were pH, Fe (VI) dose and initial dye concentration (C o ). R 2 and adjusted R 2 values were very high that indicated very good accuracy for the employed model. Optimum operational conditions were: 4.08-7.69 for pH, 24-118.83 mg/L for Fe (VI) dose and 60.68-99.13 mg/L for complete removal of IC. Produced by electrochemical method Ferrate (VI) provides high effectiveness for IC dye-containing synthetic wastewater.