جستجوی مقالات مرتبط با کلیدواژه « COD » در نشریات گروه « مواد و متالورژی »

This study was conducted to improve the voltage production, desalination, and COD removal efficiencies of a five-chamber Microbial Desalination Cell (MDC). To do this, rhamnolipid was added to anolytes only and catholytes stirred to determine the effects of these factors on the MDC activity. This was followed by a factorial study to investigate the effects of the interactions of rhamnolipid and stirring on the voltage production, desalination, and COD removal efficiencies of the MDC. Increasing the concentration of rhamnolipid to 240 mg/L improved the peak voltage produced from 164.50 ± 0.11 to 623.70 ± 1.32 mV. Also, the desalination efficiency increased from 20.16 ± 1.97 % when no rhamnolipid was added to 24.89 ± 0.50 % at a rhamnolipid concentration of 240 mg/L, and COD removal efficiency increased from 48.74 ± 8.06 % to 64.17 ± 5.00 % at a rhamnolipid concentration of 400 mg/L. In the stirring experiments, increasing the number of stirring events increased peak voltage from 164.50 ± 0.11 to 567.27 ± 18.06 mV. Similarly, desalination and COD removal efficiencies increased from 20.16 ± 1.97 % and 48.74 ± 8.06 % to 24.26 ± 0.97 % and 50.23 ± 1.60 %, respectively, when the number of stirring events was more than twice a day. In the factorial study, voltage production, desalination, and COD removal efficiencies were 647.07 mV, 25.50 %, and 68.15 %, respectively. However, the effect of the interaction between rhamnolipid and stirring was found to be insignificant (p>0.05). Thus, the addition of only rhamnolipid or the stirring of catholytes only can improve the performance of the five-chamber MDC.

A mixture of 10 wt% CuO-10 wt% Fe2O3 supported on cordierite were prepared by wet impregnation. The as-prepared solids doped with Li2O (0.75-3 mol %) were calcined at 500-900 ºC. The crystalline phase, morphology, and surface area were investigated by XRD, HR-TEM and N2-adsoprtion-desorption. Moreover, their photocatalytic activities of samples calcined at 700°C on the degradation of phenol were evaluated under UV-irradiation. The catalytic activity of different solids toward H2O2 decomposition was studied. Nano-materials were used to adsorb dyes as Remazole-Red and Congo-Red from aqueous solution. The sorption process was in good agreement of pseudo-second order equation and the Langmuir equation through their adsorption kinetics and isotherms, respectively. The CuO-Fe2O3/ cordierite doped with 0.75% Li2O at 700 ºC adsorbent was found to possess the highest removal efficiency of Remazole-Red and/or Congo-Red dyes and potentially lowering capital and operational costs for practical applications. The highest removal efficiency of the anionic dyes over 0.75% Li2O at 700 ºC can be discussed by observing the appearance of new active phases as CuO, CuFe2O4 and LiCuO, decreasing the crystallite size of these active phases. 0.75 mol% Li2O has the greatest activity in H2O2 decomposition reached 700 %. This result may be related to the lowest particle size and the highest surface area of this sample, which also produced a large number of electrons donating active sites for H2O2 decomposition

The aim of this research was to evaluate the effective parameters such as pH, current density (mA/cm2), H2O2/Fe2 molar ratio, volume ratio of H2O2 to pharmaceutical wastewater (PhW) (ml/l) and reaction time (min) on the electro-Fenton process for the ibuprofen (as a pharmaceutical waste in water) removal. Since a synthetic wastewater with the same concentration of ibuprofen in a real pharmaceutical wastewater (400 ppm) was chosen in this research, the sample was tested in terms of the chemical oxygen demand (COD). The parameters were statistically optimized under response surface mythology (RSM). The software was also applied to minimize the number of runs. The optimum conditions for 98.290% COD removal were at pH of 2.43, current density of 23.08 mA/cm2, H2O2/Fe2 molar ratio of 2.69, volume ratio of H2O2/PhW of 1.84 ml/l and reaction time of 28.08 min.

Vinasse that has high COD and total solid content is bottom of distillation from unit of bioethanol production Vinasse treatment using anaerobic digestion produced biogas. This research used anaerobic digester-laboratory scale at room temperature and batch system. The purpose of this research was investigation the effect of total solid content to biogas production rate from vinasse, pH profil and COD removal. Initial pH for all variables were adjusted 7 by using NaOH. The result showed that vinasse:water ratio of 1:3 (TS 7.015±0.007%) produced the most total biogas (37.409 mL/g COD) however vinasse:water ratio of 1:2 (TS 9.310±0.014%) had the biggest COD removal (23.580±0.532%) than others. Variables with TS more than 7.015±0.007% caused the overloading in the digester whereas below of that caused unstable in decomposition process. Total solid that was in high level indicated COD content of substrates in high level. The more of COD concentration of substrates in the digester made the more of COD removal after fermentation process at anaerobic condition.