Abbas Rezaee

Photoelectrochemical treatment of ammonium using seawater as a natural supporting electrolyte

In the present study, a photoelectrochemical process containing seawater as a natural low-cost supporting electrolyte was used to remove ammonium from wastewater in a continuous flow mode. Based on central composite design (CCD), response surface methodology (RSM) was employed to evaluate the performance of the process in ammonia removal. The effect of four main independent parameters, including initial ammonium concentration, hydraulic retention time (HRT), current intensity and initial pH on the removal of ammonia was evaluated by the model. The optimal initial ammonium concentration, HRT, current intensity and initial pH were 917 mg NH 4− N;·L −1, 108 min, 1.8 A and 8.4, respectively. The high coefficients (R 2=0.97 and adjusted R 2=0.94) obtained by the analysis of variance (ANOVA) demonstrated close correlation between predicted and experimental values. Also, treating the reject water from the sludge dewatering unit as an ammonium-rich wastewater showed the effectiveness of the process for treating real wastewaters (86% ammonium removal). The results revealed that the present process can be an efficient method for ammonium removal from polluted effluents in coastal areas based on the availability of seawater as a cost-efficient supporting electrolyte.

Photocatalytic decolorization of methylene blue using immobilized ZnO nanoparticles prepared by solution combustion method

Abstract Photocatalytic decolorization of methylene blue (MB) in aqueous solution was investigated using ZnO nanoparticles immobilized on glass plate. The ZnO nanoparticles were prepared by solution combustion method (SCM) using zinc nitrate as oxidant and glycine as fuel. In the slurry ZnO system the separation and recycling of the photocatalyst is practically difficult. Thus, the ZnO nanoparticles were immobilized on glass supports to solve this problem. The effects of process parameters like, catalyst loading, initial dye concentration, and UV-radiation intensity have been investigated. The best results of MB removal were reported in the 1800 μW cm−2 UVC using two layers immobilized ZnO nanoparticles. In addition to removing the color from the wastewater, the photocatalytic reaction simultaneously reduced 62% COD. These results suggest that the photocatalytic decolorization of MB using immobilized ZnO nanoparticles prepared by SCM can be proposed and developed as a method for the treatment of colored w...

Photocatalytic degradation of formaldehyde in aqueous solution using ZnO nanoparticles immobilized on glass plates

AbstractIn the present study, the application of a photocatalytic process equipped with immobilized ZnO nanoparticles on glass plates was studied for removing formaldehyde in an aqueous phase. According to the obtained data, the removal efficiency of formaldehyde was sharply decreased to 12.96% as the solution experienced strong acidic conditions (pH 2). In addition, the removal efficiency was decreased from 56.41 to 44.02% with increasing pH values from 7 to 10, respectively, indicating a considerable drop in the removal efficiency at basic conditions. As the initial concentration of formaldehyde fed into the reactor was increased from 500 to 4000 mg/L, its removal efficiency decreased from 62.30 to 11.96%, respectively, in a short time of 30 min. The obtained removal efficiency of chemical oxygen demand (41%) demonstrated a considerable mineralization of formaldehyde along with a removal efficiency of 56.41%. The kinetic study was performed and the result indicated a significant reaction rate of the pho...

TiO2 nanofibre assisted photocatalytic degradation of Reactive Blue 19 dye from aqueous solution

The photocatalytic degradation of Reactive Blue 19 (RB19) dye has been studied using TiO2 nanofibre as the photocatalyst in aqueous solution under UV irradiation. Titanium dioxide nanofibre was prepared using a templating method with tetraisopropylorthotitanate as a precursor. The experiments were carried out in the presence of the TiO2 nanofibre, and the effects of pH and electron acceptors on the degradation process were investigated. In order to observe the quality of the aqueous solution, chemical oxygen demand (COD) measurements were also carried out before and after the treatments. The photocatalytic decomposition of RB19 was most efficient in acidic solution. With the addition of hydrogen peroxide and potassium persulphate, as electron acceptors, into illuminated TiO2 nanofibre suspensions, a synergistic effect was observed leading to an enhancement of the decolorization. From experimental results, under the condition of 1 g TiO2 nanofibre L−1, pH 3, and UVC light irradiation, decolorization would be complete in two hours. A significant decrease in the COD values was observed, which clearly indicates that the photocatalytic method offers good potential for the removal of RB19 from aqueous solution. The kinetic of photocatalytic removal of RB19 followed the Langmuir–Hinshelwood model. These results suggest that TiO2 nanofibres with UV photocatalysis can be envisaged as a method for the treatment of coloured wastewaters, in particular in textile industries.

Application of Biosurfactants Produced by Pseudomonas aeruginosa SP4 for Bioremediation of Soils Contaminated by Pyrene

Biosurfactants are considered to facilitate PAHs dissolution in soil slurries for bioremediation applications. In this work, the carbon and nitrogen sources, pH, C/N ratio, and salinity, were considered for optimization of biosurfactant production by Pseudomonas aeruginosa SP4 isolate to enhance pyrene removal from the contaminated soil. Analysis of ANOVA indicated that the carbon source was the most effective factor, followed by pH, nitrogen source, C/N ratio, and salinity. Taguchi experimental design proposed the optimum operating conditions of olive oil, NH4NO3, C/N ratio of 5, salinity of 0.5%, and pH 7. Applying the conditions determined by Taguchi design led to a production yield of 452 mg L−1 (13% improvement) at the optimum conditions. The main characteristics of produced biosurfactant included the critical micelle concentration (CMC) of 60 mg L−1 and liquid medium surface tension of 29.5 mN m−1. Produced biosurfactant was used for bioremediation of soil artificially contaminated with 500 mg kg−1 of pyrene. Following the addition of 250 mg L−1 biosurfactant, the pyrene removal of 84.6% was obtained compared to 59.8% for control sample without any surfactant.

Simultaneous nitrification and denitrification using a polypyrrole/microbial cellulose electrode in a membraneless bio-electrochemical system

In this study, the feasibility of ammonium and total nitrogen (TN) removal from aqueous solution using a simultaneous nitrification and denitrification process was studied in a membraneless (single chamber) bio-electrochemical system with a novel electrode. The main objectives were to synthesize a polypyrrole/microbial cellulose (PPy/MC) composite and utilize it as a novel electrode material. To determine the mechanical properties of PPy/MC, the tensile strength and Young’s modulus were investigated. A biofilm was prepared using the fabricated electrode during the first few weeks. Effective parameters such as initial ammonium concentrations (NH4+ ∼ 15–150 mg N L−1), HRT (6–72 h), carbon/nitrogen ratio (C/N ratio ∼ 0–4), current intensity (2–10 mA), and pH (6.5–8.5) were evaluated. The following optimum values were obtained: HRT, 24 h; C/N ratio, 2; electric current, 6 mA; and pH, 7–7.5 at a constant ammonium concentration of 77.77 mg N L−1. It can be concluded from the experimental data that under optimal conditions about 97.42 and 62.47% of ammonium and TN were removed successfully, respectively.

Overview of bio nanofabric from bacterial cellulose

Nanofibers and bio-nonwoven fabrics of pure cellulose can be made from some bacteria such as Acetobacter xylinum. Bacterial cellulose fibers are very pure, 10 nm in diameter and about 0.5 micron long. The molecular formula of bacterial cellulose is similar to that of plant cellulose. Its fibers are very stiff and it has high tensile strength, high porosity, and nanofibrillar structure. They can potentially be produced in industrial quantities at greatly lowered cost and water content, and with triple the yield by a new process. This article presents a critical review of the available information on bacterial cellulose as a biological nonwoven fabric with special emphasis on its fermentative production and applications. Characteristics of bacterial cellulose biofabric with respect to its structure and physicochemical properties are discussed. Current and potential applications of bacterial cellulose in textile, nonwoven cloth, paper, films, synthetic fiber coating, food, pharmaceutical, and other industries are also presented.

Bioelectrochemical denitrification using carbon felt/multiwall carbon nanotube

The aim of this work was to enhance the efficiency of a bioelectrochemical denitrification process using a biocathode of carbon felt (CF)/multiwall carbon nanotube (MWCNT) composite. The efficiency of the bioelectrochemical denitrification was assessed as the function of various operational parameters, such as ORP, pH, current density, retention time and nitrate concentrations. Scanning electron microscope (SEM) images of the biocathode surfaces revealed a homogeneous distribution of the MWCNT on the CF matrix. Optimum ORP, pH, current density and retention time were −100 mV, 7.0, 15 mA/cm2 and 6 h, respectively. The highest nitrate removal efficiency at the optimum condition was 92.7% for CF/MWCNT. The reduction time for achieving the nitrate standard using CF/MWCNT was 4 h. It is proposed that the prepared nanocomposite will have the best biocathode properties in the bioelectrochemistry denitrification experiments.

Electrochemical degradation of RB19 dye using low-frequency alternating current: effect of a square wave

This study mainly aims to investigate the effects of alternating current (AC) on Remazol Brilliant Blue R (RB19) dye removal from aqueous solutions by an electrochemical (EC) process. The effects of operating conditions on RB19 removal were investigated; the conditions include the AC frequency, the magnitude of a waveform in Vpp (AMPL) accompanied with a constant voltage that is added to an AC source (OFST), the supporting electrolyte (type and concentration), and the initial dye concentration. Moreover, the effects of variation in electrical conductivity, oxidation–reduction potential, and pH on the efficacy of the process were evaluated. Results showed that the highest RB19 removal efficiency with low electrode weight loss was obtained at AMPL and OFST of 8 Vpp and 0.2 V, respectively. Results of our kinetic study showed that the addition of NaCl as a supporting electrolyte has an enhancing effect on the rate constant, possibly because of an increase in the concentration of active oxidant species such as Cl2/OCl− in the electrolyte. A morphology study on the electrode surface showed that electrodes dissolved uniformly during the EC process. The loss on ignition (LOI) was determined to be 43.25% by X-ray fluorescence (XRF) analysis. The energy consumption and operating costs for RB19 removal using a square wave AC were evaluated. The results indicated that the use of a square wave AC is a promising wastewater treatment technique.

Enhancement of lipase activity for the oily wastewater treatment by an electrostimulation process

The efficacy of electrostimulation on bacterial lipase activity and COD removal was studied using a laboratory bioelectrochemical system. A stainless steel mesh was used as both anode and cathode. The results showed that the maximum lipase activity obtained was 38 Umol mL−1 at an applied current of 1 mA and a COD concentration of 1100 mg L−1. COD removal efficiency decreased when the reaction time was shorter. Moreover, the lipase activity increased when current was increased to 10 mA. The optimum pH for the lipase activity was 7.0, and when the pH value was increased to 9.0, the lipase activity decreased. The kinetics for the COD removal were specified based on the data for the decomposition time, which was the reaction time required to attain a COD removal of more than 99% in the feed wastewater. Linear plotting showed that the experimental data fitted very well with that of the Michaelis–Menten model (R2 = 0.9955). This shows that a suitable applied current could stimulate and improve the lipase activity. Therefore, this study provides useful information to correct the bioelectrochemical system designs and increase the removal efficiency of dissolved oils.