Co-doped carbon nanofiber mats can be prepared by the addition of cobalt acetate to the polyacrylonitrile/DMF electrospun solution. Wastewater obtained from food industries was utilized as the anolyte as well as microorganisms as the source in single-chamber batch mode microbial fuel cells. The results indicated that the single Co-free carbon nanofiber mat was not a good anode in the used microbial fuel cells. However, the generated power can be distinctly enhanced by using double active layers of pristine carbon nanofiber mats or a single layer Co-doped carbon nanofiber mat as anodes. Typically, after 24 h batching time, the estimated generated power densities were 10, 92, and 121 mW/m2 for single, double active layers, and Co-doped carbon nanofiber anodes, respectively. For comparison, the performance of the cell was investigated using carbon cloth and carbon paper as anodes, the observed power densities were smaller than the introduced modified anodes at 58 and 62 mW/m2, respectively. Moreover, the COD removal and Columbic efficiency were calculated for the proposed anodes as well as the used commercial ones. The results further confirm the priority of using double active layer or metal-doped carbon nanofiber anodes over the commercial ones. Numerically, the calculated COD removals were 29.16 and 38.95% for carbon paper and carbon cloth while 40.53 and 45.79% COD removals were obtained with double active layer and Co-doped carbon nanofiber anodes, respectively. With a similar trend, the calculated Columbic efficiencies were 26, 42, 52, and 71% for the same sequence.

To enhance the treatment of real industrial wastewater effluents, a new design of an electromagnetic field-enhanced electrochemical cell consisting of a tubular screen roll anode and two cathodes (an inner and outer cathode) has been used. The treatment of real beet sugar mill effluent by the electrocoagulation process has been studied. The cell has a uniform current distribution, a low IR drop, and good mixing. Different parameters have been investigated, like: current density (CD), effluent concentration, NaCl concentration, rpm, number of screen layers per anode, and the effect of the addition of an electromagnetic field. The results showed that, under the optimum conditions of CD at 3.13 Am− 2, two screens per anode, NaCl concentration of 12 g/L, and rotation speed at 120 rpm, the percentage of color removal was 85. 5% and the electrical energy consumption was 3.595 kWhm− 3. In addition, the presence of electromagnetic field enhanced the energy consumption for the wastewater treatment by accelerating the coagulation step as indicated by simulation results. Numerically, applying the magnetic field resulted in performing a color removal efficiency of 97.7% using a power consumption of 2.569 KWh/m3 which is considered a distinct achievement in industrial wastewater treatment process. This design has proven to be a promising one for continuous treatment of industrial effluents and to be a possible competent to the currently available techniques due to the high removal efficiency and low energy consumption.

Phenolic compounds are the major source of colour in sugar mill effluent. Details mechanism of diffusional resistances for removal of phenolic compounds namely: phenol, 2-4 dichlrophenol and 2-4 dinitrophenol by adsorption onto activated carbon rice husk (ACRH) was studied. The mechanism studied was based on three diffusional resistance models: external mass transfer, intraparticle diffusion and twin resistance mass transfer. The relationship of mass transfer coefficient versus time shows that the adsorption process follows two regimes started with high mass transfer and then low mass transfer, due to high diffusion from bulk to surface of ACRH particles then slow mass transfer into pores of ACRH. The comparison between the three models was followed up by using the relationship of mass transfer coefficient versus time (kα c n ).It was found that adsorption of phenol in the intraparticle structure is 180% higher than adsorption on the external surface of the ACRH. The value of mass transfer coefficient of the twin resistance model is close to that of external mass transfer model and both are lower than that of intraparticle diffusion model. The experimental results proved that intraparticle diffusion is controlling step. Moreover, three adsorption isotherms were studied: Langmuir, Freundlich and Dubinini -Roduch (D-R) for the three phenolic compounds.

Carbon nanofiber-decorated graphite rods are introduced as effective and low-cost anodes for industrial wastewater-driven microbial fuel cells. Carbon nanofiber deposition on the surface of the graphite rods could be performed by the electrospinning of polyacrylonitrile/N,N-Dimethylformamide solution using the rod as nanofiber collector, which was calcined under inert atmosphere. The experimental results indicated that at 10 min electrospinning time, the proposed graphite anode demonstrates very good performance compared to the commercial anodes. Typically, the generated power density from sugarcane industry wastewater-driven air cathode microbial fuel cells were 13 ± 0.3, 23 ± 0.7, 43 ± 1.3, and 185 ± 7.4 mW/m2 using carbon paper, carbon felt, carbon cloth, and graphite rod coated by 10-min electrospinning time carbon nanofibers anodes, respectively. The distinct performance of the proposed anode came from creating 3D carbon nanofiber layer filled with the biocatalyst. Moreover, to annihilate the internal cell resistance, a membrane-less cell was assembled by utilizing a poly(vinylidene fluoride) electrospun nanofiber layer-coated cathode. This novel strategy inspired a highly hydrophobic layer on the cathode surface, preventing water leakage to avoid utilizing the membrane. However, in both anode and cathode modifications, the electrospinning time should be optimized. The best results were obtained at 5 and 10 min for the cathode and anode, respectively.

The treatment of real beet sugar mill effluent by a modified electrocoagulation process is proposed. An innovative design of an electromagnetic field-enhanced electrochemical cell consisting of a tubular screen roll anode and two cathodes (an inner and outer cathode) has been used. Different parameters have been investigated including current density, effluent concentration, NaCl concentration, rpm, number of screen layers per anode, and the effect of addition and direction of an electromagnetic field. The results showed that, under the optimum conditions, current density of 3.13 A/m2, two screens per anode, NaCl concentration of 12 g/l, and rotation speed of 120 rpm, the percentage of color removal was 85.5% and the electrical energy consumption was 3.595 kWh/m3. However, the presence of an electromagnetic field distinctly enhanced the energy consumption and the color removal percentage. Numerically, applying the magnetic field resulted in performing a color removal efficiency of 97.7% using a power consumption of 2.569 KWh/m3 which is considered a distinct achievement in industrial wastewater treatment process. The strong enhancement in color removal using a low power consumption significantly reduced the required treatment cost; the estimated treatment cost was 0.00017 $/h.m2. This design has proven to be a promising one for the continuous treatment of beet sugar industrial effluents and to be a competitor to the currently available techniques.