Global NEST Journal

Protozoa play a significant role in activated sludge systems, since they graze on dispersed bacteria, supporting a healthy food web in the activated sludge artificial ecosystem. However, operational parameters and influent properties are the most important factors affecting the composition of activated sludge microfauna. The objective of this study was the assessment of the treatment efficiency and the protozoan populations in activated sludge systems with and without the addition of polyvinyl alcohol (PVA) gel beads while treating wastewater in the presence of phenol. Six activated sludge reactors - 3 of them supplied with PVA gel beads –were used for the treatment of synthetic wastewater influent containing phenol at concentrations up to 10 mg/L. During the treatment of synthetic wastewater, dominance of the sessile species was observed mainly in the reactors supplied with PVA beads. Physicochemical analyses of the effluent indicated good efficiency of reactors supplied with PVA beads in removing nutrients and organic load. Introduction of phenol in the influent at a concentration of 5 mg/L did not affect significantly the operation of the reactors and the composition and abundance of activated sludge microfauna, while a high phenol removal rate was observed. The increase of influent phenol concentration to 10 mg/L resulted to the formation of foam on the surface of the reactors and the presence of Zoogleasp, while an increase was observed in the abundance of crawling species in activated sludge and PVA supplied reactors respectively.

This study was conducted to remove Methylene Blue (MB) from aqueous solution using activated carbon prepared from N. microphyllum (AC-NM) as a new, cheap, and non-toxic. Design of experiments based on Response Surface Methodology (RSM) conducted to investigate the effect of variables namely; initial dye concentration, pH, contact time and absorbent dosage. An empirical model was developed applying ANOVA analysis. The interaction effects of all factors and their optimization have been carried out using RSM. Dye removal efficiency increased to more than 90% with increasing pH and initial concentration of dye from 3 to 11 and 10 to 210 mg/L, respectively under 1.1 to 1.4 g/L of absorbent dosage. Among factors, initial concentration of MB known as an important factor with P- value <0.0001. The experimental data are fitted with Freundlich model based on multi layer adsorption states (R2=0.99). The adsorption kinetics well described by second order model with R2 = 0.98. This novel absorbent has different advantages such as low cost, high ability to absorb pollutants and easily available that can be suggested for water and wastewater treatment.

This study investigates the feasibility of using cathode catalyst (Iron phthalocyanine (FePc) combined multi walled carbon nano tubes (MWCNT) and compares the oxygen reduction rate under different conductivity of catholite solution (50 mM, 100mM) in double chamber Microbial Fuel Cell. Microbial fuel cell (MFC) research is going on for few decades to increase the power density and improve the removal efficiency. Iron phthalocyanine (FePc) combined multi walled carbon nano tubes (MWCNT) cathode catalyst showed the highest power density
(9.34 w/m2) in 100 mM PBS than 50 mM (7.58 W/m2). The electrodes are characterized by scanning electron microscopy (SEM) and the electrocatylitic activity of the catalyst coated electrodes were examined by cyclic voltammetry(CV). The high power density indicates a potential alternative to precious platinum metal catalyst in treatment as well as electricity production Microbial Fuel cell.

The biosorption of Cr (III), Zn (II) and Ni (II) ions from aqueous solution by dead blue algal biomass (Cyanophyta) was investigated in single metal system and batch conditions. Experimental parameters included contact time (0-140 min), pH (2-8), sorbent dose (0.1-2.0 g), initial concentrations (10-120 mg/L), agitation speeds (50-300 rpm) and temperatures (298-232K) were investigated. The best values of pH were found 4 for Cr+3, Zn+2 and 5 for Ni+2, respectively. The biosorption process was relatively fast and equilibrium established after 90 min. Equilibrium isotherm experiments data were analyzed by Langmuir and Freundlich isotherm models and Langmuir isotherms gives the best fit to the experimental data. Biosorption kinetic models were used for the single metal system using the dead blue algal biomass, good matching was found between pseudo second order kinetic model and experimental data for Cr (III), Zn (II), and Ni (II) ions systems. Thermodynamic parameters included Go; Ho and So during the process were calculated, the results show that the biosorption process applied to remove Cr (III), Zn (II) and Ni (II) ions using blue algal biomass (Cyanophyta) is feasible, spontaneous and exothermic at 10 – 30 °C. The results indicated that blue algal biomass (Cyanophyta) could be used as a good sorbent for treatment of industrial effluents containing Cr (III), Zn (II) and Ni (II) ions in single metal system.