Nickel, a prevalent metal in the ecosystem, is released into the environment through various anthropogenic activities, leading to adverse effects. This research explored utilizing zeolite scony mobile-5 (ZSM-5) nanoparticles encapsulated in sodium alginate (SA) for nickel (II) removal from aqueous solutions. The adsorption characteristics of SA/ZSM-5 were examined concerning contact duration, initial metal ion concentration, pH level, temperature, and sorbent dosage. The findings revealed that a rising pH reduced Ni (II) uptake by the sorbent while increasing the Ni (II) concentration from 25 to 100 mg L⁻¹ led to a decrease in removal percentage from 91 to 80% under optimal conditions. Furthermore, as sorbent dosage increased from 4 to 16 g L⁻¹, uptake capacity declined from 9.972 to 1.55 mg g⁻¹. Concurrently, SA/ZSM-5 beads' Ni (II) sorption capacity decreased from 96.12 to 59.14% with a temperature increase ranging from 25 to 55 °C. The Ni (II) sorption data on SA/ZSM-5 beads are aptly represented by Langmuir and Freundlich equilibrium isotherm models. Moreover, a second-order kinetic model characterizes the adsorption kinetics of Ni (II) on the SA/ZSM-5 beads. A negative free energy change (ΔG°) demonstrates that the process is both viable and spontaneous. The negative enthalpy values indicate an exothermic nature at the solid–liquid interface while negative entropy values suggest a decrease in randomness. In conclusion, this novel adsorbent exhibits promise for removing nickel from aqueous solutions and could potentially be employed in small-scale industries under similar conditions.

This study aimed to investigate, from a techno-economic point of view, cattle slaughterhouse wastewater (CSWW) treatment via the electrocoagulation (EC) technique. A novel lab-scale EC unit with a 3 L volume was manufactured and tested. The EC unit contains nine identical cylindrical shape electrodes from aluminum material in connection with a controllable DC power supply. Investigation of optimum operating parameters in terms of pH, current density (CD), contact time, and electrolyte concentration was carried out in batch mode and then applied to continuous mode. At each batch, a cost analysis was calculated in terms of the consumption of electrode material and electrical power. The optimum operating conditions at which the best removal efficiency was achieved were pH 7, contact time 75 min, total dissolved solids of 3000 mg L⁻¹, and CD of 4 mA cm⁻². After application of these conditions on continuous flow mode, the removal efficiency of chemical oxygen demand, color, turbidity, biological oxygen demand, and oil, grease were 95, 99, 99, 97 and 95%, respectively. The total electrode consumption and electrical consumptions were 0.6 kg m⁻³and 0.87 kWh m⁻³with an operational cost of about $1.5 m⁻³. This proved that EC is a techno-economically effective treatment method than other conventional treatment methods for high-rate removal of pollutants from CSWW.

This study aimed to evaluate the efficiency of a novel pilot-scale passively aerated biological filter (PABF) as a low energy consumption system for the treatment of municipal wastewater. It consists of four similar compartments, each containing 40% of a non-woven polyester fabric as a bio-bed. The PABF was fed with primary treated wastewater under a hydraulic retention time (HRT) of 3.5 hr and a hydraulic loading rate of 5.5 m²/m³/d. The effect of media depth, HRT, dissolved oxygen (DO) and surface area of the media on the removal efficiency of pollutants was investigated. Results indicated that increasing media depth along the axis of the reactor and consequently increasing the HRT and DO resulted in great removal of different pollutants. A significant increase in the DO levels in the final effluent up to 6.7 mg/l resulted in good nitrification processes. Statistical analysis using SPSS showed that the reactor performance has significant removal efficiency (p < .05) for all pollutants. Overall results indicated that PABF is a viable ecological engineering approach that can be optimized and applied to improve water quality with minimal consumption of energy and low sludge production compared with conventional activated sludge and trickling filter systems.