Economically feasible approaches are needed for wastewater treatment. Electrocoagulation (EC) is an electrochemical treatment method that removes various pollutants from wastewater. It has grown in popularity over conventional treatment methods, especially in industrial wastewater, due to its high performance and the ability to remove toxic compounds. However, it is crucial to reduce the costs associated with EC for widespread implementation. It is also important to decrease nickel (Ni) concentrations in wastewater to prevent potential health and environmental problems. Therefore, this study investigates Ni removal from synthetic and real wastewater using electrocoagulation. Zinc, as a novel electrode, was used as the sacrificial anode. Several operating conditions were assessed, including current density, initial pH, electrolysis time, and spacing between electrodes. The maximum Ni removal efficiency, after 90 min, reached 99.9% at a current density of 10 mA/cm² when the pH was 9.2 and the gap distance was 4 cm. The Ni removal rate reached 94.4% and 94.9% at a 2- and 6-cm spacing, respectively, after 90 min. Anode morphology, kinetic modeling, electrical energy consumption, and cost analysis were also investigated. The type of corrosion was uniform, which is easily predicted compared to pitting corrosion. The comparison between chemical coagulation and electrocoagulation was also reported. Experimental results indicated that the maximum Ni removal rates reached 99.89% after 90 min. The optimum spacing between electrodes was 4 cm, and the optimum current density was 10 mA/cm². Additionally, the kinetic data were best represented through the second-order Lagergren model. The results demonstrated that the electrocoagulation performance was better than that of chemical coagulation for Ni removal. The maximum electrical energy consumption was 23.79 KWh/m³ for Ni removal.

This study investigated the ability of granular activated alumina to remove urea from wastewater through adsorption, and compared its performance with granular activated carbon. XRF, EDX, XRD, and TGA were used to investigate the adsorbents. The removal of urea as a function of pH value was studied. The point of zero charge for activated alumina was found to be 8.8, while that for activated carbon was found to be 7.1. The experimental data of the adsorption process were explored by fitting to different kinetic models to determine the adsorption kinetics and mechanisms. Then, the equilibrium data were examined by fitting to various two-parameter and three-parameter isotherm models. Results showed that the removal efficiency increased with the increasing pH value. The maximum removal efficiencies were 24% and 31% for granular activated alumina and granular activated carbon, respectively, at pH = 9.0. Kinetic studies showed that adsorption of urea onto both activated alumina and activated carbon can be expressed by pseudo second order kinetics. Equilibrium studies showed that the adsorption isotherms could be expressed by the Redlich-Peterson isotherm and Temkin isotherm for activated alumina and activated carbon, respectively. Adsorbents were investigated using FTIR and SEM, and results showed the occurrence of adsorption.

Nowadays, beneficial microorganisms are getting wider applicability. One example is referred to as Effective Microorganisms (EM) having its composition kept a secret. EM is a product in liquid form, which consists of a variety of not only effective and beneficial microorganisms but also nonpathogenic ones, with admirable coexistence between aerobic and anaerobic types of microorganisms. The aim of this narrative review is to provide a summary of the different uses and applications of EM, their applications, their benefits, and the expected results when using them in different applications. This is the first review to focus on the uses of EM in environmental engineering systems and processes such as wastewater treatment processes. Originally, EM was manufactured to be utilized in organic farming, but at the moment, this substance is getting wider applications such as in medicine, environment, livestock sector, forestry, and agriculture. When it comes to the protection of the environment, EM helps in waste deodorization, eutrophication control, and wastewater. Investigation on EM use in water quality restoration, wastewater treatment, the treatment of sludge, and composting has been undertaken by researchers. This review provides an overview of the current situation of environmental application of EM in various fields including water quality, wastewater treatment, sludge treatment, and composting.