A hybrid system for Nickel ions removal from synthesized wastewater using adsorption assisted with electrocoagulation.

The presence of heavy metal ions in water environments has raised significant concerns, necessitating practical solutions for their complete removal. In this study, a combination of adsorption and electrocoagulation (ADS + EC) techniques was introduced as an efficient approach for removing high concentrations of nickel ions (Ni2+) from aqueous solutions, employing low-cost sunflower seed shell biochar (SSSB). The combined techniques demonstrated superior removal efficiency compared to individual methods. The synthesized SSSB was characterized using SEM, FT-IR, XRD, N2-adsorption-desorption isotherms, XPS, and TEM. Batch processes were optimized by investigating pH, adsorbent dosage, initial nickel concentration, electrode effects, and current density. An aluminum (Al) electrode electrocoagulated particles and removed residual Ni2+ after adsorption. Kinetic and isotherm models examined Ni2+ adsorption and electrocoagulation coupling with SSSB-based adsorbent. The results indicated that the kinetic data fit well with a pseudo-second-order model, while the experimental equilibrium adsorption data conformed to a Langmuir isotherm under optimized conditions. The maximum adsorption capacity of the activated sunflower seed shell was determined to be 44.247 mg.g-1. The highest nickel ion removal efficiency of 99.98% was observed at initial pH values of 6.0 for ADS and 4.0 for ADS/EC; initial Ni2+ concentrations of 30.0 mg/L and 1.5 g/L of SSSB; initial current densities of 0.59 mA/cm2 and 1.32 kWh/m3 were also found to be optimal. The mechanisms involved in the removal of Ni2+ from wastewater were also examined in this research. These findings suggest that the adsorption-assisted electrocoagulation technique has a remarkable capacity for the cost-effective removal of heavy metals from various wastewater sources.

Towards a sustainable and green approach of electrical and electronic waste management in Rwanda: a critical review.

Electric and electronic equipment (EEE) consumption has grown to worrisome proportions in developing countries (DCS), resulting in massive amounts of electrical and electronic waste (e-waste) being produced. A diagnosis of e-waste proliferation is required for its sustainable management plan in Rwanda. This review is based on open-access papers with e-waste as a keyword, the present situation of EEE, and e-waste in Rwanda. The need for various information communication and technology (ICT) tools, such as end-user devices, cooling-system devices, network equipment, and telecommunication devices, is strongly encouraged by Rwandan national plans, which deem ICT as a vital enabler of knowledge-based economy and development. In 2014, EEE was 33,449 tonnes (t), which is expected to be 267,741 t in 2050, with a yearly increase rate of 5.95%. In this regard, out-of-date EEE is being dumped as e-waste in large quantities and at an increasing rate across Rwanda. E-waste is often disposed of in uncontrolled landfills together with other types of household waste. To address this rising threat, as well as to preserve the environment and human health, proper e-waste management involving e-waste sorting/separation from other waste streams, repairs, reuse, recycling, remanufacturing, and disposal has been proposed.

An Integrated Approach to Assess the Environmental Impacts of Large-Scale Gold Mining: The Nzema-Gold Mines in the Ellembelle District of Ghana as a Case Study.

The mining industry is a significant asset to the development of countries. Ghana, Africa's second-largest gold producer, has benefited from gold mining as the sector generates about 90% of the country's total exports. Just like all industries, mining is associated with benefits and risks to indigenes and the host environment. Small-scale miners are mostly accused in Ghana of being environmentally disruptive, due to their modes of operations. As a result, this paper seeks to assess the environmental impacts of large-scale gold mining with the Nzema Mines in Ellembelle as a case study. The study employs a double-phase mixed-method approach-a case study approach, consisting of site visitation, key informant interviews, questionnaires, and literature reviews, and the Normalized Difference Vegetation Index (NDVI) analysis method. The NDVI analysis shows that agricultural land reduced by -0.98%, while the bare area increases by 5.21% between the 2008 and 2015 periods. Our results show that forest reserves and bare area were reduced by -4.99% and -29%, respectively, while residential areas increased by 28.17% between 2015 and 2020. Vegetation, land, air, and water quality are highly threatened by large-scale mining in the area. Weak enforcement of mining policies, ineffective stakeholder institution collaborations, and limited community participation in decision-making processes were also noticed during the study. The authors conclude by giving recommendations to help enhance sustainable mining and ensure environmental sustainability in the district and beyond.