Copper and zinc adsorption from bacterial biomass - possibility of low-cost industrial wastewater treatment.

The increasing interest of all stakeholders to achieve environmental protection with socioeconomic development puts pressure on industrial processes for less negative impact on the environment. The use of biomass for wastewater treatment has increased due to its low costs and technical feasibility. The present study aimed the use of biomass from a waste of known polluted area for the adsorption of Zn and Cu in a fixed-bed reactor. Samples were collected in Cubatão (Brazil) and cultivated in LB medium. Resulting cultivable bacterial communities were identified as Enterococcus faecalis and Pseudomonas aeruginosa. Adsorption experiments were performed varying the metallic ion concentration and the amount of biomass. Adsorption experiments showed efficiency rates up to 90%. As the concentration of metallic ions increased, the adsorption efficiency decreased, indicating that the active sites were saturated. Activated charcoal demonstrated lower adsorption rates than biomass. Elution process showed that HNO3 had better efficiency than HCl. Zn adsorption fitted better for Lineweaver-Burk model (Qmax = 200 mg/g of biomass), while Cu adsorption fitted better for Langmuir model (Qmax = 164 mg/g of biomass). Results here demonstrated that the adsorption of Zn and Cu simulating an industrial wastewater by the biomass from a contaminated area is technically feasible.

Copper recovery through biohydrometallurgy route: chemical and physical characterization of magnetic (m), non-magnetic (nm) and mix samples from obsolete smartphones.

The more modern electronics are, the smaller and complex printed circuit boards are. Thus, these materials are continually changed (physicochemically), increasing the copper concentrations in smartphones. In this sense, it is challenging to set standardized recycling processes to improve metal recovery. In addition, biohydrometallurgy is a clean and cheap process to obtain critical metals from low-grade sources and waste electronic equipment. Therefore, the aim of this work was to characterize, physicochemically, 21 PCBs from smartphones manufactured from 2010 to 2015, and then to recover the copper by Acidithiobacillus ferrooxidans (biohydrometallurgy). The PCBs were comminuted and separated into Magnetic (M), Nonmagnetic (NM) and without magnetic separation (MIX) samples. It was identified 217.8; 560.3 and 401.3 mg Cu/g of PCBs for M, NM and MIX samples, respectively. Regarding biohydrometallurgy, the culture media iron-supplemented (NM + Fe and MIX + Fe) increased the copper content by 2.6 and 7.2%, respectively, and the magnetic separation step was insignificant.

Electric car battery: An overview on global demand, recycling and future approaches towards sustainability.

Li-ion batteries are daily present in our electronic devices. These batteries are used in electric and hybrid vehicles supporting the current agreements to decrease greenhouse gas emissions. As a result, the electric vehicle demand has increased in the world. As Li-ion batteries are composed of critical metals in which there is a risk of interruption of supply in the medium term, recycling is the key to a sustainable future without internal combustion vehicles. Understanding the current scenario and future perspectives is important for strategies of new battery design, recycling routes and reverse logistics, as well as policies for sustainable development. This paper presents an overview of current and future vehicles used worldwide. An increase from 1.3 to 2 billion vehicles is expected worldwide until 2030; an outstanding demand will occur mainly in BRICS countries. The data demonstrated a correlation between the number of vehicles in use and GDP. Patents and processes designed for recycling Li-ion batteries and the new developments on pyro-, hydro-, and bio-metallurgical routes have been revised. The manuscript describes the importance and benefits of recycling as regards the supply of critical metals and future trends towards a circular economy.