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.

E-waste management and sustainability: a case study in Brazil.

The advancement of technology and development of new electronic and electrical equipment with a reduced life cycle has increased the need for the disposal of them (called Waste of Electric and Electronic Equipment or simply e-waste) due to defects presented during use, replacement of obsolete equipment, and ease of acquisition of new equipment. There is a lack of consumer awareness regarding the use, handling storage, and disposal of this equipment. In Brazil, the disposal of post-consumer waste is regulated by the National Solid Waste Policy, established by Law No. 12305 and regulated on the 23rd December 2010. Under this legislation, manufacturers and importers are required to perform a project for the Reverse Logistics of e-waste, though its implementation is not well defined. This work focuses on the verification of the sustainability of reverse logistics suggested by the legislation and the mandatory points, evaluating its costs and the possible financial gain with recycling of the waste. The management of reverse logistics and recycling of waste electrical and electronic equipment, or simply recycling of e-waste, as suggested by the government, will be the responsibility of the managing organization to be formed by the manufacturers/importers in Brazil.

Recycling of WEEE: characterization of spent printed circuit boards from mobile phones and computers.

This paper presents a comparison between printed circuit boards from computers and mobile phones. Since printed circuits boards are becoming more complex and smaller, the amount of materials is constantly changing. The main objective of this work was to characterize spent printed circuit boards from computers and mobile phones applying mineral processing technique to separate the metal, ceramic, and polymer fractions. The processing was performed by comminution in a hammer mill, followed by particle size analysis, and by magnetic and electrostatic separation. Aqua regia leaching, loss-on-ignition and chemical analysis (inductively coupled plasma atomic emission spectroscopy - ICP-OES) were carried out to determine the composition of printed circuit boards and the metal rich fraction. The composition of the studied mobile phones printed circuit boards (PCB-MP) was 63 wt.% metals; 24 wt.% ceramics and 13 wt.% polymers; and of the printed circuit boards from studied personal computers (PCB-PC) was 45 wt.% metals; 27 wt.% polymers and ceramics 28 wt.% ceramics. The chemical analysis showed that copper concentration in printed circuit boards from personal computers was 20 wt.% and in printed circuit boards from mobile phones was 34.5 wt.%. According to the characteristics of each type of printed circuit board, the recovery of precious metals may be the main goal of the recycling process of printed circuit boards from personal computers and the recovery of copper should be the main goal of the recycling process of printed circuit boards from mobile phones. Hence, these printed circuit boards would not be mixed prior treatment. The results of this paper show that copper concentration is increasing in mobile phones and remaining constant in personal computers.

Metal separation from mixed types of batteries using selective precipitation and liquid-liquid extraction techniques.

The purpose of this paper is to study metal separation from a sample composed of a mixture of the main types of spent household batteries, using a hydrometallurgical route, comparing selective precipitation and liquid-liquid extraction separation techniques. The preparation of the solution consisted of: grinding the waste of mixed batteries, reduction and volatile metals elimination using electric furnace and acid leaching. From this solution two different routes were studied: selective precipitation with sodium hydroxide and liquid-liquid extraction using Cyanex 272 [bis(2,4,4-trimethylpentyl) phosphoric acid] as extracting agent. The best results were obtained from liquid-liquid extraction in which Zn had a 99% extraction rate at pH 2.5. More than 95% Fe was extracted at pH 7.0, the same pH at which more than 90% Ce was extracted. About 88% Mn, Cr and Co was extracted at this pH. At pH 3.0, more than 85% Ni was extracted, and at pH 3.5 more than 80% of Cd and La was extracted.

Electronic scraps--recovering of valuable materials from parallel wire cables.

Every year, the number of discarded electro-electronic products is increasing. For this reason recycling is needed, to avoid wasting non-renewable natural resources. The objective of this work is to study the recycling of materials from parallel wire cable through unit operations of mineral processing. Parallel wire cables are basically composed of polymer and copper. The following unit operations were tested: grinding, size classification, dense medium separation, electrostatic separation, scrubbing, panning, and elutriation. It was observed that the operations used obtained copper and PVC concentrates with a low degree of cross contamination. It was concluded that total liberation of the materials was accomplished after grinding to less than 3 mm, using a cage mill. Separation using panning and elutriation presented the best results in terms of recovery and cross contamination.

Recovery of copper from printed circuit boards scraps by mechanical processing and electrometallurgy.

The constant growth in generation of solid wastes stimulates studies of recycling processes. The electronic scrap is part of this universe of obsolete and/or defective materials that need to be disposed of more appropriately, or then recycled. In this work, printed circuit boards, that are part of electronic scrap and are found in almost all electro-electronic equipments, were studied. Printed circuit boards were collected in obsolete or defective personal computers that are the largest source of this kind of waste. Printed circuit boards are composed of different materials such as polymers, ceramics and metals, which makes the process more difficult. However, the presence of metals, such as copper and precious metals encourage recycling studies. Also the presence of heavy metals, as Pb and Cd turns this scrap into dangerous residues. This demonstrates the need to search for solutions of this kind of residue, in order to have it disposed in a proper way, without harming the environment. At the first stage of this work, mechanical processing was used, as comminution followed by size, magnetic and electrostatic separation. By this process it was possible to obtain a concentrated fraction in metals (mainly Cu, Pb and Sn) and another fraction containing polymers and ceramics. The copper content reached more than 50% in mass in most of the conductive fractions and significant content of Pb and Sn. At the second stage, the fraction concentrated in metals was dissolved with acids and treated in an electrochemical process in order to recover the metals separately, especially copper. The results demonstrate the technical viability of recovering copper using mechanical processing followed by an electrometallurgical technique. The copper content in solution decayed quickly in all the experiments and the copper obtained by electrowinning is above 98% in most of the tests.