No abstract

The goal of this study is to demonstrate that waste-based biosorbents can be cost-effective and green alternatives to commercial adsorbents for the retention of pharmaceuticals. Adsorption kinetics and equilibrium measurements allowed the determination of the adsorption capacity of commercial adsorbents (GAC-granular activated carbon and two synthetic zeolites) and waste-based biosorbents (SCG-spent coffee grounds, pine bark and cork waste) for the retention of fluoxetine from water. For commercial adsorbents, the maximum adsorption capacities followed the order GAC (233.5 mg/g) > zeolite 13× (32.11 mg/g) > zeolite 4A (21.86 mg/g), while for low-cost biosorbents, the sequence was SCG (14.31 mg/g) > pine bark (6.53 mg/g) > cork waste (4.74 mg/g). The economic feasibility of the adsorbents/biosorbents was examined through a detailed cost analysis. Commercial adsorbents present higher costs per gram of fluoxetine removed (6.85 €/g, 3.13 €/g and 1.07 €/g zeolite 4 A, zeolite 13× and GAC, respectively) when compared to low-cost biosorbents (0.92 €/g, 0.41 €/g and 0.16 €/g for pine bark, cork waste and SCG, respectively). It was found that SCG is the most economically viable option for fluoxetine removal, while cork waste, the second less expensive, is the most environmentally friendly biosorbent since its preparation does not generate any solid or liquid wastes. This manuscript demonstrates that the conversion of waste materials into adsorbents has a double environmental benefit for both improving waste management and protecting the environment.

Over the last decades, the production and consumption of pharmaceuticals and health care products grew manifold, allowing an increase in life expectancy and a better life quality for humans and animals, in general. However, the growth in pharmaceuticals production and consumption comes with an increase in waste production, which creates a number of challenges as well as opportunities for the waste management industries. The conventional current technologies used to treat effluents have shown to be inefficient to remove or just to reduce the concentrations of these types of pollutants to the legal limits. The present review provides a thorough state-of-the-art overview on the use of biological processes in the rehabilitation of ecosystems contaminated with the pharmaceutical compounds most commonly detected in the environment and eventually more studied by the scientific community. Among the different biological processes, special attention is given to biosorption and biodegradation.

The use of rare earth elements is a growing trend in diverse industrial activities, leading to the need for eco-friendly approaches to their efficient recovery and reuse. The aim of this work is the development of an environmentally friendly and competitive technology for the recovery of those elements from wastewater. Kinetic and equilibria batch assays were performed with zeolite, with and without bacterial biofilm, to entrap rare earth ions from aqueous solution. Continuous assays were also performed in column setups. Over 90% removal of lanthanum and cerium was achieved using zeolite as sorbent, with and without biofilm, decreasing to 70% and 80%, respectively, when suspended Bacillus cereus was used. Desorption from the zeolite reached over 60%, regardless of the tested conditions. When in continuous flow in columns, the removal yield was similar for all of the rare earth elements tested. Lanthanum and cerium were the elements most easily removed by all tested sorbents when tested in single- or multi-solute solutions, in batch and column assays. Rare earth removal from wastewater in open setups is possible, as well as their recovery by desorption processes, allowing a continuous mode of operation.

This work addresses the treatment of a complex industrial effluent containing high concentrations of metals and spiked with two organic solvents (diethylketone -DEK, and methyl ethyl ketone -MEK) using an eco-friendly approach. The treatment system herein proposed consists of a bio-barrier that combines the adsorption capacity of sepiolite with the properties of a Streptococcus equisimilis biofilm with proven ability in the degradation and bioremoval of a wide range of pollutants.Results from the open-systems experiments conducted with raw sepiolite exposed to a binary mixture of DEK and MEK revealed the preference of the sorbent towards DEK. The results from the biodegradation experiments also revealed the preference of S. equisimilis to degrade/bioremove DEK over MEK independently of their initial concentration (100 mg/L to 3200 mg/L). Bioremoval percentages higher than 95% were reached for all the concentrations of DEK tested. The lab-scale experiments conducted in open-system with sepiolite and sepiolite covered with biofilm, and the pilot-scale experiment conducted in closed-loop, revealed similar performances on the rehabilitation of an industrial effluent containing heavy metals and additionally spiked with DEK and MEK. Regarding the selectivity towards the different pollutants, Cu was preferentially removed over Cr and Ni, and DEK over MEK. The presence of the biofilm allowed an improvement on the removal of heavy metals, particularly Cr, besides preventing the leaching of Al, Fe, and Mg from the sepiolite structure, an extremely important advantage in comparison to the system without biofilm. EDS analyses performed in sepiolite samples revealed the presence of several metals (Cr, Cu and Ni), proving thus the occurrence of sorption processes by sepiolite and by sepiolite covered by biofilm. The breakthrough data obtained in the open-systems were properly described by the Dose Response and the Yoon and Nelson mathematical models. More research work needs to be performed with complex industrial effluents aiming the optimization of the treatment systems to be applied in real context scenarios.