Utilización de subproductos agroindustriales para la bioadsorción de metales pesados

Agro-industrial wastes and their application perspectives in metal decontamination using biocomposites and bacterial biomass: a review

Contamination of water bodies is a significant global issue that results from the deliberate release of pollutants into the environment, especially from mining and metal processing industries. The main pollutants generated by these industries are metallic wastes, particularly metals, which can cause adverse effects on the environment and human health. Therefore, it is crucial to develop effective and sustainable approaches to prevent their discharge into the environment. Biofiltration is a technique used to remediate contaminated fluids using biological processes. Microorganisms and agro-industrial wastes have been used successfully as biosorbents. Hence, this review emphasizes the innovative use of agro-industrial waste reinforced with microbial biomass as bioadsorbents, highlighting their dual capacity for metal removal through various bioremediation mechanisms. The mechanisms at play in these biocomposite materials, which offer enhanced sustainability, are also analyzed. This study contributes to the advancement of knowledge by suggesting new strategies for integrating reinforced materials in biosorption processes, thus providing a novel perspective on the potential of lignocellulosic-based systems to improve decontamination efforts. On the other hand, it shows some studies where the optimization and scaling-up of biosorption processes are reported. Additionally, the implementation of multisystem approaches, leveraging multiple bioremediation techniques simultaneously, can further enhance the efficiency and sustainability of metal removal in contaminated environments.

Isolation and identification of metallotolerant bacteria with a potential biotechnological application

Mining has led to severe environmental pollution in countries with exhaustive mining production and inadequate industrial waste regulation. Microorganisms in contaminated sites, like mine tailings, have adapted to high concentrations of heavy metals, developing the capacity of reducing or removing them from these environments. Therefore, it is essential to thoroughly characterize bacteria present in these sites to find different ways of bioremediation. In this regard, in this study, an enrichment and isolation procedure were performed to isolate bacteria with lower nutritional requirements and high tolerance to Cu(II) and Fe(II) from two Sonoran River basin mining tails. Two Staphylococcus species and a Microbacterium ginsengisoli strain were isolated and identified from the San Felipe de Jesús mining tail. Also, three strains were isolated from the Nacozari de García mining tail: Burkholderia cenocepacia, Sphingomonas sp. and Staphylococcus warneri. Significant microbiological differences were found between the two sites. All these species exhibited tolerance up to 300 mg/L for Cu (II)-Fe (II) solutions, indicating their capacity to grow in these conditions. Moreover, a consortium of isolated bacteria was immobilized in two different biocomposites and the biocomposite with larger pore size achieved greater bacterial immobilization showcasing the potential of these bacteria in biotechnological applications.

Desorption of Coffee Pulp Used as an Adsorbent Material for Cr(III and VI) Ions in Synthetic Wastewater: A Preliminary Study

Some of the diverse agro-industrial waste generated in primary or secondary stages have proved to be promising biomaterials for treating aqueous effluents contaminated, in this case, with heavy metals. Therefore, it is necessary to know their optimal operating conditions and the regeneration or reusability of the solid by-product, an aspect related to desorption. Considering the above, this article presents the findings of a preliminary study related to the desorption process of coffee pulp without physicochemical modification (Castilla variety), an agricultural waste used as a sorbent of Cr(III and VI) ions in synthetic wastewater. The desorption efficiency of four eluting agents at defined concentrations (0.10M)-HC1, HNO₃, H₂SO₄, and EDTA-was evaluated in a time interval of 1 to 9 days. Likewise, the proposals for the sorption and/or desorption mechanisms proposed and reported in the literature with respect to the use of biosorbents derived from the coffee crop are presented. With respect to the results, the coffee pulp used in previous studies of the adsorption of chromium species mentioned (optimal conditions in synthetic water of particle size 180 μm, dose 20 g·L^-1, agitation 100 RPM, room temperature, time of 90 to 105 min) showed efficiencies in the removal of Cr(III) and Cr(VI) of 93.26% and 74.80%, respectively. Regarding the extracting substances used, H₂SO₄ 0.10 M was the one that presented the highest desorption percentage in both chromic species, with a desorption of 45.75% Cr(VI) and 66.84% Cr(III) in periods of 5 and 9 days, respectively, with agitation of 100 RPM and room temperature. Finally, the dissemination of preliminary results on the desorption of coffee pulp contaminated with chromic species without physicochemical modification is novel in this study, as similar work with this specific material has not yet been reported in the literature. On the other hand, the limitations of the study and future research are related to the evaluation at different concentrations and of other extractor solutions that allow improving the efficiency of desorption of these chemical species in a shorter time from the coffee pulp (with and without modification) as well as the reuse cycles. As a result, the desorption of coffee pulp used as an adsorbent material in real water could help researchers identify the possible interfering factors that affect the process (foreign anions and cations, organic matter, environmental conditions, among others).

Fruit Peels as a Sustainable Waste for the Biosorption of Heavy Metals in Wastewater: A Review

One of the environmental challenges that is currently negatively affecting the ecosystem is the continuous discharge of untreated industrial waste into both water sources and soils. For this reason, one of the objectives of this qualitative study of exploratory-descriptive scope was the review of scientific articles in different databases-Scopus, Web of Science, and Science Direct-published from 2010 to 2021 on the use of fruit peels as a sustainable waste in the removal of heavy metals present in industrial wastewater. For the selection of articles, the authors used the PRISMA guide as a basis, with which 210 publications were found and 93 were compiled. Considering the reported work, a content analysis was carried out using NVivo 12 Plus and VOSviewer 1.6.17 software. The results show that the fruits mentioned in these publications are lemon, banana, mango, tree tomato, pineapple, passion fruit, orange, coconut, avocado, apple, lulo, and tangerine. However, no studies were found with lulo and tree tomato peels. On the other hand, the heavy metals removed with the selected fruit peels were Pb+2, Cr+3, Cr+6, Ni+2, Cd+2, As+5, Cu+2, and Zn+2.

Development and Characterization of Bioadsorbents Derived from Different Agricultural Wastes for Water Reclamation: A Review

The presence of dangerous pollutants in different water sources has restricted the availability of this natural resource. Thus, the development of new low-cost and environmentally-friendly technologies is currently required to ensure access to clean water. Various approaches to the recovery of contaminated water have been considered, including the generation of biomaterials with adsorption capacity for dangerous compounds. Research on bioadsorbents has boomed in recent years, as they constitute one of the most sustainable options for water treatment thanks to their abundance and high cellulose content. Thanks to the vast amount of information published to date, the present review addresses the current status of different biosorbents and the principal processes and characterization methods involved, focusing on base biomaterials such as fruits and vegetables, grains and seeds, and herbage and forage. In comparison to other reviews, this work reports more than 60 adsorbents obtained from agricultural wastes. The removal efficiencies and/or maximum adsorption capacities for heavy metals, industrial contaminants, nutrients and pharmaceuticals are presented as well. In addition to the valuable information provided in the literature investigation, challenges and perspectives concerning the implementation of bioadsorbents are discussed in order to comprehensively guide selection of the most suitable biomaterials according to the target contaminant and the available biowastes.

Removal of Cobalt (II) from Waters Contaminated by the Biomass of Eichhornia crassipes

Due to the increase in contamination of aquatic niches by different heavy metals, different technologies have been studied to eliminate these pollutants from contaminated aquatic sources. So the objective of this work was to determine the removal of cobalt (II) in aqueous solution by the biomass of the aquatic lily or water hyacinth (Eichhornia crassipes) which, is one of the main weeds present in fresh water, due to its rapid reproduction, growth, and high competitiveness, by the colorimetric method of the methyl isobutyl ketone. The removal was evaluated at different pHs (4.0–8.0) for 28 h. The effect of temperature in the range from 20 °C to 50 °C and the removal at different initial concentrations of cobalt (II) of 100 to 500 mg/L was also studied. The highest bioadsorption (100 mg/L) was at 28 h, at pH 5.0 and 28 °C, with a removal capacity of 73.1%, which is like some reports in the literature. Regarding the temperature, the highest removal was at 50 °C, at 28 h, with a removal of 89%. At the metal and biomass concentrations analyzed, its removal was 82% with 400–500 mg/L, and 100% with 5 g of natural biomass at 20 h. In addition, this completely removes the metal in situ (100 mg/L in contaminated water, at 7 days of incubation, with 10 g of natural biomass in 100 mL). So, the natural biomass can be used to remove it from industrial wastewater, even if in vivo, only eliminate 17.3% in 4 weeks.