Search Results (15)

Industrial effluents pose a significant concern because they contain a variety of metals and metalloids that have detrimental effects on the environment. Conventional techniques are widely used in effluent treatment plants (ETPs) to remove metallic pollutants; however, they are less effective, are costly, and generate secondary toxic waste. Mycosorbent would be a sustainable and economical alternative to conventional techniques, as it offers numerous advantages. In this study, we shed light on the development of mycosorbent, which could be potentially applicable in the treatment of industrial effluent. In a competitive (i.e., multimetal system) optimisation study, mycosorbent AD2 exhibited a maximum biosorption capacity of 3.7 to 6.20 mg/g at pH 6.0, with an initial metal ion concentration of 25 mg/L, a contact time of 2 h, at 50 ± 2 °C, and a pH_PZC of 5.3. The metal-removal capacity increased up to 1.23-fold after optimisation. The thermodynamic parameters confirmed that the AD2 mycosorbent facilitated an endothermic, feasible, and spontaneous biosorption process. The FT-IR and SEM characterisation analysis confirmed the adsorption of metals on the surface of the mycosorbent from the aqueous system. This study demonstrated that mycosorbent could be an effective tool for combating metallic pollutants in various industrial effluents. Full article

Understanding microbial adaptation and tolerance based on the cellular concentration and biosorption capacity provides critical insights for evaluating microbial performance under heavy metal stress, which is essential for selecting efficient strains or consortia for bioremediation applications. In this study, the adaptation and tolerance of Bacillus megaterium and Rhodotorula mucilaginosa to elevated concentrations of copper (Cu) and manganese (Mn) were investigated by introducing the maximum adaptation concentration (MAC) alongside the maximum tolerable concentration (MTC) and the minimum inhibitory concentration (MIC). A Gaussian model was fitted to the relative growth responses to estimate the MACs, MTCs, and MICs. B. megaterium exhibited MACs of 4.6 ppm Cu and 393.9 ppm Mn, while R. mucilaginosa showed MACs of 59.6 ppm Cu and 64.4 ppm Mn, corresponding to concentrations that stimulated their maximum cell density. A biosorption analysis revealed average capacities of 6.3 ± 5.3 mg Cu/g biomass and 28.6 ± 17.2 mg Mn/g biomass, positively correlated with the MTCs, indicating enhanced metal uptake under sublethal stress. The co-culture assays demonstrated dynamic microbial interactions shaped by the type and concentration of metal, including coexistence, competitive substitution, and dominance by tolerance. These findings support the use of MACs as indicators of growth stimulation and MTCs as thresholds for enhanced metal uptake, providing a dual-parameter framework for selecting metallotolerant microorganisms for metal recovery strategies. Full article

The bioavailability of heavy metals is profoundly influenced by their interactions with active soil components (microorganisms, organic matter, and iron minerals). However, the effects of urease-producing bacteria combined with organo-Fe hydroxide coprecipitates (OFCs) on Cd accumulation in wheat, as well as the mechanisms underlying these effects, remain unclear. In this study, pot experiments integrated with high-throughput sequencing were employed to investigate the impacts of the urease-producing bacterial strain TJ6, ferrihydrite (Fh), and OFCs on Cd enrichment in wheat grains, alongside the underlying soil–microbial mechanisms. The results demonstrate that the strain TJ6-Fh/OFC consortium significantly (p < 0.05) reduced (50.1–66.7%) the bioavailable Cd content in rhizosphere soil while increasing residual Cd fractions, thereby decreasing (77.4%) Cd accumulation in grains. The combined amendments elevated rhizosphere pH (7.35), iron oxide content, and electrical conductivity while reducing (14.5–21.1%) dissolved organic carbon levels. These changes enhanced soil-colloid-mediated Cd immobilization and reduced Cd mobility. Notably, the NH₄⁺ content and NH₄⁺/NO₃⁻ ratio were significantly (p < 0.05) increased, attributed to the ureolytic activity of TJ6, which concurrently alkalinized the soil and inhibited Cd uptake via competitive ion channel interactions. Furthermore, the relative abundance of functional bacterial taxa (Proteobacteria, Gemmatimonadota, Enterobacter, Rhodanobacter, Massilia, Nocardioides, and Arthrobacter) was markedly increased in the rhizosphere soil. These microbes exhibited enhanced abilities to produce extracellular polymeric substances, induce phosphate precipitation, facilitate biosorption, and promote nutrient (C/N) cycling, synergizing with the amendments to immobilize Cd. This study for the first time analyzed the effect and soil science mechanism of urease-producing bacteria combined with OFCs in blocking wheat’s absorption of Cd. Moreover, this study provides foundational insights and a practical framework for the remediation of Cd-contaminated wheat fields through microbial–organic–mineral collaborative strategies. Full article

The rapid expansion of industrial and agricultural activities in recent years has significantly contributed to water pollution leading to a decline in water quality and the need for effective treatment and reuse strategies. Metal contamination in water bodies poses severe environmental and health risks, making the development of cost-effective and sustainable remediation methods essential. Among the various treatment approaches, biosorption using biological adsorbents has emerged as a promising alternative due to its low cost and high efficiency. However, while the adsorption mechanisms of single metals are well understood, the competitive interactions between multiple metal ions during the sorption process remain less explored. In this review, we analyze the competitive biosorption of metals in multi-metallic wastewater systems. Key factors influencing metal removal, such as pH, contact time, biosorbent dosage, and initial metal concentration, are discussed, along with the intrinsic properties of biosorbents and metal ions that affect sorption efficiency. Additionally, we highlight recent studies on agroforestry byproducts as effective biosorbents for metal removal, showcasing their potential for sustainable water treatment. Heavy metals pose significant risks even at low concentrations, necessitating robust regulations and advanced treatment technologies; biomass byproducts, as cost-effective biosorbents, can be optimized through pre-treatment, activation, pH and temperature control, and particle size reduction, while effectively managing competitive multi-metal adsorption remains crucial for industrial effluent treatment. Full article

This study investigates the potential of released polysaccharides (RPS) from the halophilic cyanobacterium Cyanothece sp. CE4 as biosorbents for heavy metals, specifically copper (Cu), nickel (Ni), and zinc (Zn). By combining ICP-OES, SEM-EDX, FT-IR spectroscopy, and XAS techniques, this work provides a comprehensive chemical and spectroscopic analysis of the biosorption mechanisms driving metal removal. The results revealed a strong binding affinity for Cu, followed by Ni and Zn, with RPS functional groups playing a key role in metal coordination. The RPS efficiently removed metals from both monometallic and multimetallic solutions, emphasizing their adaptability in competitive environments. XAS analysis highlighted unique metal-specific coordination patterns. Ni preferentially binds to oxygen donors and Zn to chlorine, and Cu exhibits non-selective binding. Remarkably, the extracted RPS achieved a maximum Cu removal capacity of 67 mg per gram of RPS dry weight, surpassing previously reported biosorption capacities. This study not only advances the understanding of biosorption mechanisms by cyanobacterial RPS but also emphasizes their dual role in environmental remediation and circular resource management. The insights provided here establish a foundation for the development of sustainable, cyanobacteria-based solutions for heavy-metal recovery and environmental sustainability. Full article

This study investigates the biosorption capabilities of kefir grains, a polysaccharide-based byproduct of the fermentation process, for removing copper(II) and arsenic(V) from contaminated water. Unlike traditional heavy-metal removal methods, which are typically expensive and involve environmentally harmful chemicals, biopolymeric materials such as kefir grains provide a sustainable and cost-effective alternative for adsorbing hazardous inorganic pollutants from aqueous solutions. Our experimental results revealed significant differences in the sorption capacities of two types of kefir grains. Grains of milk kefir outperformed water kefir, particularly in copper(II) removal, achieving up to 95% efficiency at low copper concentrations (0.16 mmol·L⁻¹) and demonstrating a maximum sorption capacity of 49 µmol·g⁻¹. In contrast, water kefir grains achieved only 35.5% maximum removal efficiency and exhibited lower sorption capacity. For arsenic(V) removal, milk kefir grains also showed superior performance, removing up to 56% of arsenic in diluted solution with experimental sorption capacities reaching up to 20 µmol·g⁻¹, whereas water kefir grains achieved a maximum removal efficiency of 34.5%. However, these findings also suggest that while kefir grains show potential as low-cost biosorbents, further modifications are needed to enhance their competitiveness for large-scale water treatment applications. Full article

Batch experiments were conducted to test orange waste (OW), an agricultural solid waste byproduct from the orange juice manufacturing industry, as adsorbent for binary solutions of Cd²⁺-Cr³⁺ and Zn²⁺-Cr³⁺. Fourier transform infrared spectroscopy (FTIR) and the point of zero charge (pH_pzc) were used to identify the functional groups on the OW surface involved in biosorption. The biosorption equilibrium data for both binary-metal solutions were obtained and fitted to various isotherm models. The extended Sips and the non-modified Redlich-Peterson isotherm models gave the best fit for the experimental data. According to the extended Sips model, the maximum biosorption capacity of OW was 0.573 mmol·g⁻¹ for Cd²⁺, 0.453 mmol·g⁻¹ for Zn²⁺, and 1.96 mmol·g⁻¹ for Cr³⁺. The sorption capacity dropped to 0.061 mmol·g⁻¹ for Cd²⁺ and to 0.101 mmol·g¹ for Zn²⁺ in their binary systems with Cr³⁺ for the higher initial metal concentrations in the solution. However, the maximum sorption capacity of chromium was only slightly affected by the presence of Cd²⁺ or Zn²⁺. For both binary systems, the presence of a second metal ion in the solution always conduces to a reduction in the sorption of the other metal in the solution. The presence of Cr³⁺ decreased the sorption of Cd²⁺ and Zn²⁺ more than vice versa. Conclusively, effective removal of Cr³⁺ ions from an aqueous solution can still be achieved in the presence of Cd²⁺ or Zn²⁺. Full article

There is a wide range of renewable materials with attractive prospects for the development of green technologies for the removal and recovery of metals from aqueous streams. A special category among them are natural fibers of biological origin, which combine remarkable biosorption properties with the adaptability of useful forms for cleanup and recycling purposes. To support the efficient exploitation of these advantages, this article reviews the current state of research on the potential and real applications of natural cellulosic and protein fibers as biosorbents for the sequestration of metals from aqueous solutions. The discussion on the scientific literature reports is made in sections that consider the classification and characterization of natural fibers and the analysis of performances of lignocellulosic biofibers and wool, silk, and human hair waste fibers to the metal uptake from diluted aqueous solutions. Finally, future research directions are recommended. Compared to other reviews, this work debates, systematizes, and correlates the available data on the metal biosorption on plant and protein biofibers, under non-competitive and competitive conditions, from synthetic, simulated, and real solutions, providing a deep insight into the biosorbents based on both types of eco-friendly fibers. Full article

Biosorption is a variant of sorption techniques in which the adsorbent is a material of biological origin. It has become an economic and ecological alternative for the treatment of effluents. Among the biomasses employed in biosorption, algae have emerged as a sustainable solution for producing environmentally friendly adsorbents due to their abundance in seawater and freshwater, profitability, reuse and high metal absorption capacities. Although the research on the use of biosorbents is extensive and has grown in recent years, there are not many cases of their use for the treatment of real industrial solutions, which are more challenging due to the complex composition of metals that results in interference or competition over the functional sites of the biomass. This review aims to highlight the current state of research, focusing on the application of algae biosorption to remove copper from effluents. The most studied metals are those with the most significant health connotations, such as Cd, Cu and Pb. Regarding copper, only 2% of the biosorption works using seaweeds have been applied to real effluents, which leaves a relevant gap to advance the technology in the treatment of polluted solutions. Full article

The biosorption behaviour of arsenic(V) and cadmium(II) ions by unmodified and five types of chemically modified Chlorella vulgaris and Spirulina platensis was investigated. The biosorption rates of As(V) and Cd(II) in binary metal solutions were lower than those in sole metal systems, which exhibited a competition between As(V) and Cd(II) ions to occupy the active sites of the adsorbent. Among the five chemical reagents, NaCl and ZnCl₂ were the most suitable modifiers for improving the biosorption performance of C. vulgaris and S. platensis, respectively. The maximum biosorption capacities of As(V) and Cd(II) were: (a) 20.9 and 1.2 mg/g, respectively, for C. vulgaris modified with NaCl; (b) 24.8 and 29.4 mg/g, respectively, for S. platensis modified with ZnCl₂, which were much higher than those using other chemically modifying methods. The pseudo-second-order kinetic model fitted well with all the biosorption processes. The SEM analysis revealed that the modification changed the surface morphologies and enhanced the porosity of the algae biomass. The FTIR analysis established the presence of diverse groups of compounds that were largely hydroxyl, carboxylate, amino, and amide groups on the adsorbents that contributed significantly to the upregulated biosorption. This work showed the potential application of chemically modified C. vulgaris and S. platensis biomasses to effectively remove both from water. Full article

The biosorption ability of Lemna gibba for removing Ni²⁺ and Zn²⁺ ions in aqueous batch systems, both individually and simultaneously, was examined. The influences of solution pH and initial single and binary metal concentrations on equilibrium Ni²⁺ and Zn²⁺ biosorption was explored. The optimal solution pH for Ni²⁺ and Zn²⁺ biosorption was 6.0, for both the single and binary metal systems. Ni²⁺ and Zn²⁺ biosorption capacities increased with increasing initial metal concentrations. The presence of Zn²⁺ ions more adversely affected the biosorption of Ni²⁺ ions in the binary metal systems than vice versa. The single and binary biosorption isotherms of Ni²⁺ and Zn²⁺ revealed that L. gibba’s affinity for Zn²⁺ ions was higher than that for Ni²⁺ ions. The Redlich–Peterson and Freundlich isotherm models fit well to the experimental equilibrium data of Ni²⁺ ions, whereas Redlich–Peterson and Langmuir models better described the equilibrium data of Zn²⁺ ions in single metal systems. The modified Sips isotherm model best fit the competitive biosorption data of Ni²⁺-Zn²⁺ on L. gibba. FTIR analyses suggest the involvement of hemicellulose and cellulose in the biosorption of Ni²⁺ and Zn²⁺. The presence of Ni²⁺ and Zn²⁺ on the L.gibba surface was validated by SEM-EDX. Full article

Autochthonous fungi from contaminated wastewater are potential successful agents bioremediation thanks to their adaptation to pollutant toxicity and to competition with other microorganisms present in wastewater treatment plant. Biological treatment by means of selected fungal strains could be a potential tool to integrate the leachate depuration process, thanks to their fungal extracellular enzymes with non-selective catalytical activity. In the present work, the treatability of two real samples (a crude landfill leachate and the effluent coming from a traditional wastewater treatment plant) was investigated in decolorization experiments with fungal biomasses. Five autochthonous fungi, Penicillium brevicompactum MUT 793, Pseudallescheria boydii MUT 721, P. boydii MUT 1269, Phanerochaete sanguinea MUT 1284, and Flammulina velutipes MUT 1275, were selected in a previous miniaturized decolorization screening. Their effectiveness in terms of decolorization, enzymatic activity (laccases and peroxidases), biomass growth and ecotoxicity removal was compared with that of five allochthonous fungal strains, Pleurotus ostreatus MUT 2976, Porostereum spadiceum MUT 1585, Trametespubescens MUT 2400, Bjerkanderaadusta MUT 3060 and B. adusta MUT 2295, selected for their well known capability to degrade recalcitrant pollutants. Moreover, the effect of biomass immobilization on polyurethane foam (PUF) cube was assessed. The best decolorization (60%) was achieved by P. spadiceum MUT 1585, P. boydii MUT 721 and MUT 1269. In the first case, the DP was achieved gradually, suggesting a biodegradation process with the involvement of peroxidases. On the contrary, the two autochthonous fungi seem to bioremediate the effluent mainly by biosorption, with the abatement of the toxicity (up to 100%). The biomass immobilization enhanced enzymatic activity, but not the DP. Moreover, it limited the biomass growth for the fast growing fungi, MUT 721 and MUT 1269. In conclusion, robust and versatile strains coming from well-characterized collections of microorganisms can obtain excellent results comparing and even exceeding the bioremediation yields of strains already adapted to pollutants. Full article

In this work the biosorption of cationic dyes thioflavin T (TT) and methylene blue (MB) from single and binary solutions on dried biomass of freshwater moss Vesicularia dubyana as a function of contact time, pH, and biomass or sorbate concentration has been investigated. The prediction of maximum sorption capacities using adsorption isotherm models were also realized. Biosorption of TT and MB is a rapid process strongly affected by solution pH. Maximum sorption capacities Q_max calculated from Langmuir isotherm were 119 ± 11 mg/g for TT and 229 ± 9 mg/g for MB. In binary mixture, the presence of MB caused significant decrease of TT sorption, advocating the competitive sorption between TT and MB. Results revealed that V. dubyana biomass exhibited significantly higher affinity to thiazine dye MB in comparison with benzothiazole dye TT from both single and binary solutions. Based on the obtained results, the competitive effects in binary system can substantially influence the sorption process and should be thoroughly evaluated before application of selected adsorbents for removal of basic dyes from colored effluents. Full article

The biosorption of three reactive azo dyes (red, black and orange II) found in textile effluents by inactive mycelium of Cunninghamella elegans has been investigated. It was found that after 120 hours of contact the adsorption led to 70%, 85%, 93% and 88% removal of reactive orange II, reactive black, reactive red and a mixture of them, respectively. The mycelium surface was found to be selective towards the azo dyes in the following order: reactive red > reactive black > orange II. Dye removal from a mixture solution resulted in 48.4 mg/g retention by mycelium and indicated a competition amongst the dyes for the cellular surface. A Freundlich adsorption isotherm model exhibited a better fit, thus suggesting the presence of heterogeneous binding sites. Electrondense deposits observed on the mycelium ultrastructure suggest that the dyes are mainly retained under the cellular surface of the inactive biomass of C. elegans. Full article

Textile effluents are among the most difficult-to-treat wastewaters, due to their considerable amount of recalcitrant and toxic substances. Fungal biosorption is viewed as a valuable additional treatment for removing pollutants from textile wastewaters. In this study the efficiency of Cunninghamella elegans biomass in terms of contaminants, COD and toxicity reduction was tested against textile effluents sampled in different points of wastewater treatment plants. The results showed that C. elegans is a promising candidate for the decolourisation and detoxification of textile wastewaters and its versatility makes it very competitive compared with conventional sorbents adopted in industrial processes. Full article