Biosorption of lead(II) in aqueous solution by spent mushroom Tricholoma lobayense

Toxicity and bioremediation of the lead: a critical review

Lead is a naturally occurring, bluish-gray metal that is found in small quantities in the earth's crust. The existing literature demonstrates that non-biodegradable character and continuous use results in accumulation of lead concentration in the environment and causes various ill effects such as neurotoxicity, change in psychological and behavioral development of different organisms. Nowadays the most effective technique in the revival of the environment is bioremediation and it is environmentally friendly and cost-effective. Bacterial strains such as Oceanobacillus profundus and Lactobacillus acidophilus ATCC4356 have the ability to reduce lead 97% and 73.9%, respectively. Similarly some species of algae and fungal strains also showed lead removal efficiency as 74% (spirulina), 97.1% (Chlorella kessleri), 95.5% (Penicillium janthinillum) and 86% (Aspergillus flavus). Biodegradation of lead by various microbes would be the most efficient and sustainable approach. This review focuses on toxicity, fate of lead in the environment and its microbial degradation.

Experimental study on the treatment of acid mine drainage containing heavy metals with domestic waste pyrolysis ash

Acid mine drainage (AMD) is a special kind of acidic wastewater produced in the process of mining and utilization. In this study, AMD was treated using the adsorption method. Domestic waste was prepared by pyrolysis, and the resulting waste pyrolysis ash adsorbent was studied experimentally by a static adsorption test to treat metal ions in AMD. The results showed that the maximum adsorption amounts of Zn²⁺, Cu²⁺, Mn²⁺, Fe²⁺, Pb²⁺, and Cd²⁺ reached 0.425, 0.593, 0.498, 18.519, 0.055, and 0.039 mg/g, respectively, when the amount of pyrolysis ash was added at 30 g/L, the initial pH of the water was 4.1 and the reaction time was 150 min. It was found that the waste pyrolysis ash could be reused at least three times by using Na₂S as the regeneration agent. The SEM and BET characterization results prove that its large specific surface areas and well-developed pore structures have the potential to promote the adsorption of metal ions. The pseudo-second-order kinetic equation and Freundlich adsorption isotherms fit the adsorption process well, and the experiments reveal that the metal ions in AMD are well treated by waste pyrolysis ash through adsorption, flocculation and chemical precipitation. Waste pyrolysis ash has great potential for the treatment of acid mine drainage, providing a new approach to solid waste disposal and new ideas for water treatment as a low-cost alternative material.

Anaerobically fermented spent mushroom substrates improve nitrogen removal and lead (II) adsorption

In this study, spent mushroom substrates (SMSs) were fermented anaerobically at room temperature to gain liquid SMSs (LSMSs) that were used to remove nitrogen from the piggery wastewater with a low C/N ratio in a sequencing batch reactor (SBR) and solid SMSs (SSMSs) that were utilized to adsorb Pb²⁺ from Pb²⁺-containing wastewater in a fixed-bed reactor (FBR). After LSMSs supplement, the removal efficiency of both total nitrogen (TN) and NH⁺₄-N increased from around 50% to 60-80%. High-throughput sequencing results presented an obvious change in microbial diversity, and some functional microorganisms like Zoogloea and Hydrogenophaga predominated to promote nitrogen removal. Pb²⁺ did not emerge from the effluent until 240 min with the corresponding concentration being less than 3 mg/L when using 30-day SSMSs as adsorbents, and it was demonstrated to be appropriate to use the Thomas model to predict Pb²⁺ sorption on SSMSs. Although various functional groups played a role in binding ions, the carboxyl group was proved to contribute most to Pb²⁺ adsorption. These results certified that the anaerobically fermented SMSs are decidedly suitable for wastewater treatment.

Bioremediation of Waste Water to Remove Heavy Metals Using the Spent Mushroom Substrate of Agaricus bisporus

The presence of heavy metals in waste water brings serious environmental pollution that threatens human health and the ecosystem. Bioremediation of heavy metals has received considerable and growing interest over the years. Thus, this paper presents the use of the Spent Mushroom Substrate (SMS) of Agaricus bisporus cultivation as a bioremediating agent to remove heavy metals that are present in industrial waters. These metals include chromium, lead, iron, cobalt, nickel, manganese, zinc, copper and aluminium. In particular, this study analyses the performance of SMS bioreactors with different groups of heavy metals at various concentrations. Between 80% and 98% of all contaminants that were analysed can be removed with 5 kg of SMS at hydraulic retention times of 10 and 100 days. The best removal efficiencies and longevities were achieved when removing iron (III), nickel and cobalt from contaminated water at a pH of 2.5. These results suggest that SMS can successfully treat waste water that has been contaminated with heavy metals.

Uptake of Pb(II) onto nanochitosan/sodium alginate hybrid beads: Mechanism and kinetics study

Nanochitosan/sodium alginate (NCS/SA) beads were prepared using nanochitosan and alginate as a high-performance absorbent for Pb(II) removal from aqueous solution. The morphology, structure, thermal stability, surface area, and elements present in the NCS/SA beads before and after adsorption were characterized using instrumental techniques like SEM, FTIR, TGA, BET, and EDX analysis, respectively. Various adsorption parameters were studied. The results indicated that the equilibrium adsorption data were fitted to Langmuir isotherms and the maximum Langmuir monolayer capacity of Pb(II) was 178.57 mg/g at 45°C. The adsorption process was in good agreement with pseudo-first-order kinetic model. Mechanism studies showed that electrostatic interaction and ion exchange were the major mechanisms for lead (II) removal by the NCS/SA beads. The results of this study indicate that NCS/SA beads could be used as an effective adsorbent for the elimination of lead (II) present in aqueous solution. PRACTITIONER POINTS: Nanochitosan/sodium alginate beads were synthesized using Ca²⁺ as a crosslinking agent. NCS/SA beads were used to remove Pb(II) for the first time and working parameters were optimized. Adsorption monolayer capacity of NCS/SA adsorbent towards Pb (II) was found to be 178.57 mg/g.

A novel approach of utilization of the fungal conidia biomass to remove heavy metals from the aqueous solution through immobilization

The biomass of filamentous fungi is an important cost-effective biomass for heavy metal biosorption. However, use of free fungal cells can cause difficulties in the separation of biomass from the effluent. In this study, we immobilized the living conidia of the heavy metal-resistant Penicillium janthinillum strain GXCR by polyvinyl alcohol (PVA)-sodium alginate (SA) beads to remove heavy metals from an aqueous solution containing a low concentration (70 mg/L) of Cu, Pb, and Cd. The PVA-SA-conidia beads showed perfect characters of appropriate mechanical strength suitable for metal removal from the dynamic wastewater environment, an ideal settleability, easy separation from the solution, and a high metal biosorption and removal rate even after four cycles of successive sorption-desorption of the beads, overcoming disadvantages when fungal biomasses alone are used for heavy metal removal from wastewater. We also discuss the major biosorption-affecting factors, biosorption models, and biosorption mechanisms.

Pb tolerance and bioaccumulation by the mycelia of Flammulina velutipes in artificial enrichment medium

Mushrooms have the ability to accumulate high concentrations of heavy metals, which gives them potential for use as bioremediators of environmental contamination. The Pb(2+) tolerance and accumulation ability of living mycelia of Flammulina velutipes were studied in this work. Mycelial growth was inhibited when exposed to 1 mM Pb(2+). The colony diameter on solid medium decreased almost 10% compared with the control. Growth decreased almost 50% when the Pb(2+) concentration increased to 4 mM in the medium, with the colony diameter decreasing from 80 mm to 43.4 mm, and dry biomass production in liquid cultures decreasing from 9.23±0.55 to 4.27±0.28 g/L. Lead ions were efficiently accumulated in the mycelia. The amount of Pb(2+) in the mycelia increased with increasing Pb(2+) concentration in the medium, with the maximum concentration up to 707±91.4 mg/kg dry weight. We also show evidence that a large amount of the Pb(2+) was adsorbed to the mycelial surface, which may indicate that an exclusion mechanism is involved in Pb tolerance. These results demonstrate that F. velutipes could be useful as a remediator of heavy metal contamination because of the characteristics of high tolerance to Pb(2+) and efficient accumulation of Pb(2+) ions by the mycelia.