Yeast—As Bioremediator of Silver-Containing Synthetic Effluents

Abstract

Yeast Saccharomyces cerevisiae may be regarded as a cost-effective and environmentally friendly biosorbent for complex effluent treatment. The effect of pH, contact time, temperature, and silver concentration on metal removal from silver-containing synthetic effluents using Saccharomyces cerevisiae was examined. The biosorbent before and after biosorption process was analysed using Fourier-transform infrared spectroscopy, scanning electron microscopy, and neutron activation analysis. Maximum removal of silver ions, which constituted 94–99%, was attained at the pH 3.0, contact time 60 min, and temperature 20 °C. High removal of copper, zinc, and nickel ions (63–100%) was obtained at pH 3.0–6.0. The equilibrium results were described using Langmuir and Freundlich isotherm, while pseudo-first-order and pseudo-second-order models were applied to explain the kinetics of the biosorption. The Langmuir isotherm model and the pseudo-second-order model fitted better experimental data with maximum adsorption capacity in the range of 43.6–108 mg/g. The negative Gibbs energy values pointed at the feasibility and spontaneous character of the biosorption process. The possible mechanisms of metal ions removal were discussed. Saccharomyces cerevisiae have all necessary characteristics to be applied to the development of the technology of silver-containing effluents treatment.

Spent brewer’s yeast as a selective biosorbent for metal recovery from polymetallic waste streams

“…Based on this, at pH values below 4.0, protonation of the functional groups on the yeast surface is expected whereas at higher pH values the yeast surface may have an overall negative charge. This could be beneficial for attracting positively charged metal ions, if the biosorption is mainly driven by electrostatic interactions ( Stathatou et al, 2022 ; Zinicovscaia et al, 2023 ). According to the results of the DoE experiments, pH 3.5 for Al 3+ , 5.0 for Cu 2+ , 7.5 for Zn 2+ and 8.5 for Ni 2+ have been proven to be most suitable for removal of the respective metal ion out of single-metal solutions within these experimental conditions.…”

“…Figure 2A shows the characteristic absorbance peaks of lyophilized brewer’s yeast between 1,100 and 1,700 cm −1 . The most prominent peaks in this area correspond to the C=O stretching vibration of carboxyl groups and N-H bending of protein amide I band (1,644 cm −1 ), N-H bending and C-N stretching vibration of protein amide II band (1,533 cm −1 ) ( De Rossi et al, 2018 ; Zinicovscaia et al, 2023 ), C-O stretching vibration of COOH in uronic acid (1,393 cm −1 ) and C-N stretching vibration of amide band II (1,238 cm −1 ) ( Dong et al, 2009 ). After metal adsorption, changes could be observed in the yeast biomass spectra.…”

“…Additionally, it was reported that the surface of brewer’s yeast can become wrinkled and wizened after about 1 month of soaking in fermented liquor ( Wang et al, 2018 ; Kulkarni et al, 2019 ). The rough surface allows easier access for metal ions for the active sites, facilitating the biosorption process ( Zinicovscaia et al, 2023 ). In the present study, cells were partly aggregating.…”

“…During the next biosorption step at pH 7.5, 74.8% of Zn 2+ could be adsorbed onto the yeast surface and additional 15.4% of Cu 2+ were removed. The removal efficiency of Cu 2+ at this step needs to be evaluated with care as copper starts to precipitate at pH 6.4 ( Zinicovscaia et al, 2023 ). At the last pH step of 8.5, Zn 2+ was almost completely removed (>98%) whereas more than 50% of the initial Ni 2+ amount was still in solution.…”

“…Hence, some of the obvious advantages of using brewer’s yeast as biosorbent are the availability of large quantities of waste biomass, its low cost and eco-friendliness ( Costa et al, 2021 ). Besides, the chemical composition of Saccharomyces cerevisiae , including functional groups on the cell surface, is well described in literature, facilitating the discovery of structural changes upon metal binding and the understanding of the mechanisms involved ( Zinicovscaia et al, 2023 ). Nevertheless, there is limited published work exploring the potential of inactive residual S. cerevisiae from the brewing industry ( Gonçalves et al, 2023 ).…”