Abstract
The increase of industrial discharges is the first cause of the contamination of water bodies. The bacterial survival strategies contribute to the equilibrium restoration of ecosystems being useful tools for the development of innovative environmental biotechnologies. The aim of this work was to study the Cu(II) and Cd(II) biosensing, removal and recovery, mediated by whole cells, exopolymeric substances (EPS) and biosurfactants of the indigenous and non-pathogenic Pseudomonas veronii 2E to be applied in the development of wastewater biotreatments. An electrochemical biosensor was developed using P. veronii 2E biosorption mechanism mediated by the cell surface associated to bound exopolymeric substances. A Carbon Paste Electrode modified with P. veronii 2E (CPEM) was built using mineral oil, pre-washed graphite power and 24 h-dried cells. For Cd(II) quantification the CPEM was immersed in Cd(II) (1–25 μM), detected by Square Wave Voltammetry. A similar procedure was used for 1–50 μM Cu(II). Regarding Cd(II), removal mediated by immobilized EPS was tested in a 50 ml bioreactor with 0.13 mM Cd(II), pH 7.5. A 54% metal retention by EPS was achieved after 7 h of continuous operation, while a 40% was removed by a control resin. In addition, surfactants produced by P. veronii 2E were studied for recovery of Cd(II) adsorbed on diatomite, obtaining a 36% desorption efficiency at pH 6.5. Cu(II) adsorption from a 1 mM solution was tested using P. veronii 2E purified soluble EPS in 50 mL- batch reactors (pH = 5.5, 32°C). An 80% of the initial Cu(II) was retained using 1.04 g immobilized EPS. Focusing on metal recovery, Cu nanoparticles (NPs) biosynthesis by P. veronii 2E was carried out in Cu(II)-PYG Broth at 25°C for 5 days. Extracellular CuNPs were characterized by UV-Vis spectral analysis while both extracellular and intracellular NPs were analyzed by SEM and TEM techniques. Responses of P. veronii 2E and its products as biosurfactants, bound and soluble EPS allowed Cu(II) and Cd(II) removal, recovery and biosensing resulting in a multiple and versatile tool for sustainable wastewater biotreatments.
Highlights
The increase of industrial activities together with the consequent effluent discharges, is the first cause of the contamination of water bodies from anthropogenic origin
The modified Carbon paste electrodes (CPE) (CPEM) was built using a homogenous paste of power graphite (60%), commercial mineral oil (30%), and P. veronii 2E dry biomass (10%)
Cd(II) recovery from diatomite was tested using P. veronii 2E biosurfactant (Figure 2; Barrionuevo, 2017). 5.0 g diatomite was exposed for 24 h to 500 mL 2.7 mM Cd(II)
Summary
The increase of industrial activities together with the consequent effluent discharges, is the first cause of the contamination of water bodies from anthropogenic origin. The generation of high hazardous pollutants compromises water quality with the consequent severe environmental damages including human health (Dai et al, 2020). In this context, environmental relevance metals (ERM) are considered as potentially toxic pollutants even at small concentrations as are usually involved in the bioaccumulation process through the food chain. (Kiran Marella et al, 2020) These conventional methods are often found to be unsustainable practices from the environmental perspective and cannot be implemented at higher scale due to their cost. Biological treatments could be a suitable alternative and comparably inexpensive to conventional remediation strategies for the removal of the ERM from contaminated habitats (Mahapatra et al, 2020)
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