Effective removal of Cr(VI) in aqueous solutions using Caulis lonicerae residue fermented by Phanerochaete chrysosporium

Effective removal of Cr (VI) ions using low-cost biomass leaves (Sambucus nigra L.) in aqueous solution

The tannery industries have become an important part of societal growth; however, these processes have produced huge volumes of effluents containing heavy metals, particularly Cr(VI) oxyanions. The study is crucial and cost-effective for reducing the chromium (VI) from industrial wastewater. In order to meet the sustainable development goal (SDG) objective 6.3, the capacity of Sambucus nigra L. to adsorb heavy metal is established with the purpose of eradicating hazardous chemical contamination and reducing pollution. In this study, discontinuous tests were carried out to determine the efficiency of Cr(VI) sorption on leaves of Sambucus nigra L. Adsorption factors such as pH, temperature, adsorbent dosage, and contact time were evaluated. At a dosage of 3 g/L and pH 2, an efficiency of 98.22% was achieved under favorable conditions. The equilibrium and kinetic models that best fitted the experimental data are non-linear Freundlich and; pseudo-second order, and intra-particle diffusion, respectively. The thermodynamic parameters of the adsorption process, including Gibbs free energy (ΔG0), enthalpy (ΔH0), and entropy (ΔS0), were measured at 291, 303, 323, and 343 K, indicating that the phenomena was spontaneous and endothermic. The chemical analyses and surface morphology of the adsorbent were analyzed using SEM (scanning electron microscopy), EDS (energy dispersive spectroscopy), FTIR (Fourier transform infra-red), XRD (X-ray diffraction), and ICP-OES (inductively coupled plasma optical-emission spectroscopy) techniques. The results showed that Sambucus nigra L. has a significant removal efficiency of Cr(VI) in the contaminated solutions, establishing adsorbent as a low cost, readily available, and environmentally friendly and ensuring its potential for industrial usage.

Bioreactor level optimization of chromium(VI) reduction through Pseudomonas putida APRRJVITS11 and sustainable remediation of pathogenic DNA in water

Background

Bioremediation is one of the indispensable features of Pseudomonas putida. The use of Pseudomonas has been proved to be an effective treatment of tannery released chromium (VI). The current study is the first attempt for the optimization of chromate reduction by Pseudomonas putida strain APRRJVITS11 in an optimized bench-scale bioreactor with successful thermo-pressure elimination of the strain thereby eliminating the health risk caused by antibiotic resistant genes (ARGs).

Results

The growth media, modified with optimized 1.0% nitrogen, 0.5% yeast extract and 0.3% sodium, showed enhanced bacterial growth for 72 h of incubation. The optimization of aeration (1.0 vvm) and agitation (150 rpm) rates enhanced the chromate reduction by about 40% at 72 h fermentation. Thermo-pressure pathogenic DNA degradation was achieved at 90 °C and 5868 Pa for 10 min.

Conclusions

Successful chromium reduction and total elimination of ARGs from effluent. A two-step treatment train was proposed for chromium reduction in the environment, which should be incorporated by the existing leather industries running on conventional treatment units.

Graphical Abstract

Fir bark modified by Phanerodontia chrysosporium: A low-cost amendment for cd-contaminated water and agricultural soil

In this study, a modified fir barks (MFB) was prepared by mixing fir barks (FB) and white-rot fungi (Phanerodontia chrysosporium) under aerobic fermentation. The potential of MFB for Cd²⁺ adsorption was investigated by batch experiments combined with kinetic, isotherm, and thermodynamics analyses. The results revealed that the modification greatly increased the porous structures on the surfaces of fir barks and the surface area of MFB was much higher than that of FB. As a result, the adsorption capacity of Cd²⁺ on MFB (17.4 mg g^-1) was more than two times higher than that on FB (7.2 mg g^-1), and the adsorption of Cd²⁺ on MFB was controlled by physisorption and chemisorption. The immobilization of Cd by MFB in a contaminated agricultural soil was also investigated. The effect of MFB on the bioavailability of Cd was investigated using a leaching test (the European standard EN 12457-2) combined with a typical sequential extraction procedure (the community bureau of reference, BCR). The experimental results showed that the Cd leachability was reduced by 71% when the added MFB dosage was 30 mg g^-1. Besides, the MFB amendment could transform Cd from unstable geochemical fractions into more stable fractions. In total, the MFB, as a chemical-free and eco-friendly material, could be potentially employed for in-situ remediation of Cd-contaminated agricultural soils.