A combined approach to remediate cadmium contaminated sediment using the acidophilic sulfur-oxidizing bacterial SV5 and untreated coffee ground

Cadmium (Cd) contamination in sediment is an emerging concern for the sustainability of aquatic ecosystem due to the toxicity of Cd is correlated to different trophic levels. An effective and inexpensive remediation strategy for Cd-contaminated sediment is desirable. The feasibility of using a newly isolated acidophilic sulfur-oxidizing bacterium and untreated coffee ground to remediate Cd-contaminated sediment was evaluated. The bioleaching approach was firstly conducted with the acidophilic sulfur-oxidizing bacterial SV5, resulting in Cd(II) release from Cd(II)-contaminated sediment. Subsequently, Cd(II) in the acidic leachate was further removed using untreated agricultural wastes. Untreated coffee ground exhibited about 2-fold Cd(II) removal efficiency comparing to that of rice husk and peanut shell. Scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR) analysis were conducted to characterize the coffee ground after the adsorption of 0 or 200 mg/L Cd(II). At pH 4, the optimal coffee ground concentration was 30 g/L along with 100 mg/L Cd(II) concentration. Adsorption of Cd(II) by coffee ground was rapid and the adsorption kinetic followed pseudo-second order model. Cd(II) sorption by coffee ground was a favorable process and Langmuir isotherm model well described the experimental data. Taken together, even at pH 4, coffee ground still showed good biosorption capacity for Cd(II) with short equilibrium time. This study suggests that acidophilic sulfur-oxidizing bacterial SV5 and untreated coffee ground could be used as inexpensive and environment-friendly biomaterial and agricultural waste for the remediation of Cd-contaminated sediment. ? 2021 Elsevier Ltd