Effects of KMnO4 amounts on antibacterial properties of activated carbon for efficient treatment of northern Benin hospital wastewater in a fixed bed column system.

In this study, the wastewater from the Departmental Hospital Center of Atacora in Benin was characterized and then treated with activated carbon/potassium permanganate (AC/KMnO4) composite in a fixed bed column system. The AC/KMnO4 composites with impregnation ratios range 0.025-0.100 were prepared from peanut shell activated carbon and potassium permanganate. The wastewater characteristics revealed that 75% of Escherichia coli strains identified were extended-spectrum lactamases (ESBL) with CTX-M dominance, while 25% of Staphylococcus aureus strains produced Panton and Valentine leucocidin and 77.80% of Salmonella typhi strains were resistant to Trimethoprim/Sulfamethoxazole. The fixed bed column system results showed removal efficiency of 72.18 ± 4.98% turbidity, 63.12 ± 4.11% COD, 0.70 ± 0.04 log10 against E. coli and 3.82 ± 0.01 log10 against S. typhi strains using activated carbon as adsorbent with 0.7 cm bed depth after 3 h of treatment. The composite adsorbent AC/KMnO4 significantly increased the effectiveness of treatment due to the strong oxidant power of KMnO4 in the composite material. The results depicted a removal rate of 83.88 ± 5.00%, 89 ± 1.95%, 90 ± 0.65% turbidity, 66.47 ± 1.62%, 69.82 ± 2.00%, 78.20 ± 2.82% COD, 2.0 ± 0.08 log10, 5.0 ± 0.07 log10 against E. coli and 3.82 ± 0.01 log10 against S. typhi strains using AC/KMnO4 with 0.025, 0.050 and 0.100 ratios respectively at 0.7 cm bed depth. Finally, AC/KMnO4 revealed more adsorption potential and antibacterial property than AC, hence, the composite material could be used as a cost-effective adsorbent for efficient removing of multi-resistant bacteria from hospital wastewater.

Removal of atrazine from aqueous solutions onto a magnetite/chitosan/activated carbon composite in a fixed-bed column system: optimization using response surface methodology.

In this study, a magnetite/chitosan/activated carbon (MCHAC) composite is proposed as an efficient adsorbent for the removal of atrazine from aqueous solutions. The prepared composite was characterized using Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) methods. Response surface methodology (RSM) coupled with composite central design (CCD) were used to optimize the effects of the four independent variables, pH, initial concentration of atrazine (C 0), bed depth (H), and flow rate (Q), which influence the adsorption process. The experimental results modeled using response surface methodology (RSM) coupled with central composite design (CCD) (RSM-CCD) indicated a quadratic relationship with p < 0.0001 for adsorption capacity at saturation (q s) and fraction of bed utilization (FBU). The results of the experiments performed under the optimized conditions, pH = 5.07, C 0 = 137.86 mg L-1, H = 2.99 cm and Q = 1.038 mL min-1, showed a q s value of 62.32 mg g-1 and FBU of 72.26%, with a deviation value of less than 0.05 from the predicted q s and FBU values. The obtained breakthrough curves were fitted with four mathematical models, Thomas, Bohart-Adams, Yan and Yoon-Nelson, in order to determine the limiting step of the mass transfer of the atrazine adsorption onto the composite. A desorption study of the composite revealed the high reuse potential for MCHAC, thus, the prepared material could be used as a low-cost and efficient adsorbent for the decontamination of polluted wastewater.