Abstract:
The global concern about the water pollution caused by heavy metals necessitates effective
water treatment methods. Adsorption, with its substantial advantages, stands out as a promising approach.
This study delves into the efficiency of Pb(II) removal using metabolically inhibited microbial
cultures. These cultures encompass waste-activated sewage sludge (SS), industrially sourced bioremediation
microbes (commercial 1—C1 and commercial 2—C2), an industrially acquired Pb(II) remediating
consortium (Cons), and refined strains (derived from Cons) of Paraclostridium bifermentans
(PB) and Klebsiella pneumoniae (KP). Our findings reveal maximum Pb(II) adsorption capacities
of 141.2 mg/g (SS), 208.5 mg/g (C1), 193.8 mg/g (C2), 220.4 mg/g (Cons), 153.2 mg/g (PB), and
217.7 mg/g (KP). The adsorption kinetics adhere to a two-phase pseudo-first-order model, indicative
of distinct fast and slow adsorption rates. Equilibrium isotherms align well with the two-surface
Langmuir model, implying varied adsorption sites with differing energies. The Crank mass transfer
model highlights external mass transfer as the primary mechanism for Pb(II) removal. Surface
interactions between sulfur (S) and lead (Pb) point to the formation of robust surface complexes.
FTIR analysis detects diverse functional groups on the adsorbents’ surfaces, while BET analyses
reveal non-porous agglomerates with a minimal internal surface area. The Pb(II) recovery rates are
notable, with values of 72.4% (SS), 68.6% (C1), 69.7% (C2), 69.6% (Cons), 61.0% (PB), and 72.4% (KP),
underscoring the potential of these cost-effective adsorbents for treating Pb(II)-contaminated aqueous
streams and contributing to enhanced pollution control measures. Nevertheless, optimization studies
are imperative to evaluate the optimal operational conditions and extend the application to adsorb
diverse environmental contaminants.
