Abstract

Heavy metal contamination of water resources poses a serious global environmental challenge. This study investigated the combined use of freshwater Kara algae and Pseudomonas aeruginosa as biological components in continuous packed bed reactors (CPBRs) for the removal of copper (Cu), lead (Pb), and chromium (Cr) at concentrations ranging from 0.05 to 1 g L⁻¹. Batch adsorption experiments established baseline performance for both algae and activated sludge substrates, revealing that Pb achieved the highest adsorption capacity at 100 ppm g⁻¹ using algae, while Cu and Cr showed comparable values near 90–96 ppm g⁻¹. Two CPBRs were operated over ten days at a constant flowrate of 150 mL day⁻¹ with a mixed influent of 100 ppm each of Cu, Pb, and Cr. Both reactors sustained heavy metal removal well beyond the theoretical adsorption saturation threshold, demonstrating that P. aeruginosa biofilm activity extended reactor performance significantly. Scanning electron microscopy confirmed stable bacterial colonisation on the algae substrate throughout the experiment. The isolated P. aeruginosa strain was identified by 16S rRNA gene sequencing and VITEK analysis, and phylogenetic reconstruction placed it within a well-supported clade of metal-tolerant Pseudomonas strains. In silico screening against the BacMet and CARD databases identified the full cop operon (Cu resistance), chrA/B (Cr efflux), and pbrA/T (Pb efflux) genes in the PAO1 reference genome, providing a genomic basis for the observed metal tolerance hierarchy. These findings support the practical application of hybrid biosorption–bioremediation systems incorporating genomically characterised microorganisms for continuous heavy metals wastewater treatment.