In this study, biosorption potential of nine epiphytic bacteria isolated from the rhizosphere of Lepironia articulata and Scirpus grossus were assessed. Identification of the isolated epiphytic rhizobacteria using 16S rRNA analysis showed species belonging to the four genera of Bacillus, Enterobacter, Aeromonas, and Chromobacterium. Batch biosorption studies were carried out to assess the capacity of the isolated bacteria to act as Pb and Cu biosorbents. Different initial concentrations of the two heavy metals (50, 100, 200, 300, and 400 ppm) were used to determine the ability of the biosorbent to reach a tolerance level and then calculate the percentage of biosorption with respect to 0.1 g dry weight. Initial concentration of Pb and Cu exposed showed that the isolated bacteria have high tolerance up to 400 ppm. Bacteria prefer Pb ions over Cu, which is indicated by higher removal of Pb in all tested reactors. Bacillus sp. (coded Sc1) showed the highest biosorption capacity with 100% Pb and 97% Cu removal.

Phytoremediation is one of the green technologies that is friendly to nature, utilizes fewer chemicals, and exhibits good performance. In this study, phytoremediation was used to treat diesel-contaminated sand using a local aquatic plant species, Scirpus mucronatus, by analyzing the amount of total petroleum hydrocarbons (TPHs). Optimization of diesel removal was performed according to Response Surface Methodology (RSM) using Box-Behnken Design (BBD) under pilot-scale conditions. The quadratic model showed the best fit to describe the obtained data. Actual vs. predicted values from BBD showed a total of 9.1 % error for the concentration of TPH in sand and 0 % error for the concentration of TPH in plants. Maximum TPH removal of 42.3 ± 2.1 % was obtained under optimized conditions at a diesel initial concentration of 50 mg/kg, an aeration rate of 0.48 L/min, and a retention time of 72 days. The addition of two species of rhizobacteria (Bacillus subtilis and Bacillus licheniformis) at optimum conditions increased the TPH removal to 51.9 ± 2.6 %. The obtained model and optimum condition can be adopted to treat diesel-contaminated sand within the same TPH range (50–3000 mg/kg) in sand.