Alginate production of Pseudomonas strains and its application in preparation of alginate-biomass hydrogel for heavy metal adsorption br

In this study, 7 Pseudomonas strains were isolated from a wastewater treatment plant, and the alginate production of Pseudomonas strains under different environmental conditions was evaluated. Subsequently, alginate-biomass hydrogel beads were prepared using alginate and biomass of Pseudomonas, and their adsorption performances and mechanism to Pb2+ and Cd2+ were analyzed. The results show that weakly acidic pH and 37 degrees C is favorable for alginate synthesis of Pseudomonas strains, and P. alcaligenes YLS18 have the highest alginate yield (29.4 mg/ g). The adsorption processes of Pb2+ and Cd2+ by hydrogel beads are well described by Langmuir model, indicating that the adsorption process is monolayer. Among the biomass of these strains, P. nitroreducens YLB32 shows the highest biosorption capacities, reaching 110.7 mg/g for Pb2+ and 54.3 mg/g for Cd2+ at pH 5. Alginate-biomass hydrogel beads obtain higher adsorption capacity to Pb2+ (184.0 mg/g) and Cd2+ (92.4 mg/g), and exhibit good reusability. The adsorption mechanism of Pb2+ and Cd2+ by hydrogel beads involves physical tapping of ions, electrostatic interactions, complexation, cation exchange and precipitation. These results provide strong support for promoting alginate recovery from activated sludge and for treating heavy metal wastewater.