Immobilized consortium of heterotrophic nitrifying-aerobic denitrifying bacteria on various matrices for nitrogen removal from synthetic wastewater

Abstract

Environmental contamination by nitrogen compounds such as ammonium and nitrate has increased extensively in the recent past, which necessitates the development of eco-friendly remediation technologies. In this study, three matrix types including pumice, aquarium ceramic filter, and calcium alginate beads were used to facilitate nitrogen removal with an immobilized heterotrophic nitrifying-aerobic denitrifying (HNAD) bacterial consortium. The HNAD bacterial consortium was made of Pseudomonas monteilii Nht, Pseudomonas mendocina AquaN, Rhodococcus erythropolis R1, and Acinetobacter calcoaceticus SCC2. The quality parameters for immobilization, such as the number of immobilized cells and their viability, were assessed. The highest number of bacterial cells (3.4 × 10 ⁹) was immobilized on the aquarium ceramic filter, with 53% cell viability at 30°Ⅽ for two months. Pumice, aquarium ceramic filter, and calcium alginate achieved NH₄⁺-N removal efficiencies of 85.3 ± 1.7%, 87.3 ± 2.2%, and 77.5 ± 3.99% within 24 h, respectively, and removed NO₃⁻-N by 88.23 ± 0.36%, 93.95 ± 0.00%, and 71.29 ± 6.49% over 60 h. Additionally, immobilized cells on pumice and ceramic filter retained up to 84% of NH₄⁺-N removal efficiency after 14 reuse cycles. These findings indicate that the immobilized HNAD bacterial consortium on the aquarium ceramic filter can be used as a suitable biofilter for treatment of high nitrogen wastewater.