Genomics and metabolic characteristics of simultaneous heterotrophic nitrification aerobic denitrification and aerobic phosphorus removal by Acinetobacter indicus CZH-5.

This study provides for the first time a systematic understanding of Acinetobacter indicus CZH-5 performance, metabolic pathway and genomic characteristics for aerobic nitrogen (N) and phosphorus (P) removal. Acinetobacter indicus CZH-5 showed promising performance in heterotrophic nitrification aerobic denitrification and aerobic phosphorus removal. Under optimal conditions, the maximum ammonia-N, total nitrogen and orthophosphate-P removal efficiencies were 90.17%, 86.33%, and 99.89%, respectively. The wide tolerance range suggests the strong environmental adaptability of the bacteria. The complete genome of this strain was reconstructed. Whole genome annotation was used to re-construct the N and P metabolic pathways, and related intracellular substance metabolic pathways were proposed. The transcription levels of related functional genes and enzyme activities further confirmed these metabolic mechanisms. N removal was achieved via the nitrification-denitrification pathway. Furthermore, CZH-5 exhibited significant aerobic P uptake, with phosphate diesters as the main species of intracellular P.

Development of polyaminated chitosan-zirconium(IV) complex bead adsorbent for highly efficient removal and recovery of phosphorus in aqueous solutions.

The aim of this work is to examine the adsorption performance and mechanism of phosphorus (P) onto polyethyene polyamine (PEPA) grafted chitosan-zirconium(IV) composite beads (CS-Zr-PEPA) from aqueous solutions. The morphology, functional groups, and surface area of the CS-Zr-PEPA beads were characterized by SEM, FTIR, and BET analysis. Batch adsorption experiments were conducted via different operating parameters such as solution pH, initial phosphate concentration, co-existing anions and temperature. The adsorption kinetics, equilibrium isotherms and adsorption stability of the adsorbent were scrutinized. In comparison with other CS-based beads, the CS-Zr-PEPA had a greater affinity towards P and exhibited a maximum adsorption capacity of 103.96 mg-P/g predicted by Langmuir mode. The reusability studies of CS-Zr-PEPA beads were carried out. The CS-Zr-PEPA beads exhibit preferable sequestration of P through specific interactions, as further demonstrated by studying physicochemical characteristics of the virgin beads and P-adsorbed beads using X-ray photoelectron spectroscopy (XPS). The column performance of CS-Zr-PEPA beads was tested with P-containing wastewater. Results indicated that the developed CS-Zr-PEPA composite beads could be utilized as a promising adsorbent for effective removal and recovery of P from water and wastewater.