A novel denitrifying phosphorus removal and partial nitrification, anammox (DPR-PNA) process for advanced nutrients removal from high-strength wastewater.

This study developed a novel DPR-PNA (denitrifying phosphorus removal, partial nitrification and anammox) process for sustaining high-strength wastewater treatment in a modified continuous flow reactor without external carbon source. After 259-days operation, a synchronous highly-efficient total inorganic nitrogen, PO43--P and CODcr removal efficiencies of 88.5%, 89.5% and 90.1% were obtained, respectively even influent nitrogen loading rate up to 3.2 kg m-3 d-1. Batch tests revealed that denitrifying phosphorus accumulating organisms (DPAOs) using NO3--N as electron acceptors significantly enriched (74% in total PAOs), which emerged remarkable positive impacts on deep-level nutrient removal as the key limiting factor. Furthermore, the NO2--N inhibitory threshold value (∼20.0 mg L-1) for DPAOs was identified, which demonstrated as an inhibitory component in excessive recycling NOx--N. From the molecular biology perspective, Dechloromonas-DPAOs group (18.59%) dominated the excellent dephosphatation performance, while Nitrosomonas-AOB (ammonia oxidizing bacteria) group (16.26%) and Candidatus_Brocadia-AnAOB (anammox bacteria) group (15.12%) were responsible for the desirable nitrogen loss process. Overall, the present work highlighted the novel DPR-PNA process for nutrients removal is a promising alternation for wastewater of high nitrogen but low carbon.

Feasibility of applying intermittent aeration and baffles for achieving granular nitritation in a continuous short-cut denitrifying phosphorus removal system.

It was difficult to obtain a stable and efficient short-cut denitrification and phosphorus removal process for domestic sewage treatment, therefore, the possibility of using granulation technology of nitritation sludge and intermittent aeration was evaluated to resolve the difficulty. Results showed that the nitrogen and phosphorus removal efficiencies of the system were 72% and 93%, respectively, under the condition of mode 3 (a period of 10 min with aeration 8 min and stop 2 min) with aeration energy consumption decreasing 20%. Microbial community revealed that Rhodocyclales was the dominant short-cut denitrifying phosphorus removing bacteria in the process, closely related to the performance of short-cut denitrifying phosphorus removal. Furthermore, Thauera and Denitratisoma belonging to the Rhodocyclales play a significant role of short-cut denitrifying phosphorus removal in the process. In addition, Aeromonas improved the performance of short-cut denitrifying phosphorus removal. Finally, nutrient removal efficiency was improved 8% in intermittent aeration mode 3 based on short-cut denitrifying phosphorus removal.

Characterization of the start-up of single and two-stage Anammox processes with real low-strength wastewater treatment.

In order to promote the application of anaerobic ammonium oxidation (Anammox) for municipal wastewater treatment, single and two-stage Anammox processes were started up for real low-strength wastewater treatment under similar conditions for the comparison. Results showed that the anaerobic baffled reactor (ABR)-Nitritation-Anammox and the ABR-Completely Autotrophic Nitrogen removal Over Nitrite (CANON) process took 75 days and 101 days to start up with a total nitrogen removal rate of 86-92% and 81-87% under steady state, respectively. The 16 S rRNA sequencing analysis revealed that the phylum of Proteobacteria dominated in CANON system and Anammox system with the relative abundance of 35.39% and 15.27%, respectively. Phylogenetic analysis showed that Anammox species, related to Ca. Brocadia Sinica JPN1 and Ca. Kuenenia stuttgartiensis, dominated in these two systems, respectively. The nitrogen removal performance of two-stage process was 5% higher than that of single stage process, while the start-up period and dominated Anammox species were different.