Feasibility of Partial Nitrification Combined with Nitrite-Denitrification Phosphorus Removal and Simultaneous Nitrification–Endogenous Denitrification for Synchronous Chemical Oxygen Demand, Nitrogen, and Phosphorus Removal

Abstract

A combination of partial nitrification and nitrite-denitrifying phosphorus removal and simultaneous nitrification-endogenous denitrification (nDNPR-SNED) in two sequencing batch reactors was developed for synchronous chemical oxygen demand (COD), nitrogen (N), and phosphorus (P) removal by regulating dissolved oxygen (DO) and influent nitrite concentrations. COD, total nitrogen, and P removal efficiencies of 87.4 ± 0.5, 91.6 ± 1.1, and 97.8 ± 0.6% were obtained after 112 days of anaerobic/anoxic/aerobic operation. Mass balance analysis confirmed that 91.9% of the COD was stored as intracellular carbon at the anaerobic stage, and 99.6% of PO4 3––P and 99.8% of NO2 ––N were eliminated via the nDNPR process at the anoxic stage, and at the aerobic stage, the SNED process contributed to 68.7% nitrogen removal. Genera of Candidatus Competibacter, Dechloromonas, Ellin6067, and Nitrospirae were the dominant consortia with a relative abundance of 26.5, 16.5, 1.0, and 1.1%, respectively. In the metabolic pathway model, β-hydroxybutyrate was the main endogenous driving force for nitrogen and phosphorus removal. Compared with conventional biological nitrogen and phosphorus removal processes, the combined process could achieve 6.7% saving in the total cost. The proposed approach provides an economic and technical alternative for C-, N-, and P-laden wastewater treatment, reducing both carbon demand and aeration consumption.

Divalent manganese stimulates the removal of nitrate by anaerobic sludge

“…4b). C10-SB1A is considered a DNRA bacteria, 31 and its relative abundance first increased and then decreased with the increase in Mn 2+ concentration, and reached the maximum in the group with 10 mM Mn 2+ treatment. The phenomenon revealed that the DNRA in the system was first enhanced and then weakened.…”

“…GAOs are functional bacteria in the process of endogenous denitrication of treated municipal wastewater, which can convert NO 3 − -N and NO 2 − -N to N 2 . 31 As the Mn 2+ concentration increased, the relative abundance of Candidatus_Competibacter gradually decreased, and endogenous denitrication weakened. Ellin6067 is an ammoniaoxidizing bacteria (AOB), which oxidizes ammonia to nitrite.…”

“…At the genus level, the bacteria associated with denitrication in the top 15 dominant genera included SC-I-84, C10-SB1A, PHOS-HE36, Ellin6067, Candidatus_Competibacter, Subgroup_10, and Nitrospira. [29][30][31] SC-I-84 is known as an anaerobic ammoniaoxidizing bacteria. 32 As the Mn 2+ concentration increased, the relative abundance of SC-I-84 gradually decreased, and anaerobic ammonia oxidation gradually weakened (Fig.…”

Phosphorus Removal and Storage Polymer Synthesis by Tetrasphaera-Related Bacteria with Different Carbon Sources

“…With regard to nitrogen metabolism, Tetrasphaera-MAGs lacked the complete denitrification pathway, despite most MAGs encoding enzymes for nitrate reduction. Genes encoding enzymes for nitrite, nitric oxide, and nitrous oxide reduction were sparse …”

“…Genes encoding enzymes for nitrite, nitric oxide, and nitrous oxide reduction were sparse. 46 3.3. Phosphorus Release and Uptake by the Community with Different Carbon Sources.…”