A two-sludge system for simultaneous biological C, N and P removal via the nitrite pathway

Abstract

Nitrogen removal via the nitrite pathway results in significant savings in both aeration costs and COD requirements for denitrification when compared to the conventional biological nitrogen removal process. Implementation of the nitrite pathway for simultaneous C/N/P removal in a single sludge system has a major drawback: the aeration phase disfavours denitrifying phosphorus removal. A possible configuration to overcome this issue is the utilisation of a two-sludge system where autotrophic and heterotrophic populations are physically separated. This paper experimentally demonstrates the feasibility of a nitrite-based two-sludge system with sequencing batch reactors (SBR) for the treatment of urban wastewater: a heterotrophic SBR with denitrifying PAOs for P removal and an aerobic SBR for N removal. Partial nitrification was attained in the autotrophic SBR so that shortcut biological nitrogen removal was achieved by using the anoxic dephosphatation activity of DPAOs. Finally, the effect of operating this system without pH control was studied using different influent pH values (pH = 6.8, 7.5 and 8.2) and, despite some efficiency lost due to the pH fluctuations, the system was able to remove most of the C, N and P present in the wastewater.

Metagenomic Profiling of Antibiotic Resistance Genes and Mobile Genetic Elements in a Tannery Wastewater Treatment Plant

“…However, acid stress subsystem was richer in the aerobic sludge than in the anaerobic sludge (Figure S3B). Oxygen availability may facilitate conversion of ammonia to nitrite or nitrate to induce pH decrease [47,48], which might result in the higher level of acid stress in aerobic sludge. Anaerobic sludge had higher abundance of dimethylarginine metabolism subsystems than aerobic sludge (Figure S3B).…”

Metagenomic Profiling of Antibiotic Resistance Genes and Mobile Genetic Elements in a Tannery Wastewater Treatment Plant

“…However, acid stress subsystem was richer in the aerobic sludge than in the anaerobic sludge ( Figure S3B). Oxygen availability may facilitate conversion of ammonia to nitrite or nitrate to induce pH decrease [47,48], which might result in the higher level of acid stress in aerobic sludge. Anaerobic sludge had higher abundance of dimethylarginine Relative distribution of sequencing reads in major level 1 subsystems in anaerobic and aerobic sludge.…”

Ammonia‐Based Feedforward and Feedback Aeration Control in Activated Sludge Processes

“…• It has been suggested that benefits may be gained from a denitrification shortcut where nitrite generated by AOB is reduced directly to nitrogen gas (also called "nitrite shunt") (Marcelino et al, 2011). This would lead to significant savings in aeration energy as compared to nitrifying all the way to nitrate, and reduced carbon needs for denitrification.…”

“…Increased denitrification occurs through simultaneous nitrification and denitrification at low dissolved oxygen concentrations (Münch et al, 1996;Jimenez et al, 2010); conventional denitrification occurs if aeration is switched off completely. It has been suggested that benefits may be gained from a denitrification shortcut where nitrite generated by AOB is reduced directly to nitrogen gas (also called ''nitrite shunt'') (Marcelino et al, 2011). This would lead to significant savings in aeration energy as compared to nitrifying all the way to nitrate, and reduced carbon needs for denitrification.…”