Enhanced and robust nitrogen removal using an integrated zeolite and partial denitrification anammox process

Area of Science:

• Environmental Science
• Microbiology
• Chemical Engineering

Background:

• Anammox (anaerobic ammonium oxidation) offers cost-efficient nitrogen removal but faces challenges with influent ratio demands and nitrate byproduct.
• Partial denitrification and anammox (PDA) systems improve nitrogen removal but require strict operational control.

Purpose of the Study:

• To investigate the efficacy of a novel zeolite-integrated partial denitrification and anammox (Z-PDA) system in an up-flow anaerobic sludge bed (UASB) reactor.
• To evaluate the system's performance under fluctuating influent conditions and elucidate the role of zeolite.

Main Methods:

• Implementation of a UASB reactor combining zeolite with partial denitrification and anammox processes.
• Utilized 16S rRNA gene sequencing to identify key microbial communities (Candidatus Brocadia, Thauera).
• Performed metagenomic analysis to assess functional genes and metabolic pathways involved in nitrogen removal.

Main Results:

• Achieved ultra-high nitrogen removal efficiency (NRE) of 93.0 ± 2.0%.
• Zeolite facilitated robust nitrogen removal by adsorbing and desorbing ammonium, accommodating variable NO2--N to NH4+--N ratios.
• Demonstrated significant enrichment of anammox bacteria (Candidatus Brocadia at 49.2%) and identified key nitrogen removal genes (nrfA/H, narG/H/I).

Conclusions:

• The Z-PDA system offers a resilient and efficient solution for nitrogen removal in wastewater treatment.
• Zeolite plays a crucial role as a biological carrier and in managing ammonium dynamics, enhancing system stability.
• This study provides fundamental insights into zeolite's mechanism in PDA systems and its practical application for sewage treatment.