In situ enrichment of denitrifying consortia for biological wastewater treatment using a membrane-based microbial incubator at pilot-scale

Spatial management of functional microbial subpopulations is of importance for achieving efficient nutrient removal in wastewater treatment. Inspired by the construction of synthetic microbiota, a membrane-based microbial incubator (MMIR) is developed for in situ enrichment of targeted consortia. The MMIR can help to achieve satisfactory nitrogen removal during a pilot-scale anaerobic-anoxic -aerobic process. A 16S rRNA analysis suggests that the efficient denitrification is attributed to the enrichment of small genome-sized denitrifiers in MMIR (e.g., Sulfurimonas, Sulfurospirillum, and Sulfurovum), with a total abundance of 42.12%. In comparison, such denitrifiers are of much lower abundances in the sludge flocs (<0.78%). Metagenome analysis further suggests that the enriched denitrifying consortia contain more abundant genes (fold changes >2), contributing to nitrate reduction and carbon utilization. This study provides us with a new method to regulate the denitrifying consortia and optimize the carbon source supplementation, contributing to the improvement of bioreactor performance in wastewater treatment plants.