Retention and recycling of granules in continuous flow-through system to accomplish denitrification and perchlorate reduction

This study employed a completely anoxic reactor and a gravity-settling design for continuously capturing and separating granules from flocculated biomass, and recycling granules back to the main reactor. The average chemical oxygen demand (COD) removal in the reactor was 98%. Average nitrate (NO3  -N) and perchlorate (ClO4  ) removal efficiencies of 99% and 74 & PLUSMN; 19% were observed, respectively. Preferential utilization of NO3  over ClO4  led to COD limiting conditions, which resulted in ClO4  in the effluent. The average granule diameter in continuous flow-through bubble-column (CFB) anoxic granular sludge (AxGS) bioreactor was 6325 & PLUSMN; 2434 & mu;m, and the average SVI30/SVI1 was >90 % throughout its operation. 16s rDNA amplicon sequencing revealed Proteobacteria (68.53%-88.57%) and Dechloromonas (10.46%-54.77%) to be the most abundant phylum and the genus present in reactor sludge representing the denitrifying and ClO4  reducing microbial community. This work represents a pioneering development of CFB-AxGS bioreactor.

Automated summary

This study utilized an anoxic reactor and gravity-settling design to continuously capture and separate granular biomass, achieving high removal efficiencies of chemical oxygen demand (COD), nitrate (NO3 -N), and perchlorate (ClO4 -). The reactor exhibited an average COD removal rate of 98%, with average removal efficiencies of 99% for NO3 -N and 74±19% for ClO4 -. The study also identified the dominant microbial communities present in the reactor sludge, including Proteobacteria and Dechloromonas.