Enhancement of denitrification by sulfur-based carrier in sequencing batch reactor (SBR) for advanced wastewater treatment

Abstract

This study was to enhance the nitrogen removal efficiency in the sequencing batch reactor (SBR) process by adding sulfur-based carriers. The nitrogen removal efficiency of the control group was compared with that of the experimental group through a two-series operation of SBR1 without carrier and SBR2 with the carrier under the condition of no external carbon source. A total nitrogen (T-N) removal efficiency of 6.6%, 72.6%, and 79.9% was observed in SBR1, SBR2 (5%), and (10%), respectively. The T-N removal efficiency was improved in the system with carriers, which showed an increase in the removal efficiency of approximately 91.7%. The results suggest that the inclusion of the carrier led to an elevation in the sulfur ratio, implying an augmented surface area for sulfur-based denitrifying microorganisms. Additionally, CaCO3 contributed essential alkalinity for sulfur denitrification, thereby preventing a decline in pH. Regardless of the carrier, the efficiency of organic matter removal surpassed 89%, indicating that the sulfur-based carrier did not adversely affect the biological reaction associated with organic matter. Therefore, autotrophic denitrification was successfully performed using a sulfur carrier in the SBR process without an external carbon source, improving the nitrogen removal efficiency.