# Comparison of Simultaneous Nitrification and Denitrification for Three Different Reactors

## TL;DR

This study compares three wastewater treatment reactors for removing nitrogen, finding that one achieves 98.3% efficiency by enabling simultaneous nitrification and denitrification.

## Contribution

The entrapped sludge reactor (ESR) achieves high nitrogen removal efficiency through efficient internal carbon consumption for denitrification.

## Key findings

- The entrapped sludge reactor (ESR) achieved 98.3% nitrogen removal efficiency.
- The suspended and mixed sludge reactors had lower efficiencies of 64.7% and 45.1%, respectively.
- Incomplete denitrification led to high nitrate levels in the effluent due to insufficient organic carbon.

## Abstract

Discharge of high NH4-N containing wastewater into water bodies has become a critical and serious issue due to its negative impact on water and environmental quality. In this research, the performance of three different reactors was assessed and compared with regard to the removal of NH4-N from wastewater. The highest nitrogen removal efficiency of 98.3% was found when the entrapped sludge reactor (ESR), in which the sludge was entrapped in polyethylene glycol polymer, was used. Under intermittent aeration, nitrification and denitrification occurred simultaneously in the aerobic and anaerobic periods. Moreover, internal carbon was consumed efficiently for denitrification. On the other hand, internal carbon consumption was not found to occur in the suspended sludge reactor (SSR) and the mixed sludge reactor (MSR) and this resulted in nitrogen removal efficiencies of SSR and MSR being 64.7 and 45.1%, respectively. Nitrification and denitrification were the main nitrogen removal processes in the aerobic and anaerobic periods, respectively. However, due to the absence of sufficient organic carbon, denitrification was uncompleted resulting in high NO3-N contents in the effluent.