Performance of one-stage autotrophic nitrogen removal in a biofilm reactor with low C/N ratio

Abstract

Wastewater with C/N ratios ranging from 1.00 to 0.33 caused by a gradual increase in influent NH4+-N concentration was used to evaluate the performance of the one-stage nitrogen removal process in a biofilm reactor. The system was operated for 197 days under chemical oxygen demand (COD) concentration of 250 mg L(-1) and influent NH4+-N concentrations ranging from 250 to 750 mg L(-1). The effects of the C/N ratio and dissolved oxygen (DO) on nitrogen removal were evaluated at different influent C/N ratios and DO concentrations, respectively. The microbial composition of the system was examined by scanning electron microscopy and polymerase chain reaction-denaturing gradient gel electrophoresis, and the relative contribution of anaerobic ammonium oxidation (ANAMMOX) to nitrogen removal was assessed by calculating the average rates of ANAMMOX and denitrification in batch experiments. Results showed that the removal efficiencies of total nitrogen (TN), NH4+-N and COD were 74-97%, 75-99% and 64-97%, respectively. The C/N ratio had a significant influence on nitrogen removal efficiency when it was decreased from 1.00 to 0.70, but no significant change was observed when it was reduced from 0.70 to 0.33. DO also correlated with the NH4+-N concentration in the influent, and 3.0 mg L(-1) was found to be a suitable concentration for the influent NH4+-N concentration of 450±5 mg L(-1). Analysis of microbial composition of the system revealed that biofilm and activated sludge were mainly composed of aerobic ammonium-oxidizing bacteria, anaerobic ammonium-oxidizing bacteria (AnAOB) and denitrifying bacteria. Activity tests suggested that AnAOB played an important role in the one-stage autotrophic nitrogen removal process, contributing to about 52.7% of total TN removal via ANAMMOX.

Carrier effects on tertiary nitrifying moving bed biofilm reactor: An examination of performance, biofilm and biologically produced solids

“…The carriers demonstrated high ammonia removal rates and removal efficiencies; as was demonstrated in previous nitrifying biofilm studies operated at elevated DO and pH values along with temperatures above 20°C. [20,21,28,29] The P carriers demonstrated a transitional phase with respect to the detachment of solids from the carriers for a period of approximately 300 HRTs. This extended transitional period of increased solids detachment observed for the P carriers did not result in a statistically significant reduction in the SARR or per cent removal performance as compared to the acclimatized phase of the carriers or compared to the K3 and M carriers.…”

Effective remediation of fish processing waste using mixed culture biofilms capable of simultaneous nitrification and denitrification

“…2b and c). Together, on carriers, the selected bacteria removed $89 and $95% of the total nitrogenous wastes from 2 and 20 L systems, respectively in 24 h. The fresh waste water of fish processing with low C:N ratio showed higher total carbon and total nitrogen removal efficiency than other reported systems with low C:N ratio [14][15][16].…”

Investigation of the flow dynamics of a Vertical Bioreactor using the Residence Time Distribution

“…The activated sludge and the attached growth cultures in a SBBR are identical, but at different proportions [15]. Anaerobic Ammonium Oxidation (ANAMMOX) bacteria, bacteria that reduce ammonium directly to nitrogen gas, are found in higher concentrations in the attached growth [15].…”