Effect of wastewater temperature and concentration of organic compounds on the effi ciency of ammonium nitrogen removal in a household treatment plant servicing a school building

Abstract

The aim of this study was to determine the impact of the temperature of wastewater in a biological reactor with activated sludge and the BOD5/N-NH4 ratio in the infl uent to the treatment plant on nitrifi cation effi ciency and the concentration of ammonium nitrogen in treated wastewater. Tests were carried out in a household wastewater treatment plant which collects and treats sewage from a school building and a teacher's house. During the 3-year study, large fl uctuations in the sewage temperature in bioreactor were noted which was closely related to the ambient temperature. There were also large fl uctuations in the concentration of organic matter and the concentration of ammonium nitrogen in infl owing sewage. The influence of wastewater temperature in the bioreactor and the BOD5/N-NH4 ratio on the concentration of ammonium nitrogen in treated wastewater was determined using Pearson's linear correlation. A statistical analysis showed that a 1°C decrease in the temperature of wastewater in the bioreactor increased the concentration of ammonium nitrogen in treated wastewater by 2.64 mgN-NH4 L-1. Moreover, it was found that nitrifi cation depended on the ratio of BOD5 to the concentration of ammonium nitrogen in wastewater fl owing into the bioreactor. An increase in the BOD5/N-NH4 ratio by 1 value led to a 5.41 mgN-NH4 L-1 decrease in the concentration of ammonium nitrogen.