Nitrogen removal from activated sludge process (ASP) treated municipal wastewater by biofilm channeling

Abstract

The pathways and kinetic behaviors of nitrogen compounds have been examined in biofilm channeling for the purification of wastewa‐ter treated by the activated sludge process (ASP) under laminar and turbulent flow conditions. The continuous water flow experiments show that the flow velocity will significantly influence the nitrification and denitrification conversion rates. The optimal total Kjeldahl nitrogen (TKN‐N) and total nitrogen (TN‐N) removal rates can be achieved during the initial turbulent flow condition. Concentrations of TKN‐N and TN‐N variations in the biofilm channel follow zero order kinetics. In our 54‐m biofilm channel, pathways of nitrogen compound conversions demonstrate that trapped suspended solids in the biofilm form an anoxic environment and are hydrolyzed to produce a carbon source, which may be the main reason for the occurrence of denitrification. The nitrification and denitrification processes occur simultaneously in the biofilm channel.