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

The pathways and kinetic behaviors of nitrogen compounds have been examined in biofilm channeling for the purification of wastewater treated by the ac tivated sludge process (ASP) under laminar and turbulent flow conditions. T he continuous water flow experiments show that the flow velocity will signi ficantly influence the nitrification and denitrification conversion rates. The optimal total Kjeldahl nitrogen (TKN-N) and total nitrogen (TN-N) remov al rates can be achieved during the initial turbulent flow condition. Conce ntrations of TKN-N and TN-N variations in the biofilm channel follow,zero o rder kinetics. In our 54-m biofilm channel, pathways of nitrogen compound c onversions demonstrate that trapped suspended solids in the biofilm form an anoxic environment and are hydrolyzed to produce a carbon source, which ma y be the main reason for the occurrence of denitrification. The nitrificati on and denitrification processes occur simultaneously in the biofilm channe l.