MITIGATING THE COST OF DENITRIFICATION IN FIXED FILM PLANT WITH NITRATE RECYCLE

This paper describes the extensive modeling carried out to determine the design expansion requirements for each unit process of the Littleton/Englewood wastewater treatment plant. The Mass Balance Model allows an accurate determination of the number and size of each unit process in the plant.Studies of alternative post-denitrification processes are presented, together with details of the final options selected for implementation at the plant. Various full-scale operating plants were visited which included MBBR, BAF and denitrification filter technologies for denitrification with methanol. The results of pilot plant trials using BAF technology at the Littleton/Englewood wastewater treatment plant are described.Implementation of an intra-plant denitrification recycle is described. The results of full-scale tests are presented. By incorporating the intra-plant recycle, redundant post-denitrification units are avoided. Other ancillary benefits include the attenuation of odors in preliminary and primary treatment processes.