Pilot-Scale Evaluation Of Separate Stage Nitrification Utilizing An Attached Growth Moving Bed Media Process

Robert A. Zimmerman, Don Richard, Andrew T. Bradshaw, Patti P. Craddock

City of Moorhead, Minnesota
PO Box 779, Moorhead, Minnesota 56561-0779

Abstract

Submerged attached growth processes, both fixed and moving bed, are becoming more popular. These processes may or may not be used in combination with suspended growth treatment. The objective of this project was to evaluate a tertiary attached growth moving bed media nitrification system. Of particular interest was the ammonia-nitrogen removal rates and effluent concentrations achieved. A pilot-scale system for nitrification of secondary municipal wastewater effluent was operated for 142 days. Results indicated that the minimum aeration requirements for media mixing provided sufficient dissolved oxygen. The generation of biological solids from nitrification was insignificant. Design effluent ammonia-nitrogen concentrations (less than 6 mg/L) were achieved at influent loading rates greater than design (1.18 g ammonia-nitrogen/m²/d) coincident with detention times below design conditions (four hours). Empirical relationships for the ammonia-nitrogen removal rate and effluent concentration as a function of influent ammonia-nitrogen loading were developed. Detention time is believed to be an important parameter affecting these relationships.

Keywords

Ammonia, Nitrification, Attached Growth, Fixed Growth, Moving Bed Media

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