FIELD APPLICATION OF WERF LOW F/M PROTOCOL TO MEASURE NITRIFIER GROWTH AND ENDOGENOUS DECAY

Over the last decade, environmental engineers have developed and applied computerized process simulation models to optimize the design of suspended growth biological wastewater treatment systems. Such models have proven especially useful for designing biological nutrient removal (BNR) plants. The utility of computer simulation depends to a large degree on model calibration, which in turn requires reliable estimates of influent wastewater characteristics as well as the stoichiometric and kinetic constants for each reaction included in the simulator. Unfortunately, reported literature values for several activated sludge model parameters, particularly those related to biological nitrification kinetics, are quite variable. This has led engineers to make conservative assumptions that have resulted in significant overdesign and increased facilities costs.Recognizing these concerns, the Water Environment Research Foundation (WERF) sponsored a project to develop state-of-the-art measurement procedures for activated sludge process model parameters (Melcer et al., 2003). The goal was to provide peer-reviewed methods for process model parameter estimation that would be simple, reproducible, and relatively inexpensive to implement. WERF focused extensively on methods to estimate the maximum specific growth rate (μAUT) and endogenous decay rate (bAUT) of nitrifying bacteria.This paper presents the results of a field application of the WERF low food-to-microorganism (F/M) protocol at Marine Corps Base Camp Pendleton (MCBCP), Oceanside, California. Adjusted to 20 degrees Celsius (°C), the site-specific estimates for μAUT obtained during this project were in the range of 0.82 d−1 to 0.84 d−1, while bAUT was estimated at 0.20 d−1. These values are comparable to values reported by other researchers at North American domestic sewage treatment plants. This 96-day study demonstrated that reliable nitrification parameter estimates can be obtained using the WERF low F/M protocol, although the procedure is labor intensive and demands significant attention to detail to be executed successfully in a field setting.