No abstract

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 (µ AUT ) and endogenous decay rate (b AUT ) 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 (ºC), the site-specific estimates for µ AUT obtained during this project were in the range of 0.82 d -1 to 0.84 d -1 , while b AUT 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.

Organic nitrogen (N org ) removal by the reverse osmosis (RO) process is not well documented in the literature. Unlike inorganic nitrogen (e.g. ammonia, nitrate, nitrite), which is consistently removed across a RO membrane as a function of process operation (e.g. flux and recovery), pH and membrane type; N org removal may vary depending on its characteristics (e.g. size, charge and hydrophobicity). The results of a pilot study that was conducted to determine the total nitrogen (TN) removal by the RO process are presented. The N org removal rates are compared with removals observed from three full-scale RO facilities and four pilot studies. The results of this analysis suggest that N org removal is variable and that RO may not consistently produce TN levels <1.0 mg/L without additional treatment. Three hypotheses to explain the variability in N org removal in the different data sets are presented.

The results of a pilot study that was conducted to determine the total nitrogen removal by the reverse osmosis process are presented. The organic nitrogen removal rates are compared with removals observed from three full-scale reverse osmosis facilities and four pilot studies. The results of this analysis suggest that organic nitrogen removal is variable and that reverse osmosis may not consistently produce total nitrogen levels less than 1.0 mg/L without additional treatment. Three hypotheses to explain the variability in organic nitrogen removal in the different data sets are presented. Water Environ. Res., 84, 588 (2012).

Organic nitrogen (N org ) removal by the reverse osmosis (RO) process is not well documented in the literature. Unlike inorganic nitrogen (i.e. ammonia, nitrate, nitrite), which is consistently removed across a RO membrane as a function of process operation (i.e. flux and recovery), pH and membrane type; the N org removal will vary depending on its characteristics. Characteristics of N org that could affect its removal include size, charge and hydrophobicity. The results of a pilot study that was conducted to determine the total nitrogen (TN) removal possible with the RO process are presented. The N org removal rates are compared with removals observed from three full-scale RO facilities and four pilot studies. The results of this analysis suggest that RO may not consistently produced TN levels less than 1.0 mg/L without additional treatment. Biological nutrient removal (BNR) followed by RO treatment would be necessary to meet stringent TN limits. Additional processes such as coagulation or activated carbon may be necessary as well.