Good model calibration requires knowledge of not only model parameters but also influent wastewater characteristics, which can significantly influence plant performance, especially BNR systems. Given that these parameters vary from system to system, knowledge of wastewater characteristics and nitrification rate is extremely important for accurate process simulation.
Using a structured approach and many years of experience, EnviroSim will conduct or assist in the design of wastewater characterization and nitrification experiments on behalf of our clients.
Influent Wastewater Characteristics
Influent organic material consists of different fractions and sub-fractions; for example, biodegradable and unbiodegradable, each of these with soluble and particulate portions. The magnitudes of these fractions are very important in the description of activated sludge system behavior, particularly with respect to effluent COD quality, solids production and oxygen demand. Similarly, different influent nitrogen fractions can be identified; for example, the portion of the influent TKN which is in the form of saline ammonia. Influent wastewater characteristics may vary, often appreciably, from one municipal waste to another.
In addition to the influent wastewater characteristics, there are a number of parameters which must be defined in order to apply a model to predict system behavior (for example, yields and growth rates). Studies have shown that these stoichiometric and kinetic parameters do not change appreciably for different systems treating municipal wastewaters with the exception of the maximum specific growth rate of nitrifying organisms. In the design and operation of wastewater treatment plants that must remove ammonia, nitrification kinetics are the single most important consideration that determines the size (and hence cost) of the secondary treatment tankage and its operation, once the flows and contaminant loads to be treated are defined. Therefore in the design of a wastewater treatment plant, it is desirable to measure nitrification kinetics to avoid conservative (and costly) assumptions in sizing the secondary treatment tankage.
EnviroSim has extensive experience in measuring this important data. Please contact us for more information.