Design Models

Data were collected on a frequent schedule from every cell at all of the lagoon systems shown in Table 4.17 for at least a full annual cycle. This large body of data allowed quantitative analysis that included all major variables, and several design models were independently developed. The two models discussed here have been shown to be the most accurate in predicting nitrogen removal in facultative lagoon systems. These have been validated using data from sources not used in model development. The two models are summarized in Table 4.18 and Table 4.19, and details on the theoretical development of the models were presented above. Further validation of the two models can be found in Reed et al. (1995), Reed (1984, 1985), and USEPA (1983). Both are first-order models and both depend on pH, temperature, and detention time in the system. Although they both predict the removal of total nitrogen, it is implied in the development of each that volatilization of ammonia is the major pathway for nitrogen removal from wastewater stabilization lagoons. The application of the two models is shown in Figure 4.29, and the predicted total nitrogen in the effluent is compared to the actual monthly average values measured at Peterborough, New Hampshire. Both

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