Table 1 presents existing models and their corresponding parameters for predicting chlorine decay in water distribution systems (Haas & Karra 1984). The first-order model is based on the assumption that the reaction rate is proportional to the residual chlorine concentration. The nth-order model is similar, but the decay rate in this model is proportional to the nth power of chlorine concentration. Limited models assume that some chlorine remains in the water unreacted. The parallel first-order model assumes that the overall rate of chlorine decay can be derived from the fast and slow components of the decay processes; therefore, the parallel first-order model consists of the weighted sum of two different first-order models.
Existing models for chlorine decay in water distribution systems
| Title | Governing equation | Parameters |
|---|---|---|
| 1st order | ||
| 2nd order | ||
| 3rd order | ||
| 4th order | ||
| Limited 1st order | ||
| Limited 2nd order | ||
| Limited 3rd order | ||
| Limited 4th order | ||
| Parallel 1st order |
| Title | Governing equation | Parameters |
|---|---|---|
| 1st order | ||
| 2nd order | ||
| 3rd order | ||
| 4th order | ||
| Limited 1st order | ||
| Limited 2nd order | ||
| Limited 3rd order | ||
| Limited 4th order | ||
| Parallel 1st order |