## Do sag curves calculate?

Streeter-Phelps Equation / DO Sag Curve

Data Point | Value | Equation |
---|---|---|

Initial DO of mixture | 8.789 | DOofMixture=(WasteFlow∗WasteDO)+(StreamFlow∗StreamDO)WasteFlow+StreamFlow |

Initial BOD5 of mixture | 25.008 | BOD5=(WasteFlow∗WasteBOD5)+(StreamFlow∗StreamBOD5)WasteFlow+StreamFlow |

BODL of mixture | 30.598 | BODL=BOD51−e−5∗k1 |

### What is the DO sag curve?

Oxygen sag or the oxygen sag curve refers to the reduction in dissolved oxygen plotted over a distance along a water body from a point at which sewage or other pollutants have been discharged.

**Do sag curves derive?**

The differential equation for the dissolved oxygen sag curve (DO sag curve) is derived. Moreover, the differential equation is valid for all deoxygenation and oxygenation constants, unlike the Streeter-Phelps equation, which is undefined when these constants are equal.

**Do sag curves zone?**

When pollutants (waste or excess fertilizer) enter the water, BOD and DO levels change, producing the oxygen sag curve. DO and BOD levels create characteristic zones in a stream around the point source of pollution known as the Clean zone, Decomposition Zone, Septic Zone, and Recovery Zone.

## What is deoxygenation curve?

Deoxygenation curve: The rate of deoxygenation depends upon the amount of organic matter remaining to be oxidized at a given time as well as on the temperature of reaction, hence at given temperature, the curve showing depletion of DO with time i.e. deoxygenation curve is similar to the first stage BOD-curve.

### How do you calculate deficit?

a) D = Dissolved oxygen deficit; units = mg/l; defined as the difference between the dissolved oxygen concentration at saturation and the actual instantaneous dissolved oxygen concentration at time t, i.e., D = D.O.sat – D.O.actual.

**What is the Streeter Phelps dissolved oxygen DO sag curve?**

The model describes how dissolved oxygen (DO) decreases in a river or stream along a certain distance by degradation of biochemical oxygen demand (BOD). Phelps, a consultant for the U.S. Public Health Service, in 1925, based on field data from the Ohio River. The equation is also known as the DO sag equation.

**What are the salient features of oxygen sag curve?**

The curve obtained when the concentration of dissolved oxygen in a river into which sewage or some other pollutant has been discharged is plotted against the distance downstream from the sewage outlet (see graph). Samples of water are taken at areas upstream and downstream from the sewage outlet.

## How do you calculate surplus and deficit?

The net operating surplus/-deficit is calculated by subtracting expenditure for the relevant period from the revenue for the same period. If total revenue exceeds total expenditure, the net effect is an operating surplus.