Water Quality 2

# Water Quality 2 - Water Quality and Pollution River Systems...

This preview shows pages 1–7. Sign up to view the full content.

Water Quality and Pollution: River Systems Text Reading: Chapter 9, pp. 357-374 Plug-flow reactor model DO resources in rivers and streams DO sag curve – sources and sinks Streeter-Phelps equation development Other considerations

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Plug-Flow – our third reactor “type” 1. Batch 2. Completely Mixed 3. Plug Flow Q Q x x + x Here, we do a mass balance around the volume V = Α∆ x Note: velocity = u = Q/A We will also assume first-order decay. cross-sectional area = A dt d(CV) = QC in – QC ± reactions
Plug-Flow – Mass Balance x x x x x x x x)C k(A - uAC - uAC dt dC ) x A ( + + + = Making appropriate substitutions into the mass-balance equation: x x x x x x x kC - x uC - x uC dt dC + + + = x x x x x x x kC - ) C C ( x u dt dC + + + - = : 0 x as C C and x C - x C C x x x x x = = - + + kC - x C u - t C =

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Plug-Flow – Mass Balance Please note that x = distance in the reactor (or distance downstream in a river) and u is the velocity of flow. So, time of flow = x/u. Now we have: If we now assume steady-state, that is, concentration will only vary with distance, not with time: kC - dx dC u and 0 t C = = kC - dt dC = Look familiar? Plug Flow: C = C o e -kt Note: t = θ in a PF reactor, and = time-of-travel in a river
Oxygen Resources in Streams – “DO Sag” Adding organic material (O 2 consumption)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Oxygen Resources in Streams River health is directly related to DO levels. The critical level of DO for “good” health is 4 to 5 mg/L O 2 . When DO concentrations are below this, many problems occur as we have
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 06/03/2011 for the course 53 50 taught by Professor Parkin during the Spring '11 term at University of Iowa.

### Page1 / 18

Water Quality 2 - Water Quality and Pollution River Systems...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online