Chapter 7: Water Quality Management

Question 1

Water Quality Objectives

Answer 1

A numerical concentration limit or narrative statement, which has been negotiated to support and protect the designated uses of water at a specific site

Question 2

Water Quality Standard

Answer 2

A water quality objective that is recognized in enforceable environmental control laws of a level of government

Question 3

Economic Optimization

Answer 3

Balancing costs and loses in revenue against benefits for various alternatives

Question 4

Chemical purification methods (3)

Answer 4

1. Function of solubility products
2. Precipitation
3. Adsorption & Absorption

Question 5

Bacterial purification methods (4)

Answer 5

1. Endogenous respiration
2. Die-off
3. Toxicity
4. Growth of predators

Question 6

Organic purification methods (3)

Answer 6

1. Conversion
2. Deposits
3. Adsorption

Question 7

Suspended purification methods (2)

Answer 7

1. Flocculation
2. Sedimentation

Question 8

Water point sources

Answer 8

Collected by a network of pipes and/or channels and transported to a single point of discharge into the receiving water. (EX: sewage)

Question 9

Water nonpoint sources

Answer 9

Polluted water flows over the surface of the land or along the natural drainage channels to the nearest water body. Origin of discharge is not well defined and discontinuous (EX: urban and agricultural runoff, groundwater infiltration, atmospheric deposition)

Question 10

Oxygen demanding materials

Answer 10

Substances that oxidize in water. (EX: algae)

Question 11

Maximum dissolved oxygen (DO) in a water

Answer 11

9 mg/L, healthy if > 5 mg/L

Question 12

Biochemical Oxygen Demand (BOD)

Answer 12

When biodegradable organic matter is released into water, microorganisms feed on the waste and break them down into simpler organic and inorganic substances (EX: stable products: CO2, SO4, PO4, NO3)

Question 13

Theoretical oxygen demand (ThOD)

Answer 13

The amount of oxygen required to oxidize a substance to carbon dioxide and water calculated by stoichiometry

Question 14

Chemical Oxygen Demand (COD)

Answer 14

Measured quantity where a strong chemical oxidizing agent (chromic acid) is mixed with a water sample and then refluxed. The difference between the amount of oxidizing agent at the beginning of the test and that remaining at the end is used to calculate the COD.

Question 15

Value differences between BOD, ThOD, COD

Answer 15

BOD < COD < ThOD
COD = 1.25 BOD

Question 16

DO in a river

Answer 16

Indicator of the general health of a river.

Question 17

Deoxygenation

Answer 17

Removal of oxygen, affected by temperature

Question 18

Reaeration

Answer 18

Addition of oxygen, affected by temperature, velocity and stream depth