energy flow in ecosystems (section 5.3) representation by effect (section 2.5.4) biochemical oxygen...
Post on 20-Dec-2015
216 views
TRANSCRIPT
Energy Flow in Ecosystems (Section 5.3)
Representation by Effect (Section 2.5.4)
Biochemical Oxygen Demand (Section 5.4)
Energy Flow in EcosystemsEnergy Flow in Ecosystems
Energy fixationOrganic matterAutotrophsHeterotrophs
Aerobic respiration
Energy Flow in EcosystemsEnergy Flow in Ecosystems
Nitrate removal
Drinking water
Mercury cycling
Sludge digestion
Anaerobic respiration
Energy Flow in EcosystemsEnergy Flow in Ecosystems BiomassProduction
AutotrophsPrimary producersAlgaePhytoplankton
HeterotrophsSecondary producersPrimary ConsumersHerbivoresZooplankton
HeterotrophsSecondary consumersPlanktivores
HeterotrophsTertiary consumersPiscivoresCarnivores (also omnivores)
Organic Matter.Organic Matter.
2 2CO H
Carbohydrates(sugar and the polymers starch and cellulose)
Proteins(polymers of amino acids)
Fats ( Fats(formed from glycerol and fatty acids)
Organic Matter.Organic Matter.
2 22 2 ( )C H OC H O OO
Photosynthesis
2 2 22( )C O HO COH O
Respiration
also …mineralizationoxidationstabilization
Representation by Effect - Organic Matter.Representation by Effect - Organic Matter.
2 2CO H
2 2 22( )C O HO COH O
Respiration
When organic matter is used as a substrate for respiration,
… when it is oxidized… when it is mineralized… when it is stabilized
it exerts a “biochemical oxygen demand” or BOD.
Biochemical Oxygen DemandBiochemical Oxygen Demand
BOD: the amount of dissolved oxygen (mg/L) required to oxidize the organic matter in water.
CBOD: BOD exerted through oxidation of carbonaceous material.
NBOD: BOD exerted through oxidation of ammonia.
2 2 2 2( )C H O O CO H O
4 3 2 3 2 22 2 2 3NH HCO O NO CO H O
Biochemical Oxygen DemandBiochemical Oxygen Demand
NBOD is simple stoichiometry,
Stoichiometry does not work for CBOD because not all of the organic matter present is biodegradable.
Thus the CBOD is never greater and almost always less than the theoretical BOD (ThBOD).
but for wastewater, not so much!
2 2 2 2( )C H O O CO H O
4 3 2 3 2 22 2 2 3NH HCO O NO CO H O
6 12 6 2 2 26 6 6C H O O CO H O
Biochemical Oxygen DemandBiochemical Oxygen Demand
Distance or TimeTime (yr)
Co
nc
en
tra
tio
n
L
dLk L
dt
0 exp Lk ttL L
L0
BOD Exerted (y)
BOD Remaining (L)
0 exp Lk ttL L
Biochemical Oxygen DemandBiochemical Oxygen Demand
0t ty L L
0 (1 exp )Lk tty L
0 0 exp Lk tty L L