WN

1
F
WN
gZ
gB
Ni
aN?
g1
N
B
Z
WP
e
kd
Zi
aP?
d
P
D
kd
ks
2
Dynamic Ecosystem Models for Eutrophication
Assessment
3
Phytoplankton Zooplankton Interactions
4
Phytoplankton Zooplankton InteractionsParameter
Definition

• ?max0.3 d-1
• ?0.6
• d0.1 d-1
• g11.5 m3gC-1d-1
• aPB1.0 mgP mgChl-1
• apz25 mgP gC-1
• aca0.04 gC mgChl-1
• ksp2 mgP m-3
• ?20.0 d-1
• Zin0.5 mgChl-1
• Pin10.0 mgP m-3

5
http//www.engr.uconn.edu/7Eewebhk/
6
Conventional Pollutants in Rivers and Estuaries
ORGANIC MATTER
OXYGEN
DECOMPOSITION (bacteria/animals)
PRODUCTION (plants)
Chemical energy
Solar energy
CARBON DIOXIDE
INORGANIC NUTRIENTS
7
THE DISSOLVED OXYGEN SAG
WWTP
River
DO (mgL-1)
Critical concentration (decompositionreaeration)
Distance
Decomposition dominates
Rearetion dominates
8
BIOCHEMICAL OXYGEN DEMAND

• Experiment
• decomposition of carbonaceous matter
• C6H12O66O2? 6CO26H2O
• Mass balance ?
• General solution gg0e -k1t
• Oxygen mass balance ?
• General solution for oxygen

9
BIOCHEMICAL OXYGEN DEMAND(ctd.)

• Matlab code
• tspan00.150
• x01 0.05 20'
• parameter definition
• global k1 rog
• rog1.067
• k10.1
• x08 10'
• initial concentrations are given in mg/L
• T,x ODE45('dxodt',tspan,x0)
• plot(tspan, x(,1),'linewidth',1.25)
• hold on
• plot(tspan, x(,2),'r','linewidth',1.25)
• ylabel('mg L-1')
• xlabel('Time (d)')
• legend('Glucose', 'Oxygen')

10
BIOCHEMICAL OXYGEN DEMAND(ctd.)

• Lrog g
• LL0 exp(-k1t)
• BODL0-L

11
BOD MODEL FOR A STREAM

• Mass balance ?
• krkdks (total removal decay settling)
• Steady state solution