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F. W N. g Z. g B. N i. a N . g 1. N. B. Z. W P. k d. e. Z i. a P . d. P. D. k d. k s. Dynamic Ecosystem Models for Eutrophication Assessment. Phytoplankton Zooplankton Interactions. Phytoplankton Zooplankton Interactions Parameter Definition. max = 0.3 d -1 = 0.6
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F WN gZ gB Ni aN g1 N B Z WP kd e Zi aP d P D kd ks
Phytoplankton Zooplankton InteractionsParameter Definition • max=0.3 d-1 • =0.6 • d=0.1 d-1 • g1=1.5 m3gC-1d-1 • aPB=1.0 mgP mgChl-1 • apz=25 mgP gC-1 • aca=0.04 gC mgChl-1 • ksp=2 mgP m-3 • =20.0 d-1 • Zin=0.5 mgChl-1 • Pin=10.0mgP m-3
Conventional Pollutants in Rivers and Estuaries ORGANIC MATTER OXYGEN DECOMPOSITION (bacteria/animals) PRODUCTION (plants) Chemical energy Solar energy CARBON DIOXIDE INORGANIC NUTRIENTS
THE DISSOLVED OXYGEN SAG WWTP River DO (mgL-1) Critical concentration (decomposition=reaeration) Distance Decomposition dominates Rearetion dominates
BIOCHEMICAL OXYGEN DEMAND • Experiment • decomposition of carbonaceous matter • C6H12O6+6O2 6CO2+6H2O • Mass balance • General solution g=g0e -k1t • Oxygen mass balance • General solution for oxygen
BIOCHEMICAL OXYGEN DEMAND(ctd.) Matlab “code” • tspan=0:0.1:50; • x0=[1 0.05 20]'; • %parameter definition • global k1 rog • rog=1.067; • k1=0.1; • x0=[8 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')
BIOCHEMICAL OXYGEN DEMAND(ctd.) L=rog g L=L0 exp(-k1t) BOD=L0-L
BOD MODEL FOR A STREAM • Mass balance • kr=kd+ks (total removal = decay + settling) • Steady state solution: