生物脱氮—原理及工艺
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=4.57 mgO2/mgNO3--NProduced
(2）消耗碱度（Alkalinity）
Ex. alk. = 200 mg/L as CaCO3; nitrate production = 24 mg N/L.
Expected alk. = 200 - 7.14•24 = 29 mg/L as CaCO3.
Secondary clarifier
Effluent Qeff, Xeff
Sludge Return Qr, Xr
Net Growth Rate ≥ Sludge Wastage Rate
Waste Sludge Qw, Xr
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
If alkalinity < 40 mg/L as CaCO3; then dangerous.
生物脱氮过程
硝化反应—计量系数(Stoichiometry)
考虑合成
产率系数（Yield coefficient）:
生物脱氮过程
硝化反应—动力学（Kinetics）
Growth Rate:
Decay Rate :
Waste Sludge Qw, Xr
Sludge Wastage Rate = XA/SRT (mg VSS/(L∙d))
(Days)
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
(1). Minimum SRT Influent Q
Aeration basin X, V
(5). Inhibition and Toxicity
Complete inhibition to Nitrosomonas
Nickel Chromium Copper Zinc
生物脱氮—原理及工艺
污水中氮的存在形式
Subdivision of Nitrogen in Wastewater (Influent)
Nitrogen Removal: N in Wastewater→N2 (into atmosphere)
COD related
SA: 0 SF: iN,SF=0.03 gN/gCODSF SI: iN,SI=0.01 gN/gCODSI XS: iN,XS=0.03 gN/gCODXS XI: iN,XI=0.04 gN/gCODXI
iN,BM=0.07 gN/gCODBM
SI*iN,SI (~3%) XI*iN,XI (~10%) SF*iN,SF+XS*iN,XS (~12%)
生物脱氮过程
Nitrification
NH4+
NO2-
Aerobic (DO); Autotrophic
NO3-
NO2-
Denitrification
(3). Alkalinity and pH
1) Lack of inorganic carbon source; 2) Decrease of pH.
Optimal pH: 7.2-8.5 For 5<pH<7.2:
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
Net GrHale Waihona Puke Baiduwth Rate:
mg VSS/(L∙d) mg VSS/(L∙d)
mg VSS/(L∙d)
XA: Nitrifiers Concentration (mg VSS∙L-1); μ: Specific growth rate of nitrifiers (d-1);
μmax: Maximum specific growth rate of nitrifiers (d-1); SNH: Ammonium-N concentration (mg∙L-1); KNH: Half saturation coefficient for ammonium (mgN∙L-1); bA: Decay rate of nitrifiers (d-1)
(2). Temperature
For every 6°C drop, the value will halve. Design for nitrification plant should be based on the minimum expected temperature.
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
(4). Dissolved Oxygen (DO) Concentration
SO: DO Concentration, mg/L; KO: Half saturation coefficient for DO, 0.5 mgO2/L
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
(1). Minimum SRT
At steady state:
T=20 μmax=0.4/d
bA=0.04/d KNH=1 mg N/L
SRTmin
Question: 1) Calculate SRTmin; SRT for SNH=1 mg/l.
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
NO(g)
N2O(g)
N2(g)
Anoxic; Heterotrophic (Organic Carbon)
tG=ln2/μmax
生物脱氮过程
硝化反应—计量系数(Stoichiometry)
不考虑合成
pH decreases
(1）硝化需氧量（NOD） 1.5*32/14=3.43 mgO2/mgNH4+-N 0.5*32/14=1.14 mgO2/mgNO2--N
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
(1). Minimum SRT
Aeration basin
Influent Q
X, V
Secondary clarifier
Effluent Qeff, Xeff
Sludge Return Qr, Xr
(2）消耗碱度（Alkalinity）
Ex. alk. = 200 mg/L as CaCO3; nitrate production = 24 mg N/L.
Expected alk. = 200 - 7.14•24 = 29 mg/L as CaCO3.
Secondary clarifier
Effluent Qeff, Xeff
Sludge Return Qr, Xr
Net Growth Rate ≥ Sludge Wastage Rate
Waste Sludge Qw, Xr
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
If alkalinity < 40 mg/L as CaCO3; then dangerous.
生物脱氮过程
硝化反应—计量系数(Stoichiometry)
考虑合成
产率系数（Yield coefficient）:
生物脱氮过程
硝化反应—动力学（Kinetics）
Growth Rate:
Decay Rate :
Waste Sludge Qw, Xr
Sludge Wastage Rate = XA/SRT (mg VSS/(L∙d))
(Days)
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
(1). Minimum SRT Influent Q
Aeration basin X, V
(5). Inhibition and Toxicity
Complete inhibition to Nitrosomonas
Nickel Chromium Copper Zinc
生物脱氮—原理及工艺
污水中氮的存在形式
Subdivision of Nitrogen in Wastewater (Influent)
Nitrogen Removal: N in Wastewater→N2 (into atmosphere)
COD related
SA: 0 SF: iN,SF=0.03 gN/gCODSF SI: iN,SI=0.01 gN/gCODSI XS: iN,XS=0.03 gN/gCODXS XI: iN,XI=0.04 gN/gCODXI
iN,BM=0.07 gN/gCODBM
SI*iN,SI (~3%) XI*iN,XI (~10%) SF*iN,SF+XS*iN,XS (~12%)
生物脱氮过程
Nitrification
NH4+
NO2-
Aerobic (DO); Autotrophic
NO3-
NO2-
Denitrification
(3). Alkalinity and pH
1) Lack of inorganic carbon source; 2) Decrease of pH.
Optimal pH: 7.2-8.5 For 5<pH<7.2:
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
Net GrHale Waihona Puke Baiduwth Rate:
mg VSS/(L∙d) mg VSS/(L∙d)
mg VSS/(L∙d)
XA: Nitrifiers Concentration (mg VSS∙L-1); μ: Specific growth rate of nitrifiers (d-1);
μmax: Maximum specific growth rate of nitrifiers (d-1); SNH: Ammonium-N concentration (mg∙L-1); KNH: Half saturation coefficient for ammonium (mgN∙L-1); bA: Decay rate of nitrifiers (d-1)
(2). Temperature
For every 6°C drop, the value will halve. Design for nitrification plant should be based on the minimum expected temperature.
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
(4). Dissolved Oxygen (DO) Concentration
SO: DO Concentration, mg/L; KO: Half saturation coefficient for DO, 0.5 mgO2/L
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
(1). Minimum SRT
At steady state:
T=20 μmax=0.4/d
bA=0.04/d KNH=1 mg N/L
SRTmin
Question: 1) Calculate SRTmin; SRT for SNH=1 mg/l.
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
NO(g)
N2O(g)
N2(g)
Anoxic; Heterotrophic (Organic Carbon)
tG=ln2/μmax
生物脱氮过程
硝化反应—计量系数(Stoichiometry)
不考虑合成
pH decreases
(1）硝化需氧量（NOD） 1.5*32/14=3.43 mgO2/mgNH4+-N 0.5*32/14=1.14 mgO2/mgNO2--N
生物脱氮过程
硝化反应—影响因素（Factors Influencing Nitrification）
(1). Minimum SRT
Aeration basin
Influent Q
X, V
Secondary clarifier
Effluent Qeff, Xeff
Sludge Return Qr, Xr