Design and calculation of tanks in the wastewater treatment system

Designing a wastewater treatment system is the job for an environmental engineer. Calculating the many parameters and choosing the correct coefficient can be a very complicated task. However, the Nam Viet environmental engineering company has designed a quick spreadsheet to assist engineers and help customers with calculating the size and volume of wastewater treatment tanks.

How to use the wastewater treatment system design calculation table:

Click on the type of tank you would like to calculate
Enter the system parameters and select the appropriate coefficient
Press enter and the system will display the relevant results

Designing the wastewater collection tank

Calculating the flotation tank

Calculating the settling tank

Calculating the equalization tank

Calculating the anoxic tank

Calculating the disinfection tank

Calculating the flocculation tank

Calculating the aerotank

Calculating the sludge tank

DESIGNING THE WASTEWATER COLLECTION TANK

Q_day: The average flowrate per day

m³/day.night

h: The operating hours

Q_hr: The average flowrate per hour

m³/hr

t: The hydraulic retention time (t = 15 - 30 minutes)

minute

V: The volume of the tank

m³

h: The height of the tank

meter

A: The acreage of the tank

m²

l: The length of the tank

meter

r: The width of the tank

meter

CALCULATING THE EQUALIZATION TANK

Q_day: The average flowrate per day

m³/day.night

a: The safety factor

Q_max: The average maximum flowrate per day

m³/day.night

h: The operating hours

Q_hr: The average maximum flowrate per hour

m³/hr

t: The hydraulic retention time (t = 4 - 12 hours)

V: The volume of the tank

m³

h: The height of the tank

meter

A: The acreage of the tank

m²

l: The length of the tank

meter

r: The width of the tank

meter

CALCULATING THE DISINFECTION TANK

Q_day: The average flowrate per day

m³/day.night

a: The safety factor 1.2-1.3

Q_max: The average maximum flowrate per day

m³/day.night

h: The operating hours

Q_max: The average flowrate per hour

m³/hr

t: The hydraulic retention time

minute

V: The volume of the tank

m³

h: The height of the tank

meter

A: The acreage of the tank

m²

l: The length of the tank

meter

r: The width of the tank

meter

CALCULATING THE ANOXIC TANK

Q_day: The average flowrate per day

m³/day.night

a: The safety factor 1.2-1.3

Q_max: The average maximum flowrate per day

m³/day.night

h: The operating hours

Q_hr: The average flowrate per hour

m³/hr

DO: The dissolved oxygen

milligram/litre

ρN₂: The denitrification rate at 20°C

mgNO^3-/mg sludge

T: The temperature of the wastewater

°C

The denitrification rate, ρN_2t

mgNO^3-/mg sludge

X: The concentration of the activated sludge in the tank

milligram/litre

N_v: The total nitrogen input

milligram/litre

N_r: The total nitrogen output

milligram/litre

The safety factor

The hydraulic retention time for denitrification, θ

day^-1

V_at: The volume of the anoxic tank: V_at

m³

The total wastewater volume

m³/hr

The wastewater flow of the equalization tank

m³/hr

The percent of the circulating water flow denitrifying

The amount of the circulating sludge

The effective height of the anoxic tank

meter

The protected height of the tank

meter

The total height of the tank

meter

The acreage of the anoxic tank

m²

The length

meter

The width

meter

CALCULATING THE AEROTANK

Q_day: The average flowrate per day

m³/day.night

a: The safety factor 1.2-1.3

Q_max: The average maximum flowrate per day

m³/day.night

h: The operating hours

Q_hr: The average flowrate per hour

m³/hr

θ_c: The age of the sludge

day

Y: The maximum growth coefficient

X: The amount of the mixed liquor volatile suspended solids (MLVSS)

milligram/litre

F/M: The ratio of the activated sludge in wastewater

S_o: The concentration of BOD5 in wastewater in the tank

milligram/litre

S: The concentration of BOD5 in effluent wastewater

milligram/litre

K_d: The coefficient of decompositional intracellular

V: The volume of the air blowing tank depends on the age of the sludge

m³

The effective height of the tank

meter

The protected height of the tank

meter

The total height of the tank

meter

The acreage of the aerotank

m²

The constructed volume

m³

The retention time in the design

CALCULATING THE SETTLING TANK

Q_day: The average flowrate per day

m³/day.night

a: The safety factor 1.2-1.3

Q_max: The average maximum flowrate per day

m³/day.night

h: The operating hours

Q_hr: The average flowrate per hour

m³/hr

α: The periodic coefficient, α = 0,6-0,8

C_o: The concentration of the activated sludge in the settling tank

g/m³

S_o: The concentration of BOD5 in wastewater in the settling tank

milligram/litre

X: The amount of the mixed liquor volatile suspended solids (MLVSS)
If S_o ≤ 100, X ≤ 1500 (milligram/litre)
If S_o = 100-150, X ≤ 1000 (milligram/litre)
If S_o = 150-200, X ≤ 2800 (milligram/litre)
If S_o > 200, X = 2800-4000 (milligram/litre)

milligram/litre

C_t: The concentration of the activated sludge in the circulating stream

g/m³

V_max

m/hr

CL: The concentration of the residue at the sedimentation section

g/m³

VL: The sedimentation velocity of the interface

m/hr

S: The acreage of the sedimentation area

m²

v: The speed of the flow in the pipe

mm/s

m/hr

Q_max: The average flow + The circulating flow

m³/hr

The acreage of the center tank, F_b

m²

The total acreage of the tank, F

m²

The length and the width of the settling tank, B = L

meter

The diameter of the distributive pipe

meter

a: The hydraulic weight

m³/m².day

SL = 103-F_b

m²

The rising velocity of the water in the tank, V

meter/hr

The diameter of the water collection trough, D_m

meter

The total length of the water collection trough, L_m

meter

The effective height of the tank

meter

The height of the water after settling, h₂

meter

The height of the sludge collected pit, h₃

meter

The height of the sludge, h₄

meter

CALCULATING THE SLUDGE TANK

The sludge suction time

day

The aerobic sludge flow

m³/day.night

Selecting the pumped sludge flow rate

m³/hr

The volume of the sludge tank

m³

The effective height of the sludge tank

meter

The protective height of the sludge tank

meter

The total height of the sludge tank

meter

The acreage of the sludge tank

m²

The constructed volume of the sludge tank

m³

CALCULATING THE FLOCCULATION TANK

Q_day: The average flowrate per day

m³/day.night

a: The safety factor 1.2-1.3

Q_max: The average maximum flowrate per day

m³/day.night

h: The operating hours

Q_hr: The average flowrate per hour

m³/hr

The flocculation tank

The hydraulic retention time in the flocculation tank (10 - 30 minutes)

minute

The volume of the flocculation tank

m³

The effective height of the tank

meter

The protected height of the tank

meter

The total height of the tank

meter

The acreage of the tank

m²

The length

meter

The width

meter

The constructed volume of the flocculation tank

m³

The coagulation tank

The hydraulic retention time in the coagulation tank (10 - 30 minutes)

minute

The volume of the sludge tank

m³

The effective height of the tank

meter

The protected height of the tank

meter

The total height of the tank

meter

The acreage of the tank

m²

The length

meter

The width

meter

The constructed volume of the tank

m³

The settling tank

The hydraulic retention time

The height of settling chamber

meter

The volume of the settling chamber volume

m³

The effective height of the tank

meter

The protected height of the tank

meter

The total height of the tank

meter

The acreage of the tank

m²

The length

meter

The width

meter

The constructed volume of the flocculation tank

m³

CALCULATING THE FLOTATION TANK

Q_day: The average flowrate per day

m³/day.night

a: The safety factor 1.2 - 1.3

Q_max: The average maximum flowrate per day

m³/day.night

h: The operating hours

Q_hr: The average flowrate per hour

m³/hr

The flotation time, 20 - 60 minutes

minute

The ventilation coefficient, 0.2 - 0.3

The volume of the flotation tank

m³

The height of the water layer in the flotation tank, 1 - 3 m

meter

The height of the sludge

meter

The effective height

meter

The surface acreage of the tank

m²

The width

meter

The length of the flotation zone

meter

The length of the water distribution area

meter

The length of the water collection area

meter

The total length of the flotation tank

meter