5-10 years

15-20 years

30-40 years

40-50 years

specific gravity of solid particles

size of particles

depth of tank

temperature of liquid

20°C - 1day

25°C- 3day

20°C - 5day

30°C- 5day

5 day BOD is the ultimate BOD.

5 day BOD is greater than 4 day BOD keeping other conditions same.

5 day BOD is less than 4 day BOD keeping other conditions same.

BOD does nof depend on time.

100000

1000

4000

400000