Strength of sewage is expressed in terms of all EXCEPT:
Ans. d (Coliform count). (Ref. Park PSM 22nd/pg. 708)SEWAGE# It is wastewater from community containing solid and liquid excreta, derived from houses, street and yard washing, factories and industries.# It resembles dirt water with unpleasant smell.# Composition of sewage is 99.9% water.# Average adult person excretes daily some 100 gm of faeces.# "Strength" of sewage is expressed in terms of - BOD, COD and suspended solids.Biological Oxygen Demand (BOD)# It is most imp. Test done on sewage.# It is a std test indicating organic content of the sewage.# It is defined as the amount of 02 absorbed by a sample of sewage during a specified temperature, generally 20 deg C for aerobic destruction or use of organic matter by living organisms. BOD values range from about 1 mg per litre for natural waters to about 300 mg/L for unRxed domestic sewage.Chemical oxygen demand (COD)Measures the O2 equivalent of that portion of the organic matter in a sample which is susceptible to oxidation by strong chemical oxidizer.Suspended solidsIf the amount of SS is 100 mg/L, the sewage is said to be weak; if the amount is 500 mg/L the sewage is said to be strong.
Biological Oxygen Demand
Chemical oxygen demand
Suspended solids
Coliform count
Environment and Health