Mumbai university > Civil > SEM 8 > Industrial Waste Treatment

Marks: 10M

Year: Dec 2015, May 2014

The various biological treatment methods of industrial wastes are:

• Activate sludge process

• Trickling filter

• Rotating Biological Contactor (RBC)

• Anaerobic digester

• Sludge drying bed

• Centrifuge

• Vacuum filtration

• Oxidation ditch

• Oxidation pond

• Aerated lagoons.

Biochemical Oxygen demand (BOD):

• Biochemical oxygen demand is the amount of dissolved oxygen needed by aerobic biological organisms to breakdown organic material present in a given water sample at certain temperature over a specific time period.

• The BOD value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days of incubation at 20oC and is often used as a surrogate of the degree of organic pollution of water.

• BOD can be used as a gauge of the effectiveness of wastewater treatment plants. It is listed as a conventional pollutant in the U.S. Clean Water Act.

• BOD is similar in function to chemical oxygen demand, in that both measure the amount of organic compounds in water.

• However COD is less specific, since it measures everything that can be chemically oxidized, rather than just levels of biodegradable organic matter.

Chemical Oxygen demand (COD):

• Chemical oxygen demand or COD is a measurement of the oxygen required to oxidize soluble and particulate organic matter in water.

• Chemical oxygen demand is an important water quality parameter because similar to BOD it provides an index to assess the effect discharged waste water will have on the receiving environment.

• Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen levels.

• A reduction in DO can lead to anaerobic conditions, which is deleterious to higher aquatic life forms.

• The COD test is often used as an alternate to BOD due to shorter length of testing time.