Biological Oxygen Demand, Chemical Oxygen Demand, Total Suspended Solid

Biological Oxygen Demand, Chemical Oxygen Demand, Total Suspended Solid

Subject: Environment

Context: The Central Pollution Control Board (CPCB) and Ministry of Environment, Forests and Climate Change said that 100 of 156 drains in catchment of river Yamuna ‘are not meeting standards’ on a plea in the SC which is hearing on “remediation of polluted rivers”.

Concept:

About BOD

• BOD is the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic conditions
• Biological oxygen demand is essentially a measure of the amount of oxygen required to remove waste organic matter from water in the process of decomposition by aerobic bacteria.
• Main sources of BOD are: leaves and woody debris; dead plants and animals; animal manure; effluents from pulp and paper mills, wastewater treatment plants, feedlots, and food-processing plants; failing septic systems; and urban storm water runoff etc.
• Higher BOD indicates more oxygen is required, signifying lower water quality. Low BOD means less oxygen is being removed from water, so the water is usually more pure.

Chemical Oxygen Demand (COD)

• COD is a method of estimating how much oxygen would be depleted from a body of receiving water as a result of bacterial action.
• The difference between BOD and COD is: COD or Chemical Oxygen Demand is the total measurement of all chemicals (organics & in-organics) in the water, whereas, BOD is a measure of, the amount of oxygen that require for the bacteria to degrade the organic components present in water.

Total suspended Solids (TSS):

• It is the dry-weight of suspended particles, that are not dissolved, in a sample of water that can be trapped by a filter. These are analyzed through filtering methods.
• It is used to assess the quality of a specimen of any type of water or water body