Chemistry World

BOD & COD BOD  Biological oxygen demand measures the amount of oxygen required by microorganisms like Bacteria to oxidize biodegradable wastes in waters.  SI unit  It is measured in mg/l as milligram per liter. In other words, mass of oxygen consumed per liter of solution.  Explanation  Small amount of oxygen is present in water is called as dissolved oxygen which is consumed by water bodies. Microorganisms like Bacteria uses this DO (dissolved oxygen) to oxidize the wastes in water. If large amount of wastes present, number of microorganisms will increase. Hence, higher BOD value, higher oxidation takes place and then amount of DO will begin to decline.  Similarly, if there is no waste body present in bacteria, there will be no bacteria existence in water. Hence the value of BOD will be lower and amount of Dissolved oxygen (DO) would be higher.  Diagrammatically,  Waste-bodies ⬆️~Bacteria⬆️~BOD⬆️~DO ⬇️ Method  Take a water sample conta...

 There are 17 sources of water pollution described below. Let's have a look!  Industrial wastes  Sewage and domestic wastes  Animal wastes  Radioactive wastes  Mining Activities  Marine dumping  Accident oil leakage  Leakage from landfills  Leakage from underground storage  Leakage from sewer line  Burning of fossil fuels  Global warming  Urban development  Detergents  Siltation  Agriculture discharge  Chemical fertilizer and Pesticides 

 Lead  Lead is heavy metal water pollution. It may cause many health problem when it is inhaled with water. It enters in our body and cause many health problems to human life. Causes  Major causes are as follows;  1. Lead pipes in sewage system  In our houses, if sewage system uses pipes made up of lead then it would be one cause of lead poisoning in water. When drinking water pass out from these pipes, lead mixed with water and inhaled by us while drinking water. 2. Aerator  In aerator, debris and lead may produce which may effect the human life 3. Industrial activities Lead is found in paints, printing, welding works and auto mechanic industries etc are major source of lead. Besides industries, mining is also source of lead in +2 oxidation state.  4. In atmosphere  Lead exists in form of PbSO⁴ and PbCO³.  5. Galena (PbS)  Galena also adds lead to water.  6. Gasoline  Leaded gasoline is also source of lead that adds into water...