Explain The Significance And Optimum Value Of Acid?

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QUESTION
Explain the significance and optimum value of the following parameter
i. pH ii. DO iii. TDS iv. COD
v. BOD
ANSWER
pH ph is the concentration of hydronium ion. It represents the ratio of hydronium ions (H3O
+
) to Hydroxide ion (OH-
). It is numeric scale which decides the basic and alkalinity of water. If the ph of the solution is less than 7 than then the solution is said to alkaline and if the ph is greater then 7 then the solution is said to be basic.
The ph of pure water at 25o C is 7.0. If the pH of water is the >6.5 or 8.5 it is considered harmful. The water sample obtained from industrial contaminants is of the pH ranging from 3.4 to 8.4, mineral acids (HCl, HNO3 etc) have pH below 3.5. Water with greather p causese Corrosion
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A commonly used oxidant in COD assays is potassium dichromate (K2Cr2O7) which is used in combination with boiling sulphuric acid (H2SO4). Because this chemical oxidant is not specific to oxygen-consuming chemicals that are organic or inorganic, both of these sources of oxygen demand are measured in a COD. It is expressed in milligrams per litre (mg/L), which indicates the mass of oxygen consumed per litre of solution.
BOD
Biochemical oxygen demand or B.O.D. is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period Consumers like fish and other aquatic animals eat some of the producers, and the nutrients move up the food chain. When these organisms die, bacteria decompose the organic compounds and release into the water inorganic nutrients such as nitrate,phosphate, calcium, and others. Some of these nutrients end up down stream or in sediments, but most of them recycle again and again. Most of the bacteria in the aquatic water column are aerobic. That means that they use
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Record your final BOD result in ppm.
A BOD level of 1-2 ppm is considered very good. There will not be much organic waste present in the water supply. A water supply with a BOD level of 3-5 ppm is considered moderately clean. In water with a BOD level of 6-9 ppm, the water is considered somewhat polluted because there is usually organic matter present and bacteria are decomposing this waste. At BOD levels of 100 ppm or greater, the water supply is considered very polluted with organic waste. Generally, when BOD levels are high, there is a decline in DO levels. This is because the demand for oxygen by the bacteria is high and they are taking that oxygen from the oxygen dissolved in the water. If there is no organic waste present in the water, there won't be as many bacteria present to decompose it and thus the
BOD will tend to be lower and the DO level will tend to be higher.
At high BOD levels, organisms that are more tolerant of lower dissolved oxygen (i.e. leeches and sludge worms) may appear and become numerous.
Organisms that need higher oxygen levels (i.e. caddisfly larvae and mayfly nymphs) will not

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