I want to use C/N of 1.8 for treating nitrate (NO3) from groundwater using slow sand filter. the nitrate concentration in groundwater is known, is equal to 15 mg/ l in form nitrate nitrogen. So now I want find out the ethanol amount in millilitres to add as carbon source in the water to get C/N of 1.8, ethanol is in luiqed form which I am using now.
I L of water contains 15 mg NO3-N
Required C:N ratio is 1.8
Therefore required C = 1.8 x 15/1 = 27 mg
C2H5OH molecular weight (MW) = 46 (I have rounded but you can use the exact MWs)
According to the MW of ethanol, a total of 24 mg C is in 46 mg ethanol
Therefore 27 mg C is equivalent to 46 x 27/24 mg ethanol which is 51.75 mg
The density of ethanol at 20oC is 789.3 mg/mL
Therefore the required ethanol volume is 51.75/789.3 = 0.0656 mL per litre of groundwater.
Yes 27 mg/L of carbon. The pure Ethanol is C2H5OH and the weight of ethanol contains 52% of carbon weight. If you have pure ethanol (27/0,52) you need to add 52 mg/L of ethanol to add 27 mg/L of carbon.
Yann
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