Evaluation of organic pollution

Since sewage waters contain mostly easily-degmdable organic substances it is possible to use the BOD value, determination of COD or total organic carbon for evaluation of their total organic pollution. 

At the demand of 200 1 of water per capita per day, an average BOD5 value of about 300 mg 1 can be expected. About half of the BOD5 value is ascribed to dissolved solids and a half to the total quantity of suspended solids. About 65% of total BOD5 is attributed to BOD5 of the dissolved and non-sedimentable solids which means that by sedimentation alone the BOD5 of sewage water can be reduced by one third. 

The specific quantity of BOD5, i.e. 60 g per capita per day can be derived from the given BOD5 values and water demand. 

In countries with a higher daily demand of water per capita (e.g. in USA, Switzerland, Sweden) sewage waters are more diluted and thus they show lower BOD5 values (lower than 100 mg F ). Also, the value of the specific quantity of BOD5 is higher (70 BOD5 per capita per day). 

Total contents of organic substances present in sewage waters can also be determined by measuring the organically bonded carbon. 

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Ciccoli, P., Bertoni, G., Brancaleoni, E., Fratarcangeli, R., Bruner, F. Evaluation of Organic Pollutants in the Open Air and Atmosphere in Industrial Sites Using Graphitized Carbon Black Traps and GC/MS Analysis with Specific Detectors, J. Chromatogr. 126, 757(1976)... 

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