Study of Wastewater Discharge

This part is related to studies of wastewater discharges, generally treated, into rivers and the sea. 

The existence of a direct isosbestic point is not always observed in case of the study of wastewater discharge. Another experiment has been realised for the study of the evolution of the Calavon river quality (Southern France), between Apt and Cavaillon (25 km). This part of the river receives the discharge of a 20,000-inhabitant biological treatment plant, with a small dilution factor (5) in summertime. 

Considering the shape of UV spectra of the river water and treated wastewater, a hidden isosbestic point (HIP) can only be found after normalisation. In this case, the spectra set evolution clearly shows a dilution of anthropogenic matter discharged (and the partly self purification of river water) and of nitrate concentration of the upstream river water. The presence of an HIP is related to the quality conservation of water (see Chapter 2). 

Another study based on the use of UV spectrophotometry for the evaluation of the impact of treated wastewater discharge in rivers [25] has shown that not only the qualitative and quantitative evolution of river water quality was possible, but also some hydraulic parameters such as the dilution factor of discharge or confluences. 

The dilution factor (F) of a mixture can generally be calculated as follows  

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