TOC explanation

The first case (Fig. 5) shows the effect of wastewater dilution leading to the same value of TOC than the treated sample. Obviously, the nature of organic matter is different as the treated effluent contains small oxygenated organic molecules, confirmed by the presence of nitrate (high Gaussian absorbance for short wavelengths see Chapter 5). From the environmental point of view, the impact of both effluents is obviously not similar. 

The second example (Fig. 6) is different. The difference between the shape of wastewater spectra is due to the distribution of suspended and colloids matters (see Chapter 6) and to the nature of dissolved organic matter. For example, the importance of the absorption peak at 225 nm (related to benzenic surfactants) of the samples is variable. 

The last example is shown in Fig. 7 with two spectra, one corresponding to urban wastewater, with a mixture of organic compounds, and the other one to a phenol solution of 60 mgL-1. The TOC value is the same for the two samples, but as for the first example (Fig. 5), the environmental impacts are very different. In case of the presence 

The interest in the explanation of TOC is thus evident, both to state on the stability degree of organic matter in wastewater, and to estimate the complexity of the corresponding mixture, for the toxicity evaluation, for example, if a major pollutant (obviously absorbing) is present. 

As the measurement of TOC is not sufficient for the determination of the biodegradable fraction of organic matter, the knowledge of which is very useful, a parameter based on the measurement of dissolved organic carbon (TOC after 1- xm filtration), 

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The main application of UV spectrophotometry for TOC explanation is to state on the risk of global organic pollution evolution. Figures 5 and 6 present spectra of wastewater samples with the same TOC value. 

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