SINTEF, one of Europe’s largest independent research organizations, teamed with MANTECH to perform a study on PeCOD as an alternative to DOC (dissolved organic carbon).
DOC is the filtered version of TOC (total organic carbon), and both are common parameters measured at drinking water treatment plants to determine the amount of organics in the raw water, and the removal of these organics through treatment. TOC and DOC can be difficult and time-consuming tests to perform manually, and automated analyzers also tend to be complex and expensive. Contrarily, PeCOD is a fast and easy test that can be performed directly by treatment plant operators without formal lab training. PeCOD has also been shown to be more sensitive than DOC/TOC in previous studies, since PeCOD measures the reactivity of the bulk organic load rather than just the quantity of carbon present.
The study compared PeCOD to DOC at three water treatment plants in Finland, Sweden, and Norway. Comparisons were performed on raw untreated water, following each of the treatment processes, then also from the distribution network. PeCOD was found to have an excellent correlation to DOC across the entire treatment process, with an R^2 correlation of 0.9843. Results and the correlation are displayed below:
NOMiNOR Water Samples – Finland WTP
NOMiNOR Water Samples – Sweden WTP
NOMiNOR Water Samples – Norway WTP
PeCOD to DOC Correlation from NOMiNOR Water Samples
Conclusions from the study were as follows:
- PeCOD more sensitive than DOC
- PeCOD measures soluble COD when performing sample filtering – not including proteins, macromolecules or cellulose
- Though the use of a homogenizer, PeCOD can be used for measuring Total COD and correlated to TOC as well
- PeCOD can be automated
- PeCOD can be used as a portable field analyser
- PeCOD can be used on-line
Some further lines of research were also realized from the project:
- Could PeCOD be an alternative to DOC for NOM fractionation and BDOC?
- Can PeCOD provide supplementary information?
You can view the full presentation of the NOMiNOR PeCOD vs TOC study at this link.