Changes in the nature of dissolved organics during pulp and paper mill wastewater treatment: a multivariate statistical study combining data from three analytical techniques

Abstract

The paper-making process can produce large amounts of wastewater (WW) with high particulate and dissolved organic loads. Generally, in developed countries, stringent international regulations for environmental protection require pulp and paper mill WW to be treated to reduce the organic load prior to discharge into the receiving environment. This can be achieved by primary and secondary treatments involving both chemical and biological processes. These processes result in complex changes in the nature of the organic material, as some components are mineralised and others are transformed. In this study, changes in the nature of organics through different stages of secondary treatment of pulp and paper mill WW were followed using three advanced characterisation techniques: solid-state (13)C nuclear magnetic resonance (NMR) spectroscopy, pyrolysis-gas chromatography mass spectrometry (py-GCMS) and high-performance size-exclusion chromatography (HPSEC). Each technique provided a different perspective on the changes that occurred. To compare the different chemical perspectives in terms of the degree of similarity/difference between samples, we employed non-metric multidimensional scaling. Results indicate that NMR and HPSEC provided strongly correlated perspectives, with 86 % of the discrimination between the organic samples common to both techniques. Conversely, py-GCMS was found to provide a unique, and thus complementary, perspective.

Influence of extractants and filter materials in the extraction of dissolved organic matter (DOM) from subtropical agricultural soil

“…Products not detected in samples were given a zero value in the statistical treatments. The identified products were categorized into several general chemical classes, such as lipids, aromatics, organic acids, phenols and N-compounds (Lu et al, 2005;Plant et al, 2015). The lipids and aromatics were classified as hydrophobic compounds (Ho-compounds) (Karickhoff et al, 1979;Kalmykova et al, 2014), whereas the organic acids, phenols, and N-compounds were grouped as hydrophilic compounds (Hi-compounds) (Kalbitz et al, 2003;Pullicino and Gigliotti, 2007).…”