Structural analysis and characterization of biosolids. A case study of biosolids from wastewater treatment plants in Western Greece

Abstract

The great interest of modern societies in the reuse of wastes opens up new horizons in the field of wastewater, as well. In particular, the treated sludge resulting from a Wastewater Treatment Plant (WWTP) is dealed with a new perspective in the context of circular economy. The aim of this study is the characterization of its complex matrix, and the evaluation for reuse. Biosolids (BS) collected from four urban WWTPs in the Western region of Greece i.e. Agrinio (AG), Amaliada (AM), Aegio (AE) and Itea (IT). Analytical and spectroscopical methods namely TGA, ICP-OES, Fluorescence, SEM/EDS, XRD, FT-IR and NMR were the means that served this purpose. SEM along with XRD proved the amorphous nature of BS. The dominant metals detected in the samples are: Fe, Zn, Mn, with concentrations which meet the guidelines included in 86/278/EEC Directive. The inorganic load is of great importance, along with their humic acid content, adding value at the samples as fertilizers. BS appeared to be rich in organic matter with long aliphatic chains and numerous functional groups, as capturedin FT-IR spectra. The applied methods form an analytical protocol of the BS mapping, highlighting its potential as a material to be utilized in agriculture.

Keywords: Biosolids; Heavy metals; NMR; SEM; Structural characterization; XRD.