Phragmites australis for sewage sludge stabilization
The purpose of this paper is to determine the effectiveness of a reed bed sludge treatment system in Italy after 1 year of operation in two urban wastewater treatment plants, where Phragmites australis was planted directly in emergency beds rearranged for the project. To evaluate the process of stabilization of the sludge parameters were detected which were conventional and not conventional to estimate the evolution of organic matter quality (watersoluble carbon (WSC), dehydrogenase activity (Dhase), fulvic acids, humic acids, pyrolytic indices of mineralization and humification (B/E3)). The analyses were carried out on both sludges and plant tissues, to assess the sludge biostabilization and nutrient and heavy metal uptake by the plants. The results showed that mineralization and stabilization of the sludge over time occurred as shown by the decrease of dissolved organic carbon and re-synthesis of humic-like matter. The combined system reed bed–biosolids is efficient not only in detoxifying heavy metals and removing nutrients (N, P) from biosolids, which accumulated in plants, but also in reducing sludge volume dramatically (95–99%).