Sludge dewatering and mineralization in two full-scale drying reed beds in Catalonia, Spain

Abstract

Optimization of sludge management should help reducing sludge handling costs in wastewater treatment plants. Sludge drying reed beds appear as a new and alternative technology. The study have been carried out in two systems where samples of influent sludge and sludge accumulated on the drying reed beds (surface and bottom layers) were analysed for total and volatile solids (TS and VS), chemical oxygen demand, nutrients, heavy metals and pathogens (E.coli and Salmonella sp.). Similar patterns and removal efficiencies were observed in both facilities. The results showed a high degree of dewatering (24-26% TS) and suggested a progressive organic matter removal and sludge mineralization processes within the drying reed beds. The concentration of nutrients, heavy metals and pathogens, indicated a good quality of the sludge for land application.