Combination of the OSA process with thermal treatment at moderate temperature for excess sludge minimization. (March 2020)

• Record Type: Journal Article
• Authors: Corsino, Santo Fabio; Capodici, Marco; Di Trapani, Daniele; Torregrossa, Michele; Viviani, Gaspare
• Is Part Of: Bioresource technology. Volume 300(2020)
• Publication Date: 2020-03
• Subjects: Activated sludge -- Biomass kinetics -- OSA process -- Sludge minimization -- Thermic treatment; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2019.122679
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: A thermic-OSA process at low temperature for excess sludge minimization was studied. Thermic-OSA enabled 80% of sludge reduction at HRT lower than conventional OSA. The abundance of filamentous bacteria decreased when the thermic-OSA was implemented. The thermic-OSA process produced an increase of the bacterial endogenous decay. Abstract: This study investigated the chance to couple the conventional Oxic Settling Anaerobic (OSA) process with a thermic treatment at moderate temperature (35 °C). The maximum excess sludge reduction rate (80%) was achieved when the plant was operated under 3 h of hydraulic retention time (HRT). Compared with the conventional OSA system, the thermic treatment enabled a further improvement in excess sludge minimization of 35%. The observed yield coefficient decreased from 0.25 gTSS gCOD −1 to 0.10 gTSS gCOD −1 when the temperature in the anaerobic reactor was increased to 35 °C, despite the lower HRT (3 h vs 6 h). Moreover, the thermic treatment enabled the decrease of filamentous bacteria, thereby improving the sludge settling properties. The thermic treatment enhanced the destruction of extracellular polymeric substances and the increase of endogenous decay rate (from 0.64 d −1 to 1.16 d −1 ) that reduced the biomass active fraction (from 22% to 4%).