Assessment of a sludge treatment reed bed mesocosm under an arid and hot climate

This work is the first mesocosm study that evaluates the performance of sludge treatment reed beds (STRB) under hot and arid climatic conditions, focusing on the dewatering and mineralization of surplus activated sludge. Two mesocosms with and without plants were loaded with sludge at loading rate of 100 kg TS/m 2 /year and monitored for more than a year before the application of a one-month resting phase. The STRB showed higher sludge volume and total solids reduction than the unplanted drying bed, indicating enhanced dewatering capacity. The STRB achieved outstanding dewatering with more than 98 % of sludge volume reduction at the end of the study, with the total solids content exceeding 60 %. The STRB displayed a gradual mineralization of organic matter, as indicated by the reduction of the volatile solids from 73 % in the activated sludge to levels below 55 %. Metals in the residual sludge remained within national/international limits for sludge reuse in agriculture. Overall, the findings of this study highlight the efficiency and feasibility of STRB as a nature-based technology for sustainable sludge management sludge in arid and hot environments, affording valuable perspectives for real-world implementations and prospective expansion. • Mesocosms of planted and unplanted sludge treatment reed beds were compared. • First STRB mesocosm study under the challenging hot and arid desert climate. • Sludge treatment reed bed outperformed the unplanted bed. • Sludge volume reduction reached 97 %, total solids up to 85 %. • Heavy metals below national and international limits for agricultural reuse.