p Combined treatment of sludge from a wastewater treatment plant and wastewater from a stormwater basin in a Sludge Treatment Reed Bed System during >25 years

A review of treatment of stormwater and dewatering of sludge in a Sludge Treatment Reed Bed system (STRB) during operation and emptying of the basins over >25 years of operation. Kallerup Wastewater Treatment Plant (WWTP) was designed with mechanical, biological, and chemical treatment including nitrification and denitri-fication and since 2009, the sludge production has stabilized to 160-200 tons DS yr � 1, which resulted in an area load of 24.7-40.9 kg DS m � 2 yr � 1. Four-to-six-time yearly wastewater has been pumped from the stormwater basin to the STRB system representing volumes in the order of magnitude that corresponds to 64-383 loads of 70 m3. During the operation period (2003-2022), approximately up to 1.40 m of sludge residue, equivalent to an accumulation rate of 0.06-0.10 m yr � 1, had accumulated in the basins. During the operation period 2012-2016, the maximum runoff rates have been very stable with maximum runoff rates of up to 0.018-0.024 l sec � 1 m � 2 and 0.011-0.024 l sec � 1 m � 2 for the first and last batch, respectively.