Dosing at 5 °C: Why a Leachate Batch Takes 18 Minutes Instead of 6

A landfill in northern England ran its first batch of the winter on 4 February: 12 m³ of leachate at 4.8 °C, COD 21,000 mg/L, ammonia 1,150 mg/L, dosed at 22 kg of polymer per cubic metre with the same recipe that had set firm in six minutes the previous August. At eighteen minutes the paddle was st…