Achieving Reliable Cold Weather Tertiary Ammonia Removal Using Novel Biocatalysts

A novel biocatalyst ammonia removal system, operating in a single pass configuration was trialled by Thames Water to establish its ability to effectively removal ammonia in a tertiary application under cold weather conditions. The process was tested at pilot scale from July 2018 for a period of 11 months and demonstrated average effluent ammonia as low as 0.09 mg/l NH4-N under a fixed hydraulic retention time. Temperatures as low as 10˚C were observed during the pilot. Despite higher ammonia loading rates, the biocatalyst outperformed the existing site nitrifying sand filters for ammonia removal. No TSS removal or increase in solids was recorded across the reactor and an average of 36% biochemical oxygen demand was measured. The process was demonstrated to be effective in this application, showing resilience towards flow and load changes and recovery from short and long term shutdowns.