Short SRT Nitrification Through Seeding Nitrifying Bacteria Into Cold, Non-Nitrifying Sequencing Batch Reactors

Abstract

This study was developed to determine whether nitrifying bacteria grown on centrate at 20, 25, and 30 o C could induce nitrification in sequencing batch reactors (SBRs) operating at 10 o C with a solids retention time (SRT) of 4 days. A seeding rate of 6.7 mg VSS/L·d with biomass acclimated to 20 o C achieved full nitrification in SBRs with hydraulic retention times (HRTs) greater than 43.3 hours. When seeding was stopped, effluent ammonia nitrogen (NH 3 -N) concentrations increased quickly, eventually reaching influent levels. When the HRT was reduced to 24 hours, partial NH 3 -N removal was achieved for all three of the nitrifying biomasses. Nitrification was not induced in any reactors when HRT was 12 hours.