Long-term performance of the Anammox process under low nitrogen sludge loading rate and moderate to low temperature

Anammox process was studied during 1048 days in a Sequencing Batch Reactor (SBR) fed with synthetic sewage, under a Nitrogen Sludge Loading Rate (NSLR) less than 0.080 g-N/g-VSS·d and a temperature range of 30.5 ± 0.5-13.2 ± 0.3 °C. Anammox granular biomass from a full-scale plant for sludge reject water treatment was used as inoculum; this plant had a NSLR of 0.238 g-N/g-TSS·d at 34 ± 2.5 °C. The research was divided in four phases according to the NSLRs and temperatures applied. In order to assess the long-term influence of a NSLR lower than the NSLR capacity of the biomass and the diminishing of temperature on the Anammox process, the total nitrogen removal efficiency, specific activity, granular size stability, biomass concentration and microbial population variations were analyzed. The results provide useful information for the operation of Anammox SBR for sewage treatment using inoculum with a high NSLR, especially during the start-up period.