Control of partial nitrification using pulse aeration for treating digested effluent of swine wastewater

Three sequencing batch reactors (SBRs) were used to investigate the influence of pulse frequencies on the partial nitrification (PN) process in this study. At a total aeration time of 6 min each hour, the aerated frequencies of R1, R2 and R3 were 6, 3 and 2 time h−1. During the steady period (117-143d), the nitrite accumulation rates (NARs) were 90.80%, 90.71% and 90.23% in R1, R2 and R3, respectively, indicating a steady nitritation was acquired. Activity measurements of the sludge samples taken at day 138 showed the activity of nitrite oxidating bacteria (NOB) was 0, indicating NOBs were successfully suppressed. The ratio of NO2−-N to NH4+-N in the effluent of R3 was 1.35, which most closely matched the influent of Anammox process. However, the energy efficiency evaluation showed that R1 had the highest actual oxygen transfer efficiency (AOTE) and dynamical efficiency (DE).