A rapid and effective way to cultivate anammox granular sludge through vibration

Abstract

Anaerobic ammonium oxidation (anammox) enriched granular sludge has long been considered slow-growing. The main aim of the present study was to investigate the granular sludge cultivation process using a vibration anaerobic sludge blanket (VASB) reactor, which was successfully operated for 170 days. A nitrogen loading rate (NLR) of up to 7-8 kg-N·m−3·d−1 was achieved at 35 °C and a nitrogen removal rate of 5 ± 0.2 kg-N·m−3·d−1 was obtained after about 100 days operation. Anammox granules were observed on the surface of the biofilm on the 80th day and could be collected after the 118th day. Three groups of anammox granular sludge, taken from the blanket portion of the VASB reactor under different conditions, were used to evaluate the quality of anammox granular sludge using batch assays. Most of the granule sizes were distributed from around 1.5 to 3.1 mm. Under a higher vibration intensity, the settling granules occupied about 82% of the total anammox biomass and the specific anammox activity reached 0.621 g-N·g-VSS−1·d−1. These results indicate that combine vibration on a biofilm reactor is a quick and effective way to form great settleable granules.