Start-up of Aerobic Granular Biomass System: Fate of Organics and Nutrients Removal From Anaerobic Effluent

PurposeThe up-flow anaerobic sludge blanket reactor (UASB) treated effluent does not meet the national disposal standards of certain countries, such as India and Brazil. To meet the required standards, it is necessary to upgrade the UASB technology through a post-treatment system. The present work aimed to investigate the optimal operating conditions for the formation of granules in an anaerobic/oxic/anoxic (A/O/A) cyclic mode aerobic granular biomass reactor (AGBR) for the treatment of anaerobic effluent (UASB effluent).MethodsTwo rectangular reactors, R1 and R2, were used to cultivate aerobic granular biomass (AGB). R1 served as the control reactor and was fed with low-strength synthetic wastewater throughout the study, while R2 was fed with medium strength sewage and UASB effluent over the study periods.ResultsGranules start-ups were observed on the 30th and 20th days in R1 and R2, respectively. In R1, the removal efficiency of COD, NH4+-N, total nitrogen (TN), and PO43--P was achieved 80.86%, 97.46%, 53.6%, and 45%, respectively. Whereas the removal efficiency of COD, NH4+-N, TN, and PO43--P was observed 63.61%, 58.18%, 50%, and 40%, respectively, in R2. The results indicated that the short aeration time, comprising 50% of the total cycle time over a 3-h duration, was the most effective operational phase for achieving high removal of organics and nutrients.ConclusionThe study demonstrates that the A/O/A AGBR effectively cultivates AGB and removes organics and nutrients from anaerobic effluent. The use of medium-strength sewage as a substrate in R2 proved beneficial in reducing the granule start-up time for treating low-strength anaerobic effluent.

Automated summary

The study investigated the optimal operating conditions for the formation of granules in an A/O/A cyclic mode aerobic granular biomass reactor (AGBR) for the treatment of anaerobic effluent. The results showed that the short aeration time, comprising 50% of the total cycle time, was the most effective phase for achieving high removal of organics and nutrients.