Anammox Granules Acclimatized to Mainstream Conditions Can Achieve a Volumetric Nitrogen Removal Rate Comparable to Sidestream Systems

Abstract

The implementation of mainstream anammox has gained increasing attention. In this study, the feasibility of using sidestream anammox granules to start up mainstream reactors was investigated by comparing two switching strategies. A maximum nitrogen removal potential of 3.6 ± 0.2 kg N m −3 d −1 was obtained for the reactor after direct switching to mainstream conditions (70 mg TN L −1 , 15 °C). Nevertheless, the reactor preacclimatized to 25 °C (Ma) exhibited a higher nitrogen removal potential of 7.0 ± 0.3 kg N m −3 d −1 at 15 °C, which is the highest volumetric nitrogen removal rate of mainstream anammox reactors to date. Candidatus Kuenenia stuttgartiensis was identified as the dominant anammox bacterium, and its relative abundance in two reactors remained stable throughout the whole operation (200 days). Moreover, with the aid of acclimatization, the activation energy was reduced and the specific growth rate became higher. These results indicated that the physiological evolution of the dominant anammox bacterium instead of interspecies selection was the main reason for the high potential during the switch to mainstream conditions. Therefore, using sidestream anammox granules as seed sludge to start up mainstream reactors was demonstrated to be feasible, and a switching strategy of acclimatization at 25 °C was recommended.

Combination of Sequencing Batch Operation and A/O Process to Achieve Partial Mainstream Anammox: Pilot-Scale Demonstration and Microbial Ecological Mechanism

“…For the BNR activity tests, the bulk sludge and biofilm were collected from the aerobic and anaerobic tanks, respectively. Specific nitrification rates (SNRs), specific denitrification rates (SDNRs), specific anammox activity (SAA), anaerobic phosphorus-release rates (PRRs), and aerobic and anoxic phosphorus uptake rates (PURs) of the biomass were measured according to previous studies. , The batch tests were conducted on days 142, 201, and 231. The details on the batch tests can be found in Method S1.…”

“…Moreover, the inoculated anammox biomass had poor adaptability to adverse environments under mainstream conditions, resulting in washout of anammox bacteria and performance instability. 9 Therefore, developing novel processes or operation strategies for in situ enriching anammox bacteria is of great importance for sustainable operation of mainstream anammox in practical applications.…”

Adding exogenous protein relieves the toxicity of nanoparticles to anammox granular sludge by adsorption and the formation of eco-coronas

“…The key functional genes involved in the nitrogen cycle ( hzs A, hdh , nir S, nir K, nos Z and nor B) were determined by quantitative polymerase chain reaction (qPCR, QuantStudio 3, Applied Biosystems, USA) in triplicate. 33 The plasmids containing target genes were synthesized as standard curve preparation. In each test, DNA was replaced by ddH 2 O as negative control.…”

Highly Enriched Anammox Bacteria with a Novel Granulation Model Regulated by Epistylis spp. in Domestic Wastewater Treatment

“…To date, several strategies for culturing and retaining AnAOB have been reported in forms such as biofilms, microbial aggregates, granules, or entrapped forms such as gel carriers . Among these, anammox granulation has been regarded as a particularly efficient method that has been widely applied in anammox configurations. , The numerous advantages of granules facilitate good settleability and reduce biomass loss with a slow growth rate. This also results in a high volumetric loading rate, strong resistance to adverse environmental effects, and a high settling velocity .…”