Effect of Tourmaline on Enrichment of Anammox Bacteria and Start-up of Reactors

In this study,the effect of tourmaline on the enrichment of Anammox bacteria for nitrogen removal was investigated by two parallel lab-scale continuously stirred tank bioreactors(CSTR) with tourmaline addition R2 and without tourmaline as control Rl,respectively.After 23 days of operation,Anammox activity was achieved with a simultaneous consumption of NH₄⁺-N and NO₂^--N in both reactors.Time of sludge adaptation period of R2 was shorter than that of Rl by 42 days(R2:12d,Rl:54 d).R2 showed a stronger capacity for nitrogen removal and resisting nitrogen shock load with the maximum nitrogen loading rate(NLR) of 205.0 mg/(L'd).In addition,tourmaline can control pH and oxidation reduction potential(ORP) values to provide a stable environment for enrichment of Anammox bacteria.Anammox activity batch tests demonstrate that addition of tourmaline can enhance the activity of Anammox bacteria with a maximum increase of 48.8% higher than the control.Analysis of extracellular polymeric substances(EPS) show that the maximum increase of carbohydrate,protein and total EPS production is obtained in R2 by 7.6% ,86.7% and 43.8% ,respectively,which indicate that tourmaline can promote the growth and metabolism of bacteria and enhance the activity of Anammox reaction.According to the results of the particle size observation and scanning electron microscope(SEM) images,there is no visible benefit for the granulation of Anammox sludge by adding tourmaline and great number of the Amammox sludge and tourmaline developed separately in the component.Phylogenetic tree of bacteria demonstrates that numbers of the functional bacteria such as denitrifying bacteria and nitrococcus are extracted from the seed sludge which contain a big quantity of brevibacterium and filamentous bacteria during the enrichment process.