Effect of temperature and load variation of pda system initiated by anammox bacteria self-enrichment
A UASB inoculated with PDA sludge initiated by anammox bacteria self-enrichment was used to gradually increase the influent nitrogen concentration from 20mg/L to 100mg/L at 25℃ down to 19℃(the nitrogen load increased from 3.2g/(m3·d)to 4.0g/(m3·d)).The reactor was operated for 115 days with a maximum total nitrogen removal efficiency of 89.9%.16S rRNA gene sequencing results showed that Candidatus Brocadia as the main anammox functional bacterium reached 3.7%abundance in the bio-carriers and the partial denitrifying functional bacterium Thaurea reached a maximum abundance of 15.7%in the floc sludge.Metagenomic analysis showed that the genes Nar and Nap,associated with partial denitrification,and Nir,Hzs and Hdh,associated with anammox,were fully expressed.