Influence of Tourmaline on the Anaerobic Ammonium Oxidation Process in Sequencing Batch Reactors

This paper aims to investigate the enhancement effect of tourmaline on anaerobic ammonium oxidation (ANAMMOX) process in two sequencing batch reactors (SBRs). SBR1 was operated in parallel with SBR2, but 2 g tourmaline was added to the reactor. The results showed that when the nitrogen loading rate (NLR) was gradually increased from 181.8 to 727.3 mg/(L·d), the nitrogen removal rate (NRR) of SBR2 decreased to 99.0 mg/(L·d) from 576.7 mg/(L·d), corresponding to an increase of specific ANAMMOX activity (SAA) from 0.65 to 3.69 mgN/(gVSS·h).Tourmaline could control pH value to provide a stable environment for enrichment of ANAMMOX bacteria. Tourmaline promoted the growth and metabolism of ANAMMOX bacteria and enhanced the activity of the ANAMMOX reaction but was not a benefit for the granulation of ANAMMOX sludge. At the end of the start-up period, the 16S rRNA genes of ANAMMOX bacteria in SBR1 (8.21±0.07×109 copies/mL) were two orders of magnitude higher than that in SBR2 (5.13±0.08×107 copies/mL). The ANAMMOX sludge of SBR1 possessed a higher extracellular polymer substances (EPS) content than the SBR2 reactor (194–287 mg/g VSS in SBR1 and 203–252 mg/g VSS in SBR2). The level of heme c and TTC-dehydrogenase in SBR1 were still higher than that in SBR2.