Achieving nitrogen removal with low material and energy consumption through partial nitrification coupled with short-cut sulfur autotrophic denitrification in a single-stage SBR

An innovative partial nitrification and short-cut sulfur autotrophic denitrification (PN-SSAD, NH 4 + -N → NO 2 − -N → N 2 ) coupled system in a single-stage SBR was proposed to treat low C/N wastewater with low material and energy consumption. Nearly 50 % alkalinity consumption and 40 % sulfate production were reduced in S 0 -SSAD compared with S 0 -SAD, whereas the autotrophic denitrification rate was increased by 65 %. In S 0 -PN-SSAD, the TN removal efficiency reached almost 99 % without additional organic carbon. Furthermore, pyrite (FeS 2 ) rather than S 0 served as the electron donor to optimize the PN-SSAD process. The practical sulfate production in S 0 -PN-SSAD and FeS 2 -PN-SSAD were about 38 % and 52 % lower than complete nitrification and sulfur autotrophic denitrification (CN-SAD), respectively. Thiobacillus was the major autotrophic denitrification bacteria in S 0 -PN-SSAD (34.47 %) and FeS 2 -PN-SSAD (14.88 %). Nitrosomonas and Thiobacillus played a synergistic effect in the coupled system. FeS 2 -PN-SSAD is expected as an alternative technology for nitrification and heterotrophic denitrification (HD) in treating low C/N wastewater.