Recovery of partial nitrification in a down-flow hanging sponge reactor by salt shock loading

Miri Matsubayashi, Hideki Harada, Tsutomu Okubo, Shigeki Uemura

Research output: Contribution to journalArticlepeer-review


Partial nitrification of ammonium-containing artificial wastewater was achieved using a down-flow hanging sponge (DHS) reactor with a hydraulic retention time (HRT) of 2 h by adjusting the influent salinity to 25 g Cl L-1 with NaCl. The effect of HRT on partial nitrification was examined by varying HRT from 1 to 4 h. Extending HRT from 2 to 4 h had the effect of decreasing nitrite production and increasing nitrates. Since partial nitrification was not completely recovered after returning the HRT to 2 h, we examined the effect of salt shock loading on the recovery of partial nitrification. Salt shock loading with 150 gCl L-1 for 72 h resulted in the fraction of NO2-N to total inorganic nitrogen in the effluent reaching 83.0% as much as 83 days after returning the salinity to the original level. Thus, despite the time required for the restoration of partial nitrification, the effectiveness of salt shock loading to achieve this aim was verified.

Original languageEnglish
Pages (from-to)262-266
Number of pages5
JournalJournal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering
Issue number3
Publication statusPublished - 2016 Feb 23


  • DHS
  • partial nitrification
  • recovery
  • salinity
  • salt shock loading

ASJC Scopus subject areas

  • Environmental Engineering

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