Anammox-zeolite system acting as buffer to achieve stable effluent nitrogen values


Yapsakli K. , KALKAN AKTAN Ç. , MERTOĞLU B.

BIODEGRADATION, vol.28, no.1, pp.69-79, 2017 (Journal Indexed in SCI) identifier

  • Publication Type: Article / Article
  • Volume: 28 Issue: 1
  • Publication Date: 2017
  • Doi Number: 10.1007/s10532-016-9778-1
  • Title of Journal : BIODEGRADATION
  • Page Numbers: pp.69-79
  • Keywords: Anammox, Biodegradation, Zeolite, Ion-exchange, Ammonium removal, ION-EXCHANGE, AMMONIUM OXIDATION, BIOLOGICAL REGENERATION, GRANULAR SLUDGE, FLUIDIZED-BED, WASTE-WATER, REMOVAL, NITRIFICATION, REACTOR, CLINOPTILOLITE

Abstract

For a successful nitrogen removal, Anammox process needs to be established in line with a stable partial nitritation pretreatment unit since wastewater influent is mostly unsuitable for direct treatment by Anammox. Partial nitritation is, however, a critical bottleneck for the nitrogen removal since it is often difficult to maintain the right proportions of NO2-N and NH4-N during long periods of time for Anammox process. This study investigated the potential of Anammox-zeolite biofilter to buffer inequalities in nitrite and ammonium nitrogen in the influent feed. Anammox-zeolite biofilter combines the ion-exchange property of zeolite with the biological removal by Anammox process. Continuous-flow biofilter was operated for 570 days to test the response of Anammox-zeolite system for irregular ammonium and nitrite nitrogen entries. The reactor demonstrated stable and high nitrogen removal efficiencies (approximately 95 %) even when the influent NO2-N to NH4-N ratios were far from the stoichiometric ratio for Anammox reaction (i.e. NO2-N to NH4-N ranging from 0 to infinity). This is achieved by the sorption of surplus NH4-N by zeolite particles in case ammonium rich influent came in excess with respect to Anammox stoichiometry. Similarly, when ammonium-poor influent is fed to the reactor, ammonium desorption took place due to shifts in ion-exchange equilibrium and deficient amount were supplied by previously sorbed NH4-N. Here, zeolite acted as a preserving reservoir of ammonium where both sorption and desorption took place when needed and this caused the Anammox-zeolite system to act as a buffer system to generate a stable effluent.