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

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 NO-N and NH-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 NO-N to NH-N ratios were far from the stoichiometric ratio for Anammox reaction (i.e. NO-N to NH-N ranging from 0 to infinity). This is achieved by the sorption of surplus NH-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 NH-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.

Application of zeolites for biological treatment processes of solid wastes and wastewaters – A review

“…On the other hand, as a fixed-media bed system, the zeolite-anammox reactors could be affected by pore clogging and a pre-treatment for solid removal must be previously applied. Earlier, Yapsakli et al, (2017) proposed a biofilter with zeolite as carrier in order to study the Anammox process. This work indicated that the high efficiencies obtained even at NO 2 -N:NH 4 + ratio far from stoichiometry could be feasible because the sorption of surplus NH 4 -N by zeolite particles in case that ammonium rich influent came in excess with respect to Anammox stoichiometry.…”

Zeolite as a Potential Medium for Ammonium Recovery and Second Cheese Whey Treatment

“…The desorption tests were conducted using deionized water and the results showed that ammonium release was remarkably slow and final desorption equilibrium was achieved after 7200 min, at which time only 1.59% of the absorbed ammonium had been released. These results may be explained by the characteristics of the aqueous solution used in the desorption experiments [41] since the solution lacks any ion exchange capacity to release and replace ammonium anions. According to the literature, a strong ion exchange solution is needed to regenerate used zeolite, such as sodium hydroxide that can increase NH 4 + -N desorption rates by up to 99% [42].…”

Recovery profile of anaerobic ammonium oxidation (anammox) bacteria inhibited by ZnO nanoparticles

“…Preparation of synthetic wastewater and ZnO NPs stock solution Synthetic wastewater was prepared as previously described by Yapsakli et al (2017). Ammonium nitrogen (NH 4 þ -N) and nitrite nitrogen (NO 2 À -N) was prepared in the forms of (NH 4 ) 2 SO 4 and NaNO 2 , respectively.…”