Start-up and stabilization of an Anammox process from a non-acclimatized sludge in CSTR

Abstract

Development of an Anammox (anaerobic ammonium oxidation) process using non-acclimatized sludge requires a long start-up period owing to the very slow growth rate of Anammox bacteria. This article addresses the issue of achieving a shorter start-up period for Anammox activity in a well-mixed continuously stirred tank reactor (CSTR) using non-acclimatized anaerobic sludge. Proper selection of enrichment conditions and low stirring speed of 30 +/- 5 rpm resulted in a shorter start-up period (82 days). Activity tests revealed the microbial community structure of Anammox micro-granules. Ammonia-oxidizing bacteria (AOB) were found on the surface and on the outer most layers of granules while nitrite-oxidizing bacteria (NOB) and Anammox bacteria were present inside. Fine-tuning of influent NO2(-)/NH4+ ratio allowed Anammox activity to be maintained when mixed microbial populations were present. The maximum nitrogen removal rate achieved in the system was 0.216 kg N/(m(3) day) with a maximum specific nitrogen removal rate of 0.434 g N/(g VSS day). During the study period, Anammox activity was not inhibited by pH changes and free ammonia toxicity.

Enrichment of ANAMMOX bacteria from conventional activated sludge entrapped in poly(vinyl alcohol)/sodium alginate gel

“…However, a CSTR equipped with a cell recycling system offered a relatively short start-up period of around 40 days at a NLR of 0.057 kg-N/m 3 -day and a HRT of 48 hr to observe the depletion of NH 4 + and NO 2 ‾ even with non-acclimated seed sludge [52]. The advantage of the CSTR mode for ANAMMOX enrichment is the continuous feeding which supports consistent exponential growth rate comparing to semi-continuous feeding in the SBR mode.…”

The Increasing Interest of ANAMMOX Research in China: Bacteria, Process Development, and Application

“…Synthetic wastewater was mostly prepared as influent with the addition of ammonium and nitrite in the form of NH 4 Cl/(NH 4 ) 2 SO 4 and NaNO 2 . A variety of reactor types including sequencing batch reactor (SBR) [77], upflow anaerobic sludge blanket (UASB) [78], continuous stirred tank reactor (CSTR) [79], and membrane bioreactor (MBR) [80] have been tested for ANAMMOX startup and all show advantages and disadvantages. Usually 20 days matured sludges are better for the reactor start up.…”

Characterization of a Microbial Community in an Anammox Process Using Stored Anammox Sludge

“…However, the start-up period for reactors seeded with non-acclimatized sludge is still quite long [8] due to low numbers of Anammox bacteria present in the sludge [9], aerobic inhibition, or the presence of organic matter [10][11][12]. Many different habitats, including engineered systems [1,13] and natural environments [14], contain anaerobic ammonium-oxidizing bacteria.…”

“…Several types of seed sludge have been tested for Anammox bacteria enrichment, including conventional activated sludge, denitrifying sludge, and nitrifying sludge. However, the start-up period for reactors seeded with non-acclimatized sludge is still quite long [8] due to low numbers of Anammox bacteria present in the sludge [9], aerobic inhibition, or the presence of organic matter [10][11][12].…”