Impact of seeding on the start-up of one-stage deammonification MBBRs

Abstract

Treating nitrogen-rich reject water from anaerobically digested sludge with deammonification has become a very beneficial side stream process. One common technique is the one-stage moving bed bioreactors (MBBRs), which in comparison with the other deammonification techniques can be started up without seeding anammox bacteria. This study investigated the impact of biofilm seeding on the start-up of one-stage deammonification MBBRs. Two lab-scale reactors were run in parallel with partial nitritation for 56 days until 11% of the carrier area in one reactor was replaced with fully developed deammonification biofilm to work as the seeding material. The seeded reactor started nitrogen reduction immediately up to a plateau of 1.3 g N m⁻² d⁻¹; after another 54 days on day 110, the reduction significantly increased. At the same time, the non-seeded reactor also started to reduce nitrogen due to deammonification. The development was followed with both nitrogen analyses and fluorescence in situ hybridization analyses. On day 134, the biofilm in both reactors contained>90% anammox bacteria and reached maximum nitrogen removal rates of 7.5 and 5.6 g N m⁻² d⁻¹ in the seeded and non-seeded reactor, respectively. Over 80% of the inorganic nitrogen was reduced. In conclusion, the seeding did not contribute to a shorter start-up time or the achieved anammox enrichment, although it did contribute to a partial, immediate nitrogen reduction. The boundary conditions are the most important factors for a successful start-up in a deammonification MBBR system.

Startup strategies for mainstream anammox polishing in moving bed biofilm reactors

“…For instance, Klaus et al (2017) observed startup within 120 days in a sidestream ANITA™ Mox MBBR process with AMX biomass inoculation. Kanders et al (2014) showed AMX activity in a sidestream PNA MBBR after 50 days on carriers with a preliminary biofilm of nitrifiers and without AMX biomass inoculation. Given these results, it was expected that AMX establishment on carriers without any AMX biomass inoculation in a mainstream process would take longer than the observed startup times.…”

“…The performance of all three reactors indicates that fast startup of AMX in mainstream MBBRs with no additional AMX biomass seeding is possible. In other experiments involving mainstream and sidestream PNA processes, AMX was inoculated through biomass or carrier seeding (Kanders et al, 2014; Klaus et al, 2017), so it was unknown how long it would take for AMX activity to begin in a mainstream reactor without any AMX biomass seeding. For instance, Klaus et al (2017) observed startup within 120 days in a sidestream ANITA™ Mox MBBR process with AMX biomass inoculation.…”

“…These startup methods are not widely applicable for most mainstream systems because full-scale flowrates are much higher than sidestream, making seeding expensive or even entirely impossible. Seeding is also potentially unnecessary for attachment and growth of AMX (Kanders et al, 2014).…”

In-situ restoration of one-stage partial nitritation-anammox process deteriorated by nitrate build-up via elevated substrate levels

“…Sometime NOB activity may increase again after changing operation pattern even under low NOB abundant56. If NOB contamination was serious, the problem of nitrate build-up could be simply solved only by discarding the sludge with more NOB and reinoculation, if enough seeding sludge with anammox bacteria was available conveniently26.…”

Startup of a Partial Nitritation‐Anammox MBBR and the Implementation of pH‐Based Aeration Control

“…According to Christensson et al (2013) and Lemaire et al (2011), seeding decreases startup time, while Kanders et al (2014) and Ling (2009) argue that seeding is not necessary. Regardless of seeding influence on startup time, seeding provides the benefit of immediate nitrite consumption by AMX, which allows for a higher initial ammonia load and reduced risk of nitrite inhibition (Kanders et al, 2014). Startup of the deammonification MBBR was limited by AMX due to their slow growth rate and sensitivity to nitrite.…”