Cold shocks of Anammox biofilm stimulate nitrogen removal at low temperatures

Abstract

The adaptation of Anammox (ANaerobic AMMonium OXidation) to low temperatures (10-15°C) is crucial for sustaining energy-efficient nitrogen removal from the mainstream of municipal wastewater. But, current adaptation methods take months or even years. To speed up the adaption of Anammox to low temperatures, this study describes a new approach: exposing Anammox microorganisms to an abrupt temporary reduction of temperature, i.e., cold shock. Anammox biomass in a moving bed biofilm reactor was subjected to three consecutive cold shocks (reduction from 24 ± 2 to 5.0 ± 0.2°C), each taking eight hours. Before the cold shocks, Anammox activity determined in ex situ tests using the temperature range of 12.5-19.5°C was 0.005-0.015 kg-N kg-VSS day . Cold shocks increased the activity of Anammox at 10°C to 0.054 kg-N kg-VSS day after the third shock, which is similar to the highest activities obtained for cold-enriched or adapted Anammox reported in the literature (0.080 kg-N kg-VSS day ). Fluorescence in situ hybridization analysis showed that Ca. Brocadia fulgida was the dominant species. Thus, cold shocks are an intriguing new strategy for the adaptation of Anammox to low temperature. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:277-281, 2018.

Adaptation of flocculent anammox culture to low temperature by cold shock: long-term response of the microbial population

“…The somewhat higher average improvement in activity in our previous study may be attributed to the batch assays nature of that work. Further differences in experimental design, such as anammox cultivation in biofilm and continuous operation at 24°C, may also have influenced the adaptive response [28]. Despite this, our current work reinforces the trend we reported previously.…”

“…Brocadia anammoxidans was also present, but Ca. Brocadia fulgida remained the dominant anammox detected species throughout [28]. In the absence of Ca.…”

“…Recently, Kouba et al [14] explored the possibility of accelerating anammox acclimation to main-stream temperatures using cold shocks. Over 45 days, three consecutive cold shocks (24-5°C, 8 h) increased the nitrogen removal rate of anammox biofilm at 10°C to 0.082 kg-N/kg-VSS/d.…”

Adaptation of anammox bacteria to low temperature via gradual acclimation and cold shocks: distinctions in protein expression, membrane composition and activities

“…Although some studies have reported that anammox bacteria deteriorated in activity at ≤20 °C (Hoekstra et al, 2018), others have shown that anammox adapted and culture activity increased (Lv et al, 2020;Wang et al, 2018). This activity can be further elevated by the enrichment of cold-adapted species (Hendrickx et al, 2014;Park et al, 2017), by the gradual acclimation of 4 mesophilic cultures to a psychrophilic regime (De Cocker et al, 2018) or by short-term exposure to extremely low temperature called the cold shock (Kouba et al, 2018). Different cold-adaptation strategies have been applied to enhance anammox activities at low temperatures.…”

“…Third, cold shock strategy has included a rapid cooling of anammox biomass (“ Candidatus Brocadia”) from 24 °C to 5 °C, then 8 hours of exposure to 5 °C, after which the temperature has been raised back to 24 °C. Three such shocks applied over the period of 45 days have incrementally increased the anammox activity at 10 °C to a relevant 54 g-N/kg-VSS/d, compared to an order of magnitude less active control (Kouba et al, 2018). Most recently, a single cold shock (5 °C, 8 h) doubled anammox (“ Ca .…”