Fast start-up of anammox process with hydrazine addition

Abstract

The anammox process is an economically favourable nitrogen removal process; however, low growth rates of anammox biomass block its more widespread application. As different approaches on techniques for anammox bacteria growth acceleration were tested, this study focused on long-term evaluation of hydrazine addition in the start-up phase. Effect of hydrazine addition (dose 3.7 mgN 2 H 4 dm −3 ) was investigated in a pilot-scale SBR treating ammonia-rich reject water from sludge dewatering after partial nitritation process, and effects were compared to a reference reactor. Hydrazine addition resulted in much higher anammox biomass enrichment observed as higher nitrogen removal rate [0.512 kgN (m 3 d) −1 with hydrazine versus 0.256 kgN (m 3 d) −1 without reagent]. Sludge from chemically stimulated reactor revealed also higher (by 22.6%) specific anammox activity rate than the reference. After the hydrazine addition was stopped, observed process rates remained stable and no regression in the nitrogen removal efficiency could be noticed. In the final phase, nitrogen removal rate was only 48.7% of process rate in the reactor previously stimulated by hydrazine. Results of the experiment confirmed positive effect of hydrazine presence on anammox bacteria enrichment process.

Key enzymes involved in anammox‐based processes for wastewater treatment: An applied overview

“…N 2 H 4 can also be used to recover and enhance the autotrophic N‐removal capacity by promoting anammox enzyme activity after exposure and inhibition by high NO 2 − concentrations. Miodoński et al (2019) demonstrated that the addition of 3.7 mg N 2 H 4 L −1 in an anammox reactor promoted an increase in the specific activity of anammox (22.6%) compared with a system without the addition of N 2 H 4 ; Yao et al (2013) also verified the positive effects of the addition of N 2 H 4 in the anammox process, with an increase of approximately 12% in the efficiency of N‐removal with the addition of 3.99 mg N 2 H 4 L −1 . According to Ma et al (2018), the addition of N 2 H 4 promoted the generation of azide in the presence of NO 2 − , accelerating the activity of AnAOB in the degradation of NO 2 − , mainly inhibiting the activity of NXR, thus reducing the formation of NO 3 − .…”

Recovery of nitrogen removal by N2H4 after nitrite inhibited anammox reaction

“…However, most of the above-mentioned studies were based on the results of small-scale tests obtained from sequential batch experiments, and pilot tests or engineering application data for continuous water inflow have rarely been reported. Anammox bacteria are extremely sensitive to their living environment (Khramenkov et al, 2013;Miodoński et al, 2019;Strous et al, 1998). In pilot-scale and engineering applications, due to changes in the reactor and its operating conditions, relevant research results would likely differ somewhat, or even significantly, from those of small-scale tests.…”

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

“…Therefore, in order to shorten the start-up time of the Anammox process, many researchers have focused on optimizing key parameters such as seeding sludge, operational strategy, biomass immobilization, etc. (Verma et al 2021), and the addition of chemical reagents into the system for stimulating the bacteria (Ganesan & Vadivelu 2019;Miodonśki et al 2019). Therefore, in full-scale applications of Anammox process, in case of a sudden toxicity, recovery would be a better way than restarting it.…”