Complete Nitrogen Removal from Synthetic Anaerobic Sludge Digestion Liquor through Integrating Anammox and Denitrifying Anaerobic Methane Oxidation in a Membrane Biofilm Reactor

Abstract

Partial nitritation and Anammox processes are increasingly used for nitrogen removal from anaerobic sludge digestion liquor. However, their nitrogen removal efficiency is often limited due to the production of nitrate by the Anammox reaction and the sensitivity to the nitrite to ammonium ratio. This work develops and demonstrates an innovative process that achieves complete nitrogen removal from partially nitrified anaerobic sludge digestion liquor through the use of a membrane biofilm reactor (MBfR), with methane supplied through hollow fiber membranes. When steady state with a hydraulic retention time (HRT) of 1 day was reached, the process achieved complete nitrite and ammonium removal at rates of 560 mg N/L/d and 470 mg N/L/d, respectively, without any nitrate accumulation. The process is relatively insensitive to the nitrite to ammonium ratio, achieving complete nitrogen removal when their ratio in influent varied in the range of 1.125-1.32. Pyrosequencing and fluorescence in situ hybridization analysis revealed that denitrifying anaerobic methane oxidation (DAMO) archaea, Anammox bacteria and DAMO bacteria jointly dominated the microbial community. Mass balance analysis showed that nitrate produced by Anammox (122.2 mg N/L/d) was entirely converted to nitrite by DAMO archaea, while nitrite in the feed and produced by DAMO archaea was jointly removed by Anammox (90%) and DAMO bacteria (10%). The nitrogen removal rate of over 1 kg N/m/d is comparable to the practical rates reported for side-stream nitrogen removal processes.

Interactions between anaerobic ammonium- and methane-oxidizing microorganisms in a laboratory-scale sequencing batch reactor

“…Methanoperedens-like archaea at a rate of 57 mg N L −1 day −1 and the total nitrogen removal efficiency of the culture was as high as 97.5%. The rates for ammonium and nitrite removal reported here are amongst the higher rates for anammox/N-damo cultures (Allegue et al 2018; Liu et al 2019; Luesken et al 2011a, 2011b; Shi et al 2013; Xie et al 2017a, b). Yet, as in these previous studies, it was shown that in a mixed anammox/N-damo culture, the presence of Ca.…”

“…Methylomirabilis-like bacteria and Ca. Methanoperedens-like archaea can be cultured together in laboratory-scale membrane reactors, together removing methane, ammonium, nitrite, and nitrate from the influent (Ding et al 2017; Lu et al 2017; Shi et al 2013; Xie et al 2017a, b). In addition to cooperation, these organisms may also compete with each other under substrate limitation (Luesken et al 2011a, 2011b; Arshad et al 2017; Guerrero-Cruz et al 2019; Welte et al 2016).…”

Enhancing methane oxidation in a bioelectrochemical membrane reactor using a soluble electron mediator

“…As a possible solution to the poor CH 4 mass transfer issue, our group has previously proposed the use of hollow fibre membranes (HFMs) to supply CH 4 gas in membrane biofilm reactors (MBfRs) driving denitrification, resulting in an increase in the denitrification performance by 20-30 times relative to a control [21,22]. This significant improvement can be understood by considering that in MBfRs, methanotrophic biofilm colonize and grow on the outer surface of the membranes, having therefore direct access to CH 4 at supersaturation levels.…”

Membrane-based technologies for post-treatment of anaerobic effluents

“…These membrane processes provide a better control over the cultivation of microorganisms as well as allow a higher quality of effluent and a smaller bioreactor footprint. 67 For P removal, MBR coupled with a biological process known as enhanced biological phosphorous (Bio-P) have demonstrated good P removal efficiency for tertiary wastewater treatment. 68 However, no direct work on the treatment of anaerobic effluents has been reported for these processes so far to our knowledge.…”