Stable nitritation of mature landfill leachate via in-situ selective inhibition by free nitrous acid

Landfill leachate can present extremely elevated concentrations of ammonium (up to 6,000 mg N-NH4+ L−1) and a low biodegradable organic matter fraction. As an alternative to conventional systems, this wastewater can be treated on a more sustainable way by a fully autotrophic partial nitritation–anammox system. The operation of the first step of this system, the partial nitritation, is critical since the elevated concentrations of ammonium and nitrite in the reactor can severely inhibit ammonium oxidizing bacteria (AOB) activity. In this way, the inclusion of anoxic phases during the feeding events to promote the denitrification via nitrite can be a good option for upgrading the process performance and increasing the stability of the system. This paper deals with the evaluation of an anoxic–aerobic step-feed strategy for the operation of a partial nitritation SBR. Results of this study have revealed a decrease on the total nitrogen inside the reactor of more than 200 mg N L−1 without prejudice on the partial nitritation process. Furthermore, this study has also allowed detecting an AOB activity reduction at the end of aerobic phases due to bicarbonate limitation and/or free nitrous acid inhibition.

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Biological Treatment of High Ammonium Content Urban Landfill Leachate Using an Anaerobic-Aerobic Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.781-784.2095 ◽

2013 ◽

Vol 781-784 ◽

pp. 2095-2099

Author(s):

Hong Wei Sun ◽

Yong Jun You ◽

Ying Guo

Keyword(s):

Landfill Leachate ◽

Inhibitory Effect ◽

Nitrifying Bacteria ◽

Anaerobic Sludge ◽

Nitrite Accumulation ◽

Fish Analysis ◽

Free Nitrous Acid ◽

Nitrite Oxidizing Bacteria ◽

Anaerobic Sludge Blanket

Biological system consisting of an up-flow anaerobic sludge blanket (UASB) and anoxic-oxic (A/O) reactor was applied to treat high ammonium content urban landfill leachate. Inhibitory effect of free ammonia (FA) and free nitrous acid (FNA) on nitrifying bacteria activity was used to achieve nitrogen removal via nitrite pathway in the A/O. Results demonstrated that removed efficiencies of COD, total nitrogen (TN) and NH4+-N were 95.3%, 84.6 %and 99.2%, respectively. Stable nitrite pathway with above 90% nitrite accumulation was successfully achieved in the A/O reactor by synergetic inhibition of FA and FNA on the activity of nitrite oxidizing bacteria (NOB). Moreover, Fluorescence in situ hybridization (FISH) analysis showed that AOB was dominant microorganism.

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Achieving nitrogen removal via nitrite pathway from urban landfill leachate using the synergetic inhibition of free ammonia and free nitrous acid on nitrifying bacteria activity

Water Science & Technology ◽

10.2166/wst.2013.432 ◽

2013 ◽

Vol 68 (9) ◽

pp. 2035-2041 ◽

Cited By ~ 11

Author(s):

H. W. Sun ◽

Y. Bai ◽

Y. Z. Peng ◽

H. G. Xie ◽

X. N. Shi

Keyword(s):

Landfill Leachate ◽

Biological System ◽

Nitrous Acid ◽

Free Ammonia ◽

Nitrifying Bacteria ◽

Anaerobic Sludge ◽

Nitrite Accumulation ◽

Fish Analysis ◽

Ammonia Oxidizing Bacteria ◽

Free Nitrous Acid

In this study, a biological system consisting of an up-flow anaerobic sludge blanket (UASB) and anoxic–oxic (A/O) reactor was established for the advanced treatment of high ammonium urban landfill leachate. The inhibitory effect of free ammonia (FA) and free nitrous acid (FNA) on the nitrifying bacterial activity was used to achieve stable nitritation in the A/O reactor. The results demonstrated that the biological system achieved chemical oxygen demand (COD), total nitrogen (TN) and NH4+-N removal efficiencies of 95.3, 84.6 and 99.2%, respectively at a low carbon-to-nitrogen ratio of 3:1. Simultaneous denitritation and methanogenesis in the UASB could improve the removal of COD and TN. Nitritation with above 90% nitrite accumulation was successfully achieved in the A/O reactor by synergetic inhibition of FA and FNA on the activity of nitrite oxidizing bacteria (NOB). Fluorescence in situ hybridization (FISH) analysis showed that ammonia oxidizing bacteria (AOB) was dominant and was considered to be responsible for the satisfactory nitritation performance.

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