Nitrogen removal by a nitritation- anammox bioreactor at low temperature.
ABSTRACT Currently, nitritation-anammox (anaerobic ammonium oxidation) bioreactors are designed to treat wastewaters with high ammonium concentration at mesophilic temperatures (25 - 40 °C). The implementation of this technology at ambient temperatures for nitrogen removal from municipal wastewater following carbon removal could lead to more sustainable technology with energy and cost savings. However the application of nitritation-anammox bioreactors at low temperature (characteristic of municipal wastewaters expect tropical and subtropical regions) is not yet explored. To this end, a laboratory-scale (5 l) nitritation-anammox sequencing batch reactor was adapted to 12 °C in 10 days and operated for more than 300 days to investigate the feasibility of nitrogen removal from synthetic pre-treated municipal wastewater by the combination of aerobic ammonium-oxidizing bacteria (AOB) and anammox. The activities of both anammox and AOB were high enough to remove more than 90 % of the supplied nitrogen. Multiple aspects, including the presence and activity of anammox, AOB, and aerobic nitrite oxidizers (NOB) and nitrous oxide (N(2)O) emission were monitored to evaluate the stability of the bioreactor at 12 °C. There was no nitrite accumulation throughout the operational period indicating that anammox bacteria were active at 12 °C and that AOB and anammox bacteria outcompeted NOB. Moreover, our results showed that sludge from wastewater treatment plants designed for treating high ammonium load wastewaters could be used as seeding sludge for wastewater treatment plants aimed at treating municipal wastewater that has low temperature and low ammonium concentrations.
- SourceAvailable from: Jose Ramon Vazquez-Padin[show abstract] [hide abstract]
ABSTRACT: In this work the autotrophic nitrogen removal was carried out at moderately low temperatures using two configurations: a) two-units one comprising a SHARON reactor coupled to an Anammox SBR and b) single-unit one consisting of a granular SBR performing the CANON process. At 20°C the two-units system was limited by the Anammox step and its nitrogen removal capacity was around ten times lower than the CANON system (0.08 g N/(L d) versus 1 g N/(L d)). When the CANON system was operated at 15°C the average removed nitrogen loading rate decreased to 0.2 g N/(L d). The CANON system was operated in order to limit the ammonia oxidation rate to avoid nitrite inhibition of Anammox bacteria. Since both, temperature and dissolved oxygen (DO) concentration regulate ammonia oxidizing bacteria activity, once the temperature of the reactor is decreased the DO concentration must be decreased to avoid the deeper oxygen penetration inside the granule which could cause inhibition of Anammox bacteria by oxygen and/or nitrite.Water Science & Technology 01/2011; 63(6):1282-8. · 1.10 Impact Factor
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ABSTRACT: Nitrous oxide (N(2)O), a potent greenhouse gas, can be emitted during wastewater treatment, significantly contributing to the greenhouse gas footprint. Measurements at lab-scale and full-scale wastewater treatment plants (WWTPs) have demonstrated that N(2)O can be emitted in substantial amounts during nitrogen removal in WWTPs, however, a large variation in reported emission values exists. Analysis of literature data enabled the identification of the most important operational parameters leading to N(2)O emission in WWTPs: (i) low dissolved oxygen concentration in the nitrification and denitrification stages, (ii) increased nitrite concentrations in both nitrification and denitrification stages, and (iii) low COD/N ratio in the denitrification stage. From the literature it remains unclear whether nitrifying or denitrifying microorganisms are the main source of N(2)O emissions. Operational strategies to prevent N(2)O emission from WWTPs are discussed and areas in which further research is urgently required are identified.Water Research 04/2009; 43(17):4093-103. · 4.66 Impact Factor
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ABSTRACT: The group of planctomycetes represents a separate line of descent within the domain Bacteria. Two phylum-specific 16S rRNA-targeted oligonucleotide probes for planctomycetes have been designed, optimized for in situ hybridization and used in different habitats to detect members of the group in situ. The probes, named PLA46 and PLA886, are targeting all or nearly all members of the planctomycete line of descent. Planctomycetes could be detected in almost all samples examined, e.g. a brackish water lagoon, activated sludge, and other wastewater habitats. In situ probing revealed quite uniform morphology and spatial arrangement of the detected cells but profound differences in abundance ranging from less than 0.1% to several percentage of the total cells. Single coccoid cells with diameters between 1 and 2.5 microm were dominating in most samples with the exception of the lagoon, in which rosettes of pear-shaped cells were abundant. The planctomycetes showed generally no hybridization signals with the bacterial probe EUB338, which is in accordance with base changes in their 165 rRNA sequences. A discrete ultrastructure of planctomycete cells was suggested by double staining with rRNA-targeted probes and the DNA-binding dye 4',6-diamidino-2-phenylindole (DAPI). The probe-conferred fluorescence was distributed in a ring-shaped manner around a central DAPI spot. The two probes developed extend the existing set of group-specific rRNA-targeted probes and help to elucidate the basic composition of bacterial communities in a first step of differential analysis. In situ hybridization of environmental samples indicated widespread presence of planctomycetes in different ecosystems.Microbiology 01/1999; 144 ( Pt 12):3257-66. · 2.85 Impact Factor