Partial nitritation/anammox can provide energy-efficient nitrogen removal from the main stream of municipal wastewater. The main bottleneck is the growth of nitrite oxidizing bacteria (NOB) at low temperatures (<15 °C). To produce effluent suitable for anammox, real municipal wastewater after anaerobic pretreatment was treated by enriched ammonium oxidizing bacteria (AOB) in suspended sludge SBR at 12 °C. NOB were continually washed out using aerobic duration control strategy (ADCS). Solids retention time was set to 9-16 days. Using this approach, average ammonia conversion higher than 57% at high oxidation rate of 0.4 ± 0.1 kg-N kg-VSS-1 d-1 was achieved for more than 100 days. Nitrite accumulation (N-NO2-/N-NOX) of 92% was maintained. Thus, consistently small amounts of present NOB were efficiently suppressed. Our mathematical model explained how ADCS enhanced the inhibition of NOB growth via NH3 and HNO2. This approach will produce effluent suitable for anammox even under winter conditions in mild climates.

• MeSH
• bioreaktory * MeSH
• dusík MeSH
• dusitany MeSH
• odpad tekutý - odstraňování * MeSH
• odpadní voda * MeSH
• odpadní vody MeSH
• Publikační typ
• časopisecké články MeSH

Energy consumption of municipal wastewater treatment plants can be reduced by the anaerobic pre-treatment of the main wastewater stream. After this pre-treatment, nitrogen can potentially be removed by partial nitritation and anammox (PN/A). Currently, the application of PN/A is limited to nitrogen-rich streams (>500 mg L(-1)) and temperatures 25-35 °C. But, anaerobically pretreated municipal wastewater is characterized by much lower nitrogen concentrations (20-100 mg L(-1)) and lower temperatures (10-25 °C). We operated PN/A under similar conditions: total ammonium nitrogen concentration 50 mg L(-1) and lab temperature (22 °C). PN/A was operated for 342 days in a 4 L moving bed biofilm reactor (MBBR). At 0.4 mg O2 L(-1), nitrogen removal rate 33 g N m(-3) day(-1) and 80 % total nitrogen removal efficiency was achieved. The capacity of the reactor was limited by low AOB activity. We observed significant anammox activity (40 g N m(-3) day(-1)) even at 12 °C, improving the applicability of PN/A for municipal wastewater treatment.

• MeSH
• amoniové sloučeniny chemie   MeSH
• anaerobióza MeSH
• biofilmy MeSH
• bioreaktory MeSH
• čištění vody MeSH
• dusík chemie   MeSH
• hybridizace in situ fluorescenční MeSH
• kyslík chemie   MeSH
• nízká teplota MeSH
• odpad tekutý - odstraňování metody   MeSH
• odpadní voda chemie   MeSH
• teoretické modely MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The application of nitrification-denitrification over nitrite (nitritation-denitritation) with municipal (i.e. diluted and cold (or low-temperature)) wastewater can substantially improve the energy balance of municipal wastewater treatment plants. For the accumulation of nitrite, it is crucial to inhibit nitrite-oxidizing bacteria (NOB) with simultaneous proliferation of ammonium-oxidizing bacteria (AOB). The present study describes the effect of the influent total ammonium nitrogen (TAN) concentration on AOB and NOB activity in two moving bed biofilm reactors operated as sequencing batch reactors (SBR) at 15 °C (SBR I) and 21 °C (SBR II). The reactors were fed with diluted reject water containing 600, 300, 150 and 75 mg TAN L(-1). The only factor limiting NOB activity in these reactors was the high concentrations of free ammonia and/or free nitrous acid (FNA) during the SBR cycles. Nitrite accumulation was observed with influents containing 600, 300 and 150 mg TAN L(-1) in SBR I and 600 and 300 in SBR II. Once nitrate production established in the reactors, the increase of influent TAN concentration up to the original 600 mg TAN L(-1) did not limit NOB activity. This was due to the massive development of NOB clusters throughout the biofilm that were able to cope with faster formation of FNA. The results of the fluorescence in situ hybridization analysis preliminarily showed the stratification of bacteria in the biofilm.

• MeSH
• amoniak toxicita   MeSH
• amoniové sloučeniny toxicita   MeSH
• biofilmy účinky léků   MeSH
• biomasa MeSH
• bioreaktory mikrobiologie   MeSH
• čištění vody MeSH
• hybridizace in situ fluorescenční MeSH
• kyselina dusitá toxicita   MeSH
• oxidace-redukce MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH