Pellicer i Nàcher, Carles

Ruscalleda, Maël

Smets, Barth F.

Terada, Akihiko

Due to the necessity of a source of nitrite, most of the processes involving Anaerobic Ammonium Oxidation (Anammox) are based on a separated two-step process with a previous partial-nitritation reactor. However, these two processes can occur simultaneously in the same reactor by taking advantage of bacterial granules or biofilms. In this sense, completely autotrophic nitrogen removal from high ammonium strength wastewater was achieved in a Membrane-Aereated Biofilm Reactor (MABR) in a single step. Here, a biofilm containing nitrifiers (Aerobic Ammonium and Nitrite Oxidizing Bacteria, AOB and NOB, respectively) and Anaerobic Ammonium Oxidizing Bacteria (AnAOB) is grown on bubbleless aeration membranes to remove ammonium. Since oxygen permeates through the membrane-biofilm interface while ammonium diffuses into the biofilm from the biofilm-liquid interface, oxygen gradients can be established across the biofilm, allowing nitrogen removal in a single reactor by simultaneous activity of the mentioned biocatalysts. This work consists on the analysis of the microbial community existing in two laboratory-scale reactors operated for more than 300 days, which removed up to 5.5 g-N/m2/day. The system contained 1028 hollow fiber membranes (200/280 µm inner/outer diameter) covered homogeneously by biofilm. Samples (low, middle and upper part of the biofilm) were collected, fixed, embedded in OCT compound for cryosection and later Fluorescence In-Situ Hybridization (FISH). Emphasis was put on elucidating the radial and longitudinal distribution and quantification of the involved microbial communities along the membranes. Our observations confirmed that the oxygen gradient was conditioning the spatial distribution of each population inside the biofilm. Thus, AOB were mainly located in the adjacent zone to the membrane, while AnAOB were localized next to them in areas where no oxygen was available. NOB were detected in very low amounts. Results proved the feasibility of developing biofilm structures for high-rate completely autotrophic nitrogen removal

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Downloaded from orbit.dtu.dk on: Dec 17, 2017Microbial community stratification in Membrane-Aerated Biofilm Reactors forCompletely Autotrophic Nitrogen RemovalPellicer i Nàcher, Carles; Ruscalleda, Maël; Terada, Akihiko; Smets, Barth F.Publication date:2010Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Pellicer i Nàcher, C., Ruscalleda, M., Terada, A., & Smets, B. F. (2010). Microbial community stratification inMembrane-Aerated Biofilm Reactors for Completely Autotrophic Nitrogen Removal. Poster session presented atWater Research Conference 2010, Lisbon, Portugal, 11-14 April 2010, .Microbial Community Stratification in Membrane-Aerated Biofilm Reactors for Completely Autotrophic Nitrogen Removal1. IntroductionCarles Pellicer-Nàcher1†, Maël Ruscalleda 1,2†, Akihiko Terada1, Barth F. Smets1*†Both authors have contributed equally to the completition of this work1 Department of Environmental Engineering, Technical University of Denmark; 2 Laboratori d’Enginyeria Química i Ambiental (LEQUIA), Universitat de Girona, Spain.     E-mail: {capn, maels, akt, bfs*}@env.dtu.dk2. Reactor setup5. Microscopic observation & quantification - Conclusions   **This project was economically supported by Danish Agency for Science Technology and Innovation (FTP-ReSCoBiR) and a Marie Curie Excellence grant (EC Framework Program 6). The BE grant program (2009 BE 1 00358) of the Catalan Research Agency (AGAUR) supported MrRuscalleda in his stau at the Technical University of Denmark. 3. Performance 4. Materials and methodsAnaerobic Ammonium Oxidizers (Anammox): A relatively new paradigm in Nitrogen removal from wastewaterNH4+ N2, NO3-NH4+ O2 NO3- N2NO2-O2Nitritation by AOBAnammoxO2Outcompetion of NOB and HeterotrophsCODCounter-diffusionBut why using two reactors when one is enough? -> Biofilms•Need of a carrier material.•Difficulty of control ( thickness, O2 supply, microbial selection…).• Compact configuration.• Lower N2O production (NO2- is produced and consumed in-situ).AdvantagesDisadvantagesOur biofilm develops on hollow-fibre bubbleless aeration membranes. More in detail, the setup consists of(1): substrate bottle; (2): gas bag; (3): diaphragm pump; (4): reactor body and membrane module; (5): needle valve; (6): pressure gauge; (7): ball valve; (8):flow meter; (9) centrifugal pump; (10): flow cell; (11) & (12): instrument meters; (13): A/D Converter; (14):Computer; (15): Rotary electric stirrer.RPMtreatedeffluentdepletedairairNH4+NO3-AnalogsignalDigitalsignalDigitalsignalto USBportto COMportpHDOORP123456781091112131415Data flowLiquid/ gas flowCalibration /samplingSystemdrainage• V=2.41 l.• Amembrane= 0.34 m2.•Completely mixed.• AOB/NOB from WWTP.•AnAOB inoculated from pre-enriched cultures after nitrifying biofilm established.• Operated at 32°C.Through sequential aeration regimes and LO2/LNH4 tuning to 1.73 the reactor performance increased considerably since Anammox inoculation• Observed removal rates up to 0.77 g-N/L/day (5.5 g-N/m2/day, 70% of the N-load). The Anammox process is expected to remove most of it. • NOB produces 30% of the total NO3-.MBBRsRDCsSBRsRem. Rate(g-N/L/day)0.35 –0.500.4 –0.60.06 –1.00Good to know…Fluorescent In-Situ Hybridization was performed after reactor shutdown (day 470, 0.7 g-N/L/day) to study the microbial community in the reactorsA ABBABBAComplete section (x10) of a fibre targeted for EUB, AOB and AnAOB, with details of the internal part (A) and the external part (B) of the biofilm.• Results proved the possibility of engineering biofilm structures for autotrophic nitrogen removal taking advantage of DO gradients inside the biofilm• AOB grew mainly in aerobic regions, close to the membrane in the biofilm core. Communities developed in areas with high cell densities and tended to grow in radial structures with streptobacilli shape• AnAOB grew in the perimeter of the biofilm structure, where anaerobic conditions prevailed. Since nitrite was produced in-situ by AOB, AnAOB grew in clusters pointing the internal part of the biofilm• NOB developed mainly during the reactor start-up, before Anammox inoculation, and were mainly located in the transient zone of the biofilm, together with other non-identified bacteria (most likely heterotrophic).• Image quantification using DAIME  showed that AOB were the most abundant population while AnAOB only covered 20% of the biofilm area.MemMemMemMemBulkBulkBulkBulk49% AOB20% AnAOB53% AOB18%  NOBView of a section targeted for AOB, NOB and EUB and the respective details of the internal (A) and the external (B) parts, with the same magnifications used before. Mem: Membrane; Bulk: Bulk liquid. The results of quantification are expressed in percentage respect to the general probe area obtained in the complete section pictures.250 µm250 µm25 µm25 µm 25 µm50 µm

Microbial community stratification in Membrane-Aerated Biofilm Reactors for Completely Autotrophic Nitrogen Removal

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Microbial community stratification in Membrane-Aerated Biofilm Reactors for Completely Autotrophic Nitrogen Removal

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