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Controlling and monitoring of deammonification process in moving bed biofilm reactor
KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Water, Sewage and Waste technology.
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

It is considered that partial nitrification combined with anammox, named deammonification, is more environmental friendly compared with conventional nitrification/denitrification due to decrease energy requirement, low emission of CO2 and N2O. Dissolved oxygen (DO) is a significant parameter influencing the nitrogen removal rate and activity of different microorganisms. A proper level of DO concentration is needed to allow ammonium oxidizing bacteria (AOB) to produce a sufficient amount of NO2--N for anammox reaction. Too high NO2--N levels should be avoided as they cause inhibition effects on anammox bacteria or increase growth of nitrite oxidizing bacteria (NOB). In this study, investigations have been carried out, both in laboratory and pilot scales to evaluate the influence of different aeration strategies (characterized by dissolved oxygen concentration - DO and the ratio between non-aerated and aerated phase duration – R) on the deammonification process applied in the moving bed biofilm reactor (MBBR).

Three series of batch tests were conducted in laboratory scale with different DO concentrations (2, 3, 4 mg/l) and R values (0 - continuous aeration; 1/3, 1, 3 – intermittent aeration), the same initial ammonium concentration, volume of the reject water and temperature. It was found that the impact of DO on deammonification was dependent on the R value. At R=0 and R=1/3, an increase of DO caused a significant increase in nitrogen removal rate, whereas for R=1 and R=3 similar rates of the process were observed irrespectively of the DO. The highest nitrogen removal rate of 3.33 gN/m2·d was obtained at R=1/3 and DO=4 mg/l. Significantly lower nitrogen removal rates (1.17 - 1.58 gN/m2·d) were observed at R=1 and R=3 for each examined DO. It was a consequence of reduced aerated phase duration times and lower amounts of residual nitrite in non - aerated phases as compared to R=1/3.

Pilot scale experiments were carried out in a MBBR with a working volume of 200 L. The pilot plant has been operated for 1.5 years to remove nitrogen from reject water after dewatering of digested sludge. The activity of different groups of microorganisms in the biofilm was measured by specific anammox activity (SAA), oxygen uptake rate (OUR) and nitrate utilization rate (NUR) tests. The whole operation was divided into seven periods according to different nitrogen loads and different aeration strategies. The highest nitrogen removal rate and efficiency was obtained when DO was 3.5 mg/l and R equaled to 1/3. Activity tests showed that anammox bacteria and AOB play the dominating roles in the biofilm. The average and maximum values of specific anammox activity (SAA) were 3.01 gN/m2·d and 4.3 gN/m2·d, respectively. An average value of 4.0 gO2/m2·d and the maximum value of 5.1 gO2/m2·d was obtained in the oxygen uptake rate for AOB activity tests.

Study results showed that application of an appropriate selected aeration strategy reduced energy consumption without any negative impacts on the process. Introduction of anaerobic phases and high nitrogen load enhanced the activity of anammox bacteria and NOB activity was limited.

Abstract [sv]

Partiell nitrifikation i kombination med anammoxprocess, som kallas för deammonifikationprocess, anses vara mer miljövänlig jämfört med konventionell nitrifikation/denitrifikation pga minskat energibehov samt låga utsläpp av CO2 och N2O. Löst syre (DO) är en viktig parameter som påverkar hastigheten för kväverening och aktiviteten hos olika mikroorganismer. DO koncentrationer bör vara på en viss nivå för att ammoniumoxiderande bakterier (AOB) skall producera en tillräcklig mängd NO2-N för anammoxreaktionen, men inte heller för hög då hög NO2-N nivå ger en anammoxhämmande effekt eller ökad tillväxt av nitritoxiderande bakterier (NOB). I denna studie har undersökningar utförts både i laboratorie- och pilotskala för att utvärdera inverkan av olika luftningsstrategier, (som kännetecknas av koncentrationen av löst syre - DO och förhållandet (R) mellan tider för icke luftade och luftade faser), på deammonifikationprocessen i en MBBR (Moving Bed Biofilm Reactor).

Tre serier av satsvisa försök utfördes i laboratorieskala med olika syre koncentrationer (2, 3, 4 mg/l) och R värden (0 - kontinuerlig luftning; 1/3, 1, 3 - intermittent luftning), men med samma initiala ammonium-koncentration, volym av den rörliga bädden och temperatur. Man fann att effekten av löst syre (DO) på deammonifikationen var beroende på R-värde. Vid R = 0 och R = 1/3, gav en ökning av löst syre (DO) en signifikant ökning i kvävereningshastigheten, medan för R = 1 och R = 3 observerades samma hastighet i processen oberoende av löst syrehalt (DO). Den högsta hastigheten för kväveavskiljning 3,33 gN/m2.d (avskiljningsgraden var lika med 69,5%) erhölls vid R=1/3 och DO=4 mg/l. Betydligt lägre värden (från 1,17 till 1,58 gN/m2.d) observerades vid R=1 och R=3 för varje undersökt halt av löst syre (DO). Det var en följd av minskad varaktighet av luftad fas och mindre mängd av kvarvarande nitrit i icke luftade faser jämfört med R= 1/3.

Pilotskaleförsök utfördes i en MBBR med en arbetsvolym på 200 L. Pilotanläggningen har drivits i 1,5 år med att avlägsna kväve från rejektvatten från avvattning av rötslam. Aktiviteten hos olika grupper av mikroorganismer i biofilmen mättes genom tester av specifik anammoxaktivitet (SAA), syreupptagningshastighet (OUR) och nitratutnyttjandegrad (NUR). Driften var uppdelat i 7 perioder med olika kvävebelastning och luftningsstrategier. Den högsta hastigheten och grad av kväveavskiljning erhölls då DO var 3,5 mg/l och R uppgick till 1/3.

Aktivitetstester visade att anammoxbakterier och AOB spelade dominerande roller i biofilmen. De genomsnittliga och maximala värden för specifika anammoxaktiviteten (SAA) var 3,01 gO2/m2.d och 4,3 gO2/m2.d, respektive. 4,0 gO2/m2.d som medelvärde och högsta värde på 5,1 gO2/m2.d erhölls för syreupptagningen för AOB aktivitetstester. 

Studien visade att användning av en lämpligt vald luftningsstrategi minskar energiförbrukningen utan några negativa effekter på processen. Införande av anaeroba faser och hög kvävetillförseln ökar aktiviteten för anammoxbakterier och NOB-aktiviteten begränsades.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , xviii, 29 p.
Series
Trita-LWR. LIC, ISSN 1650-8629 ; 2065
National Category
Water Engineering
Identifiers
URN: urn:nbn:se:kth:diva-98624ISBN: 978-91-7501-384-8 (print)OAI: oai:DiVA.org:kth-98624DiVA: diva2:538034
Presentation
2012-06-11, V3, KTH, Teknikringen 72, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
QC 20120628Available from: 2012-06-28 Created: 2012-06-28 Last updated: 2012-07-03Bibliographically approved
List of papers
1. Evaluation of deammonification process performance at different aeration strategies
Open this publication in new window or tab >>Evaluation of deammonification process performance at different aeration strategies
2011 (English)In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 63, no 6, 1168-1176 p.Article in journal (Refereed) Published
Abstract [en]

In a deammonification process applied in the moving bed biofilm reactor (MBBR) oxygen is a crucial parameter for the process performance and efficiency. The objective of this study was to investigate different aeration strategies, characterised by the ratio between non-aerated and aerated phase times (R) and dissolved oxygen concentrations (DO). The series of batch tests were conducted with variable DO concentrations (2, 3, 4 mg L-1) and R values (0-continuous aeration; 1/3, 1, 3-intermittent aeration) but with the same initial ammonium concentration, volume of the moving bed and temperature. It was found that the impact of DO on deammonification was dependent on the R value. At R=0 and R=1/3, an increase of DO caused a significant increase in nitrogen removal rate, whereas for R=1 and R=3 similar rates of the process were observed irrespectively of the DO. The highest nitrogen removal rate of 3.33 g N m(-2) d(-1) (efficiency equal to 69.5%) was obtained at R=1/3 and DO=4 mg L-1. Significantly lower nitrogen removal rates (1.17-1.58 g N m(-2) d(-1)) were observed at R=1 and R=3 for each examined DO. It was a consequence reduced aerated phase duration times and lesser amounts of residual nitrite in non-aerated phases as compared to R 1/3.

Keyword
deammonification, dissolved oxygen, intermittent aeration, ratio between non-aerated and aerated phase timings
National Category
Water Engineering
Identifiers
urn:nbn:se:kth:diva-32222 (URN)10.2166/wst.2011.356 (DOI)000288852600012 ()2-s2.0-79955658157 (Scopus ID)
Note
QC 20110601Available from: 2011-06-01 Created: 2011-04-11 Last updated: 2017-12-11Bibliographically approved
2. Influence of aeration conditions on nitrogen removal rate in one stage partial nitritation/anammox process
Open this publication in new window or tab >>Influence of aeration conditions on nitrogen removal rate in one stage partial nitritation/anammox process
2011 (English)In: Proceedings of IWA/WEF Conference: Nutrient Recovery and Management 2011, 2011, 1307-1320 p.Conference paper, Published paper (Refereed)
Abstract [en]

In a partial nitrification/anammox process applied in the moving bed biofilm reactor (MBBR), oxygen is an important parameter for the process performance and efficiency. The objective of this study was to investigate different aeration strategies, characterized by the ratio between non - aerated and aerated phase duration (R) and dissolved oxygen concentration (DO). Experiments were carried out in a MBBR of 200 L filled with 40% of AnoxKaldnes biocarriers. Moreover activities of different groups of bacteria under each investigated aeration strategies were studied by SAA (Specific Anammox Activity), OUR (Oxygen Uptake Rate) and NUR (Nitrate Utilization Rate) tests. Four different aeration strategies were introduced in the system with DO 3 mg/l and R=0, DO 3.5 mg/l and R = 1/3, DO 3 mg/l and R = 1/3, and DO 3.5 mg/l and R = 1; air supply was decreased gradually. The obtained results showed that with the same level of DO concentration (3 mg/l) but different R (0, 1/3), nitrogen removal efficiencies were similar, which meant that with R = 1/3, energy could be saved without any loss of the process efficiency. The highest nitrogen removal efficiency of 88 % and nitrogen removal rate of 3.11 g N /m2·d were obtained at R = 1/3 and DO = 3.5 mg/l. A proper duration of non-aerated phase could improve anaerobic conditions in the biofilm and decrease possible inhibition effects of oxygen on anammox bacteria.

Keyword
dissolved oxygen (DO), intermittent aeration, moving bed biofilm reactor (MBBR), organic matter, partial nitrification/anammox
National Category
Water Engineering
Identifiers
urn:nbn:se:kth:diva-81613 (URN)
Conference
IWA/WEF Conference Miami, 9-12 januari 2011
Note
QC 20120214Available from: 2012-02-10 Created: 2012-02-10 Last updated: 2012-06-28Bibliographically approved
3. Activity of different groups of microorganisms in moving-bed biofilm reactor with one stage deammonfication process
Open this publication in new window or tab >>Activity of different groups of microorganisms in moving-bed biofilm reactor with one stage deammonfication process
2011 (English)In: Proceeding of IWA Biofilm Conference 2011: Processes in Biofilms, 2011, 112-123 p.Conference paper, Published paper (Refereed)
Abstract [en]

In a moving bed biofilm reactor (MBBR) with one stage deammonification process, ammonium oxidizing bacteria (AOB) and anammox bacteria play the dominating roles for the process performance and efficiency. However, heterotrophic bacteria and nitrite oxidizing bacteria (NOB) are very hard to avoid due to the presence of small amount of organic material and nitrite. In this study, the investigations have been carried out to evaluate the activity of different groups of microorganisms in the biofilm by specific anammox activity (SAA), oxygen uptake rate (OUR) and nitrate utilisation rate (NUR) tests. The pilot plant with MBBR has been operated for 1.5 years to remove nitrogen from reject water coming after dewatering of digested sludge. Different aeration strategies, which were characterized by dissolved oxygen concentration (DO) and the ratio between non-aerated and aerated phase duration (R), were introduced into the process. The results showed that introduction of anaerobic phase and high nitrogen load could enhance the activity of anammox bacteria. Oxygen concentration in the bulk liquid in the reactor influenced the activity of AOB. It was possible to limit the NOB activity in deammonification process by providing interval anaerobic phases. Heterotrophic bacteria activity was low when limited amount of organic carbon was available.

Series
Skriftserie
Keyword
aeration strategies, deammonification process, microorganisms activity, moving bed biofilm reactor (MBBR)
National Category
Water Engineering
Identifiers
urn:nbn:se:kth:diva-81609 (URN)
Conference
IWA Biofilm Conference 2011, 27-30 October 2011, Shanghai, China
Note
QC 20120214Available from: 2012-02-10 Created: 2012-02-10 Last updated: 2012-06-28Bibliographically approved

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