PILOT-SCALE DEMONSTRATION OF ANITA MOX PROCESS FOR SIDESTREAM DEAMMONIFICATION

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1 PILOT-SCALE DEMONSTRATION OF ANITA MOX PROCESS FOR SIDESTREAM DEAMMONIFICATION Shihu Hu 1, Romain Lemaire 2, Maxime Rattier 1, Hannah Lockie 3, Elyse Harding 4, Paul McPhee 5, Jurg Keller 1 1. University of Queensland, Brisbane, QLD, Australia 2. Veolia Technical and Performance Department, Paris, France 3. Veolia Water Technologies Australia, Sydney, NSW, Australia 4. Veolia Water Australia, Brisbane, QLD, Australia 5. Queensland Urban Utilities, Brisbane, QLD, Australia ABSTRACT ANITA Mox is a new one-stage deammonification Moving-Bed Biofilm Reactor (MBBR) developed for partial nitrification to nitrite and autotrophic N- removal from N-rich effluents. This deammonification process offers many advantages such as substancial reduction in aeration requirement and sludge production along with the lack of need for an external carbon source. In this paper, we present the experience and results of the first pilot-scale trial of using ANITA Mox process for sidestream deammonification in Brisbane, Australia. INTRODUCTION Anaerobic digestion can recover the organic matter from wastewater sludge in the form of biogas which can serve as energy source. Therefore it has gained increased popularity in recent years and is seen as one of the key processes leading towards energy-neutral or even energy producing sewage treatment plants (STPs) (Chudoba et al., 21). The drawback is the increased ammonium concentration in the sidestream reject water that is recycled to the inlet of the STP, which may constitute up to 2 3% of the overall incoming N load. In order to prevent costly oxygenation and carbon addition processes to help removing this N load in mainstream, the use of dedicated sidestream N removal treatment processes e.g. anaerobic ammonium oxidation (anammox) has now been widely accepted. Anammox is an energy-efficient N removal process since it requires less oxygen and no organic carbon compared to conventional denitrification processes. Due to the slow growth rate of anammox bacteria, long sludge ages have to be maintained, meaning that most of the current anammox processes are biofilm systems, with or without support material, operated as 2-stage systems, such as combined SHARON / Anammox-granular process (Abma et al., 27) or 1-stage systems, also referred to as the Deammonification process, such as granular Sequencing Batch Reactors (SBR) (Wett, 27; Vlaeminck et al., 28; VazquezPadin et al., 29) or Moving-Bed Biofilm Reactors (MBBR) (Rosenwinkel and Cornelius, 25; Cema, 29). The ANITA Mox process is a one-stage MBBR deammonification process where partial nitrification to nitrite by ammonia oxidizing bacteria (AOB) and autotrophic N-removal by anammox bacteria occur simultaneously within the aerobic and anoxic zones of the biofilm. Oxygen mass transfer limitation under limited dissolved oxygen (DO) conditions plays an important role in the symbiotic process. The very slow growth of anammox bacteria and sensitivity towards high concentrations of oxygen and nitrite during the start-up phase have been widely reported and therefore limit a widespread application of anammox processes. To shorten the start-up phase, new ANITA Mox processes are seeded with a small fraction of colonized carriers, which reduce the time required to develop a mature deammonification biofilm on the brand new carriers. The concept of seeding has proven to dramatically reduce the start-up time from up to a year down to few months depending on the amount of seeding (Christensson et al., 213). The first full scale anammox reactor built for wastewater treatment was started up in early 2. Today, there are more than 5 full scale anammox reactors in operation worldwide with as many more in design and commissioning (Lackner et al. 214). However, until now, there is no full scale anammox reactor in operation in Australia. In current study, an ANITA Mox pilot plant was set up to treat reject water in Brisbane, Australia. A BioFarm consisting of several smaller pilot scale reactors was set up to enrich the anammox bacteria on biofilm carriers to allow for seeding carriers in other pilot plants. The ammonium, nitrite and nitrate removal rates of these reactors were monitored to determine the activity of the anammox microorganisms. METHODOLOGY/ PROCESS Reject Water The Luggage Point STP is a 132 MLD biological nutrient removal plant, servicing 776, people and industries from Brisbane. The reject water at Luggage Point STP typically contains 6-12mgN/L of NH 4 +.

2 Anammox enrichment procedure Due to the limited amount of seeding media available, three enrichment tanks were set up in the Innovation Centre at Luggage Point STP to grow sufficient anammox biofilm on carriers before seeding the 4m 3 ANITA Mox pilot-plant. Tank 1 and Tank 2 have a working volume of 15L and contains 7L of K5 carriers from AnoxKaldnes (8m 2 /m 3 protected surface area) while Tank 3, which was started a month later, has a working volume of 5L with 2L of K5 carriers. Tank 1 and Tank 3 were both inoculated with 4L of precolonized anammox carriers. The three tanks are connected in series and diluted reject water from the onsite dewatering process was fed into the first tank resulting in HRT from 1.5 to 3 days (Figure 1). Temperature, ph and DO in the tanks were monitored and controlled. Mixing and aeration were achieved by submersible pumps and air pump respectively. Five months after the start of enrichment, all the carriers in the three enrichment tanks were taken out and evenly distributed to two larger tanks in order to improve the hydraulic conditions. Both new Tanks A and B have a total volume of 75L and working volume of 6L. New carriers were also added to these two tanks in order to reach a total volume of carriers of 25L in each tank. Tanks A and B are operated at the same conditions as the previous three tanks, except they are fed with reject water directly and discharged in parallel. Chemical analysis The profiles of NH + - 4, NO 3 were monitored online with WTW UV/VIS sensor (Xylem, Germany). Mixed liquor were also sampled and filtered at 1.6 µm before NH + 4, NO - - 3, NO 2 were analysed according to the standard methods (APHA, 1995) for calibration purpose. Specific anammox batch tests Maximum anammox activity was measured regularly in 3L reactors with N 2 sparging (2L/h) to provide mixing and maintain anoxic condition. Temperature was kept at 3 C with a thermostat bath. A known number of carriers (typical 1 pieces) were added to a synthetic medium containing NH 4 + -N (25mg/L), NO 2 - -N (25mg/L), PO 4 - -P (2.5mg/L), NaHCO3 (2g/L) and trace metal solution (2mL/L). Samples were taken every 5-1 minutes and maximum N-removal capacity was determined by plotting nitrogen concentration normalized per surface area of carriers vs time. 4 m 3 ANITA Mox pilot-plant The ANITA Mox pilot is self-contained in a 4 ft container and is fully automated with PLC system and on-line DO, ph, T C, NH and NO 3 sensors (Figure 2). The ANITA Mox pilot is composed of a 4m 3 MBBR tank with adjustable separation walls and a final clarifier to operate as an Integrated Fixed-film Activated Sludge (IFAS) system with sludge recycling. The pilot equipment (inlet/recycle pumps, blowers, tanks, clarifier) are designed for a maximum hydraulic load of 1m 3 /h. This ANITA Mox pilot is versatile and can be used for sidestream (this study) or mainstream application using either pure MBBR or IFAS operation mode. RESULTS/DISCUSSIONS + The anammox activity and NH 4 removal rate increased steadily from the inoculation, although only 4 L of precolonized anammox carriers were added to the Tank 1. After 3 months operation and with only 5% of seeding material, surface ammonium removal rate (SARR) in Tank 1 reached.6 gn/m 2.d before severe inhibition of the nitrification step occurred due to high free ammonia (FA) level in the reactor (Figure 3). Tank 2, which did not receive direct seeding media but only the wash-out biomass from Tank 1, also reached a SARR of.6 gn/m 2.d before FA inhibition limited the performance (Figure 4). Tank 3, which was connected to Tank 2 outlet one month after with only 2.5% seeding material, reached.2 gn/m 2.d after only 2 months of operation (Figure 5). Ammonia concentration in the diluted centrate ranged between 2-45 mgn-nh + 4 /L. Effluent nitrite was typically below 4 mg N/L in each tank except after occasional equipment failure (Figure 6). The ratio between nitrate produced and ammonium removed was in the range of 5 15% most of time, which is close to the stoichiometric ratio (i.e. 11%). Tank 3 showed a relatively stable increase of activity, compared to tanks 1 and 2 (Figures 3, 4 and 5). The reason for this observation might be the larger volume of tank 3 allowing for an increased buffering capacity of the solution. Therefore, five months after the start of enrichment, two bigger tanks (Tank A and B) were set up to replace the intial three smaller tanks. Indeed the performance of Tanks A and B were more stable compared to the Tanks 1, 2 and 3, and showed an exponential increase of activity two months after the transfer (Figures 7 and 8). Unfortunately an equipment failure at the wastewater treatment plant led to a sudden increase of suspended solids and ammonium concentration in the reject water in December 214. Both ammonium and suspended solids concentrations in the reject water reached more than 1 mg/l. Due to severe inhibition, the N removal rates of both tanks decreased to one-third of its peak activity, as shown by the process data (Figures 7 and 8) and specific anammox batch tests (data not shown). For the performance of the enrichment tanks to stabilize, a buffer tank was set up so the reject water can be diluted and solids were allowed to settle out, before feeding into Tanks A and B. As

3 shown in Figures 7 and 8, the activity of anammox biomass recovered after this change. In Jan 215, the surface ammonium removal rate (SARR) in Tanks A and B are.25 and.4 gn/m 2.d respectively, which is about one-third of the removal rate achieved in fullscale ANITA Mox unit (Lemaire et al. 214). With the ongoing enrichment of anammox carriers, the start-up of the 4 m 3 ANITA Mox pilot-plant is scheduled for Apr 215 in MBBR configuration mode first before switching to IFAS mode for optimal N-removal performance. A preliminary desktop study showed that operational costs of Luggage Point STP could be reduced by approximately $7k per year if side stream anammox is implemented. CONCLUSION Two MBBR enrichment tanks have been set up at Luggage Point STP to grow anammox microorganisms. A total of 5 litres of K5 carriers covered with active anammox biomass biofilm have been obtained. A 4 m 3 ANITA Mox pilot-plant which can be operated in MBBR or IFAS mode has been installed and electrically and hydraulically tested on site. The pilot-plant is scheduled to receive the seeded media and start operation in April 215. ACKNOWLEDGMENT This research project is conducted by the Advanced Water Management Centre at the University of Queensland, Veolia Water Technologies Australia and Queensland Urban Utilities. The authors would like to acknowledge all the personnel at Luggage Point WWTP (Brisbane) for their kind assistance with the ANITA Mox operation. Cema G. 29. Comparative study on different Anammox systems. PhD Thesis, KTH Stockholm. Christensson M., Ekström S., Andersson Chan A., Le Vaillant E. and Lemaire R Experience from start-ups of the first ANITA Mox plants. Water Sci. Tech., 67(12), Lackner, S.; Gilbert, E. M.; Vlaeminck, S. E.; Joss, A.; Horn, H.; van Loosdrecht, M. C. M. (214) Full-scale Partial Nitritation/Anammox Experiences An Application Survey. Water Res., 55, Lemaire, R., Christensson, M., Zhao, H., Le Noir, M., Voon, C Experience from start-up and operation of deammonification MBBR plants, and testing of a new deammonification IFAS configuration. OzWater 14, Brisbane, Australia. Rosenwinkel K. and Cornelius A. 25. Deammonification in the Moving-Bed process for the treatment of wastewater with high ammonia content. Chem. Eng. Tech., 28(1). Vazquez-Padin J., Pozo M., Jarpa M., Figueroa M., Franco A., Mosqueral-Corral A., Campos J.L. and Mendez R. 29. Treatment of anaerobic sludge digesters effluent by the Canon process in an air pulsing SBR. J. of Haz. Mat., 166, Vlaeminck S., Cloetens L., Carballa M., Boon N. and Verstraete W. 28. Granular biomass capable of partial nitritation and anammox. Wat. Sci. Tech., 58(5), Wett B. 27. Development and implementation of a robust Deammonification process. Wat. Sci. Tech., 56(7), REFERENCES APHA Standard methods for the examination of water and wastewater. 19 th edn, American Public Health Association, Washington DC, USA. Abma W., Schultz C., Mulder J., van der Star W., Strous M., Tokutomi T. and van Loosdrecht M. 27. Fullscale granular sludge Anammox process. Wat. Sci. Tech., 55(8/9), Chudoba P., Sardet C., Palko G. and Guibelin E. 21. Main factors influencing anaerobic digestion of sludge and energy efficiency at several large STP in central Europe. 2 nd European Conference on Sludge Management, Budapest, Hungary, Sept 21.

4 Figure 1: Schematic of enrichment tanks Figure 2: Photo and schematic of ANITA Mox pilot-plant recently installed at Luggage Point WWTP. This pilot can be operated in pure MBBR mode or IFAS mode with sludge recycling from the settler.

5 SARR and SALR (gn-nh4/m2.d) FA (mgn/l) and % NO3-prod/NH4-rem SARR and SALR (gn-nh4/m2.d) FA (mgn/l) and % NO3-prod/NH4-rem 1,9,8 SALR (gn/m2.d) SARR (gn-nh4/m2.d) Free Ammonia (mgn/l) % NO3-prod/NH4-rem 1 9 8,7 7,6 6,5 5,4 4,3 3,2 2,1 1 11/5 25/5 8/6 22/6 6/7 2/7 3/8 17/8 Figure 3: Surface ammonium loading rate (SALR), removal rate (SARR), free ammonia level and % NO - 3 -prod / NH + 4 -rem in Tank ,8 1,6 SALR (gn/m2.d) SARR (gn-nh4/m2.d) Free Ammonia (mgn/l) % NO3-prod/NH4-rem ,4 7 1, ,8 4,6 3,4 2,2 1 11/5 25/5 8/6 22/6 6/7 2/7 3/8 17/8 Figure 4: Surface ammonium loading rate (SALR), removal rate (SARR), free ammonia level and % NO - 3 -prod / NH + 4 -rem in Tank 2.

6 NH4in and NH4out (mgn/l) NO2out and NO3out (mgn/l) SARR and SALR (gn-nh4/m2.d) FA (mgn/l) and % NO3-prod/NH4-rem,5,45,4 SALR (gn/m2.d) SARR (gn-nh4/m2.d) Free Ammonia (mgn/l) % NO3-prod/NH4-rem 1 9 8,35 7,3 6,25 5,2 4,15 3,1 2,5 1 11/5 25/5 8/6 22/6 6/7 2/7 3/8 17/8 Figure 5: Surface ammonium loading rate (SALR), removal rate (SARR), free ammonia level and % NO - 3 -prod / NH + 4 -rem in Tank NH4in (mgn/l) NH4out (mgn/l) NO3out (mgn/l) NO2out (mgn/l) /5 25/5 8/6 22/6 6/7 2/7 3/8 17/8 Figure 6: NH 4 + level in the feed, NH 4 +, NO 3 - and NO 2 - levels in Tank 1 outlet.

7 Figure 7: Surface ammonium loading rate (SALR), removal rate (SARR), free ammonia level and % NO 3 - -prod / NH 4 + -rem in Tank A. Figure 8: Surface ammonium loading rate (SALR), removal rate (SARR), free ammonia level and % NO 3 - -prod / NH 4 + -rem in Tank B.