Nitrogen removal from municipal wastewater with the application of deammonification process offers an operational cost reduction, especially if it is combined with a maximal use of organic content of wastewater for biogas production. In this thesis, two approaches for integration of the deammonification process into the municipal wastewater treatment scheme were studied.

The first approach is based on ammonium concentration from municipal wastewater by ion exchange followed by biological removal of ammonium from the concentrated stream by deammonification process. Experiments with synthetic and real municipal wastewater showed that strong acid cation resin is suitable for ammonium concentration due to its high exchange capacity and fast regeneration. Since NaCl was used for regeneration of ion exchange materials, spent regenerant had elevated salinity. The deammonification biomass was adapted to NaCl content of 10-15 g/L by step-wise salinity increase. The technology was tested in batch mode with 99.9 % of ammonium removal from wastewater with ion exchange and up to 95 % of nitrogen removal from spent regenerant by deammonification process.

The second studied approach was to apply anammox process to low-concentrated municipal wastewater in a moving bed biofilm reactor (MBBR) and integrated fixed film activated sludge (IFAS) system without a pre-concentration step. After a 5 months period of transition to mainstream wastewater the pilot plant was operated during 22 months and stable performance of one-stage deammonification was proven. Clear advantage of IFAS system was shown. The highest stable nitrogen removal efficiency of 70 % and a nitrogen removal rate of 55 g N/(m³·d) was reached. Moreover, the influence of operation conditions on competition between ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) was studied by literature review, batch tests and continuous pilot plant operation.

This work is dedicated to the biological treatment of wastewater with increased salinity using a combination of partial nitritation and Anammox processes. Two one-stage deammonification moving bed biofilm reactors were operated with the increase in NaCl concentration every two weeks by 5 and 2.5 g/L. The strategy with a step of 5 g/L of salinity increase led to complete inhibition of the process at the salinity level of 15 g/L. The strategy with a step of 2.5 g/L gave possibility to adapt bacteria to the elevated salinity. After reaching the salinity level of 10 g NaCl/L, the reactor was operated during 92 days with a nitrogen removal rate of 0.39 +/- 0.19 g N/(m(2)center dot day) (0.078 +/- 0.038 kg N/m(3)center dot day) and an average nitrogen removal efficiency of 59%. It was shown that conductivity cannot be used for monitoring the process when a reactor is treating wastewater with increased salinity, whereas pH can be correlated to effluent ammonium concentration regardless of wastewater salinity.

In this study the combination of an upflow anaerobic sludge blanket (UASB) reactor and a deammonification moving bed biofilm reactor (MBBR) for mainstream wastewater treatment was tested. The competition between aerobic ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) was studied during a 5 months period of transition from reject water to mainstream wastewater followed by a 16 months period of mainstream wastewater treatment. The decrease of influent ammonium concentration led to a wash-out of suspended biomass which had a major contribution to nitrite production. Influence of a dissolved oxygen concentration and a transient anoxia mechanism of NOB suppression were studied. It was shown that anoxic phase duration has no effect on NOB metabolism recovery and oxygen diffusion rather than affinities of AOB and NOB to oxygen determine the rate of nitrogen conversion in a biofilm system. Anammox activity remained on the level comparable to reject water treatment systems.

In this study the system based on the combination of biofilm and activated sludge (IFAS - integrated fixed film activated sludge) was tested and compared with a system that relies only on biofilm (MBBR - moving bed biofilm reactor) for nitrogen removal from municipal wastewater by deammonification process. By introduction of suspended biomass into MBBR the nitrogen removal efficiency increased from 36 +/- 3% to 70 +/- 4% with simultaneous 3-fold increase of nitrogen removal rate. Results of batch tests and continuous reactor operation showed that organotrophic nitrate reduction to nitrite, followed by anammox reaction contributed to this high removal efficiency. After sCOD/NH4-N ratio decreased from 1.8 +/- 0.2 to 1.3 +/- 0.1 removal efficiency decreased to 52 +/- 4%, while still maintaining 150% higher removal rate, comparing to MBBR. Activity tests revealed that affinity of NOB to oxygen is higher than affinity of AOB with half-saturation constants of 0.05 and 0.41 mg/L, respectively.

The anaerobic ammonium oxidation (anammox) process is one of the most cost-effective technologies for removing excessive nitrogen compounds from effluents of wastewater treatment plants. The study was conducted to assess the feasibility of using ion exchange (IE) and reverse osmosis (RO) methods to concentrate ammonium to support partial nitritation/anammox process, which so far has been used for treating only wastewater with high concentrations of ammonium. Upflow anaerobic sludge blanket (UASB) reactor effluents with 40.40, 37.90 and 21.80 mg NH4N/L levels were concentrated with IE method to 367.20, 329.50 and 187.50 mg NH4N/L, respectively, which were about nine times the initial concentrations. RO method was also used to concentrate 41.0 mg NH4N/L of UASB effluent to 163 mg NH4N/L at volume reduction factor 5. The rates of nitrogen removal from respective RO pretreated concentrates by partial nitritation/anammox technology were 0.60, 1.10 and 0.50 g N/m(2)day. The rates were largely influenced by initial nitrogen concentration. However, rates of RO concentrates were 0.74, 0.92 and 0.81 g N/m(2)day even at lower initial NH4N concentration. It was found out from the study that higher salinity decreased the rate of nitrogen removal when using partial nitritation/anammox process. Dissolved oxygen concentration of similar to 1 mg/L was optimal for the operation of the partial nitritation/anammox process when treating IE and RO concentrates. The result shows that IE and RO methods can precede a partial nitritation/anammox process to enhance the treatment of wastewater with low ammonium loads.

In this study, a new technology of nitrogen removal from mainstream municipal wastewater is proposed. It is based on ammonium removal by ion exchange and regeneration of ion exchange material with 10-30 g/L NaCl solution with further nitrogen removal from spent regenerant by partial nitritation/Anammox process. Influence of regenerant strength on performance of ion exchange and biological parts of the proposed technology was evaluated. Moreover, the technology was tested in batch mode using pretreated municipal wastewater, strong acid cation (SAC) resin and partial nitritation/Anammox biomass. It was shown that with ion exchange it is possible to remove 99.9% of ammonium from wastewater while increasing the concentration of ammonium in spent regenerant by 18 times. Up to 95% of nitrogen from spent regenerant, produced by regeneration of SAC resin with 10 g/L NaCl solution, was removed biologically by partial nitritation/Anammox biomass. Moreover, the possibilities of integration of the technology into municipal wastewater treatment technology, and the challenges and advantages are discussed.

The scope of this study is concentration of ammonium from municipal wastewater using ion exchange process. Four types of ion exchange materials were tested in packed bed columns, namely strong and weak acid cation exchange resins and natural and synthetic zeolites. In total 23 runs of saturation and regeneration were done using synthetic wastewaters of different kinds and pretreated municipal wastewater. Due to its high exchange capacity and fast regeneration strong acid cation exchange resin was found to be the most suitable for ammonium concentration under condition that selectivity of ammonium removal is not of a main concern and it allows concentrating ammonium from 27 to 580mg NH4-N/L. If selective ammonium removal is required, natural zeolite should be used instead. Regeneration with 0.17M HCl and 0.17-0.51M NaCl was tested and suitability of different regenerants for different technologies of spent regenerant treatment was discussed. It was shown that electric conductivity measurements can be used for detection of breakthrough and estimation of ammonium concentration in outflow from an ion exchange column. Breakthrough curve fitting with Thomas and Adams-Bohart models was performed which gave information about the maximum exchange capacity of materials and kinetics of ion exchange.