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.

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.

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.