Ivar Zekker

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After sulfate-reducing ammonium oxidation (SRAO) was first assumed in 2001, several works have been published describing this process in laboratory-scale bioreactors or occurring in the nature. In this paper, the SRAO process was performed using reject water as a substrate for microorganisms and a source of NH4 +, with SO4 2− being added as an electron(More)
Autotrophic NH4(+) removal has been extensively researched, but few studies have investigated alternative electron acceptors (for example, SO4(2-)) in NH4(+) oxidation. In this study, sulfate-reducing anaerobic ammonium oxidation (SRAO) and conventional Anammox were started up in upflow anaerobic sludge blanket reactors (UASBRs) at 36 (±0.5)°C and 20(More)
The anammox bacteria were enriched from reject water of anaerobic digestion of municipal wastewater sludge onto moving bed biofilm reactor (MBBR) system carriers—the ones initially containing no biomass (MBBR1) as well as the ones containing nitrifying biomass (MBBR2). Duration of start-up periods of the both reactors was similar (about 100 days), but(More)
Anaerobic ammonium oxidation (anammox) has been studied extensively while no widely accepted optimum values for nitrite (both a substance and inhibitor) has been determined. In the current paper, nitrite spiking (abruptly increasing nitrite concentration in reactor over 20 mg NO-2-NL-1) effect on anammox process was studied on three systems: a moving bed(More)
The anaerobic ammonium oxidation (anammox) and nitritation-anammox (deammonification) processes are widely used for N-rich wastewater treatment. When deammonification applications move towards low temperature applications (mainstream wastewater has low temperature), temperature effect has to be studied. In current research, in a deammonification moving bed(More)
Nitrifying biomass on ring-shaped carriers was modified to nitritating one in a relatively short period of time (37 days) by limiting the air supply, changing the aeration regime, shortening the hydraulic retention time and increasing free ammonia (FA) concentration in the moving-bed biofilm reactor (MBBR). The most efficient strategy for the development(More)
BACKGROUND Arsenic (As) toxicity is primarily based on its chemical speciation. Although inorganic and methylated As species are well characterized in terms of metabolism and formation in the human body, the origin of thiolated methylarsenicals is still unclear. OBJECTIVES We sought to determine whether sulfate-reducing bacteria (SRB) from the human gut(More)
In biological nitrogen removal, application of the autotrophic anammox process is gaining ground worldwide. Although this field has been widely researched in last years, some aspects as the accelerating effect of putative intermediates (mainly N2H4 and NH2OH) need more specific investigation. In the current study, experiments in a moving bed biofilm reactor(More)
Robust start-up of the anaerobic ammonium oxidation (anammox) process from non-anammox-specific seeding material was achieved by using an inoculation with sludge-treating industrial [Formula: see text]-, organics- and N-rich yeast factory wastewater. N-rich reject water was treated at 20°C, which is significantly lower than optimum treatment temperature.(More)
Maintaining stability of low concentration (< 1 g L(-1)) floccular biomass in the nitritation-anaerobic ammonium oxidation (anammox) process in the sequencing batch reactor (SBR) system for the treatment of high COD (> 15,000 mg O2 L(-1)) to N (1680 mg N L(-1)) ratio real wastewater streams coming from the food industry is challenging. The anammox process(More)