The Effect of Influent Characteristics and Operational Conditions over the Performance and Microbial Community Structure of Partial Nitritation Reactors

Nitrogen is a main contaminant of wastewater worldwide. Novel processes for nitrogen removal have been developed over the last several decades. One of these is the partial nitritation process. This process includes the oxidation of ammonium to nitrite without the generation of nitrate. The partial nitritation process has several advantages over traditional nitrification-denitrification processes for nitrogen removal from wastewaters. In addition, partial nitritation is required for anammox elimination of nitrogen from wastewater. Partial nitritation is affected by operational conditions and substances present in the influent, such as quinolone antibiotics. In this review, the impact that several operational conditions, such as temperature, pH, dissolved oxygen concentration, hydraulic retention time and solids retention time, have over the partial nitritation process is covered. The effect of quinolone antibiotics and other emerging contaminants are discussed. Finally, future perspectives for the partial nitritation process are commented upon

Nutrient removal from UASB effluent in agro-industries

Phosphorus and nitrogen are important elements, making a major contribution to agricultural and industrial development, but their release to natural water bodies are the main causes of eutrophication. Anaerobic digestion yields effluents rich in ammonium and phosphate and poor in biodegradable organic carbon, thereby making them less suitable for conventional biological nitrogen and phosphorus removal. In addition, the demand for fertilizers is increasing, energy prices are rising and global phosphate reserves are declining. This requires both changes in wastewater treatment technologies and implementation of new processes. In this contribution the combination of an ureolytic MAP (magnesium ammonium phosphate) precipitation and autotrophic nitrogen removal is described on the anaerobic effluent of a potato processing company to obtain a more sustainable and cheaper method than conventional wastewater treatment processes. The results obtained during this experiment (6 weeks period) show that it is possible to recover phosphate as struvite and remove nitrogen with the autotrophic nitrogen process from wastewater after anaerobic digestion coming from a potato processing company. However further research is necessary to obtain stable results during several months, especially for the nitrite:ammonium ratio produced by the partial nitritation reactor

Dynamic simulation of N2O emissions from a full-scale partial nitritation reactor

This study deals with the potential and the limitations of dynamic models for describing and predicting nitrous oxide (N2O) emissions associated with biological nitrogen removal from wastewater. The results of a three-week monitoring campaign on a full-scale partial nitritation reactor were reproduced through a state-of-the-art model including different biological N2O formation pathways. The partial nitritation reactor under study was a SHARON reactor treating the effluent from a municipal wastewater treatment plant sludge digester. A qualitative and quantitative comparison between experimental data and simulation results was performed to identify N2O formation pathways as well as for model identification. Heterotrophic denitrifying bacteria and ammonium oxidizing bacteria (AOB) were responsible for N2O formation under anoxic conditions, whereas under aerated conditions the AOB were the most important N2O producers. Relative to previously proposed models, hydroxylamine (NH2OH) had to be included as a state variable in the AOB conversions in order to describe potential N2O formation by AOB under anoxic conditions. An oxygen inhibition term in the corresponding reaction kinetics was required to fairly represent the relative contribution of the different AOB pathways for N2O production. Nevertheless, quantitative prediction of N2O emissions with models remains a challenge, which is discussed

Small aggregates can cause nitrite accumulation in one-stage partial nitritation and anammox

C

ZeroWasteWater: short-cycling of wastewater resources for sustainable cities of the future

Sewage treatment relies mainly on conventional activated sludge (CAS) systems, reaching sufficiently low pollutant effluent levels. Yet, CAS has a low cost-effectiveness and recovery potential and a high electricity demand and environmental footprint. By 2050, globally we have to solve severe water and phosphorus shortages while significantly decreasing greenhouse gas emissions. In this review and opinion paper, the ZeroWasteWater concept is proposed as a sustainable centralised technology train to short-cycle water, energy and valuable materials from sewage, while adequately abating pathogens, heavy metals and trace organics. Electrical energy recovery from anaerobic digestion of the organics present in sewage and kitchen waste (KW) has a value of 4.0 per inhabitant equivalent (IE) per year. In addition to sewerage improvements and water conservation, prerequisites include an advanced physico-chemical and/or biological concentration step at the entry of the sewage treatment plant. In the side stream, the recovery of phosphorus and carbon-sequestrating biochar from the digested sludge and of nitrogen from the digestate has a value of 6.3IE-1 year-1. Alternatively, recovery of biogas and materials can occur directly on source-separated black water. In the main stream, partial nitritation and anammox oxidise residual nitrogen. Moreover, two serial heat pumps recover thermal energy, valued at 6.9IE-1 year-1, cooling the water by 5 degrees C, and membrane technologies recover potable water at 65IE-1 year-1. Interestingly, ZeroWasteWater is expected to be economically viable. Key steps are to incorporate water chain management into holistic urban planning and thus produce a cradle-to-cradle approach that society will find acceptable

Increased salinity improves the thermotolerance of mesophilic nitrification

Nitrification is a well-studied and established process to treat ammonia in wastewater. Although thermophilic nitrification could avoid cooling costs for the treatment of warm wastewaters, applications above 40 A degrees C remain a significant challenge. This study tested the effect of salinity on the thermotolerance of mesophilic nitrifying sludge (34 A degrees C). In batch tests, 5 g NaCl L-1 increased the activity of aerobic ammonia-oxidizing bacteria (AerAOB) by 20-21 % at 40 and 45 A degrees C. For nitrite-oxidizing bacteria (NOB), the activity remained unaltered at 40 A degrees C, yet decreased by 83 % at 45 A degrees C. In a subsequent long-term continuous reactor test, temperature was increased from 34 to 40, 42.5, 45, 47.5 and 50 A degrees C. The AerAOB activity showed 65 and 37 % higher immediate resilience in the salt reactor (7.5 g NaCl L-1) for the first two temperature transitions and lost activity from 45 A degrees C onwards. NOB activity, in contrast to the batch tests, was 37 and 21 % more resilient in the salt reactor for the first two transitions, while no difference was observed for the third temperature transition. The control reactor lost NOB activity at 47.5 A degrees C, while the salt reactor only lost activity at 50 A degrees C. Overall, this study demonstrates salt amendment as a tool for a more efficient temperature transition for mesophilic sludge (34 A degrees C) and eventually higher nitrification temperatures

Start-Up of One-Step Partial Nitritation/Anammox Moving Bed Biofilm Reactor to Treat Municipal-Like Wastewater

Màster d'Enginyeria Ambiental, Facultat de Química, Universitat de Barcelona, Curs: 2015-2016, Tutor: Isaac Fernández RodríguezThe application of partial nitritation/anammox process to remove nitrogen from wastewater is a cost effective and sustainable approach since it can save energy and resources. It was applied successfully in treating ammonium rich waste streams (Wett, 2007). This is worth to use deammonification (partial nitritation/anammox) process in sewage treatment to create an energy positive environment and therefore, this has been studied extensively for last few years to investigate its applicability in mainstream condition where both temperature (10-20 °C) and nitrogen concentration (<100 mg N/L) are very low. Systems based on Anammox can be of great help to comply with stricter wastewater discharge regulations and reduce environmental problems caused by nutrients discharges (e.g. eutrophication). In this regard, a study of one-step Partial Nitritation/Anammox process was carried out in a moving bed biofilm reactor by using municipal-like wastewater with the aim to conduct the start-up of Partial Nitritation (PN) process in the MBBR and then stabilize it, subsequently perform the Anammox process in the same MBBR system. Finally, optimise the PN/Anammox MBBR to have higher BNR rate. PN/Anammox process was successfully tested in a 4.5 L lab-scale MBBR for 141 days at 20 °C, with about 20% filled with Kaldnes K1 carriers. The feeding was prepared and calculated to have 50 mg NH4+/L, the source of the wastewater was from the rejected water of anaerobic digester from a municipal wastewater treatment plant. Several changes were made to achieve our objectives step by step. The analysis shows that the efficiency of NH4+ removal has reached a maximum of 95% while the maximum overall percentage of nitrogen removal of 32.9% after the addition of Anammox bacteria to the reacto

Stable performance of non-aerated two-stage partial nitritation/anammox (PANAM) with minimal process control

Partial nitritation/anammox (PANAM) technologies have rapidly developed over the last decade, but still considerable amounts of energy are required for active aeration. In this study, a non-aerated two-stage PANAM process was investigated. In the first-stage upflow fixed-film bioreactor, nitratation could not be prevented at ammonium loading rates up to 186 mg N l-1 d-1 and low influent dissolved oxygen (0.1 mg O2 l-1). Yet, increasing the loading rate to 416 and 747 mg N l-1 d-1 by decreasing the hydraulic retention time to 8 and 5 h, respectively, resulted in partial nitritation with the desired nitrite to ammonium nitrogen ratio for the subsequent anammox stage (0.711.05). The second-stage anammox reactor was established with a synthetic feeding based on ammonium and nitrite. After establishing anammox at low biomass content (0.5 g VSS l-1), the anammox influent was switched to partial nitritation effluent at a loading rate of 71 mg N l-1 d-1, of which 78% was removed at the stoichiometrically expected nitrite to ammonium consumption ratios (1.19) and nitrate production to ammonium consumption ratio (0.24). The combined PANAM reactors were operated for 3 months at a stable performance. Overall, PANAM appeals economically, saving about 50% of the energy costs, as well as technically, given straightforward operational principles

Partial nitritation and o-cresol removal with aerobic granular biomass in a continuous airlift reactor

Several chemical industries produce wastewaters containing both, ammonium and phenolic compounds. As an alternative to treat this kind of complex industrial wastewaters, this study presents the simultaneous partial nitritation and o-cresol biodegradation in a continuous airlift reactor using aerobic granular biomass. An aerobic granular sludge was developed in the airlift reactor for treating a high-strength ammonium wastewater containing 950+/-25 mg N-NH⁺₄ L⁻¹. Then, the airlift reactor was bioaugmented with a pnitrophenol-degrading activated sludge and o-cresol was added progressively to the ammonium feed to achieve 100 mg L⁻¹. The results showed that stable partial nitritation and full biodegradation of o-cresol were simultaneously maintained obtaining a suitable effluent for a subsequent anammox reactor. Moreover, two o-cresol shock-load events with concentrations of 300 and 1000 mg L⁻¹ were applied to assess the capabilities of the system. Despite these shock load events, the partial nitritation process was kept stable and o-cresol was totally biodegraded. Fluorescence in situ hybridization technique was used to identify the heterotrophic bacteria related to o-cresol biodegradation and the ammonia oxidising bacteria along the granules