SMOOTH TEMPERATURE DECREASING FOR NITROGEN REMOVAL IN COLD (9-15° C) ANAMMOX BIOFILM REACTOR TESTS

For N-rich wastewater treatment the anaerobic ammonium oxidation (anammox) and nitritation-anammox (deammonification) processes are widely used. In a deammonification moving bed biofilm reactor (MBBR) a maximum total nitrogen removal rate (TNRR) of 1.5 g N m-2d-1(0.6 kg N m-3d-1) was achieved. During biofilm cultivation, temperature was gradually lowered by 0.5° C per week, and a similar TNRR was sustained at 15° C. qPCR analysis showed an increase in Candidatus Brocadia quantities from 5×103 to 1×107 anammox gene copies g-1 TSS despite temperature lowered to 15° C. Fluctuations in TNRR were rather related to changes in influent NH4+ concentration. To study the short-term effect of temperature on the TNRR, a series of batch-scale experiments were performed which showed sufficient TNRRs even at 9-15° C (4.3-5.4 mg N L-1 h-1, respectively) with anammox temperature constants ranging 1.3-1.6. After biomass was adapted to 15° C, the decrease in TNRR in batch tests at 9° C was lower (15-20%) than for biomass adapted to 17-18° C. Our experiments show that a biofilm of a deammonification reactor adapted to 15° C successfully tolerates shortterm cold shocks down to 9° C retaining a high TNRR

Autotroofne lämmastikuärastus ja sellega seotud tasakaalulised protsessid

Väitekirja elektrooniline versioon ei sisalda publikatsiooneViimastel aastakümnetel on tehtud ridamisi avastusi, mis on oluliselt täiendanud teadmisi loodusliku lämmastikuringe kohta. Üks olulisemaid neist on reoveepuhastuses kasutatav anammoks-protsess, mis toimub Planctomycetes hõimkonda kuuluvate autotroofsete bakterite vahendusel ja mille käigus ammooniumlämmastik oksüdeeritakse anoksilistes tingimustes, kasutades elektronaktseptorina nitritit. On teada, et teatud osa anammoks-bakterid võivad kasutada peale ammooniumi ka teisi substraate. Käesolevas töös uuriti lämmastikuärastust, kasutades elektronaktseptorina sulfaati. Uuritud tingimustes jäi ärastuse efektiivsus madalaks (ca ¼ lämmastikust) ning protsess oli ebastabiilne. Töö ühe osana teostati autotroofse lämmastikuärastusega pilootseadme käivitamine kolmes erinevas konfiguratsioonis (eraldatud biomudaga nitritatsiooni- ja biokilepõhine anammoks reaktor, vahelduvaeratsiooniga biokilereaktor ja biomudapõhine annuspuhasti). Protsessi aluseks oli ammooniumlämmastiku osalise nitriteerimise kombineerimine konventsionaalse anammoks protsessiga. Protsessi sissevooluna kasutati munitsipaalreoveepuhasti liigmuda anaeroobsel stabiliseerimisel tekkivat eeltöötlemata vädu. Autotroofne lämmastikuärastus käivitus kõikides uuritud reaktorites, parimad tulemused (ärastuskiirus kuni 1 kg-N m–3 d–1) saavutati vahelduvaeratsiooniga biokilereaktoris. Edukas protsessi käivitamine nõuab pH kontrolli (pH<7,5), vaba ammoniaagi kontsentratsiooni jälgimist (< 10 mg-N L–1), aeratsiooni aja- ja hapniku kontsentratsiooni (0,3-0,8 mg-O2 L–1) ning sissevoolu heljumi kontrolli (heljumit < 1000 NTU). Vädu on keerulise koostisega süsteem, mille üksikute komponentide kontsentratsioonid on määratud mitmete pH-st sõltuvate tasakaaluliste protsessidega. Vädu efektiivseks käitluseks on oluline teada selle koostises olevate komponentide kontsentratsioone. Käesolevas töös tuletati matemaatilised mudelid kolmele heterogeensele tasakaalulisele süsteemile: avatud ja suletud süsteemidele CO2–HCO3––CO32––CaCO3 ning suletud süsteemile H2O–CO2–CaCO3–NH4Cl. Kõigile kolmele mudelile teostati eksperimentaalne valideerimine. Mudelite kasutamine võimaldab hinnata konjugeeritud tasakaalulisi protsesse keskkonnas ning leida nendes protsessides osalevate osakeste kontsentratsioone.In recent decades, a couple of discoveries have been made that greatly improve the knowledge of the natural nitrogen cycle. In wastewater treatment, the anammox-process is implemented, where ammonium nitrogen is oxidized under anoxic conditions using bacterial phylum Planctomycetes. In this process, nitrite is used as an electron acceptor. In present work, nitrogen removal by the bacterial consortia containing anammox bacteria under anoxic conditions using sulphate as an electron acceptor was studied. Nitrogen removal involving different groups of bacteria and different metabolic pathways took place, but only in a modest extent, (about ¼ of nitrogen was removed) and the process as a whole was unstable. As part of the work within the scope of the current thesis, the start-up of autotrophic nitrogen removal pilot plant was performed and operated in three different configurations (separated biosludge-based nitritation reactor and biofilm-based anammox reactor; intermittently aerated biofilm reactor; and biosludge-based sequence batch reactor). It was concluded that autotrophic nitrogen removal while treating reject water can be started up independently of applied technological concept, but the best results (nitrogen removal rate up to 1 kg-N m–3 d–1) were achieved in an intermittently aerated biofilm reactor. The critical factors for start-up of a deammonification process are pH control (pH <7.5), free ammonia concentration in reject water (< 10 mg-N L–1), time and concentration-based aeration control (dissolved oxygen 0.3-0.8 mg-O2 L–1) and the control of suspended solids of influent (< 1000 NTU). Reject water is a complex multi-component system. The concentrations of its components are determined by multiple pH-dependent equilibrial processes which are interconnected over protons. In order to ensure efficient and stable treatment of reject water, it is important to know the accurate concentrations of its components. In the present thesis, theoretical mathematical models for three heterogeneous equilibrium systems were derived: for open and closed systems CO2-–HCO3––CO32––CaCO3 and for closed system H2O–CO2–CaCO3–NH4Cl. All three models were experimentally validated. Mathematical models allow to calculate the concentrations of all components in the observed systems and to evaluate the impact of anthropogenic processes on the environment.https://www.ester.ee/record=b5258602~S

Recycling of Low-Quality Carbon Black Produced by Tire Pyrolysis

Pyrolysis is a promising way to reuse of waste tires. However, the carbon black generated in the process is often contaminated with various pyrolysis products. This study aims to recycle low-quality recycled carbon black (rCB) from waste tire pyrolysis, addressing the challenges posed by organic residues (up to 5 wt% bituminous substances, 112.2 mg/kg PAH). This causes the agglomeration of particles and decreases the active specific surface area. Cavitational vortex milling (both wet and dry) emerges as a promising method to valorize contaminated rCB, allowing for a significant reduction in the concentration of contaminants. This novel method allows for the generation of hydrophilic and hydrophobic black pigments. In parallel experiments, low-quality rCB is incorporated into solid biofuel to enhance its calorific value. The addition of 10 wt% rCB) to peat residues significantly elevates the calorific value from 14.5 MJ/kg to 21.0 MJ/kg. However, this improvement is accompanied by notable increases in CO2 and SO2 emissions. This dual effect underscores the necessity of considering environmental consequences when utilizing recycled carbon black as a supplement to solid biofuels. The findings provide valuable insights into the potential of cavitational vortex milling for carbon black valorization and highlight the trade-offs associated with enhancing biofuel properties through the addition of rCB

Timber Structures and Prefabricated Concrete Composite Blocks as a Novel Development in Vertical Gardening

A modern, environmentally friendly urban lifestyle requires paying attention to landscaping and green areas. The scarcity of free land in cities and the high price of land require the combination of greenery with buildings—both vertically and horizontally. The developed green technology for construction brings together computer numerical control (CNC) processing of supporting structures and prefabricated solid planting blocks made of concrete composite. The timber structures are fixed together using traditional carpentry joints. The details, which will be manufactured in the factory using CNC processing at a controlled temperature and humidity corresponding to indoor conditions, can be easily assembled on the construction site. The high bending strength but good elasticity and connections of carpentry joints endow the structure with good properties in a non-controllable environment. By combining CNC-processed wooden structures with concrete technology as substrate composites, labor-intensive manual work in landscaping and gardening will be reduced in the future. The novel material-hardening substrate composite material uses only the residues as the raw materials

Accelerating effect of hydroxylamine and hydrazine on nitrogen removal rate in moving bed biofilm reactor

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 (MBBR) and batch tests were performed to evaluate the optimum concentrations of anammox process intermediates that accelerate the autotrophic nitrogen removal and mitigate a decrease in the anammox bacteria activity using anammox (anaerobic ammonium oxidation) biomass enriched on ring-shaped biofilm carriers. Anammox biomass was previously grown on blank biofilm carriers for 450 days at moderate temperature 26.0 (+/- 0.5) A degrees C by using sludge reject water as seeding material. FISH analysis revealed that anammox microorganisms were located in clusters in the biofilm. With addition of 1.27 and 1.31 mg N L-1 of each NH2OH and N2H4, respectively, into the MBBR total nitrogen (TN) removal efficiency was rapidly restored after inhibitions by NO2 (-). Various combinations of N2H4, NH2OH, NH4 (+), and NO2 (-) were used as batch substrates. The highest total nitrogen (TN) removal rate with the optimum N2H4 concentration (4.38 mg N L-1) present in these batches was 5.43 mg N g(-1) TSS h(-1), whereas equimolar concentrations of N2H4 and NH2OH added together showed lower TN removal rates. Intermediates could be applied in practice to contribute to the recovery of inhibition-damaged wastewater treatment facilities using anammox technology

Start-Up of Anammox SBR from Non-Specific Inoculum and Process Acceleration Methods by Hydrazine

Biological nutrient removal from wastewater to reach acceptable levels is needed to protect water resources and avoid eutrophication. The start-up of an anaerobic ammonium oxidation (anammox) process from scratch was investigated in a 20 L sequence batch reactor (SBR) inoculated with a mixture of aerobic and anaerobic sludge at 30 ± 0.5 °C with a hydraulic retention time (HRT) of 2–3 days. The use of NH4Cl, NaNO2, and reject water as nitrogen sources created different salinity periods, in which the anammox process performance was assessed: low (&lt;0.2 g of Cl−/L), high (18.2 g of Cl−/L), or optimum salinity (0.5–2 g of Cl−/L). Reject water feeding gave the optimum salinity, with an average nitrogen removal efficiency of 80%, and a TNRR of 0.08 kg N/m3/d being achieved after 193 days. The main aim was to show the effect of a hydrazine addition on the specific anammox activity (SAA) and denitrification activity in the start-up process to boost the autotrophic nitrogen removal from scratch. The effect of the anammox intermediate hydrazine addition was tested to assess its concentration effect (range of 2–12.5 mg of N2H4/L) on diminishing denitrifier activity and accelerating anammox activity at the same time. Heterotrophic denitrifiers’ activity was diminished by all hydrazine additions compared to the control; 5 mg of N2H4/L added enhanced SAA compared to the control, achieving an SAA of 0.72 (±0.01) mg N/g MLSS/h, while the test with 7.5 mg of N2H4/L reached the highest overall SAA of 0.98 (±0.09) mg N g/MLSS/h. The addition of trace amounts of hydrazine for 6 h was also able to enhance SAA after inhibition by organic carbon source sodium acetate addition at a high C/N ratio of 10/1. The start-up of anammox bacteria from the aerobic–anaerobic suspended biomass was successful, with hydrazine significantly accelerating anammox activity and decreasing denitrifier activity, making the method applicable for side-stream as well as mainstream treatment

Start-Up of Anammox SBR from Non-Specific <em>Inoculum</em> and Process Acceleration Methods by Hydrazine

Biological nutrient removal from wastewater to reach acceptable levels is needed to protect water resources and avoid eutrophication. The start-up of an anaerobic ammonium oxidation (anammox) process from scratch was investigated in a 20 L sequence batch reactor (SBR) inoculated with a mixture of aerobic and anaerobic sludge at 30 ± 0.5 °C with a hydraulic retention time (HRT) of 2–3 days. The use of NH4Cl, NaNO2, and reject water as nitrogen sources created different salinity periods, in which the anammox process performance was assessed: low (−/L), high (18.2 g of Cl−/L), or optimum salinity (0.5–2 g of Cl−/L). Reject water feeding gave the optimum salinity, with an average nitrogen removal efficiency of 80%, and a TNRR of 0.08 kg N/m3/d being achieved after 193 days. The main aim was to show the effect of a hydrazine addition on the specific anammox activity (SAA) and denitrification activity in the start-up process to boost the autotrophic nitrogen removal from scratch. The effect of the anammox intermediate hydrazine addition was tested to assess its concentration effect (range of 2–12.5 mg of N2H4/L) on diminishing denitrifier activity and accelerating anammox activity at the same time. Heterotrophic denitrifiers’ activity was diminished by all hydrazine additions compared to the control; 5 mg of N2H4/L added enhanced SAA compared to the control, achieving an SAA of 0.72 (±0.01) mg N/g MLSS/h, while the test with 7.5 mg of N2H4/L reached the highest overall SAA of 0.98 (±0.09) mg N g/MLSS/h. The addition of trace amounts of hydrazine for 6 h was also able to enhance SAA after inhibition by organic carbon source sodium acetate addition at a high C/N ratio of 10/1. The start-up of anammox bacteria from the aerobic–anaerobic suspended biomass was successful, with hydrazine significantly accelerating anammox activity and decreasing denitrifier activity, making the method applicable for side-stream as well as mainstream treatment

Deammonification process start-up after enrichment of anammox microorganisms from reject water in a moving-bed biofilm reactor

Deammonification via intermittent aeration in biofilm process for the treatment of sewage sludge digester supernatant (reject water) was started up using two opposite strategies. Two moving-bed biofilm reactors were operated for 2.5 years at 26 (+/- 0.5)degrees C with spiked influent (and hence free ammonia (FA)) addition. In the first start-up strategy, an enrichment of anammox biomass was first established, followed by the development of nitrifying biomass in the system (R-1). In contrast, the second strategy aimed at the enrichment of anammox organisms into a nitrifying biofilm (R-2). The first strategy was most successful, reaching higher maximum total nitrogen (TN) removal rates over a shorter start-up period. For both reactors, increasing FA spiking frequency and increasing effluent concentrations of the anammox intermediate hydrazine correlated to decreasing aerobic nitrate production (nitritation). The bacterial consortium of aerobic and anaerobic ammonium oxidizing bacteria in the bioreactor was determined via denaturing gel gradient electrophoresis, polymerase chain reaction and pyrosequencing. In addition to a shorter start-up with a better TN removal rate, nitrite oxidizing bacteria (Nitrospira) were outcompeted by spiked ammonium feeding from R-1

Nitric oxide for anammox recovery in a nitrite-inhibited deammonification system

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