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Project titleDevelopment of scientific foundations of environmentally friendly disposal of watered swine and chicken wastes through their oxidation by supercritical water-oxygen fluid

AffiliationKutateladze Institute of Thermophysics of the Siberian Branch of the Russian Academy of Sciences,

Research area 09 - ENGINEERING SCIENCES, 09-401 - Power systems that operate using organic fuel

Keywordsbiomass; renewable energy; swine manure; chicken manure; supercritical water; gasification; oxidation; catalysis; kinetics; reaction mechanisms

Annotation
The development of new technologies for the environmentally friendly disposal of toxic watered waste is a fundamental scientific problem that has an important practical significance from the standpoint of using these wastes as renewable raw materials in the fuel energy industry. Using supercritical water (SCW: T > 647 K, P > 22.1 MPa), which is the cheapest and most environmentally friendly solvent of organic substances and gases, as well as a donor of hydrogen and oxygen, having a catalytic effect on the combustion of fuels, can become a determining factor for solving this problem. Despite a large number of studies on SCW gasification of municipal and industrial waste, the solution to the problem of waste disposal by incineration in SCW/O2 fluid is still at the stage of experimental data accumulation, which hinders developing new technologies for resource-saving and environmentally friendly fuel energy production. The purpose of the present project is to form scientific and technological groundwork that ensure the environmentally friendly disposal of swine and chicken manure (waste of hazard class III) in a supercritical water-oxygen fluid in a single-stage process with the production at the outlet of a heat carrier, industrial (circulating) water, and an ash residue, free of organic carbon. Detailed studies of the gasification and combustion of biomass (swine and chicken manure) in SCW and SCW/O2 fluids will be carried out for the first time implementing various methods of the process in flow-type tubular reactors designed by the project authors. With a temperature gradient along the vertical axis of the reactor and the supply of suspensions based on swine and chicken manure to the reactor under isobaric conditions, the effect of reagent consumption, NaOH content, and biomass in the suspension on the composition and yield of SCW gasification products will be investigated, which will allow determining process efficiency, as well as describing its mechanisms and kinetics. When pumping a water-oxygen mixture through a bed of dried samples of swine and chicken manure at a uniform increase in the reactor temperature, temperature dependences of the oxidation products yield and composition will be obtained and the intervals of intense heat release will be determined. When varying the flow rate of oxygen and suspensions based on swine and chicken manure with NaOH, fed to the upper part of a vertically positioned reactor, data on the degree of biomass burnup in the SCW/O2 fluid will be obtained depending on the oxygen excess coefficient and the residence time of the reagents in the reactor, as well as mechanisms and kinetics of the process, will be described. Employing the reactor, equipped with systems of distributed methane input and continuous supply of water-fuel suspension (based on brown coal, swine or chicken manure with added NaOH), upgraded during the project, the effect of the oxygen excess coefficient on the degree of biomass burnup in the SCW/O2 fluid in the autothermal mode will be investigated when varying the reagent consumption. In these experiments, special attention will be paid to the study of the composition and content of organic and mineral components in the water collected at the outlet of the reactor. As a result of the conducted research, the optimal modes of the disposal of swine and chicken manure in SCW/O2 fluid will be determined, as well as recommendations for improving methods related to the creation of a pilot plant for their single-stage environmentally friendly disposal will be formulated. The basis for the implementation of the goals and objectives of this project will be a unique experimental facility designed and created by the project authors, as well as original methods and the results of many years of research on fuel conversion and waste disposal in supercritical water fluids.

Expected results
Within the framework of the project, it is planned to obtain the following priority results: 1) Data on the composition, yield, and calorific value of SCW gasification products of biomass (swine and chicken manure) at a pressure of 25 MPa and a temperature gradient along the vertical axis of the reactor (663-903 K), depending on the biomass content in the suspension, the amount of added NaOH, and the residence time of reagents in the reactor, which will be used to calculate the gasification efficiency, as well as to describe process mechanisms and kinetics. 2) Temperature dependences of the composition and yield of volatile and liquid products of biomass (swine and chicken manure) oxidation when pumping water-oxygen fluid through its bed at the uniform heating of the reactor, as well as data on the composition and yield of mineral residue, based on which the oxidation mechanisms and kinetics will be described, as well as conclusions will be drawn about the efficiency of biomass burnup. Based on the time dependences of the temperature of the reactor wall and the power of the resistive heaters, the conditions for the transition to the autothermal mode due to heat released during the oxidation of biomass will be determined. 3) Data on the composition and yield of biomass (swine and chicken manure with added NaOH) oxidation products in the SCW/O2 fluid at a pressure of 25 MPa and a temperature gradient along the vertical axis of the reactor (663-873 K), depending on the oxygen excess coefficient and the residence time of the reagents in the reactor, which will be used to describe the process mechanisms and kinetics, to determine the minimum oxygen excess coefficient, at which the residual content of organic substances (phenols, polyaromatic and heterocyclic compounds) in the wastewater will be less than maximum permissible concentration. 4) Original systems of distributed methane injection and continuous supply of water-fuel suspension (based on brown coal, swine, or chicken manure with added NaOH) to the reactor will be developed and manufactured. 5) Data on the composition and yield of biomass (swine and chicken manure with added NaOH) and methane co-oxidation products in the SCW/O2 fluid at a pressure of 25 MPa and a temperature gradient along the axis of the reactor (663-873 K), depending on the oxygen excess coefficient and methane consumption, to describe the process mechanisms and kinetics. Based on the data on the product composition, the time dependences of the reactor wall temperature and the power of resistive heaters, the optimal values of methane and oxygen consumption will be determined, at which the process is implemented in the autothermal mode, and the residual content of organic substances (phenols, polyaromatic and heterocyclic compounds) in the wastewater is less than the maximum permissible concentration. 6) Data on the composition and yield of oxidation products of a water-fuel suspension (based on brown coal, swine or chicken manure with added NaOH) in an SCW/O2 fluid at a pressure of 25 MPa, a temperature gradient along the reactor axis (663-873 K), and a variation in the reagents flow rate, to describe process mechanisms and kinetics. Based on the data on the product composition, the time dependences of the reactor wall temperature and the power of the resistive heaters, the optimal values of oxygen consumption and water-fuel suspension will be determined, at which the process is carried out in an autothermal mode with the production of an ash residue free of organic carbon and water with a residual content of organic substances (phenols, polyaromatic and heterocyclic compounds) not exceeding the maximum permissible concentration. The research, stated in the project is characterized by novelty, and the proposed scientific and technical approaches are characterized by a high degree of originality. The solution to the problems set in the project will allow obtaining results at the level of the world's leading schools in Europe, China, and the USA. The research results will be presented in articles published in specialized high-ranking journals, as well as at international and all-Russian conferences. In general, the results, obtained during the project implementation, and the developed scientific and technical groundwork that ensure resource-saving environmentally friendly disposal of swine and chicken manure in supercritical water fluids in a single-stage process with the production of a heat carrier and an ash residue, free of organic carbon, will allow not only reducing significantly the ecological burden on the environment, ensure the leading positions of the Novosibirsk Region in socio-economic development, but also reduce the costs of pig-raising and poultry-farming enterprises for providing heat and industrial water.

Annotation of the results obtained in 2022
The development of new technologies for the environmentally friendly disposal of wet toxic biomass wastes is a fundamental scientific problem of important practical significance from the viewpoint of their involvement in the energy sector as a renewable fuel. Using supercritical water (SCW: T > 647 K, P > 22.1 MPa), which is the cheapest and most environmentally friendly solvent of organic substances and gases, serves as a donor of hydrogen and oxygen, and has a catalytic effect on fuel combustion, can be decisive for solving a problem under consideration. Employing tubular reactors equipped with systems to measure pressure, temperature, power of resistive heaters and flow rate of reagents, as well as physical and chemical analysis methods, studies were carried out on gasification of chicken manure (CM) in supercritical water, and oxidation of municipal sewage sludge (MSS), chicken manure and swine manure (SM) in a water-oxygen fluid. When studying the SCW gasification of chicken manure in a flow reactor at a temperature gradient along its vertical axis (663-873 K from top to bottom), a pressure of 25 MPa, a CM flow rate of 6.9-9.6 g/min, including tests with the addition of NaOH (2.4 wt%), data were obtained for the first time on the composition and yield of volatile, liquid and solid products, the composition and content of toxic organic substances (phenols, polyaromatic hydrocarbons, and N-containing aromatic substances) and mineral components in the water collected at the reactor outlet (effluent water). It has been revealed that an increase in the residence time of reagents in the high-temperature region of the reactor leads to an increase in both the conversion degree and the efficiency of CM gasification, and the content of polyaromatic hydrocarbons in liquid products and effluent water. Using extraction methods and gas-chromatography / mass-spectrometry, it was revealed that the composition of water-soluble substances is predominated by phenol, pyridine, pyrazine, pyrrole, aniline, indole, quinoline, naphthyridine, indene, pyridinoindenol, and their alkyl derivatives. The total content of identified phenols in the effluent water decreases from 1.3 to 1.1 g/dm3 with an increase in the residence time of the reagents in the high-temperature region of the reactor, and almost does not depend on the addition of NaOH, while the total content of N-containing compounds decreases from 1.0 to 0.7 g/dm3 with the addition of NaOH. Naphthalene dominates among the polyaromatic hydrocarbons detected in the effluent water; the total content of polyaromatic hydrocarbons in the water varies from 0.5 to 2.1 mg/dm3. According to capillary electrophoresis and X-ray fluorescence analysis, the content of ammonium ions in the effluent water is at the level of 10 g/dm3, and the main mineral components (Ca, K, P, S, Si, and Mg) are concentrated in the carbonized residue. When studying the oxidation of municipal sewage sludge, chicken and swine manure while pumping water-oxygen fluid through their bed in a mode of uniform (1.5 K/min) temperature increase to 733 K, temperature dependences of the volatile and liquid products yield were obtained for the first time as well as data on the content of mineral components in the ash residue and effluent water. It follows from the time behavior of the reactor wall temperature, the power of resistive heaters, and the degree of organic carbon removal, that most of the biomass is oxidized at T < 643 K. A different distribution of the combustion front along the vertical axis of the reactor was revealed: when oxidizing CM and SM, the combustion region was localized in the lower and middle parts of the reactor, whereas during the MSS oxidation, the combustion front moved from the lower to the upper part of the reactor. It is shown that the degree of organic carbon removal from biomass increases in the sequence: CM < MSS < SM and is determined by the oxygen consumption supplied to the reactor. Along with intensive oxidation of biomass, the removal of organic and mineral components by a water vapor flow was detected. The yield of volatile combustible and liquid products during the oxidation of biomass increase in the sequence: CM < SM < MSS. According to IR spectroscopy and ultimate analysis, an increase in the oxidation duration and temperature leads to a decrease in the content of functional groups and an increase in the proportion of aromatic compounds in liquid products. Liquid products, formed during the oxidation of CM are characterized by the highest N/C atomic ratio due to the high content of thermally stable N-containing aromatic compounds. It was revealed that during the biomass oxidation, from 50 to 75% of nitrogen passes into the aqueous phase in the form of ammonium ions; and the main elements (Si, Ca, Mg, P, K, and Al) are concentrated in the ash residue. The results of X-ray diffraction analysis show that the composition of CM and SM ash residues are predominated respectively by CaCO3 and SiO2. In general, the methodological approach used, consisting in continuous pumping of the water-oxygen fluid through the biomass bed at a uniform increase in temperature, allowed obtaining analytical data on the products composition and yield at each of the stages of their transformation, including the stage of heating the reaction mixture to operating temperature. The results obtained will serve the basis when selecting conditions for the CM and SM oxidation in a supercritical water-oxygen fluid in the flow mode.

Publications

1. Fedyaeva O.N., Artamonov D.O., Vostrikov A.A. Oxidation of municipal sewage sludge, chicken and swine manure in the water-oxygen fluid flow under uniform heating The Journal of Supercritical Fluids, Vol. 191. No. 105767 (year - 2022) https://doi.org/10.1016/j.supflu.2022.105767

2. Fedyaeva O.N., Vostrikov A.A. Processing watered toxic waste of pig abd poultry farming in sub-and supercritical water (Review) Russian Journal of Physical Chemistry B, Т. 16, No 8, pp. ???-???. (year - 2022) https://doi.org/10.1134/S1990793122080085

3. Fedyaeva O.N., Vostrikov A.A., Artamonov D.O., Shishkin A.V. Особенности слоевого горения биотоплив в потоке водокислородного флюида Тезисы докладов Всероссийской конференции с элементами научной школы для молодых ученых XXXVIII "Сибирский теплофизический семинар", 29-31 августа 2022 года, Новосибирск, С. 251. (year - 2022)

Annotation of the results obtained in 2023
The processing of biomass waste is of great interest due to the possibility of simultaneously reducing environmental burden and energy consumption. As part of the project, employing a tubular reactor equipped with systems to measure pressure, temperature, power of ohmic heaters and flow rate of reagents, as well as physical and chemical analysis methods, studies were carried out for the first time on gasification of swine manure in supercritical water (SCW), and oxidation of swine and chicken manures in a supercritical water-oxygen fluid in the flow mode. When studying the SCW gasification of swine manure at a temperature gradient along vertical axis of the reactor (390-600oC from top to bottom), a pressure of 25 MPa, a swine manure flow rate of 7.5-10.7 g/min, including tests with the addition of NaOH (1.0 wt%), data were obtained on the composition and yield of volatile, liquid, and solid products, the composition and concentration of contaminants (phenols, polyaromatic hydrocarbons, and N-bearing aromatic substances) and mineral components in the effluent collected at the reactor outlet. Using gas chromatography-mass spectrometry (GC-MS), it was found that the concentration of contaminants in the effluent decreases in the sequence: phenols > pyridines > pyrroles > indoles > pyrazines > anilines > quinolines. The concentration of phenols and N-bearing aromatic compounds in the effluent is about 1 g/dm3, while the concentration of PAHs is at the level of 1 mg/dm3. It is shown that increasing the residence time of the reagents reduces the content of phenols in the effluent, while the addition of NaOH leads to an increase in the yield of syngas and NH3, as well as a decrease in the concentration of N-bearing aromatic compounds and PAHs. From the research results of SCW oxidation of swine and chicken manures at a pressure of 25 MPa, a temperature of 390-600°C and varying the reagent’s flow rates (5.4-8.6 g/min), excess oxygen (OR < 1.80) and the addition of NaOH (1 wt%), it follows that the presence of oxygen in the reaction mixture not only reduces the concentration of contaminants in the effluent by several orders of magnitude, but also partially compensates for the thermal inputs of the process. Using GC-MS, it is shown that the residual concentration of phenols, N-bearing aromatic compounds, and PAHs in the effluent during SCW oxidation of swine manure (OR = 1.78) does not exceed 0.25, 0.80, and 0.014 mg/dm3, and during the of chicken manure oxidation (OR = 1.80) - 0.31, 1.65, and 0.043 mg/dm3, respectively. It is shown that pyridines, indoles, and quinolines remain stable towards oxidation, whereas the oxidation of pyrazines, pyrroles, and anilines proceeds at an acceptable rate. CO2, N2, N2O and trace amounts of NH3 were found in the gas oxidation products; the N2O/N2 ratio increases with increasing OR. The mechanisms of biomass waste oxidation under conditions of temperature and water density gradient are described. The main components of ash residues resulted from SCW oxidation of swine and chicken manures are SiO2 and CaCO3, respectively. It is revealed that despite the higher content of N-bearing compounds in chicken manure, the rate of disappearance of the latter during its SCW oxidation is higher than during the swine manure oxidation. The residual concentration of ammonium ions in the effluent at swine manure oxidation (OR = 1.8) turned out to be almost two orders of magnitude higher (138 mg/dm3) than at the chicken manure oxidation (1.83 mg/dm3). It is suggested that the mineral components contained in chicken manure have a catalytic effect on the oxidation of N-bearing compounds. Based on the results obtained, it is concluded that the processing of swine and poultry manures through SCW oxidation generates fewer pollutants and requires less input energy compared to SCW gasification.

Publications

1. Fedyaeva O.N., Morozov S.V., Vostrikov A.A. Supercritical water gasification of chicken manure continuously supplied into the reactor The Journal of Supercritical Fluids, Vol. 200, No 105998 (year - 2023) https://doi.org/10.1016/j.supflu.2023.105998

2. Fedyaeva O.N., Vostrikov A.A., Artamonov D.O., Shishkin A.V., Sokol M.Y. Окисление осадка сточных вод в потоке водокислородного флюида при равномерном увеличении температуры Химия в интересах устойчивого развития, Т. 31, №1, С. 87-97. (year - 2023) https://doi.org/10.15372/KhUR2023443

3. Fedyaeva O.N. Газификация и окисление отходов биомассы в сверхкритической воде: экологические и ресурсосберегающие аспекты XII Научно-практическая конференция с международным участием "Сверхкритические флюиды: фундаментальные основы, технологии, инновации", Тезисы докладов, 03-08 июля 2023 г. Тверь, С. 14-15. (year - 2023)

4. Fedyaeva O.N., Morozov S.V., Vostrikov A Газификация отходов биомассы в сверхкритической воде Всероссийская конференция "XXXIX Сибирский теплофизический семинар", Тезисы доклада, 28-31 августа 2023 г., Новосибирск, С. 294. (year - 2023)

5. Shishkin A.V., Alekhin S.A., Sokol M.Y., Vostrikov A.A., Fedyaeva O.N. Окисление карбамида в водокислородном флюиде Всероссийская конференция "XXXIX Сибирский теплофизический семинар", Тезисы докладов, 28-31 августа 2023 г., Новосибирск, С. 253. (year - 2023)