Ecological Engineering and Environment Protection

LIFE SUPPORT SYSTEMS BEYOND LOW EARTH ORBIT ADVOCATES FOR AN IMPROVED RESOURCES MANAGEMENT APPROACH
Chloé Audas, Sandra Ortega Ugalde, Christel Paillé, Brigitte Lamaze, Christophe Lasseur
European Space Agency, ESTEC
Abstract: Nowadays, there are still many challenges to overcome in order to enable long-termed human space exploration beyond low Earth orbit (LEO) and metabolic resources management (reliable air, water and food supply for the crew) is of utmost importance. Currently, Environmental Control and Life Support Systems (ECLSS) aim to overcome the challenge of constant re-supply from Earth requirement by revitalization of air and water. Here, we provide an overview of the existing and operating ECLSS on-board the International Space Station (ISS) as well as identify potential areas of technology development for biological ECLSS for long-term human space missions focusing on the inclusion of waste treatment and food production.
Keywords: Regenerative Life Support Systems, MELiSSA, Mars Transit Mission, ECLSS

PIG FARMS AND THEIR SURROUNDINGS AS A FACTOR IN THE SPREAD OF ANTIMICROBIAL RESISTANCE
Lyudmila Dimitrova, Maya Zaharieva, Hristo Najdenski
The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences
Abstract: In recent decades, in modern intensive animal husbandry, there has been a worrying trend towards the selection and spread of bacterial strains resistant to antibiotics. This global phenomenon has not only a certain negative effect on therapeutic practice, but also poses a serious risk to the spread of resistance in the food chain and in humans. Various genera from the family Enterobacteria like Salmonella, Shigella, Klebsiella, Yersinia, Citrobacter, etc. and especially Escherichia coli have a special place in this process. The most commonly used antibiotics for treatment of patients with complicated Salmonella infections are ceftriaxone and ciprofloxacin, to which the bacteria has already developed antibiotic resistance. For Escherichia coli, significantly increased resistance is developed to the third-generation cephalosporins, aminoglycosides, as well as combined resistance to three key antimicrobial groups (fluoroquinolones, third-generation cephalosporins and aminoglycosides). Resistance among Yersinia spp. against tetracyclines and fluorochinolones has been reported to the scientific community in numerous studies on human and animal isolates. By using the raw manure as fertilizer, these microorganisms may be transmitted to soil, wastewater or others environmental niches. Further, they can be transmitted via the food chain to humans and animals. Considering that the horizontal gene transfer is one of the most important mechanisms for transmitting of antimicrobial resistance, then after consumption of contaminated food, water, etc., genetically determined antibiotic resistance in animals can easily affect resistance among people, which makes vital drugs ineffective against serious illnesses. For the possible spread of antimicrobial resistance in pigs and related ecological niches - pig farms, manure lagoons, wastewater and soils, large-scale studies are being conducted to clarify their ecological and health significance. In addition, the results obtained will contribute to the development of an effective national strategy for the control of antimicrobial resistance.
Keywords: antimicrobial resistance, pig farms, manure lagoons, wastewater, soils

ALTERNATIVE APPROACH TO SMALL SCALE PHOTOVOLTAIC SOLAR POWER AND ENERGY STORAGE
Jason Glas
Department of Chemical and Biochemical Engineering, The University of Western Ontario, London, Ontario, Canada, N6A 5B9

Abstract. Photovoltaic solar panels remain one of the most commonly available avenues for acquiring renewable energy for small-scale end users but despite their promising potential their implementation continues to remain outside the realm of possibility for most. The combination of high upfront costs, long payback periods, and complex installation requirements results in a disincentive to purchase the technology and relies on significant appeals to morality as a driving force as opposed to purely economic incentives. An alternative implementation of photovoltaic arrays for small scale use combined with grid power supplement is herein proposed that better matches energy consumption profiles in the household and seeks to reduce cost and complexity. The system comprises a hydronic thermal storage system acting as hot water supply, furnace, and air conditioning for power regulation and distribution in combination with electrical distribution to home appliances using minor modification to the power supply. Currently used batteries, charge controllers, and inverters are eliminated and replaced with a single specialized outdoor central air-conditioning condenser unit that distributes electrical and thermal energy but would not supply electricity onto the grid. Examination of minor electronic modifications on common switched mode power supply topologies has found that regulation of a wide range of variable voltage solar electricity input is currently possible and does not cause overheat or other harm to the power supply. The proposal provides a workable solution to alleviate financial and technical burden on the individual and promotes the vision of a 100% renewable energy society while working within economic constraints.
Keywords: energy storage, solar power, lithium battery, switched mode power supply, electronically commutated motor, air conditioning, variable refrigerant flow

TWO-STAGE ANAEROBIC DIGESTION OF WHEAT STRAW USING IMMOBILIZED MICROBIAL CONSORTIA

Venelin Hubenov, Jeny Miteva-Staleva, Rumyana Eneva, Nikoleta Boteva, Lyudmila Kabaivanova

The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences

Abstract: The serious energy and environmental problems associated with the use of fossil fuels necessitate the search for alternative energy sources. One of the modern approaches is the anaerobic degradation of organic waste from agricultural wastes. The hydrogen and methane thus obtained are sources of environmentally friendly energy, which reduces carbon dioxide emissions from fossil fuels, as well as gaseous emissions resulting from natural degradation processes in the disposal of waste materials. The described two-stage anaerobic digestion (TPAD) system with an immobilized microbial consortium represents an innovative biotechnological approach that seeks to obtain an increased energy yield and raised degree of processing of waste materials. Some additional raw materials which represent waste materials from other industrial scale processes can be successfully applied and support higher biohydrogen production from wheat straw. The temperature regime suitable for wheat straw biodegradation is 55°C resulting in 2.5 time more biohydrogen production. The VFAs obtained from BR-1 are suitable substrate for the immobilized microbial consortia which is formed for nearly twenty days of bioreactor maintenance.
Keywords: biohydrogen, biomethane, two-stage anaerobic digestion, immobilized microbial consortia, wheat straw

EXTREMUM SEEKING BASED COMPOSED RECURSIVE MODEL FREE CONTROL OF TWO-STAGE ANAEROBIC DIGESTION PROCESS
Ning Pan¹, Haoping Wang¹, Yang Tian¹, Nicolai Christov², Ivan Simeonov³¹LaFCAS Laboratory, Automation School, Nanjing University of Science and Technology,
²Centre de Recherche en Informatique, Université de Lille,
³The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences
Abstract. In this paper, a new structure of extremum seeking algorithm is applied to the two-stage anaerobic digestion process to maximize the outflow rate of both hydrogen and methane. The model of the two-stage AD process is presented, which provides the characteristics of the total gas production rate. Based on the original Extremum Seeking Control (ESC), a novel Composed Recursive Model Free Controller (CRMFC) is added for maximum tracking for the gas production in the bioreactors. The proposed controller comprises a recursive model free stabilization term and a recursive time delay compensation term. Standard ESC, Newton-based ESC and Kalman filter (KF) based ESC are respectively combined with the new model-free controller to verify the proposed structure. Numerical simulations illustrate the performance of the proposed controller.
Keywords: two-stage anaerobic digestion, extremum seeking control, composed recursive control

CHARACTERISTICS OF METASEQUOIA GLYPTOSTROBOIDES ARTIFICIAL COMMUNITY КОKАLУАNЕ VILLAGE, SOFIA REGION

Plamen Glogov, Gergana Zaemdzhikova

Forest Research Institute – Bulgarian Academy of Sciences

Abstract: The aim of the present study is phytocoenological characteristics and preliminary assessment of the health status of the first Dawn redwood (Metasequoia glyptostroboides) artificial plantation in Bulgaria established in 1969. The plantation of metasequoia is located in the land of the Kokalyane village (Sofia region) on an area of about 2500 m². The study was conducted in the period April-July, 2021. The results show that the artificial stand was created on the locality of indigenous communities of Alnus glutinosa, which occupy the main part of the Iskar river banks between Plana and Lozenska mountains. The health status of the Dawn redwood plantation was assessed as “good”. From the distance of the 50-year period, the artificial afforestation with this exotic relic in the area of the village of Kokalyane can be considered successful.

Keywords: phytocoenoses, insect pests, pathogens, forest stands, Dawn redwood

SIMULATION OF CROPS YIELD GROWN ON LEACHED SMOLNITSA AND ALLUVIAL-MEADOW SOIL
Alexander Sadovski ¹, Irena Atanasova ², Zdravka Petkova ²¹ International Eurasian Academy of Sciences/EUROPE² Institute of Soil Science, Аgrotechnologies and Plant Protection "Nikola Poushkarov"

Abstract. The study presents results of field experiments with maize conducted during the year 2020 on two fields with different soils in Bulgaria, namely Leached smolnitsa and Alluvial-meadow soil. This article aims to perform a simulation experiment of crop yields to evaluate the limits of maize grain yield grown on soils with different properties and with different levels of nutrients. The multifactorial experiments include the application of mineral fertilizers - ammonium nitrate, superphosphate, potassium sulfate and diatomic earth, containing respectively – nitrogen (N), phosphorus (P), potassium (K), and diatomic earth, which represents 89-95% silica in amorphous form) in a design that allows assessment of the actions and interactions of the four factors, varying on three levels. The simulation is preceded by an analysis of variance and regression analysis of the experimental data. Simulation is performed at medium levels of all nutrients and on concurrent levels of nutrients including the high level of two fertilizers excluding two others. The summary results show that the experimental and simulated maize yields on Leached smolnitsa in Bozhurishte are significantly lower than those on Alluvial-meadow soil in Tsalapitsa.

Keywords: field experiment, maize, simulation, soils, yield

DISTRIBUTION OF TRITIUM IN SURFACE WATER AND PRECIPITATION IN RILA MOUNTAIN, BULGARIA
Elena Geleva, Dimitar Tonev, Hristo Protohristov, Svetoslav Dimitrov, Vladimir Bashev, Stefan Genchev, Anguel Demerdjiev
Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences,72, Tsarigradsko chaussee Blvd., 1784 Sofia, Bulgaria
Abstraxt. A study of the tritium content of surface water from three Rila lakes – Moussala lake, Aleko lake and Ice lake, and precipitation at Moussala mount has been performed by means of high precision nuclear and radiochemical methods. The measurements are part of a long-term environmental monitoring program developed and maintained by the Institute for Nuclear Research and Nuclear Energy, Bulgaria Academy of Science. The results for lake water and precipitation samples collected at Moussala part of Rila over the period 2012–2017 were found to range from ˂ 1.20 to 2.77 Bq.L^-1 and from 2.14 to 4.12 Bq.L^-1 respectively. The content of ³H in all samples is below the recommended level of 100 Bq.L^-1

The obtained new results are used to assess the radiation status of the investigated water sources and can be used for evaluation of possible future changes and trends.

Keywords: ³H, surface water, precipitation, Rila mountain

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