The Scientific Journal of Riga Technical University
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The Effect of Laser on the Efficiency of Biological Treatment of Pharmaceutical Wastewater
Full text linkThe aim of the work is to explain the danger of phenol and phenolic compounds to human health and the environment. In addition, it explains where and why pollution by phenol and its compounds occurs, especially in industrial wastewater. The authors investigate the possibility of using laser technologies for the decomposition of phenol, as well as for the purification of industrial wastewater from phenolic compounds. Treatment of wastewater from phenol and its compounds using microorganisms for biological treatment is widely used in the world. This method is economical and environmentally friendly. On the other hand, exceeding the permissible concentration of phenol, which is individual for each biological treatment plant, microorganisms in such treatment plants may die because they are poisoned by phenol or its compounds. Thus, the biological treatment of industrial wastewater is temporarily stopped until the concentration of phenol is reduced to an acceptable limit and the microorganisms recover. Such a procedure can take a long time and is unpredictable because microorganisms are sensitive to changing conditions. Based on this, literature sources have been explored. This could help to understand which laser devices can be used to split a phenol compound or a benzene ring into simple chemicals. It also helps to understand how phenol-containing wastewater affects the microorganisms of biological treatment plants and the course of the process, as well as to find a laser device that would not affect the usual conditions of microorganisms of biological treatment plants. Several experiments were carried out, including those with lasers, to exclude possible interfering factors and to prove the already known data for further scientific research
Impact of Climate Change on the Heating Demand of Buildings. A District Level Approach
Full text linkIn the 21st century, the importance of energy generation and carbon emissions in developing countries is indisputable. In the whole wide world, the building stock is responsible for the two fifths of the total world annual energy consumption. Considering the predictions regarding future climate due to climate change, a good understanding on the energy use due to future climate is required. The aim of this study was to evaluate the impact of future weather in the heating demand and carbon emissions for a group of buildings at district level, focusing on an area of London in the United Kingdom. The methodological approach involved the use of geospatial data for the case study area, processed with Python and Anaconda through Jupyter notebook, generation of an archetype dataset with energy performance data and TABULA typology and the use of python embedded in QGIS to calculate the heating demand in the reference weather data, 2050 and 2100 in accordance to RCP4.5 and RCP 8.5 scenarios. A validated model was used for the district level heating demand calculation. On the one hand, the results suggest that a mitigation of carbon emissions under the RCP4.5 scenario will generate a small decrease on the heating demand at district level, so slightly similar levels of heating generation must continue to be provided using sustainable alternatives. On the other hand, following the RCP 8.5 scenario of carbon emission carrying on business as usual will create a significant reduction of heating demand due to the rise on temperature but with the consequent overheating in summer, which will shift the energy generation problem. The results suggest that adaptation of the energy generation must start shifting to cope with higher temperatures and a different requirement of delivered energy from heating to cooling due to the effect of climate change
Numerical Evaluation of Wind Speed Influence on Accident Toxic Spill Consequences Scales
Full text linkThis study aims to evaluate numerically the influence of wind speed on scales of environmental harmful consequences caused by accidentally spilled toxic liquid evaporated from the surface of a free-form outlined spill spot. A coupled problem of the gas-dynamic movement of a toxic air-mixture cloud in the surface layer of the atmosphere under the influence of wind and a negative toxic inhalation impact on a human in an accident zone is solved by means of mathematical modelling and computer experiment. Physical processes of toxic liquid evaporation from the spill spot, formation of a mixture of toxic gas with the incoming air, and further dispersion of a hazardous gaseous chemical in the atmosphere under various wind speed conditions are investigated. A three-dimensional non-stationary mathematical model of the turbulent movement of a gas-air mixture is used for obtaining distribution of relative mass concentration of toxic gas impurities in time and space. The model takes into account the complex terrain, compressibility of the gas flow, three-dimensional and non-stationary nature of actual physical processes, different toxic properties of chemical substances, and arbitrary contour shape of the toxic spill spot. A probabilistic harmful impact model based on using a modernized probit analysis method is used to obtain fields of the conditional probability of a fatal human injury resulting from toxic gas inhalation. This model extracts relative mass concentration of toxic gas that could cause negative impact on humans at any control point during calculation time step exposition, collects integral toxic dose values from the multicomponent gas mixture dynamics model, calculates a value of the probit function for the corresponding toxic inhalation dose dangerous factor, and automatically assesses the human fatal injury conditional probability using partial cubic Hermitian spline. This technique allows environmental safety experts assessing the scale of considered type technogenic accident consequences numerically depending on wind speed conditions and elaborating the means to mitigate them to acceptable levels
Opportunities for Bioeconomy Development: A Study of the Latvian Forest Sector and Identification of High-Value Niche Products
Full text linkClimate change, rising food and feed demand, and biodiversity loss necessitate a more sustainable, innovative, and knowledge-based bioeconomy. This research analysed and compiled statistical data, reports, and other official information from Latvian forest sector stakeholders to understand its system components. After identifying main enablers and constraints, a methodology was established to find niche products with high added value through which the potential of the forest sector could be built. The system components of the Latvian forest sector and future growth scenarios for wood-based niche products showed similar outcomes for current constraints and drivers for the bioeconomy and forest sector. As a result, a number of action measures were proposed at government and policy planning level; measures to strengthen research and development, and activities to promote the production of higher value-added products and the development of a sustainable bioeconomy
Optimization of Ultrasound-assisted Extraction Conditions for Active Essential Oil and Anti-Alzheimer Activities from Mentha Cordifolia
Full text linkMentha C. (Lamiaceae) is distributed all over the world. Essential oils were found menthol, menthofuran, menthyl acetate, menthone, 1.8-cineole, pinene, myrcene and borneol. Mentha C. most popular herbs are widely used in cooking, in cosmetics, complementary therapy and pharmaceutical for anticarcinogenic, gastro protective, anti-inflammatory, antimicrobial and antivirotic purposes. For essential oil extraction, a steam distillation, or hydro-distillation method was used, which allows the decomposition of components. The aim of this work was to study the innovative technologies of essential oil by ultrasound-assisted extraction (UAE) that include high yields, short-extraction time and save energy. The extraction of essential oils was carried out at three ultrasonic frequencies (15 kHz, 20 kHz, and 25 kHz), sonicated times were 1, 2 and 3 hours. The solvents extracted were hexane, ethylacetate and 95 % ethanol. The sonication conditions were different of compounds showed by Thin Layer Chromatography (TLC). The extraction compounds by hexane from sonicated at 20 kHz (2 h) were terpene hydrocarbon which was nonpolar essential oil. The oxygenated terpenoids were extracted by ethyl acetate from sonicated at 20 kHz (3 h) and the phenolic compounds were extracted by 95 % ethanol. The data was treated by applying multivariate statistical analysis. The tested of antioxidant by DPPH, and ABTS radical were the best of ethanol extracted IC50 73 mg/ml, ethyl acetate extracted and ethyl acetate extracted IC50 103 mg/ml, respectively. IC50 of anti-acetylcholinesterase were 125.5 mg/ml of ethyl acetate extracted
Investigating the Performance of the Compact Particulate Matter Collector for Use in Domestic Water Systems
Full text linkThe concept of the new water treatment system was developed. The system is based on the previously invented technology – Compact Particulate Matter Collector (CPMC). A primary area was defined in which such technology is intended to be used: water treatment in compact flue-gas condensation systems for a low-power wood-fuelled biomass boiler. Such a system is intended for use in domestic conditions. Such a process involves contamination of technical water with a mixture of particulate matter, resulting in suspension. The CPMC aims to divide the suspension into the relevant fractions effectively. A prototype operating based on CPMC technology was built. An experimental plan was developed, and an experimental stand was constructed to determine the prototype’s efficiency. The experimental plan envisaged five different prototype operating modes and two research steps, depending on the degree of prototype modification. Based on the research results, it was concluded that the prototype could operate effectively in the laboratory environment: achievable efficiency is equal on average between 57.84 % and 88.09 % depending on the operating mode (see the diagram below). The result is assessed as positive. TRL 3 has been reached. The next phases of the study would be the integration of the prototype into the relevant compact flue-gas condensation system and the exploration of commercialisation capabilities, which will stimulate TRL increase
MSW Management in Mountainous Areas: Outcomes from a Comparison Between Two Italian Provinces
Full text linkIn the present paper, two case studies are reported regarding the municipal solid waste (MSW) management trend in the last decades in two Italian areas in order to propose some guidelines for replicating the approaches. The first case study has a very good selective collection (SC) rate that is expected to reach 80 % in a few years. SC is made mainly kerbside. There is no thermo-chemical plant in the territory (but a part of the residual MSW is burnt in an external combustion plant). A local plant combines anaerobic digestion with post-composting as a main destination for food waste and green waste. A sanitary landfill receives the main stream of locally pre-treated residual MSW. The adopted tariff helped increasing the SC rate: since 2013, the punctual tariff has been adopted. The second case study concerns an area where SC reached about 75 % in 2019, before the pandemic period that affected the performances of the sector. The punctual tariff has been recently introduced. In the territory, there are an incineration plant and a Solid Recovered Fuel (SRF) plant that sends the final product mainly to a cement factory. No plant for the biodegradable waste exists locally (export is adopted). Looking at the two case-studies, useful waste guidelines for similar areas could be set up starting from these experiences
Environmental Sustainability of Pasta Production: an Evaluation through Life Cycle Assessment
Full text linkThe recent policy of Green Deal aims to a transition towards ‘healthy, equitable and sustainable communities’. One of the key sectors analysed within the Green Deal is the agri-food chain, with the strategy ‘From Farm to Fork’, aiming to design a sustainable food system from production to consumption, passing through industry processing, distribution and all related activities. At the agricultural level, the objectives are in line with those presented in the United Nations 2030 Agenda, from technologies and digitalization, to organic farming. As for the transformation and distribution phases, the Commission is promoting technological and technical innovation, the restructuring of companies and the improvement of the quality of work. The aim of this study is to perform a Life Cycle Assessment related to one of the main products of a company of the agri-food sector in central Italy. The product analysed is durum wheat pasta. A cradle to gate analysis is performed, starting from the cultivation of the wheat, arriving to the final pasta product. The different transformation steps are evaluated (e.g. cleaning, grinding, compression, extrusion), including the packaging process. The analysis is aimed at identifying the most critical phases along the chain, to plan improvements in terms of efficiency of the production process, with consequent enhancement of the environmental performance
The Influence of Young People on Household Decisions on Energy Efficiency
Full text linkYoung people are the future members of the energy communities and form part of a climate-responsible society already now. However, in the context of the geopolitical and economic events of 2022, the awareness of young people in Latvia about energy efficiency issues and the readiness to engage in climate change mitigation processes, as well as the influence of their attitude on the decisions of adult household members in the field of energy efficiency have not been sufficiently studied. The aim of the study is to evaluate the knowledge of Latvian youth about energy efficiency issues, associations about a climate-responsible society, attitudes towards daily habits in the field of energy efficiency, as well as whether climate change issues are also discussed in young people’s families and whether young people believe that they can influence the family’s opinion or habits. 71 participants participated in the study, and the methods used are group questionnaires and interviews. The results of the research show that young people in the regions of Latvia are well aware of measures of energy efficiency, and the answers provide an insight into the various experiences they have had in their households. More than half of the research participants between the ages of 14 and 19 are aware of the amount of utility expenses and discuss with their relatives the possibilities of saving energy resources. The research also highlighted negative aspects, for example, concerning to reducing the level of household comfort in the name of climate change, young people are not strongly supporting – only a little more than half would be willing to live in cooler rooms. Young people believe that they can influence the attitude and behaviour of other household members in matters of energy resource management. The results of the study lead to the conclusion that more attention should be paid to messages dedicated to young people in public space, so that they associate themselves more as an existing or future part of the energy community, and they should be given the opportunity to set an example and explain why their actions are important to reduce climate change. The results obtained in the study can potentially contribute to the development of the digital tool designed within the RTU project ‘BRIDGE’ to promote the development of energy communities