In this research study, we are using CFD to better understand processes in a wastewater settling tank. Secondary sedimentation tanks belong to the most important objects at the wastewater treatment ...line. CFD plays an important part in better understanding the processes from a standpoint of operation and optimization. We conducted four CFD simulations based on a verified model of a secondary settling tank at the wastewater treatment plant in Nitra, SK. The four simulations contain four different adjustments to the inlet zone of the tank. We reached a reduction in sludge zone velocity to 6 from 12 mm/s in a representative measurement profile. We also analyze the influence of temperature-induced viscosity changes based on seasonal temperature change.
Graphical abstract
ANALYSIS OF MICROPOLLUTANTS IN URBAN WATER RUN-OFF Hrudková, Lenka; Wittmanová, Réka; Škultétyová, Ivona ...
International Multidisciplinary Scientific GeoConference : SGEM,
01/2023, Letnik:
23, Številka:
3.1
Conference Proceeding
Changing climatic conditions in urbanized areas enormously impact the quality of life in urbanized areas. Persistent prolonged dry periods, extreme downpours with heavy heaviness or prolonged ...rainfall are an extreme problem for effective water management in cities. Extreme weather changes also risk the environment when infiltrating or relieving highly contaminated water from the first run-off. These wastewaters are a potential source of groundwater and surface water pollution in which various pollutants are concentrated. In our research, we focus on evaluating water quality from surface run-off with an emphasis on concentrations of micropollutants. The analyses aim to assess concentrations of heavy metals, microplastics, and other pollutants in surface run-off concerning recipient water quality and groundwater quality. The research focuses on evaluating the current state of stormwater management in urbanized areas with a focus on the spread of pollution and the possibility of capturing such contaminated water with subsequent disposal to a wastewater treatment plant.
Due to the historical development of individual regions in Slovakia, there are still areas without access to public water networks. The main reason is the challenging and uneconomical construction of ...public networks in scattered rural settlements. The small wastewater treatment plants have gained popularity in rural areas of the Slovak Republic. The increasing adoption of decentralized wastewater management is a result of the scattered layout of numerous rural settlements, presenting economic challenges, technical complexities, and inefficiencies in the implementation of a centralized wastewater disposal system. The objective of this paper is to establish a concise methodology for conducting a Benefit-Cost Analysis within the context of the Slovak Republic. This methodology will subsequently serve as an auxiliary decision-making tool when proposing wastewater disposal methods in rural settlements. This study will assess the potential wastewater disposal methods in the specific rural area, while clarifying the proper execution of the benefit-cost analysis.
Changing climatic conditions in urbanized areas have an enormous impact on the quality of life in urbanized areas. Persistent long-term dry periods, extreme downpours with large quantities or ...long-lasting rains are an extreme problem for efficient water management in cities. Extreme changes in the weather also result in a risk to the environment when soaking in or relieving highly contaminated water from the first flush. These wastewaters are a potential source of groundwater and surface water pollution, in which various types of pollutants are concentrated. In our research, we focus on the evaluation of water quality from surface runoff with an emphasis on concentrations of micropollutants on a global scale. The article is focused on research in the subject area and is a summary of the current view on the issue of micropollutants in water from surface runoff. Research in the field of pollution focuses on the evaluation of heavy metals, polycyclic aromatic hydrocarbons, non-polar extractable substances, halogen organic compounds or nitrogenous pollution.
Due to the population increasing in urban settlements, the use of the territory and the surface variability of urban settlements are changing rapidly. The development of areas covered with impervious ...materials contributes to accelerating the runoff process, intensifying surface runoff concentration and the concentration of surface runoff pollution. Surface runoff from urban catchments can be characterized as the primary source of the receiving water's pollution during torrential rains. The aim of the paper is to obtain information about the quality of surface runoff from paved areas of roofs and roads in the urbanized area of the city of Trnava and about the of pollutants concentration by analyzing the quality parameters of the samples taken. Rainwater runoff sampling took place from 26 of November 2021 to 8 of April 2022. Ten samples were taken during the mentioned period. The number of samples is directly proportional to the current precipitation situation in the area. The aim was to capture the first flush due to the assumption of the highest pollution concentration in the initial phase of surface runoff formation. Due to low precipitation and insufficient surface runoff formation, the sampling was irregular. The analyzed qualitative parameters are pH, electrical conductivity, chemical oxygen demand, and nitrogen oxides. By comparing the quality of samples and air quality on individual days, we can state that air quality partially affects the quality of samples taken. By comparing the air quality and the daily total precipitation on separate sampling days, we can conclude that pollutants accumulate in the air and on paved areas during a more extended rainy period. The following precipitation event washes away paved areas and cleans the air. The surface runoff then contains a higher concentration of pollutants than the runoff from the precipitation event after a short rainless or multi-day precipitation event.
The inhabitants produce the sump waters and accumulate temporarily in the sumps. This is sewage that must be treated before it is discharged to surface waters. Slovak legislation does not allow the ...discharge of such waters into the soil. The possibilities of sump water treatment are given by the water management equipment of the given locality where sewage water is produced. The most common treatment method is transported at municipal wastewater treatment plants, which are, however, largely congested. In many cases, the sump water is no longer able to receive in WWTP. Another way is domestic wastewater treatment plants, and also they are wastewater treatment plants exclusively for sump waters. Sump waters have a predominantly high organic content and therefore their quality needs to be constantly monitored. The most important monitored characteristics of sump waters are COD (Chemical Oxygen Demand) and BOD5 (Biological Oxygen Demand). The high concentration of these substances in the sump water can adversely affect the processes at the municipal wastewater treatment plant. Due to the rapid development of rural settlements without a functioning sewerage system, it is necessary to intensify or adapt the existing wastewater treatment plants. However, many engineers see the solution to this problem in the construction of separate wastewater treatment plants for sump waters.
The development of urban areas, transport, and technical infrastructure is one of the natural phenomena that have been going on for several centuries. In recent years, due to migration population in ...many developed countries occurs a rapid increase of impervious areas in urban agglomerations. The rapid development of an impervious surface can cause changes in the hydrological and climatical characteristics of the area. As a result of these changes, surface runoff is creating. Surface runoff is an area source of pollution, occurring mainly during short, intense rains or flash floods. It is primarily formed in sloping or urban areas, where there is a lack of infiltration and retention objects to capture and temporarily retain rainwater. The occurrence of pollutants in surface runoff depends on land use and internal and external factors such as characteristics of air and soil pollutants, intensity and duration of precipitation, and other less important factors. The nature of pollutants in surface runoff in urban areas is diverse. Based on many studies, it can be said that the sources of contaminants in surface runoff coming from the air and paved areas like roads, roofs of buildings, facades, parking, and other impervious areas. The adverse effects of pollutants in the surface runoff negatively affect the environment. Therefore, the research study focuses on assessing the impact of contaminants in the air and on the surface of paved areas on the quality of surface runoff in urban areas. The study results could help design the proper management of surface runoff in urban agglomerations concerning environmental protection and the possibility of rainwater harvesting.
Combined sewerage is the most widespread method of wastewater management in the world. Sewage and rainwater are discharged through a combined piping system, which affects overloading the sewer ...networks during extreme rains. This method of wastewater disposal is the oldest type of sewerage. At present, this method is described as less suitable in opposite to rather on the construction of a divided sewerage system, where wastewater and rainwater flow through separate pipes. The main disadvantage of the combined sewer overflow chambers is the possible leakage of contaminants into the recipient. In the Slovak Republic, combined sewer overflow chambers are most often used to efficiently manage and separate rainwater. In this paper, we focus on the most commonly used types of chambers, emphasizing the efficiency of their operation. The most commonly used relief chambers are with a high overflow edge, on which rakes are placed to catch floating waste. These combined sewer overflow chambers are then divided according to the location of the overflow edge into three basic types: with a front overflow, with a side overflow, and with a double-sided side overflow.
The last several decades, the climate change, as one of the most serious environmental issues, has become a widely spread topic not only to individuals, but the whole international community. Weather ...extremities, such as tropical days, summer heat waves, switching of periods of extreme precipitation with periods of drought causing the decrease of water reserve capacities cannot simply be overlooked. Due to alarming climate situation, especially in urban zones, the adaptive measures are much needed, even necessary. One of the measures, known as blue-green infrastructure (henceforth BGI), in the UK considered a significant tool for the support of sustainable development in both urban and rural zones, represents a network of natural and semi-natural elements binding water and vegetation together, which can mitigate the harmful effects of climate change on ecosystems and natural resources, and improve the quality of life and health of people. The reasons, why the notion blue-green infrastructure is becoming known in Europe more and more, are connected to the problems with droughts, frequent lifethreatening floods, extreme weather conditions and last but not least, with insufficient rainwater soaking due to non-permeable surfaces in urban zones. In order to make the process of adaptation to climate change systematic and complex, an adaptation plan is needed to enable the urban population to react to expected climate change impact, to emerging risks, as well as exploit the opportunities the climate change may bring. An inseparable part of the strategy to fulfil the Agenda 2030 and adopted targets of the Paris Agreement, the European Green Deal is a new strategic plan for European Union member states which emphasizes the countryside protection with regard to the sustainable development in order to reach climate neutrality by 2050.
Combined sewer are among the most important objects of a unified sewerage network and therefore high requirements are placed on these objects, whether from hydraulic, hydrological, hygienic or ...constructional requirements. Their main function, ie hydraulic, is to divide the inflow at the time of torrential rains into a flow continuing to the WWTP and a flow that is relieved from the OK to the recipient. Another important function of relief chambers is related to pollution. Some chamber designs can successfully capture larger solids with rakes, but this purification is not possible with suspended and dissolved materials. Therefore, from the point of view of the protection of recipients, it is necessary to design relief chambers so that the dilution ratio of sewage and rainwater at the time of above-limit flows is in accordance with legislative requirements. The paper deals with the analysis of the existing relief chamber using mathematical simulations. The software used to create the mathematical models is Ansys Fluent.
