Odours in Sewerage—A Description of Emissions and of Technical Abatement Measures

Malodorous compounds arise at practically every stage of wastewater management, starting from the sewer network, via the technological sewage-treatment system, through to the sludge-management stage. The formation of hydrogen sulphide is a significant problem even while sewage remains in sewers, as anaerobic conditions prevalent in the network are conducive to wastewater putrefaction, and therefore contribute to increased malodorous emissions. The development of such anaerobic conditions is favoured by the oversizing of conduits or designs that feature inadequate gradients, causing wastewater in the network to stagnate. Where emissions to the air from wastewater occur, they are found to constitute a complex mixture of perhaps even 1000 different substances, produced under varying process conditions. Among those present are compounds of sulphur and nitrogen, chlorinated compounds, and other organics. In Poland, the issue of odour annoyance has not yet been subject to standardisation in either legal or methodological terms. Indeed, as only 11 EU Member States have regulations in place regarding air-quality standards, it is likely that such a law will soon be developed to try and resolve problems with odour annoyance, including those originating in the systems dealing with wastewater. This denotes a need to develop methods of counteracting the formation of odours, and those of a chemical nature are regarded as among the most effective, hence their growing popularity. They also abide by green-technology principles. Against that background, this article seeks to consider the process by which malodorous substances arise in sewer and wastewater-treatment systems, as well as to discuss methods of odour abatement. The work also presents the current legal regulations of relevance to the issue

Hydraulic analysis of functioning of the drainage channel with increased retention capacity

Hydraulic overload of networks and its related objects is a problem that is more and more common in drainage systems. The most popular way to prevent it from its occurring is to increase the storage capacity of the system. At present, there are numerous solutions allowing to increase retention in drainage systems, with the selection of the most beneficial one being dependent on numerous factors; it must also be preceded by a technical and financial analysis. Financial analysis is of particular importance here, since due to significant dimensions and complicated structure, these objects require high investment outlays for its construction. As a consequence, it is a priority to undertake actions aimed at developing such solutions that will allow for significant increases of retention in the drainage system, and cost reductions at the same time. One of such solutions is the Underground tank for combined sewage and stormwater that is now patent-pending. The application of this solution allows to multiply retention capacity of the drainage system, without the necessity of modernizing the existing sewer system. This paper presents the application potential of the subject method for increasing sewer retention, along with its hydraulic function analysis. The research carried out and presented was based on the analysis of individual phases of functioning of the subject solution

The use of artificial neural networks for analyzing the sensitivity of a retention tank

Designing retention facilities is a complex engineering process that requires the collection of the detailed hydrological data of a catchment and hydraulic sewerage system. The acquired data are necessary to prepare a model of the retention tank in appropriate software for hydrodynamic modelling. The article shows the results of tests concerning the analysis of the sensitivity of a sewerage model of a rainwater retention tank which may be implemented in this software. The results of tests allowed determining the impact of the individual hydraulic characteristics of the catchment and the sewerage system on the required retention capacity of a tank. A planned analysis is performed based on artificial neural networks and the required data are acquired by hydrodynamic simulations in SWMM 5.1

Analysis of the Hydraulic Efficiency of a Steerable Detention Tank—Simulation Studies

The article contains the results of the first part of the research on the analysis of the operation of the retention device cooperating with the drainage system—steerable detention tank and concerns model simulation studies. The obtained results are an introduction to conducting laboratory tests. The planned research was carried out on the basis of the theory of experimental planning and hydrodynamic modelling, in which the systems of hydraulic parameters of the drainage system and hydrological of the catchment were selected. In total, over a thousand hydrodynamic simulations were carried out using SWMM 5.1. The planned analyses had two main goals. Firstly, to verify the possibility of reducing the rainwater volume flow in the drainage system by means of controllable devices enabling cooperation with the drainage system in various hydraulic conditions of the drainage system. Secondly, determining the impact of the connection method (parallel or serial) of the device enabling retention and cooperation with the sewage system on the efficiency of the system. The conducted analyses showed that the use of a retention device cooperating with the drainage system may significantly reduce the amount of sewage outfall from system, depending on the capacity of a single micro-accumulator, even up to 83% (in the analysed data range). It was also shown that the method of connecting the device to the network has an influence on the efficiency of the system in depend on hydraulic conditions

A simplified dimensioning method for high-efficiency retention tanks

The article presents the results of research on the development of a simplified dimensioning method for sewage retention tanks equipped with a high-efficiency hydraulic system. The need to develop a new method is associated with the outdated rainfall model by Błaszczyk, which is the most popular model in Poland. According to the research made by numerous scientific centres, this model underrates the values of the maximum intensity of critical rains. As a consequence, its use affects the design of sewage systems and related facilities with insufficient hydraulic capacity

A simplified dimensioning method for high-efficiency retention tanks

The article presents the results of research on the development of a simplified dimensioning method for sewage retention tanks equipped with a high-efficiency hydraulic system. The need to develop a new method is associated with the outdated rainfall model by Błaszczyk, which is the most popular model in Poland. According to the research made by numerous scientific centres, this model underrates the values of the maximum intensity of critical rains. As a consequence, its use affects the design of sewage systems and related facilities with insufficient hydraulic capacity

An Analysis of Waste Heat Recovery from Wastewater on Livestock and Agriculture Farms

Agriculture is one of the sectors of the economy in which it is possible to conduct much more rational energy economy. The easiest way to achieve financial savings as well as reduce air pollution is to use waste heat sources. Heat pumps are perfect for this. Particularly favorable is the case when the device can operate in an alternative system and serve both heating and cooling purposes. The purpose of this article was to present possible solutions for installations enabling heat recovery from wastewater to supply agri-breeding farms with hot utility and technological water, a financial analysis of their application, and an assessment of the impact of these solutions on possible reduction of pollutant emissions. The tests were carried out for four variants of cooperation between a heat pump and an exchanger. In the first variant, waste heat was used in the process of heating water used to clean stands and prepare feed. In the second variant, waste heat took part in heating the water used for watering plants. In the third variant, waste heat was used in the process of drying cereals. In turn, in the last variant, waste heat supported the preparation of utility hot water for the breeder’s residential building. The study showed the legitimacy of using thermal energy from liquid manure as a waste heat source on farms and farming. This is mainly due to the short payback period, which can be within 2–4 years. In turn, the analysis of pollution reduction associated with the recovery of waste energy showed that the use of heat pumps allowed a significant reduction in the emission of harmful compounds to the atmosphere, in particular carbon dioxide. It is worth noting that livestock breeding is one of the most important branches of agricultural production not only in Poland but also throughout Europe, Asia and South and North America. For this reason, the use of waste heat-recovery systems enables real savings in the purchase of energy and reduction of pollutant emissions arising during traditional production processes

Opportunities and Threats of Implementing Drain Water Heat Recovery Units in Poland

In recent years an increase of interest in usage of renewable energy sources as a substitution of fossil fuels is being noticeable. However, the waste heat potential, which can be used as an additional source of energy for heating water in buildings, is being omitted. The sources of this heat can be grey water discharged from such sanitary facilities as showers or washing machines. In response to this issue, we took on the task to define and analyze key factors affecting the development of DWHR (Drain Water Heat Recovery) systems using PESTLE (political, economic, social, technological, legal and environmental) analysis. The strengths and weaknesses of these systems were also identified. The studies were based on CFD (computational fluid dynamics) modeling tools. In the Autodesk Simulation CFD software environment, a DWHR unit was made, which was then analyzed for heat exchange efficiency. The obtained results were the basis for preparing the strategy for the development of Drain Water Heat Recovery systems. It was made using the SWOT/TOWS (strengths, weaknesses, opportunities and threats/threats, opportunities, weaknesses and strengths) method, which precisely orders information and allows presenting the project characteristic in readable way for a recipient. The results of the conducted analysis indicated the lack of acceptance on the part of potential users and the resulting need to promote the use of Drain Water Heat Recovery systems at residential level

Critical Analysis of the Current State of Knowledge in the Field of Waste Heat Recovery in Sewage Systems

The need for efficient use of energy and sustainable energy management and the fact that large quantities of heat are deposited in the discharged sewage have contributed to the development of research on waste heat recovery. Gray water began to be seen not just as waste, but also as an alternative source of energy. Research related to the development, improvement, and finally, the popularization of waste energy recovery devices and systems has evolved rapidly over the last two decades. Initially, technologies for gray water reuse were not widely used, which was due to the low efficiency of the current heat exchangers and the significant investment outlays that would have to be covered by potential users. Research conducted by scientists from around the world has allowed us to eliminate construction flaws, improve efficiency, and also provide information on the selection of optimal waste heat recovery technology, depending on the installation conditions and operating parameters. The ability to correctly select the device allows for effective energy collection from gray water, which improves the investment profitability. This paper reviews the research regarding issues related to waste heat recovery from gray water in sewage installations and systems. A critical analysis of the current state of knowledge was carried out with a special consideration to the technologies intended for the residential buildings

Financial Analysis of the Use of Two Horizontal Drain Water Heat Recovery Units

The growing interest in the use of unconventional energy sources is a stimulus for the development of dedicated devices and technologies. Drain water heat recovery (DWHR) units can be an example of such devices. They allow the recovery of part of the heat energy deposited in grey water. This paper describes the results of research on the assessment of the financial profitability of the use of two horizontal heat exchanger solutions, taking into account the actual distribution of cold water temperature during the operating year in the plumbing and two operating regimes of the premises as the residential and service facilities. The analysis showed that the use of a horizontal heat exchanger with increased efficiency in a dwelling in a 15-year life cycle allowed for achieving more than twice as much savings (reaching up to EUR 1427) compared to a classic horizontal heat exchanger. At the same time, it was shown that the installation of this type of equipment was more profitable the greater the water consumption of the premises. The article also notes the impact of cold water temperature in the installation on the results of the analysis. It was featured that taking temperature on the basis of installation design recommendations led to significant distortions in the financial analysis. On the other hand, comparing the method of averaging the cold water temperature (daily, monthly and yearly), it was determined that averaging the temperature over the annual cycle was an acceptable simplification of the model. The research results presented in the paper have a practical aspect and may constitute guidelines for designers and potential investors. In addition, they can be an incentive to continue research on heat exchangers by other scientific centers, which on a global scale will increase the universality of their use