The subject of this diploma thesis is a study of two variants of sewer network of Cetechovice. Variant solutions include the use of existing segments supplemented by new gravitational or pressure sections. The proposed variant solutions are then economically assessed.

Greater environmental considerations and the desire to reduce pollution overflows to watercourses are requiring engineers to develop a better understanding of the processes involved in pollution transport through sewer networks. Furthermore, developments in modelling techniques and computer power are allowing urban drainage modellers to increase the complexity of their software and so demand additional data that can be incorporated. Presently, an important aspect is quantifying the retention time and dispersion of pollutants entering an urban drainage system. Manholes provide a means of sewer access for maintenance and inspection. Under storm flow conditions they are liable to surcharge above the level of the pipe soffit. This creates a storage volume that has an impact on the longitudinal dispersion and travel time of soluble pollutants in sewer systems. A laboratory investigation has been completed to quantify these effects for various manhole configurations. These include step heights between the inlet and outlet pipes, benching and extreme high surcharge conditions. In addition, re·analysis of previously acquired data has allowed variations in manhole diameter to be considered. Numerical modelling using computational fluid dynamics, combined with laser light sheet visualisation of the flow structures within manholes, has provided greater insight into the processes causing longitudinal dispersion. The coefficients required for two existing longitudinal dispersion models, the advection dispersion equation and the aggregated dead zone model, have been determined by means of an optimisation process. This has been undertaken with computer software specifically written for the purpose. The technique adopted for optimisation is fully detailed. Final conclusions regarding the longitudinal dispersion due to surcharged manholes are presented.

Digitized by Kansas Correctional Industries

<p>The aim of this project was to look into ten small sewer systems in the municipality of Laholm, in Sweden, in order to work out common assessment grounds for them. The sizes of the systems for purification of wastewater were within the range of 25 to 2000 population equivalents. Our method was to study literature, the laws and regulations applicable and the files at the municipality. The conclusion is that every sewer system is different and every situation is unique. We concluded that based on laws and assessment grounds sewer systems equal in size and pollution load ought to have similar demands attached to them. Four of the sewer systems are in need of adjustments or renovations. One sewer system in particular, Hishult, needs large-scale adjustments and improvements to live up to the demands attached to it. This sewer system is where we think the focus from the municipality ought to be the strongest, based on the result from this review. It requires most effort, time and money, to get it running with least amount of environmental impact. We also suggested levels for degree of purification for all of the sewer systems. As a common ground we set the demands equal to the ones for private sewer systems. The demand for purification of phosphorus was adjusted to if the system was equipped with chemical precipitation or not. Subsurface filters are left without measures. The focus of demands on systems of that kind is set to new construction or full scale restoration.</p>

Abstract The sewage sewerage system is an important public infrastructure actively pushed by the government presently, since it can improve our environmental quality and promote the nation¡¦s competitiveness. To minimize the government's short-term financial burden and attract the private capital, vigor, and efficient management, the Executive Yuan encourages the private sector to participate the sewage sewer construction plans via the BOT (Build-Operate-Transfer) model for those systems above 10,000 tons capability per day. It is estimated there are totally over 36 such systems in the country. This research consists of two parts. The first part deals with the feasibility study of the BOT model for the sewage sewer in Taitung city. Three factors, including the law, the risk, and the financing were assessed. In the aspect of the law, the completeness of related regulations, the timetable of local government¡¦s plan, the sewage sewer¡¦s fee, and others were important items for the success of the task. In the aspect of the risk, the allocation of risks in the various stages is the important item. Finally, the financial feasibility studies were conducted for the Nantz and Danshuei demonstrated cases, in which the government expenditure and the operation net income of the private part are the important items. Presently, the relevant BOT case documents and materials show that the financial structure is one of the key assessment elements provided that the promotion of the trade and investment, and the sign of contract are successful. So the second part of this research involved the questionnaire survey as to analyze the key factors that are beneficial for the success of the promotions of trade and investment, and the sign of contract. Results show that the successful factors include the favorable financial guarantees, the lowest guaranteed operation amount of sludge, and the take-hold of the construction land by the government. All these factors should be carefully assessed and planned in advance, together with the well-designed coordination mechanism for the agreement/contract. Keywords: Sewage sewer system, privatization, BOT model

The aim of this project was to look into ten small sewer systems in the municipality of Laholm, in Sweden, in order to work out common assessment grounds for them. The sizes of the systems for purification of wastewater were within the range of 25 to 2000 population equivalents. Our method was to study literature, the laws and regulations applicable and the files at the municipality. The conclusion is that every sewer system is different and every situation is unique. We concluded that based on laws and assessment grounds sewer systems equal in size and pollution load ought to have similar demands attached to them. Four of the sewer systems are in need of adjustments or renovations. One sewer system in particular, Hishult, needs large-scale adjustments and improvements to live up to the demands attached to it. This sewer system is where we think the focus from the municipality ought to be the strongest, based on the result from this review. It requires most effort, time and money, to get it running with least amount of environmental impact. We also suggested levels for degree of purification for all of the sewer systems. As a common ground we set the demands equal to the ones for private sewer systems. The demand for purification of phosphorus was adjusted to if the system was equipped with chemical precipitation or not. Subsurface filters are left without measures. The focus of demands on systems of that kind is set to new construction or full scale restoration.

No description available.

Individual Sewers in Nordmalings Municipality – Evaluation of Factors when Prioritizing Inventory Areas and Demands of Individual Sewers The purpose of this study was to examine what to consider when prioritising inventory areas for individual sewers, as well as how an inventory should be initiated in Nordmalings municipality. The information was gathered by studying legislation, documents by government agencies, maps and by conducting a questionnaire survey. The study showed that the demands on individual sewers must be separately determined in every individual case. Sewer system shall have further wastewater treatment than only septic tanks, for example an infiltration plant. The demands should be determined by the protection level of the Environmental Protection Agency's guidelines (NFS 2006:7) for small sewage systems for domestic wastewater. The areas demanding a high level of protection are sensitive to emissions from individual sewers. Such areas can for example be Natura 2000, bathing places and water that is sensitive to eutrophication. The questionnaire was sent to 85 property owners and 64 of them responded. The majority of the ones with permanent housing had septic tanks (90.5 %) and an infiltration plant (60.0 %). The questionnaire indicated that the majority of the individual sewers were acceptable but that a significant part may have serious flaws. Prioritisation of inventory areas can be based on the areas that need high level of protection. Based on these results, coastal areas in Nordmalings municipality should be prioritised for an inventory of individual sewers.

Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 83-84).

Thesis (Ph. D.)--Drexel University, 2006. / Includes abstract and vita. Includes bibliographical references (leaves 156-161).