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In particular cases, special processes are used for cleaning, such as:
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Physical methods aim at increasing the sewage flow velocity for cleaning purposes by the addition of air or polymers. The effect of the introduction of polymers is the reduction of energy losses of turbulent flow conditions. Using low concentrations (max. 60 ppm), the flow velocity of the sewage can be increased by up to 70%. The effect is not based on a change in the sewage viscosity, but rather on a lowered frictional resistance of to the rough pipe … |
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Another possibility for the removal of agglomerations and deposits in pipe systems is the ultrasonic method, which has been developed and patented in France. It can be used in a range of nominal sizes between DN 20 and DN 600 for drains, sewers and heating water systems [FI-Alben] [Loese1998] [Loese1998a]. According to the manufacturer’s specifications, pipes made of PVC, PE, polymer cement, cast iron, steel or vitrified clay can be cleaned at an … |
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Chemical methods are used to remove:
The first application is generally restricted to industrial pipes and pipelines for oil and gas. For sewers, this method is only used in exceptional circumstances. A detailed example for the removal of incrustations in a water dam drainage system is described in [Siebe1981]. Preconditions for the application of the chemical method include:
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The mechanical root removal methods used today, e.g. by cutting or boring, usually lead to strengthened new root formations requiring re-treatment at relatively short intervals Alternatively, the use of chemical root removal method by applying various herbicides has been tried and tested in several comprehensive studies [Sulli1977] [Ahren1970] [Townl1973]. The respective line is taken out of service, and the herbicide is injected into the line as a … |
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Biological cleaning methods are used to decompose fats and fibres in the biofilm, as well as phenols, proteins and mineral oils. They are also applied to eliminate or reduce odour nuisances [Baig1976] [Jense1977]. A two-components detergent is mainly used in sewage systems of hospitals, kitchens, large cafeterias and the food processing industry [FI-Aladi]. |
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The first component comes in a liquid form and is composed of a mixture of fatty acid esters, fatty acid amides and urea. It is fed into the sewage system via kitchen drains, floor inlets, etc. and then flushed with lukewarm water. After a reaction time of about six hours, the second component, containing microorganisms, is mixed with the lukewarm water. A soaking time of about 10 to 15 minutes is required, and the mixture is then fed into the sewage … |
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Feb 04, 2013 This module focuses on the different possibilities for mechanical cleaning of sewers. In this context, a wide range of mechanically operating cleaning equipment is presented, and a practical impression is given. After completing this module, you will have knowledge regarding:
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May 27, 2013 Course This course includes tutorial services and a final examination. Cleaning is one of the most important maintenance measures when it comes to ensuring a continuous performance of drainage systems. This module covers essential knowledge regarding the cause and effect of deposits, and provides a strategic approach to the development of a cleaning plan that enables for the optimisation of operating costs and in particular asset preservation. The course consists of 4 Modules on the following topics:
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Oct 25, 2013 Course This course includes tutorial services and a final examination. Cleaning is one of the most important maintenance measures when it comes to ensuring a continuous performance of drainage systems. This module expands on the topics covered in module "D-05 cleaning I", by providing further knowledge on the applications and limits of flushing methods, mechanical cleaning methods and special methods, such as physical and chemical sewer cleaning. Discussed are both the accessible and non-accessible lines, as well as pressure lines. It concludes with providing constructive solutions for the minimization of solids entry into the sewer system, with the aim of preventing the formation of deposits and hence the reduction of cleaning efforts and frequencies. The course consists of 5 modules covering the following topics:
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Nov 04, 2004 According to [ATVM143-1:1989], the term maintenance is defined as: Measures for maintaining the nominal condition. The nominal condition is understood to be the determined (required) condition for the respective case of an installation, a structure or individual components (Abschnitt 2.1) (Abschnitt 5.1). Maintenance is closely linked with the other two main groups of measures of rehabilitation and maintenance, i.e. the inspection and the rehabilitation. … |
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The cleaning of sewer systems is an important part of maintenance. It is carried out:
Besides the above-… |
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(Image: Flushing manhole with overflow [Frühl10]) According to EN 752-7 [DINEN752-7] surge flushing is understood to be "the creation of a short-term strongly increased flow for the purpose of removing obstacles or deposits in sewage pipes and sewers." In this process, the sewage or clean water is backed up in manholes (Bild 3.2.2.1), or chambers specially suited for this purpose, and then suddenly released. The shock wave of the backed-up water that … |
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In this process, devices are introduced into the sewer that reduce the cross-section and back-up the sewage. This back-up wash round the devices and moves them which causes the non-hardened deposits to be loosened and conveyed further [Führb80]. With back-up flushing, the following apparatus are used [ATVA140] [NASSCO89a] [Führb80] [Frühl10] [Gürsc21] [ATV95c] [Tchob89] :
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The oldest sewer cleaning processes, which are still partly used today under special circumstances in the sections of the sewer suitable for their use, belong to the group of flushing processes [Frühl10] [Gürsc21] whereby they are divided into:
Both methods can only be used for the removal of loose, non-hardened deposits. They assume a free flow of sewage and a high flow … |
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Feb 16, 2011 In these investigations, the position of the cleaning nozzle lying on the pipe invert remains unaltered. It is positioned in such a manner that any damage that occurs in the pipes and pipe joints can be observed. The investigations are carried out at various pressure levels, whereby the pressure begins at 75 or 100 bar and is raised by steps of 25 bar up to the maximum pressure of the cleaning system. Each level of pressure is maintained for 1 minute … |
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Nov 04, 2004 In order to simulate long-term loading, the respective cleaning nozzle is pulled through the 12 m long test section 40 to 60 times with a constant water pressure of 150 bar measured at the HP pump and a constant speed of approximately 4 m/min. This pull-through speed was determined on the basis of evaluation of several applications in practice as well as calculation documentation. In the course of the investigations, 30 l of sand, gravel and stones … |
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Nov 04, 2004 Rehabilitation and Maintenance of Drains and Sewers High pressure Water Jetting Process (HP Water Jetting Process)
Unprofessional application of the high pressure water jetting process can cause pipe damage in the form of grooves, chipping, cracks or holes in pipe walling and linings (Abschnitt 2.1) (Bild 3.2.3.1) (Bild 3.2.3.1). Especially dangerous moments occur … |
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The high pressure water jetting process (HP water jetting process) [Lenz96] is the almost universal process, used in about 90 % of all sewer cleaning processes for removing deposits within the scope of regular maintenance as well as for cleaning as a preparatory measure for sewer inspection or rehabilitation. It can usually not be used when hardened deposits are present or for removal of flow obstacles, e.g. internally projecting laterals, artificial … |
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Nov 04, 2004 In accessible sewers manual cleaning can be carried out, on the one hand, for the removal of extended, hardened or crystalline deposits and, on the other hand, for careful preparation for rehabilitation measures. In the first case, pickaxes, compressed air hammers, careful blasting, small motor graders, loaders and others are used. In the second case, and depending on the piping material and the selected method of rehabilitation, special tools such … |
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Feb 16, 2011 Mechanical cleaning apparatus are primarily used for removing and loosening hardened deposits and then for the removal of solids. They are introduced into the sewer through the manholes and pulled (hoist pull), pushed (spiral) or pressed (transport medium of a pressure pipe) through the section of the sewer to be cleaned.
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Nov 04, 2004 A member of this group is the pipe ring chisel, which is utilised in straight sections from DN 400 or ovoid cross sections from 200/300 for removing hard deposits also on all sides (Bild 3.2.4.3.1) (Bild 3.2.4.3.1) [Schop81].
The apparatus is driven by compressed … |
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Feb 16, 2011 This type of apparatus is remote controlled and used with TV monitoring in the nominal size region DN 200 to DN 600 for removing hardened deposits (Bild 3.2.4.3.2) (Bild 3.2.4.3.2) (Bild 3.2.4.3.2) (Bild 3.2.4.3.2), internally projecting laterals (Bild 3.2.4.3.2) (Bild 3.2.4.3.2) and other flow obstacles such as roots (Bild 3.2.4.3.2). The motive force is hydro-dynamic or hydraulic oil. In order to ensure that the process will protect the pipe, … |
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Nov 04, 2004
The "automatic hammer-bore nozzles" (Bild 3.2.4.3.3) (Bild 3.2.4.3.3) belong to this category. They were developed for the removal of hardened deposits, blockages and root ingress in the nominal size region of DN 100 to 1000. The motive power is provided by the … |
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