RU2079453C1 - Silt site - Google Patents

Abstract

FIELD: cleaning municipal sewage water. SUBSTANCE: silt site is intended for dewatering of municipal sewage water sediment and it has water-proof base 1, drainage filtering devices with filters 2 and water branching pipes 3 provided with removable stoppers, water receiving troughs 4, pipeline 5 for delivery of liquid sediment, water branching pits 6 and guarding dike 7 made of horizontal layers of filtering material. Dam pad rests on water-proof base of silt site and layers are arranged with displacement towards central vertical axis and they create reservoir in the form of truncated pyramid. Water branching pits are sectional and made of circular members 14, 15, 16 placed vertically one upon other. Used as filtering material for dike is dewatered sediment of municipal sewage water. Silt site is operated as follows. Primarily it is filled with liquid sediment, then it is filtered through drainage filtering devices and dike. Above-silt water is branched away through water branching pits, dewatered sediment is held untouched for certain period, then removed. Before filling, silt site is guarded by lower layer of dike and water branching pipes 3 are closed with their stoppers. In process of filling and as sediment is being accumulated, further layers of dike are erected together with raising height of water branching pits. Upon filling of silt site to top level of dike, sediment is kept untouched for some time. At this time stoppers are removed from water branching pipes 3 and dewatering takes place by filtering through drainage filtering devices and dike. During holding period sediment of municipal sewage water is fully stabilized and decontaminated. EFFECT: high efficiency. 3 cl, 3 dwg

Description

 The invention relates to utilities, in particular, to dehydration of sewage sludge in natural conditions at silt sites and can be used in urban wastewater treatment plants.

The simplest and most common way to dehydrate liquid sewage sludge is to dry it in silt sites. The latter are planned drainage areas on a natural or artificial base, surrounded on all sides by earthen rollers up to 1.5 m high, at least 0.7 m wide at the top and a drainage system [1, 2]
With a relatively simple technology and low operating costs, sludge sites provide an extremely low dehydration effect, especially in areas with a large amount of rainfall. Such areas include most of the territory of Russia, where silt sites are forced to turn into sludge collectors for long-term storage of liquid sludge.

 After filling the sites, dewatering of the sludge mixture up to 80% lasts from almost 3 to 10 years, depending on the specific climatic and hydrogeological conditions, design decisions for the removal of forced and drainage waters. Currently, the problem of sludge dewatering in vivo is being solved by diverting additional territories to silt sites. Hundreds of hectares are occupied by silt sites at sewage treatment plants of large cities; therefore, improvement of their design is in the direction of intensifying dehydration. A number of inventions provide for the use of vertical filtering devices for this purpose.

 Known sludge site [3] which contains a waterproof base with enclosing walls, pressure sludge pipe, prefabricated collector drainage system with vertical filter elements.

 The walls of the site are made windows with stepped slide devices. On the opposite side of the walls mounted cassette-filtering vertical devices that provide additional filtering and water drainage. The design of this sludge site is complicated and not effective enough, since filtration is carried out on the entire surface of the enclosing walls, but only through its individual sections. The maintenance of this site is also becoming more complicated, since, due to calcination, the filter load requires frequent regeneration or replacement.

 Various materials are used as filter materials for drains and vertical filters, including dehydrated, stabilized sewage sludge. The invention [4] protects dewatering of sewage sludge, in which a layer of dry sludge with a humidity of 65-70% with a thickness of 15-20 cm is laid on the gravel surface on a sludge platform with asphalt concrete coating and with a drainage device in the form of trays filled with gravel. liquid sludge is fed to the site by periodic inlets, alternating them with interruptions, during which filtering through the sediment layer, drainage gravel backfill occurs. After a period of inlays, which lasts several months, a period of drying the sediment follows, and then mechanized cleaning and preparation of the site for the next cycle is carried out. This method is also not effective enough, because the dehydration process is carried out only by filtration and natural drying, it does not use the process of natural phase separation of the liquid sludge mixture. The method does not reduce the volume of loading and unloading, does not contribute to the reduction of occupied territories for silt sites.

 The sludge site [5] and the method of its operation are closest to the claimed technical solution. The platform contains a waterproof base, a drainage system of vertical filter elements and a pipe for supplying sludge. When dewatering sludge from urban wastewater, drainage wells for removing superfluous waters are also a necessary element of the site. The filtering elements of this site are made of porous concrete with through slotted holes.

 They are installed around the perimeter of the silt site and perpendicular to the movement of silt water, with the formation of maps.

 The bottom mark of the slotted holes is buried under the waterproof base, and the sediment supply pipelines are perforated and mounted on the filter elements. With this design of the sludge pad, the sediment spills gradually from the edge of the map to its middle, and under the influence of gravity, the sediment is hydroclassified, an inverse filter is formed from it, which helps to retain particles that have not yet settled into the sediment.

 The dewatering technology at this site comes down to the fact that sludge is filled continuously throughout the entire working depth of the site, along the entire height of the layer. Water is discharged through a layer of sediment and moves along a waterproof base to the filter elements. After filling the site make an exposure to dehydration and drying of sludge.

 Then the vertical filtering elements are removed and the site is freed from the dried sludge using mechanical means.

 Warehousing and storage of dehydrated sludge is carried out at the warehouses and landfills at wastewater treatment plants. Before the new cycle and the supply of the next portion of the liquid sludge, vertical filter elements are again installed on the site. The disadvantages of this design are: a large complexity of maintenance, insufficient capacity of the site, limited by the height of the enclosing walls and vertical filtering elements, a large amount of unproductive preparatory and loading and unloading operations, frequent repeatability of work cycles.

 In addition, the dehydration process is carried out only by filtering through vertical filter elements. The required dehydration rate is achieved by an increased number of these elements, which become clogged during operation, require frequent regeneration and replacement, which also complicates the operation of the sludge site.

 The aim of the present invention is to intensify the dehydration processor, increase the capacity of the site and simplify maintenance.

 This goal is achieved by the design of the inventive sludge site containing a waterproof base, drainage filtering devices, drainage wells, water trays and a liquid sludge supply pipe, in accordance with the invention, the site is additionally equipped with a boundary dam made of horizontal layers of filter material, the sole of the dam being placed on the waterproof base of the site, the layers are laid with an offset to the vertical axis and form a container in the shape of a truncated pyramid, and drainage wells formed constituents of the annular elements mounted on each other to level the top of the dam. To achieve this goal, the most appropriate option is the implementation of the enclosing dam from the dehydrated sludge of urban wastewater.

 This goal is also achieved by the method of operation of the proposed sludge site, including filling it with liquid sludge, filtering through drainage filtering devices and a dam, diverting nadil water through drainage wells, holding and removing dehydrated sludge, so that according to the invention, it is fenced with the lower one before filling the site a layer of the dam, in the process of filling periodically, as sediment accumulates, the following layers of the dam and the height of the water intake wells are built up, and filtered through the drainage filtering devices, they are produced after filling is completed, during the holding period.

 The proposed sludge site with a wall of filtering material has a significantly increased capacity by increasing the height, without expanding the occupied territory. The design allows to intensify the dehydration process by increasing the hydrostatic pressure of the liquid phase, to organize filtration not only through the bottom drainage, but also through the dam itself. Dehydration is also intensified by the diversion of superficial waters from various levels along the dam height through the stackable elements of the composite drainage wells. The use of dehydrated sludge from urban wastewater as a filter material is most appropriate, since this ensures the uniformity of the composition of the dehydrated sludge, which is important for its subsequent use for economic purposes. The dam provides not only dehydration, but also the storage of multi-year volumes of sewage sludge, eliminates loading and unloading operations for transferring the dried sludge to landfills for its storage and greatly simplifies the maintenance of the sludge site.

 The proposed sequence of operations during operation of the sludge platform allows to improve the conditions of sludge dewatering both at the first stage when filling the sludge platform to the level of the dam top, when dewatering is mainly due to sedimentation, and at the second stage during the aging period, when the dewatering process is carried out by filtering .

 The invention is illustrated by drawings, where shown: in FIG. 1 - the proposed sludge site in plan at the time of the device of the 1st layer of the dam (view along arrows 1-1 in Fig. 2); in FIG. 2 vertical section of the site with the scheme of building 5 layers of the dam and, accordingly, the height of the drainage wells; in FIG. 3 drainage well in section.

 The proposed sludge site contains a waterproof base 1, made, for example, of several layers of plastic film or a layer of crumpled clay, drainage filtering devices 2 of the type "inverse filter" and perforated drainage pipes 3, equipped with removable plugs at the ends (not shown in Fig.) , water intake trays 4, located around the perimeter of the site, the pipeline 5 for the supply of liquid sediment, drainage wells 6 for the removal of nadilovyh water and the boundary dam 7, made of stacked on top of each other layers 8, 9, 10, 11, 12 filter media. The sole of the dam is located directly on the waterproof base of 1 platform. The layers of filtering material 8-12 are located with an offset to the vertical axis of the site, and form a container in the shape of a truncated pyramid.

 As a filtering material of the dam, dried sludge from urban wastewater treatment plants is used.

 In the absence of sludge, for example, during the commissioning of new treatment facilities, sand or other similar filter material suitable for the construction of a dam can be temporarily used as a filter material.

 The drainage wells 6 are made of composite concrete base 13 and annular elements 14, 15, 16 mounted on top of each other. The wells 6 and dam 7 have the same height all the time, which grows in parallel during the filling of the silt site. The base of the wells 6 are connected to the discharge pipe 17.

 At the level of the inlet 18 of the wells 6 in the guides 19 there is a "floating" hydraulic lock 20 with a foam pad 21.

 The height of the inlet 18 is regulated by a set of bars 22 overlapping its bore, laid in grooves 23.

The sludge site works as follows:
Before putting into operation, the site is fenced with the lower layer 8 of the dam. In this case, the drainage wells 6 also have a minimum height and consist of a concrete base 13 and one lower ring element 14, the “floating” water trap 20 is in the lower position. The liquid precipitate is fed continuously through line 5. It gradually fills the entire area to the top of the lower layer of the dam. In this case, the pipes 3 of the drainage filtering devices are blocked by plugs and there is no filtering process through them. In the sludge site volume, sedimentation occurs with separation of the liquid and solid phases, with the formation of a bottom sediment layer, a "pond" and a crust-like sediment layer floating up on its surface. Nadilovaya water from the "pond" is discharged through the holes 18 of the drainage wells 6. In this case, the water trap 20 is always in the liquid phase and prevents the floating crust-like layer of sediment from entering the wells 6. Since the height of the lower layer of the dam is significantly (2-3 times) higher than the height of the enclosing rollers of well-known silt sites, their capacity and filling time increase.

 Duration of filling the site may last season, year or more. During this time, the sediment condenses. When filling the site to the upper level of the lower layer of the dam, the second layer is built up, shifting it to the central vertical axis of the site. At the same time, the height of the drainage wells 6 is increased to the level of the top of the second layer of the dam. This is achieved by installing the next annular element 15 of the drainage wells. Building is carried out using construction equipment (bulldozers, excavators, etc.). This is facilitated by the pyramidal shape of the dam with a natural external slope, providing movement and lifting of equipment along a serpentine-type road.

 With further filling of the site, the sediment layer at its bottom increases and compacts, the liquid “pond” phase moves up, floating hydraulic shutters 20 on the drainage wells also move up along the guides 19. The pressurized water is removed through the wells 6 and is discharged through the pipe 17 outside the area. Surface and melt water flowing from the slopes of the dam during rains and snow melt are discharged into the water receiving trays 4. During the filling of the site, periodically build up all subsequent layers of the dam, and at the same time increase the height of the drainage wells to the level of the top of the dam. The duration of the sludge pad filling period may be 10-20 years or more.

 Due to the fact that the outlet openings of the pipes 3 of the drainage filtering devices are closed with plugs during the entire period of filling the site, the clogging of clogged drainage filters during this period is excluded.

 Dehydration at this first stage is mainly due to the process of sedimentation with the separation of liquid and solid phases and the removal of superficial waters through the drainage wells.

 After the period of filling the sludge pad to the upper level of the last layer of the dam and the removal of supra-water from the "pond", the plugs from the pipelines of 3 drainage filtering devices are removed.

 The next technological aging period begins, during which further dehydration by filtration and stabilization of the sludge take place. After opening the plugs, the filters of 2 drainage filtering devices begin to work.

 Filtration also goes through the entire side surface of the dam with water being drained into the drainage system of the site and the water intake trays 4. At this stage, dehydration occurs in natural conditions and lasts several years. At the same time, the process of deeper stabilization and sediment disinfection continues. After exposure, the sludge site is ready for unloading of sediment, which is produced using mechanization means. Dehydrated stabilized sludge can be used for household purposes, for example, as fertilizer for farmland, for filling lowlands, during planning works. It is most advisable to use a dehydrated, stabilized sludge as a filter material for dam barriers at adjacent silt sites. It is advisable to have at least two identical sludge sites of the proposed design operating in different modes: filling, holding and unloading at the wastewater treatment plant of urban wastewater. At the same time, silt sites completely provide each other with filter material for the construction of the dam.

 The proposed design of the silt site and the method of its operation provide the following advantages compared to the prototype.

 Occupied sites are many times reduced by increasing the capacity of the site. The height of the loaded site can be 10-20 m or more.

 Operating costs are reduced, including the cost of preparing and restoring a waterproof base and drainage devices, as their service life is increased significantly, loading and unloading operations for transshipment of sludge from silt sites to storage landfills are eliminated.

 During the entire period of filling the sludge site with liquid sludge, optimal conditions are provided for the separation of solid and liquid phases and the introduction of the settling process.

 Due to the development of the sludge platform in height, conditions are created for the pressure mode of filtration of the liquid phase through the dam, which increases the efficiency of natural dehydration.

Claims (3)

 1. A sludge platform containing a waterproof base, drainage filtering devices, drainage wells, water trays and a liquid sludge supply pipe, characterized in that it is additionally provided with a wall dam made of horizontal layers of filter material, the sole of the dam being placed on the waterproof base of the platform, the layers are laid with an offset to the vertical axis and form a container in the shape of a truncated pyramid, and the drainage wells are made of composite ring elements, anovlennyh each other to level the top of the dam.  2. The site according to claim 1, characterized in that the enclosing dam is made of dehydrated sludge from municipal wastewater.  3. The method of operation of the sludge site according to claim 1, including filling it with liquid sludge, filtering through drainage filtering devices and a dam, diverting forced water through drainage wells, holding and removing dehydrated sludge, characterized in that it is fenced with a lower layer before filling the site dams, in the process of filling, as sediment accumulates, periodically build up the following layers of the dam and the height of the drainage wells, and filtering through drainage filtering devices is performed ny after filling in a holding period.

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