The device of a drainage on silt platforms. Silt platform. Mechanical Stage Wastewater Treatment
The simplest and most common method of sludge dewatering is drying them on sludge beds with a natural base (with or without drainage), with surface water drainage and on sealing pads.
The first are planned plots of land (maps) surrounded on all sides by earthen ridges (4.60). Raw sludge from settling tanks or digested from digesters, two-story settling tanks or other structures, having a moisture content of 90% (from two-story settling tanks) to 99.5% (non-fermented activated sludge), is periodically poured into areas in a small layer and dried to a moisture content of 75-80% .
Moisture from the sediment partially seeps into the soil, but most of it is removed by evaporation. As a result, the sediment volume decreases. Dried sediment receives the structure of wet earth. It can be taken on a shovel and loaded into trolleys and dump trucks for transportation to the place of use.
Silt pads on a natural base without drainage are used in cases where the soil has good filtering ability (sand, sandy loam, light loam), the groundwater level is at least 1.5 m below the surface of the map, and seeping drainage water can be discharged into soil according to sanitary conditions. With a shallower depth of groundwater, a decrease in their level is envisaged.
If the soil is dense, poorly permeable, the sites are equipped with tubular drainage laid in ditches filled with crushed stone and gravel. The distance between the drainage ditches is recommended to be taken equal to 6-8 m, the initial depth of the ditch is 0.6 m with a slope of 0.003.
At small treatment plants, for ease of operation, the width of individual cards is taken no more than 10 m. At medium and large stations, the width of the cards can be increased to 35-40 m. 0.25-0.3 m and in winter 0.5 m.
The cards are separated from each other by protective rollers, the height of which is taken 0.3 m above the working level.
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Sediment is distributed over the cards using pipes or wooden trays, which are mostly laid in the body of a separating roller with a slope of 0.01-0.03 and supplied with outlets.
Sludge beds must be freed from dried sludge in a timely manner. At small sewage treatment plants, the sludge is manually loaded into trucks and transported to nearby collective farms and state farms for use as fertilizer.
Sometimes narrow-gauge tracks for trolleys are laid on separating rollers, on which the sediment is transported outside the area and unloaded into trucks there.
In winter, the frozen sediment is broken up by special machines into separate blocks, which are then taken out to the collective farm fields.
At medium and large stations, scrapers and bulldozers are used to rake the sediment. The posture collected in dumps is loaded into vehicles using a peat or manure loader mounted on the basis of a DT-54 tractor, or a bucket loader. The latter is the most economical of the used mechanisms - its capacity is up to 40 m3/h.
In areas with an average annual air temperature of 3-6 ° C and an average annual precipitation of up to 500 mm, it is recommended to arrange sludge sites with settling and surface drainage of sludge water for treatment facilities with a capacity of more than 10,000 m3 / day. Figure 4.61 shows silt pads of this type built at the Kuryanovskaya aeration station. Sludge beds with surface drainage of sludge water are designed in the form of several (4-7) independently operating cascades. Each cascade consists of four to eight stepped cards. Sediment inlet from the supply pipelines is provided for the upper cards. As it accumulates, the upper layer of interstitial water (or sediment) is discharged to the underlying map through reinforced concrete wells. Settled interstitial water from the lower map of the cascade is pumped to the primary settling tanks of the treatment plant, since the content of suspended solids in it can reach 1.5-2 g/l. The volume of settled interstitial water is 30-50% of the volume of the dehydrated sludge, the moisture content of which is reduced from 97 to 94-95%. Further dehydration of the sludge occurs due to the evaporation of moisture from the surface of the sludge.
The useful area of one map is taken equal to 0.25-1 ha with a ratio of width to length of 1: 2-1: 2.5.
Sludge compactors developed by the Soyuzvodokanalproekt Institute together with the Sewerage Department of the Leningrad Institute of Civil Engineering. The sites consist of rectangular tanks with waterproof bottoms and walls. The walls are constructed from prefabricated reinforced concrete unified panels 2.4 m high, the bottom is monolithic. The working depth of the platform is 2 m.
If there is not enough space for arranging open silt pads, then sometimes covered sludge sites are arranged like greenhouses, covering them with glazed frames. Such sites were built in Kislovodsk. According to experimental data, the annual load on them is 9-10 m3/m2 when drying sediments from digesters.
The area of sludge sites depends on the volume of sediment, the nature of the soil on which the site is arranged, climatic conditions, and also on the structure of the sediment.
When designing sludge sites with surface drainage of sludge water, the load is assumed to be 1 m3/m2 per year.
Sludge compactors are calculated according to the load q, which depends on the working depth of the site and the number of unloadings per year, taken depending on the properties of the sediment and climatic conditions from 1 to 5.
It is necessary to check the sufficiency of the area obtained in the calculation, taking into account the freezing of the sediment in winter. Continuous! The period during which freezing occurs is determined by the number of days with an average daily temperature below -10 ° C. Part of the moisture (25%) is filtered and evaporated in winter. Under freezing, 80% of the surface of the maps of silt sites is allocated, and 20% is left for use during the spring thaw.
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One of the oldest and most proven ways to dispose of sediments formed in primary clarifiers, digesters, two-tier clarifiers are sludge beds, and it is also the easiest and cheapest method. The sites are also used for other types of precipitation, the main thing is that their humidity is more than 90%.
Sludge platforms are allowed to be designed:
- With a natural base;
- With drainage system;
- Without drainage system;
- With surface water drainage;
- As sealing pads.
Silt pads on a natural basis are a piece of land specially planned in the form of several sites, which are called maps. Each site is fenced with an earthen roller on all sides (but an entrance for vehicles can be arranged on one side). A system of supply pipes is organized on the site, through which raw sludge or activated sludge is periodically supplied evenly over the area. It is dried to a moisture content of about 75-80%. After that, the “dry sediment” is loaded onto vehicles or trolleys and taken to landfills or for further processing. Silt water seeps through the ground. There are two options for collecting sludge water:
- If the soil under the silt pads does not have sufficient filtering properties, then a drainage system is arranged. It consists of pipes located in ditches, covered with gravel or crushed stone. Such ditches are arranged at a depth of more than 0.6 m. Silt water is most often sent to the beginning of the treatment plant.
- If through the soil under the silt pads it has good filtering abilities (sand, loam, sandy loam), then you can not arrange drainage. But only if the interstitial water is not dangerous in sanitary terms and the groundwater is located at a depth of 1.5 m, otherwise a decrease in their level is required.
Types of silt pads
Sludge beds with surface water drainage are recommended to be designed in areas with an average annual temperature of 3-6 0С and rainfall up to 500 mm/year. Such silt pads are made in the form of a cascade of maps located at different altitude levels. Sediment is fed to the highest card, as it dries, it is discharged down through bypass wells. Silt water is discharged from the bottom card to the primary settling tank.
Sludge compactors are tanks (often reinforced concrete with a monolithic bottom), with a depth of 2 m or more.
Calculation of silt pads
The calculation of silt pads consists in determining the dimensions of maps, rollers, slopes and diameters of pipelines.
The area of silt maps depends on the volume, structure of the sediment, climatic conditions and the type of soil that serves as the base. In general, it is calculated by the formula:
S = (Vο 365)÷(a b C)
Where, Vo– sludge volume, t/day; a- coefficient taken to take into account the decrease in the volume of sediment due to its decay during fermentation (reference value and depends on the type of structure from which the sediment is taken); b- coefficient taken to account for the decrease in volume due to loss of moisture; FROM- load on the sludge beds (reference value and depends on the design of the sludge bed, climatic conditions, type of sediment), m³/m².
The sufficiency of the area obtained by calculation is checked by the condition of freezing in the winter period. To do this, calculate the height of the freezing layer:
Hus = (W t K2)÷(S K1)
Where, W– sediment volume per day, m³; t– freezing period, days; S– useful area of maps, m²; K1- part of the usable area of the sludge site allocated for freezing, m²; K2- coefficient taking into account filtration and evaporation.
The dimensions of the map are taken from the condition of the aspect ratio of 1:2 or 1:2.5. The number of cards is at least 2.
The height of the rollers is taken from 0.3 m, their slope depends on the soil.
The slope of the drainage network is taken from 0.003, and the supply network is 0.01-0.03.
Operation of silt pads
The operation of sludge sites consists in monitoring the condition of the distribution, outlet, supply, and drainage pipes, the condition of the rollers (for collapses and other types of deformation), the humidity and chemical composition of the sediment (supply and discharge) and its timely removal. Dried sludge is taken manually by shovels into trolleys that move along rollers (for small stations), by manual loading, by peat and manure loaders for vehicles, scrapers, bulldozers (for medium and large stations).
WASTEWATER TREATMENT FACILITIES.
Wastewater treatment plants, as the name suggests, are designed to treat wastewater. Their main purpose is to treat wastewater to a level suitable for further use. Wastewater treatment methods are varied and depend on the type of wastewater, polluting factors and the level of pollution.
Purification - treatment for the purpose of destruction or removal of harmful substances from waste water. The release of wastewater from pollution is a rather complex process that can be compared with production. It contains raw materials (waste water) and finished products (purified water).
Wastewater treatment plants are installed on drains of various types.
Household drains- formed as a result of human activity. Drains come from plumbing fixtures (wash basins, sinks, toilet bowls, etc.) of residential buildings, institutions, public buildings. Domestic sewage is dangerous because it is a breeding ground for pathogenic bacteria.
Industrial waste- formed in enterprises. The category is characterized by the possible presence of various impurities, some of which significantly complicate the purification process. Industrial wastewater treatment plants are usually complex in design and have several treatment stages. The composition of such structures is selected in accordance with the composition of the effluents. Industrial wastewater can be toxic, acidic, alkaline, with mechanical impurities.
Storm drains- due to the method of formation, they are also called superficial. Effluent of this type is a liquid that collects on roofs, roads, squares during precipitation. Stormwater treatment plants usually include several stages and are capable of removing various types of impurities from the liquid, mainly mechanical and sorption treatment. Stormwater runoff is the least hazardous and least polluted of all.
Water treatment systems are vital for human settlements. The consequences of dumping untreated wastewater are detrimental to nature. Dirty water that has fallen into a reservoir destroys an established ecosystem: aquatic plants, microorganisms, fish die, and soil is poisoned. The damage is done to pets and ultimately to human health.
In 2010, modern equipment was installed - filter presses. Thanks to the new units, the volume of sludge treated has increased.
INVENTION
Patent of the Russian Federation RU2079453Inventor's name: Akchurin B.K.
Name of the patentee: Joint Stock Company "Nizhny Novgorod Santekhproekt"
Address for correspondence:
Start date of the patent: 12.01.1995Usage: dehydration of urban sewage sludge on sludge sites. The essence of the invention: the sludge platform contains a waterproof base 1, drainage filtering devices with filters 2 and drainage pipes 3 equipped with removable plugs, water intake trays 4, a liquid sediment supply pipeline 5, drainage wells 6 and an enclosing dam 7 made of horizontal layers of filter material. The sole of the dam is located on the waterproof base of the site, and the layers are laid with an offset to the central vertical axis and form a container in the form of a truncated pyramid. Drainage wells are made composite of ring elements 14, 15, 16 stacked on top of each other. Dehydrated urban sewage sludge is used as a filter material for the dam. The method for operating a sludge site includes filling it with liquid sludge, filtering through drainage filtering devices and a dam, diverting nadil water through drainage wells, holding and removing the dehydrated sludge. Before filling the site, they enclose the bottom layer of the dam and cover the drainage pipes of 3 drainage devices with removable plugs. In the process of filling, as sediment accumulates, the next layers of the dam and the height of the drainage wells are periodically built up. After completion of the filling of the silt pad to the top of the dam, holding is carried out. At the same time, the drainage pipes 3 are freed from plugs and dehydration is carried out by filtration through drainage filtering devices and a dam. In the process of exposure, there is also a complete stabilization and disinfection of urban sewage sludge.
DESCRIPTION OF THE INVENTION
The invention relates to public utilities, in particular, to the dehydration of sewage sludge in natural conditions on sludge 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 sludge beds. The latter are planned drained areas on a natural or artificial base, surrounded on all sides by earthen ridges up to 1.5 m high, at least 0.7 m wide at the top and with a drainage system.
With a relatively simple technology and low operating costs, sludge beds provide an extremely low dehydration effect, especially in areas with high rainfall. Such areas include most of the territory of Russia, where sludge sites are forced to turn into sludge reservoirs for long-term storage of liquid sludge.
After filling the sites, the dehydration of the sludge mixture up to 80% lasts practically from 3 to 10 years, depending on the specific climatic and hydrogeological conditions, design solutions for the removal of sewage and drainage water. Currently, the problem of sludge dehydration in natural conditions is being solved by allocating additional territories for sludge sites. At the treatment facilities of large cities, hundreds of hectares are occupied by sludge beds, so the improvement of their design is in the direction of intensifying dehydration. A number of inventions provide for the use of vertical filter devices for this purpose.
Known silt pad which contains a waterproof base with enclosing walls, pressure sludge, prefabricated collector drainage system with vertical filter elements.
In the walls of the platform there are windows with stepped gate devices. On the opposite side of the walls, cassette-filtering vertical devices are mounted, providing additional filtration and water removal. The design of this sludge area 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 also becomes more complicated, since, due to sedimentation, the filter media requires frequent regeneration or replacement.
Various materials are used as filter media for drains and vertical filters, including dehydrated, stabilized sewage sludge. The invention protects the dehydration of sewage sludge, in which a layer of dry sludge with a moisture content of 65-70% and a thickness of 15-20 cm is laid on the surface of the gravel on a silt pad with an asphalt concrete coating and with a drainage device in the form of trays filled with gravel. During operation, the liquid sludge is fed to the site by periodic overflows, alternating them with breaks, during which filtration occurs through a layer of sediment, drainage gravel backfill. The sludge drying period, which lasts for several months, is followed by mechanized cleaning and preparation of the site for the next cycle. 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 separation of the phases of the liquid sludge mixture. The method does not reduce the volume of loading and unloading operations, does not contribute to the reduction of the occupied territories under the sludge pads.
Closest to the claimed technical solution silt pad and how it works. The site contains a waterproof base, a drainage system of vertical filter elements and a pipeline for supplying sludge. When dehydrating urban sewage sludge, drainage wells are also a necessary element of the site for removing nadil water. The filter elements of this platform are made of porous concrete with through slotted holes.
They are installed along the perimeter of the sludge site and perpendicular to the movement of sludge water, with the formation of maps.
The lower mark of the slotted holes is buried under the waterproof base, and the sludge supply pipelines are perforated and installed on the filter elements. With this design of the sludge area, the sediment spreads gradually from the edge of the map to its middle, and under the action of gravity, the sediment is hydroclassified, a return filter is formed from it, which helps to retain particles that have not yet settled into the sediment.
The dehydration technology at this site boils down to the fact that the filling with silt is carried out continuously to the entire working depth of the site, along the entire height of the layer. Water is drained through the sediment layer and moves along the waterproof base to the filter elements. After the site is filled, an exposure is made for dehydration and drying of the sludge.
Then the vertical filter elements are removed and the platform is freed from the dried sediment using mechanical means.
Warehousing and storage of dehydrated sludge is carried out in warehouses-landfills at wastewater treatment plants. Before a 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: high labor intensity in maintenance, insufficient capacity of the site, limited by the height of the enclosing walls and vertical filter elements, a large amount of unproductive preparatory and loading and unloading operations, frequent repetition of work cycles.
In addition, the dehydration process is carried out only by filtration through vertical filter elements. The required intensity of dehydration 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 bed.
The purpose of the present invention is intensification of the dewatering processor, increase in site capacity and simplification of maintenance.
This goal is achieved by the design of the inventive sludge site, containing a waterproof base, drainage filter devices, drainage wells, water intake trays and a liquid sediment supply pipeline, in that, according to the invention, the site is additionally equipped with an enclosing dam made of horizontal layers of filter material, and the dam sole is placed on the waterproof foundation of the site, the layers are laid with an offset to the vertical axis and form a container in the form of a truncated pyramid, and the drainage wells are made of composite ring elements stacked on top of each other to the level of the top of the dam. To achieve this goal, the most expedient option is the implementation of the enclosing dam from the dehydrated sludge of urban sewage.
This goal is also achieved by the method of operating 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, by the fact that, according to the invention, before filling the site, it is fenced with a lower layer of the dam, in the process of filling, periodically, as sediment accumulates, the next layers of the dam and the height of the water intake wells are built up, and filtration through drainage filtering devices is carried out after filling is completed, during the holding period.
The proposed silt pad with a protecting dam made of filter material has a multiply increased capacity due to an increase in height, without expanding the occupied territory. The design makes it possible 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 diverting nadil waters from different levels along the height of the dam through stackable elements of composite drainage wells. The use of dehydrated urban sewage sludge as a filtering 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 presence of the dam provides not only dehydration, but also the storage of many-year volumes of sewage sludge, makes it possible to eliminate loading and unloading operations for transshipment of dried sludge to landfills for its storage, and greatly simplifies the maintenance of the sludge site.
The proposed sequence of operations during the operation of the sludge pad allows improving the conditions for sludge dehydration both at the first stage when filling the sludge pad to the level of the top of the dam, when dehydration is mainly due to settling, and at the second stage during the holding period, when the dehydration process is due to filtration .
The essence of the invention is illustrated by drawings, where it is shown: in Fig. 1 - the proposed silt pad in plan at the time of the construction of the 1st layer of the dam (view along arrows 1-1 in Fig. 2); in fig. 2 vertical section of the site with a scheme of building up 5 layers of the dam and, accordingly, the height of the drainage wells; in fig. 3 drainage well in section.
The proposed silt pad contains a waterproof base 1, made, for example, of several layers of polyethylene film or a layer of crumpled clay, drainage filtering devices 2 of the "reverse filter" type and perforated drainage pipes 3, equipped with removable plugs at the ends (not shown in Fig.) , water intake trays 4 located along the perimeter of the site, a pipeline 5 for supplying liquid sediment, drainage wells 6 for diverting nadil water and an enclosing dam 7 made of layers 8, 9, 10, 11, 12 of filter material stacked on top of each other. The sole of the dam is located directly on the waterproof base of the 1 platform. Layers of filtering material 8-12 are located with an offset to the vertical axis of the site, and form a container in the form of a truncated pyramid.
Dried sludge from urban wastewater treatment plants is used as a filtering material for the dam.
In the absence of sediment, for example, when a new sewage treatment plant is commissioned, sand or other similar filter material suitable for dam construction can be temporarily used as a filter material.
Drainage wells 6 are made composite of a concrete base 13 and annular elements 14, 15, 16 stacked on top of each other. Wells 6 and dam 7 have the same height all the time, increasing in parallel during the period of filling the silt pad. The bases of wells 6 are connected to the outlet pipeline 17.
At the level of the inlet 18 of the wells 6 in the guides 19 there is a "floating" water seal 20 with a foam packing 21.
The inlet 18 is adjusted in height by a set of bars 22 blocking its flow section, laid in grooves 23.
The silt pad works as follows:
Before putting into operation, the site is protected by the bottom layer 8 of the dam. At the same time, the drainage wells 6 also have a minimum height and consist of a concrete base 13 and one lower annular element 14, the "floating" water seal 20 is in the lower position. The liquid precipitate is fed through the pipeline 5 continuously. It gradually fills the entire area up to the level of the top of the bottom layer of the dam. At the same time, the pipes 3 of the drainage filtering devices are blocked with plugs and there is no filtering process through them. Settling takes place in the volume of the sludge bed with separation of the liquid and solid phases, with the formation of a bottom layer of sediment, a "pond" and a crust-like layer of sediment that floats on its surface. Nadilovaya water from the "pond" is discharged through the holes 18 of the drainage wells 6. In this case, the water seal 20 is always in the liquid phase and prevents the floating crusty 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 pads, their capacity and filling time increase.
The duration of filling the site can last a season, a year or more. During this time, the sediment thickens. 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 ring element 15 drainage wells. Building up is carried out using construction equipment (bulldozers, excavators, etc.). This is facilitated by the pyramidal shape of the dam with a natural outer slope, which ensures the movement and lifting of equipment along the serpentine road.
With further filling of the site, the sediment layer at its bottom increases and becomes denser, the liquid phase of the "pond" moves up, the floating hydraulic gates 20 on the drainage wells also move up along the guides 19. Nadil water is removed through the wells 6 and discharged through the pipeline 17 outside the area. Surface and melt waters flowing down from the slopes of the dam during rains and snowmelt are discharged into water intake trays 4. During the period of filling the site, all subsequent layers of the dam are periodically built up, and the height of the drainage wells is simultaneously increased to the level of the top of the dam. The duration of the period of filling the sludge site can be 10-20 years or more.
Due to the fact that the outlets of the pipes 3 of the drainage filtering devices are closed with plugs during the entire period of filling the site, sedimentation and clogging of the drainage filters during this period is excluded.
Dehydration at this first stage is mainly due to the settling process with the separation of liquid and solid phases and the removal of nadil water through drainage wells.
After the end of the period of filling the silt pad to the top level of the last layer of the dam and diverting the nadil water from the "pond", the plugs are removed from the pipelines 3 of the drainage filter devices.
The next technological holding period begins, during which further dehydration by filtration and stabilization of the precipitate takes place. After opening the plugs, the filters of the 2 drainage filtering devices begin to work.
Filtration also goes through the entire side surface of the dam with water diverted to the site drainage system and water intake trays 4. At this stage, dehydration occurs in natural conditions and lasts for several years. At the same time, the process of deeper stabilization and disinfection of the sediment continues. After soaking, the sludge bed is ready for sludge unloading, which is carried out using mechanical means. The dehydrated stabilized sludge can be used for economic purposes, for example, as a fertilizer for farmland, for backfilling low-lying areas, and for planning work. The most expedient is the use of dehydrated, stabilized sludge as a filtering material for dam enclosures on neighboring silt beds. At urban wastewater treatment plants, 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 same time, the silt pads fully provide each other with filter material for the construction of the dam.
The proposed design of the sludge pad and the method of its operation provide the following advantages compared to the prototype.
The occupied areas are repeatedly reduced by increasing the capacity of the site. The height of the loaded site can be 10-20 m or more.
Reduced operating costs, including the cost of preparing and restoring a waterproof base and drainage devices, because. their service life increases many times, loading and unloading operations for transshipment of sludge from sludge sites to storage sites are eliminated.
During the entire period of filling the sludge area with liquid sediment, 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 regime of liquid phase filtration through the enclosing dam, which increases the efficiency of natural dehydration.
CLAIM
1. A silt pad containing a waterproof base, drainage filtering devices, drainage wells, water intake trays and a liquid sludge supply pipeline, characterized in that it is additionally equipped with an enclosing dam made of horizontal layers of filter material, and the bottom of the dam is placed on the waterproof base of the site, the layers are stacked with an offset to the vertical axis and form a container in the form of a truncated pyramid, and the drainage wells are made of composite ring elements installed on top of each other to the level of the top of the dam.
2. The site according to claim 1, characterized in that the enclosing dam is made of dehydrated urban sewage sludge.
3. A method for operating a sludge site according to claim 1, 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, characterized in that before filling the site, it is fenced with a lower layer dams, in the process of filling, as sediment accumulates, the next layers of the dam and the height of the drainage wells are periodically built up, and filtration through drainage filtering devices is carried out after filling is completed during the holding period.
Sludge sites of treatment facilities are necessary for dehydration of sewage sludge.
The foundation of these sites can be both with a natural foundation (with and without drainage), as well as with surface drainage. Silt pads are planned plots of land (maps), which are surrounded on all sides by earthen ridges.
Sludge from settling tanks or digesters, the moisture content of which is from 90 to 99.5%, is poured into areas with a certain frequency and dried to 75-80%. A small part of the sediment seeps into the ground, but a larger percentage of it evaporates. Natural bed sludge beds do not provide drainage if they are placed on soil with good filtration capacity. And for dense, poorly permeable soil, tubular drainage is created, laid in ditches with crushed stone and gravel.
Wastewater treatment plants of small sizes have a width of 10 m, and for large ones it increases to 35-40 m. The pits are separated by protective rollers, with a height of 0.3 m above the working level. Sediment is distributed over the maps using pipes. Sludge beds are promptly freed from sediment. At large sewage treatment plants, the sludge is removed using bulldozers and scrapers. For treatment facilities with a capacity of more than 10,000 m3/day, sludge platforms are arranged with settling and surface drainage of sludge water. As it accumulates, the upper layer of interstitial water is pumped into primary settling tanks. Subsequent dehydration of the sludge occurs due to the evaporation of moisture from the surface.
The area of sludge beds depends on the volume of sediment, the type of soil on which they will be organized, climatic conditions and the consistency of the sediment. Natural drying can be accelerated by agitating the sediment. During this process, the vegetation layer is removed and the surface crust is destroyed, which accelerates the drying of the sediment in the warm dry season and contributes to deeper freezing in the winter. Sites of the natural cycle depend on climatic conditions, which is important in the creation of the project and the subsequent operation of such sites.
GC "Poleka" is engaged in the design, installation and subsequent maintenance of treatment facilities, including the maintenance of sludge sites. We offer our customers turnkey services and provide quality assurance for equipment with a service life of up to 50 years. The use of modern and time-tested technologies makes it possible to create reliable and easy-to-use treatment facilities.
