We are interested in cooperation with the manufacturers of sedimentation tanks, who are looking for an official and reliable distributor to deal with supply & delivery of their equipment to the industrial plants in Russia.
The company’s top management and sales team are well acquainted with the Russian market, its mentality and laws; they also understand industrial specifics of the financial and economic activities of the Russian customers. All our sales managers have a large customer database, extensive experience of successful sales and well-established connections with the potential buyers of your sedimentation tanks. This allows our managers to promptly set out the most promising directions for promotion and to ensure a rapid entry of the products into the promising Russian market. Our employees, who are fluent in English and German, are focused on working at the international market with the supplies of foreign equipment.
Our team of experienced engineers, who can handle the most serious technical problems, constantly keeps in touch with the Russian customers, holds meetings and delivers presentations regarding the latest achievements of our manufacturing partners. They point out the engineering challenges and actively communicate with all the departments at Russian plants. That is why the specifics of doing a business in the Russian Federation are well-known to us, and we also know the equipment of the local industrial plants and their up-to-date modernization needs.
Once we become your authorized representative in Russia, our marketing staff will carry out a market research in order to check the demand for sedimentation tanks, will submit a market overview for sedimentation tanks that you offer and evaluate the needs for this type of equipment at local plants. Our specialists will also estimate the potential and capacity of this market at local industrial plants. Our IT-team will start developing a website for your products in Russian. Our experts will assess the conformity between your sedimentation tanks and customer needs as well as analyze the common reaction to the new goods in general. We will look into the categories of potential customers, and pick out the largest and the most promising plants.
Upon becoming your authorized agent on the territory of Russia, ‘Intech GmbH’ LLC (ООО «Интех ГмбХ»), will obtain certificates, if required, for a batch of the goods, for various types of sedimentation tanks in compliance with Russian standards. We can also arrange the inspection in order to obtain TR TS 010 and TR TS 012 Certificates. These certificates provides permission to operate your equipment at all industrial plants of the EAEU countries (Russia, Kazakhstan, Belarus, Armenia, Kyrgyzstan), including the hazardous industrial facilities. Our company is eager to assist in issuing Technical Passports for sedimentation tanks as per Russian and other EAEU countries’ requirements.
Our engineering company ‘Intech GmbH’ LLC (ООО «Интех ГмбХ»), collaborates with several Russian design institutes in various industrial segments, which allows us to conduct preliminary design as well as subsequent design works according to the standards, construction rules and regulations that are applicable in Russia and other CIS countries. It also enables us to include your sedimentation tanks into the future projects.
The Company has its own logistics department that can provide packing service, handling as well as the most efficient and cost effective mode of transportation of the goods (incl. over dimensional and overweight goods). The goods can be delivered on DAP or DDP-customer’s warehouse basis in full compliance with all the relevant regulations and requirements that are applicable on the Russian market.
Our company has its own certified specialists who will carry out installation supervision and commissioning of the delivered equipment, as well as further guarantee and post-guarantee maintenance of sedimentation tanks. They will also provide necessary training and guidance for the customer’s personnel.
Such units are used in the domestic and industrial wastewater filtration systems with a capacity of not more than 25 thous. m3 per day. Vertical flow settling tanks have structural design of cylindrical vessels with base diameter of 3 to 10 m and conical bottom for collecting the residue. There is also a square “cellular settling tank” (each side of 12 to 14 meters). Bottom part of such settling tanks is a structure of four pyramidal sludge receivers with individual sediment discharge (separately for each receiver).
The difference in settling tank design consists in the arrangement of the input and outlet devices, and hence the value of their capacity. The latter depends not only on the geometrical shape of the settling tank, but also on the ratio of the volume efficiency.
General Principles: Vertical flow settling tank with side inlet operates as follows. The wastewater is supplied into the distributing gutter mounted on the perimeter of the settling tank (the gutter has a special design with variable profile section). Then liquid gets into the annular cavity through the spillway between the settling tank wall and training partition wall. There is a sediment barrier at the bottom of the annular cavity, which redistributes the flow of water in the sludge zone. Treated water drainage is performed through a triangular weir (located on both sides) in a circular collecting tray. At that, light materials (grease) are removed from the water surface through a funnel located in the annular cavity.
Dimensions of vertical primary settling tank can be determined from the expression:
R = √(1.1)
Where R – settling tank radius, m
Q – quantity of slime water flow, m³/h
k – coefficient of volume use (for settling tanks with a central intake system k is equal to 0.35; in case of peripheral water inlet and upstream-downward flow, k = 0.65-0.7)
υОС – speed of pollution settling, m/s.
For settling tanks with upstream-downward flow the radius value R should be increased by 1.4 times.
When calculating settling tanks with peripheral intake system, the taken initial radius should not exceed 5 meters. Dimensions of the annular area are calculated as follows:
δ = R-√(1.2)
where υin – priori water inlet velocity in the working area (is about 5-7 mm/s).
Taken value of the settling tank depth should be 8·δ; depth of the guide wall is 0.7·Н; width of the sediment barrier is 2·δ. The input flow rate into the distributing gutter (and rate of fluid flow inside it) should be 0.4-0.5 mm/s. The size of the interior partition wall in the annular water collector is 0.5·R; value of the surface loading on the triangular weir is 6 l/(s·m).
Configuration of silt-collecting part of the settling tank should have sloping walls with angle not less than 50 degrees.
Vertical flow settling tanks are calculated quite easily if performance (Q) and settling time required (t) are known.
Working capacity of the unit is calculated according to the formula:
Vp = Q·τ (1.3)
Height of working area H is calculated according to the expression (in m):
H = υ·τ (1.4)
where υ – flow rate of the slime water inside the settling tank (taken in the range 0.2-0.3 mm/s).
The area of the working section is:
Fc = Vp/H (1.5)
And settling tank diameter can be calculated as:
Dsettl tank = √(1.6)
where fc.p. – area of the useful cross section of the central pipeline:
fcp = Q/υcp (1.7)
where υc.p. – flow rate of slime water in the central pipeline that is taken no more than 300 mm/s.
With calculated values Dsettl tank and Н, it is easy to choose a suitable typical settling tank of the standard range.
Vo – amount of liquid phase, which is in suspension (m³/h).
V1 – amount of clarified liquid in the suspensions (m³/h)
V2 – amount of liquid phase in the sediment (m³/h).
x0 – concentration of the suspension before settling (kgf of dried sludge per 1 kgf of liquid).
x2 – residue concentration (kgf of dried sludge per 1 kgf of liquid in the sediment).
ω2 – settling rate (m/sec).
Fo – tank section area or settling surface (m2).
γ1 – liquid specific gravity (kgf/m³).
τ – settling time (h).
If there are no liquid losses, the equality is fulfilled:
V0 = V1 + V2
If the liquid layers after clarification (as shown in Figure above) with a height h, to express performance (m³/hour) of the settling tank, use the equation:
V1 = (F0·h) / τ
At that, the retention time t depends on the particle settling rate ωо at a certain height of the liquid phase layer:
τ = h / (3600·w0)
Substituting t in the previous equation, we get:
V1 = [F0·h] / [h/(3600·w0)] = 3600·w0·F0
Thus, it is possible to calculate the settling tank performance that does not depend on its height, and depends exclusively on the settling tank surface and particle settling rate. Therefore, modern settling tanks have a large cross-sectional area, and their height is small.
Settling surface (m2) necessary for receiving V1 (m³/h) clarified liquid, if concentrations хо and х2 are known, can be found by using the formula:
F0 = (V0-V2)/(3600·w0)
This type is a kind of a vertical flow settling tank. Their height is just 0.1-0.15 meters, diameter - 16-100 meters. They are used for clarifying wastewater having a high turbidity, as well as for industrial water supply purification. Water is supplied to the central part of the radial-flow settling tank, and treated water drainage is performed through a circular hole located in the upper part of the unit. Residue deposited on the bottom is collected with rotating scrapers.
Radial-flow settling tanks are used at the wastewater treatment plants, the performance of which is more than 20 thous. m³ per day. Radial-flow settling tanks remove about 50% of suspended solids.
Such settling tanks are used in the slime water filtration systems at a rate of 20 thous. m³ per day. In comparison with the horizontal type units, radial-flow settling tanks have:
There are settling tanks with three types of intake systems in the sewer systems:
Most often settling tanks with central liquid supply are used. A characteristic feature of this type of units is a centralized supply of filtered water from the bottom (through a special pipe). While the clarified liquid is removed in a circular channel through the tray and triangular weirs.
Usually, primary radial-flow settling tanks are fitted with sludge scrapers that draw the precipitate toward the central sludge receiver, from where it can be pumped pressed out with a mass of the incoming liquid. Light fractions floating and accumulating on the surface are removed in the floats-fat collectors lowering under the water with a special device when approaching the sludge scrapers.
Secondary settling tanks are fitted with rotating sludge suction device to collect light residue (so-called active sludge, etc.). The residue is removed directly from the liquid layer under the static pressure without moving to sludge receiver. Rotary speed of the sludge scrapers and slime pumps is 0.8-3 h-1.
During the calculation the value of the settling tank radius is determined from the expression (1.1), where coeff. k = 0.45. The diameter value is not less than 18 m; diameter-to-thickness ratio of the flowing part is from 6 to 12 (for industrial wastewater - 30); the depth of the flow part - 1.5-5 m. Location of the neutral layer is set at 0.3 m; for secondary settling tank the depth of the sludge layer should be considered (in the range 0.3-0.5 m). The load on the front end of the triangular weir should not be higher than 10 l/(s m).
Thin-layer settling tanks are used for efficient separation of finely dispersed impurities. Their relatively small depth allows clarifying liquid for 4-10 minutes presence of the filtrate in the work area. Dimensions of units are much lower than dimensions of settling tanks of other designs. In addition, thin-layer settling tanks can be installed in closed spaces. The simple design and materials available materials allow producing such settling tanks at any production site. An additional advantage is absence of necessity for “supplies” and other supplements.
The design of thin-layer settling tanks is made in the form of shallow (about 0.2-0.3 m) tanks with special inserts in the form of tube trusses or shelves. These inserts are called drains and installed at an angle to ensure natural piling of the deposited sludge to the receptacle. Settling tanks with a gentle slope of tubular inserts are applied in systems with a slime water flow rate from 100 to 10 thous. per day. Steeply inclined settling tanks (with the angle of pipes installation about 45-60 deg.) are used in water treatment systems with a flow rate up to 170 thous. m³ per day.
Thin-layer settling tanks can significantly intensify the deposition process, and increase the clarification effect on average by 25% and reduce the built-up area for settling tank by 60%. In addition, advantages include resistance to changes in water temperature, contaminants concentrations, as well as constancy of performance even at b fluctuation treated water flow.
The principle of thin-layer settling tanks is used in the reconstruction of the operating settling tanks of different types for increasing their productivity. This principle is considered to be the most efficient and sometimes even the only possible one, given the confined area of wastewater treatment plants, especially in the absence of free land areas. Thus, the reconstruction of facilities can be made within a short time, as re-equipment of wastewater treatment plants in the thin-layer settling tanks does not require a complicated and long construction work. It all comes down only to the installation of thin-layer items in the settling area.
Such items may be made of flexible materials, as well as materials of sufficient hardness. In order ensure a slipping of suspended matter in the residual part of the settling tank that is deposited on the surface of the thin-layer settling tank, its elements are inclined to the horizontally, about 55-60 degrees. Thin-layer items of the settling tank are made in the form of corrugated or planar shelves, as well as in the form of round, rectangular or square cross section.
This method is most effective for the treatment of colored water with a small or medium turbidity. For the reason that water residence time in the thin-layer settling tanks is quite short, it is necessary to ensure uniform flow distribution between all the elements and uniform mixing of water with a reagent (if used) and to create the conditions necessary for the flocculation process.
Poor performance of mixers in the usual settling tanks can be compensated due to the long storage time of water in the settling tank, but it is impossible in the thin-layer settling tanks.
Numerous studies have proven that the natural (under the action of gravity) separation of fine suspended matters proceeds much more intensive in the enclosed volume of items angled in the horizontal plane at 45-60 deg., than in open trays. As the turbulent flow increases the "carrying" capacity of the liquid, the laminar flow of slime water is organized inside the settling tank to increase their degree of clarification.
The figure above shows the design of thin-walled tube settling tank. The main working body is a tube about 60-100 cm in length and Ø 2.5-5 cm. The cross section of the tube can be square, in the form of a hexagon, rhombus, etc.
The foreign-made settling tanks are typically manufactured as standardized blocks of plastic (PVC or polystyrene). Building blocks have a length, width, height about 3 m, 0.75 m, 0.5 m, respectively. Size of tubes cross section is 5 x 5 cm. Standardized sizes facilitate installation of blocks inside the existing settling tanks of any type (including radial, horizontal and vertical).
Thin-layer plate settling tanks include a package of inclined shelves. Liquid moves along its plane, the solid particles are retained on the plates and roll down to the sludge settling tank.
Depending on the configuration of the motion of filtered water inside the settling tank, as well as a method of precipitation, a distinction is made between:
It should be noted that counterflow settling tanks are the most wide spread (due to their better performance).
The figure below shows a thin-walled settling tank. For basic operation modes of this unit (i.e., at a flow rate of 4-7 mm / s and filtration in the inter-shelf space for 20-25 min) it is achieved steady clarification of not less than 93-95% (at a concentration of a solid phase in the initial suspended matter of 4-12 mg/l). For effective cleaning of coagulated water, there are used shelf thin-walled pressure settling tanks with water in the cleaning zone up to 10 min.
Classification of thin-layer settling tanks is made by the following parameters:
In terms of pipe type, there are cross-section rectangular, square, hexagonal or circular pipes.
The gap between the individual pipes (shelves) h0 is typically 50-150 mm, operation length varies from one to two meters.
Calculation of the design of thin-layer settling tanks is made to determine geometric parameters (length, width and height of water channel) - with pre-known flow rate of filtered water Q (m³/sec), concentration of solids in suspension (before and after filtration) and chemical properties of impurities.
Horizontal settling tanks are used in wastewater treatment plants with the capacity of more than 15 thousand m³/day.
Settling tanks of rectangular form are used in most cases. Sludge hoppers are arranged in 1-2 rows at the beginning of settling tanks. Scraper mechanisms are also installed in the structure, often of carriage or a belt-type, which move residue to sludge hoppers. Residue is removed from them by means of pumps, hydraulic elevator, grabs or under hydrostatic pressure. Light residue such as activated sludge is removed without raking by airlift units.
Inlet and outlet devices have such design so that the flow of water could uniformly distribute over the entire area of the effective cross-section of the settling tank. Water is supplied through a free spillway located in the frontal part of the settling tank. In this case, guide semi-submersible membrane is arranged at the beginning of the reservoir. Water removal is made through drainage trays installed in the end of the settling tank. Semi-submersible walls are installed before trays, which entrap floating pollutants.
The flow part of the settling tank has depth of 1.5-4 m, length - more than depth by 8-12 times (or 20 times when dealing with industrial wastewater). Width of the settling tank depends on the manner in which residue is removed and is usually 6-9 m. Width of the settling tank depends on width of the aeration tank in biological treatment plants. The bottom of the tank should have slope to hoppers of at least 0.005. When calculating height of the neutral layer over the surface of residue is taken equal to 0.3 m, depth of sludge layer is taken into account for secondary settling tanks equal to 0.3-0.5 m. Wastewater flow rate is considered to be equal to 5-10 mm/sec.
Length of the settling tank may be determined by the formula:
L = (υ·H)/ωос (2.1)
where L – length of the settling tank, m;
υ – velocity of fluid movement in the settling tank, m/sec;
H – depth of the settling tank, m;
ωос – velocity of particle deposition in the settling tank, m/sec.
Velocity of particle deposition, in its turn, can be determined by the formula:
ωос = 1/18 · (dт·ρт·g)/μж (2.2)
where ωос – velocity of particle deposition in the settling tank, m/sec;
dт – minimum equivalent diameter of deposited particles, m;
ρт – apparent particle density, kg/m³;
g – acceleration due to gravity, 9.81 m/sec2;
μж – dynamic viscosity of fluid, Pa • sec.
Settling tanks are used for clarification, that is, separation of water and particulate pollutants. Depending on the type of pollution and objectives, thickeners and classifiers allowing intensifying the wastewater treatment processes are used along with the classic settling tanks. Constructive solutions for thickeners and classifiers are identical, only methodologies for calculating deposition of suspended particles have differences.
Thickeners are calculated according to deposition rate of the finest particulate matter in effluent, and calculation of classifiers is focused on substances that are to be separated in the first place. The following inputs are used to calculate deposition surface of settling tanks:
The formulas for calculating each parameter are given. Settling tanks are equipped with continuous rake mixers for activation of cleaning process. Settling of suspension is accelerated by centrifugal force.
Surface of deposition, which is the basic calculated value of settling tanks is determined by the formula:
F = Kз · Gсм/(ρосв·ωст) · [(xос-xсм)/(xос-xосв)] (2.3)
where Kp – surface reserve coefficient,
Gсм – initial suspension mass flow, kg/sec;
ρост – clarified liquid density, kg/m³;
ωст – velocity of deposition of particles of suspension, m/sec;
хос – concentration of solids in residue, mass. share;
хсм – concentration of solids in initial mixture of suspension, mass. share;
хосв – concentration of solids in clarified liquid, mass. share.
The settling process occurs in unit of continuous and discontinuous operation, and in unit of the combined type.
Suspension is poured and left to rest for a certain time, which is necessary for sedimentation of particles in units of discontinuous operation. After this, decantation of layer of clarified liquid occurs, i.e. liquid layer is poured through taps or siphon tube located above the level of residue. After draining, residue is discharged to manually through the top of unit and is removed by the lower trigger tap.
This type is used for suspension and represents pools that do not have mixer devices. The settling tank is filled with suspension, and liquid layer that has already been clarified is discharged through nozzle located above the level of residue after a certain time, which is necessary for deposition of solids. Residue, which appears to be sludge (sludge fluid) is moved either manually or through the top part of unit, or removed through the lower nozzle using the trigger tap.
The simplest continuous settling tanks are "cones", which are widely used for wet classification of ores.
Cone settling tank is a cone reservoir with 60° of slope. Suspension enters the settling tank through run, and then flows into the cone through funnel that has a floating ring. Thus, suspended particles are deposited on the bottom of the body, and clarified liquid is removed through run.
Residue accumulating at the bottom of the cone is piped to the outside. The cone is connected to pressure pipe using a flow-pipe. Thus washing of unit is performed, if it is plugged with residue.
Typically, such devices are installed in form of batteries of few cones connected in series.
The figure below shows a diagram of a multilayer continuous settling tank used for water treatment:
Water enters the reservoir, where it is processed with whitewash and soda. Thereafter, suspension is directed into the body, where several layers of conical membranes are located. Each layer of the settling tank works independently. Water after treatment is directed by central tube and removed from unit. Residue that has accumulated on the surface of conical membranes drifts and is removed through flow-pipe. It is important that the membranes angle of slope could exceed the angle essential slope of residue. Collected in the bottom residue is removed periodically.
Washing water is used for preparation of initial suspension. At the same time, the operation is carried out by the countercurrent principle in order not to introduce a lot of washing liquid. This means that residue is moving in the direction from the first to the last settling tank, and passes all devices in series. Fresh washing liquid is directed from the first to the last settling tank. It passes successively through all settling tanks in the opposite direction from movement of residue.
The method based on continuous settling with washing is more favorable when compared with washing by filter. The reason for that is based on the fact that it does not expend energy for sucking all fluid through filter membranes.
Settling tanks are used for reducing the area occupied by unit multilayer. Such settling tanks consist of several units arranged vertically one above the other.
Suspension is continuously supplied to the upper layer in such a settling tank, and fresh liquid for washing from the reservoir flows through the lower part of the penultimate layer of the settling tank. Liquid after clarification is continuously removed through run from the upper layer, and then delivered through a conduit. Run is located at the top of the settling tank. Thickened residue is collected in the interceptor located at the bottom of layer. Washing liquid is also supplied here coming from the section that is located below the reservoir and through a particular conduit. Residue is washed by washing water to the lower layer, where the process of settling and washing is performed in a similar manner. After these operations, residue is almost completely washed and freed from the initial liquid, and flows out through flow-pipe of the lower layer of the settling tank. Washing liquid in the upper tier can be used to prepare suspensions.
The main disadvantage of all settling tanks is their huge area. Therefore, quite often they are replaced by thickener filters having a more complex design, but compact size.
They are reservoirs made in the form of a cylinder with a conical bottom. Such reservoirs include mixer, fitted with rakes, stirring continuously and moving residue to the central discharge opening, while shaking it, which contributes to dehydration. Mixer has a small rotation frequency (0.00025-0.0083 s-1), so that the deposition process could not be disrupted. At the same time, suspension is continuously fed through a pipe into the center of the reservoir.
Liquid, which has already passed the clarification process is poured into the annular run and then removed through nozzle located in the conical bottom by means of a diaphragm pump. Gearbox and electric motor are used for mixer shaft.
Settling tanks equipped with rake mixer provide uniformity of residue and allow dehydrating solid phase having concentration of 25-55%. These settling tanks operate fully automatically. Bulkiness is another disadvantage of these settling tanks.
Normalized units have diameter of 1.8-30 m. Settling tanks up to 100 meters in diameter are used sometimes. Multilayer units, which are a few settling tanks put against each other and having a common shaft for rake mixer are used for reducing the area occupied by settling tank. Multilevel unit has much more complex structure than conventional one.
Large concrete pools or connected in series reservoirs are used as settling tanks operating in a combined way if it is necessary to perform settling of significant amount of liquid. Fluid flows continuously, and residue removal is made periodically in these tanks.
Settling tank used for cleaning in boiler-plants is an example of a convenient and compact settling tank.
The body of this settling tank is made in form of steel rectangular box. There are inclined membranes inside the body, which direct the flow alternately from top to bottom, and then from bottom to top. Residue is collected at the conical bottom, and then periodically removed through valves.
If concentration of suspended solids in suspension is high or residue can be used for production, continuous discharge both of liquid and of residue is required.
They have a simple design and a large surface area. Suspension entering unit is distributed through channels between conical shelves. Solid particles are deposited on the surface. Resulting residue drifts along inclined shelves toward the body walls, and then moves to the bottom of unit, where it is removed from it. After clarification, liquid enters central tube and is further removed from the top of unit.
Such structures have a large surface of deposition, they do not have moving parts and are very simple to use. Their disadvantage is high humidity of sludge compared to settling tanks with rake mixer.
Continuous settling tank, which is a horizontal reservoir equipped with a perforated membrane is used for separation of emulsions. This membrane does not allow liquid to stress in the settling tank by stream of emulsion flowing into unit. At the same time, when choosing cross-section of the settling tank fluid flow rate is taken into account. This rate should not exceed a few millimeters per second, and the flow regime should be laminar in order to avoid mixing of phases, and improve the settling process.
Light and solid phase is removed after lamination by different sides of the settling tanks. The conduit used for removal of solid phase has a connection with the atmosphere for preventing siphoning.
Upon becoming the official distributer of fabric filters, our company ‘Intech GmbH’ LLC (ООО «Интех ГмбХ»), carries out the following: finds the buyers of your products on the market, conducts technical and commercial negotiations with the customers regarding the supplies of your equipment, concludes contracts. Should a bidding take place, we will collect and prepare all the documents required for the participation, conclude all the necessary contracts for the supply of your equipment, as well as register the goods (fabric filters) and conduct customs clearance procedures. We will also register a certificate of transaction (Passport of Deal) required for all foreign trade contracts in the foreign currency control department of the authorized Russian bank so that currency transaction could be effected. If required, our company will implement an equipment spacing project in order to integrate your equipment into the existing or newly built production plant.
We are convinced that our company ‘Intech GmbH’ LLC (ООО «Интех ГмбХ»), will become your reliable, qualified and efficient partner & distributor in Russia.
We are always open for cooperation, so let’s move forward together!