FLOCCULATION IN A FLOW OF SLUDGE, AND FLOCCULATION CONTROL SYSTEM FOR REGULATING THE ADDITION OF A FLOCCULATING REAGENT

IN SAID FLOW OF SLUDGE

Field of the invention

The present invention relates to a flocculation control device in a flow of slurry or sludge, which has flocculating reagent, and to a flocculation control system of a flow of slurry or sludge wherein one wants to perform a solid-liquid separation.

Background of the invention

In solid-liquid separation treatment, the main objective of which is to eliminate pollution before it flows into the recipient watercourse, a series of by-products called slurry or sludge are generated, where the eliminated pollution is concentrated and the treatment and evacuation whereof may be problematic.

Thus, for example, flocculating reagents are used in wastewater treatment to promote the aggregation of the solids and obtain dehydrated slurry or sludge, which will be later, treated in, for example, an incinerator or as composting depending on its origin.

In general terms, the slurry or sludge undergoes an aggregation stage, called coagulation and/or flocculation, followed by dehydration, called solid-liquid separation, which is generally performed in belt filters, press filters, decanter centrifuges or basket or candle filters, among the most typical. In addition to reduction in the solid volume of the slurry, the object of this dehydration treatment is to facilitate the handling, filtration, transport and storage of this slurry or sludge once dehydrated or with a substantially lower liquid content. Thus, the quantity of flocculating treatment reagent and the efficacy of flocculation as a result of the addition of the flocculating or coagulating reagent influence the liquid content present in the separated solids, that is, the slurry or sludge once dehydrated.

From American patent US6849190, a wastewater treatment system is known which improves the solid-liquid separation in accordance with the viscosity in line of the liquid-rich flow.

Furthermore, Spanish patent ES2350934 discloses filtration systems which incorporate a peripheral apparatus which analyses the characteristics of a thick suspension, treats this suspension before and during its introduction in a filtration chamber and during its stay inside it by means of the use of fabric filters adapted for said purpose. Thus in the American patent US5477891 , from the same inventor as ES2350934, a fabric is used to separate the liquids from solids of a suspension fed to a pressure filter. The woven fabric is woven in a predetermined template and with materials that provide the desired permeability capable of capturing the solids from the suspension and allowing the fluids to flow through them.

However, the solid-liquid systems and equipments based on the type of filter used, the location or the quantity thereof have the drawback of being soiled and blocked faster, especially when the flocculating reagent is not correctly mixed with the slurry or sludge to be treated, which entails shutdowns of the system for its cleaning or replacement.

Devices based on an optical, gravity or decanting, a pressure or vacuum method has been disclosed for flocculation control. These devices continuously takes samples of the flow of slurry or sludge containing the mixed flocculating reagent and, for example, a device based on an optical method performs readings of the quantity of light that passes through said sample. However, when the density of the slurry or sludge to be treated is high or very low, these devices do not provide reliable readings of the quantity of flocculating reagent present in the slurry or sludge and even when the flocculating reagent is not correctly mixed with the slurry or sludge, the reading may be erroneous demanding the addition in the system of a greater quantity of flocculating reagent when the quantity of flocculating reagent should be precisely decreased. Furthermore, the reliability of these devices depends on the type of flocculating reagent used.

The limitations and drawbacks of the systems and devices known in the state of the art for the control of flocculation lead to a deficient solid-liquid separation and, therefore, less dehydrated solids are obtained which entails a greater cost of their transport due to the greater weight and volume, in addition to requiring a greater storage space and a solid treatment cost which is also greater. Neither have the systems and devices known in the state of the art resolved the high consumption of flocculating reagent, nor have they achieved the suitable flocculation, which would avoid or largely reduce the typical and frequent replacement of the filters used in the solid-liquid separation station.

Thus, there is not yet a system and a device which resolves the problems of the state of the art, the device whereof is easy to assembly, easy to handle, more accurate, more reliable and corrects in real time the variations in the solids concentration in a feed flow of slurry or sludge to be dehydrated.

Description of the invention

With the system and device of the invention the aforementioned drawbacks have been successfully resolved, in addition to other advantages that shall be described below.

In a first aspect, the invention relates to a flocculation control device for a flow of slurry or sludge that has mixed flocculating reagent upstream of a solid-liquid separation station.

In particular, according to the first aspect, a flocculation control device is provided for a flow of slurry or sludge containing admixed flocculating reagent therein, upstream a solid-liquid separation station, which is characterized in that said device is equipped with a container with at least two probes disposed consecutively and each one in a different position in the container and a filter capable of dividing the container into two parts, the container whereof by one end is capable of connecting to a flow of slurry or sludge containing the mixed flocculating reagent to receive a sample of said flow of slurry or sludge, and by the other end is equipped with opening and closing means to give an outlet to said sample, the filter being disposed between said two ends, where each one of said at least two probes is configured to provide a signal indicative of the presence or absence of sample in each one of said positions, allowing the difference in position, or the separated distance, of each one of said at least two consecutive probes to calculate the degree of flocculation of the sample in accordance with the time elapsed between each signal indicative of the presence or absence of sample provided by each one of said at least two probes in the filtered of said sample.

The container is substantially elongated, and in use, preferably it is disposed in vertical position.

Advantageously, with the device according to the first aspect a much more accurate reading is provided of the excess or demand of flocculating reagent to be mixed in the flow of slurry or sludge, which allows buffering the variations of solids in the flow or source of feed of slurry or sludge to be treated, and in use provide a fraction rich in solids with the dryness or humidity desired, regulate in real time the consumption of flocculating reagent according to the desired flocculation requirements and, therefore, save in the consumption of flocculating reagent. Furthermore, with the device according to the first aspect of the invention it is possible to obtain a degree of dehydration in the solid-rich fraction which is much more homogeneous throughout the flocculation of the slurry or sludge to be treated.

Advantageously, the control of flocculating reagent makes it possible to enormously reduce its consumption at the same guaranteeing an adequate flocculation, which undoubtedly represents a financial and energy saving of high importance for the wastewater treatment plant or other industries, which perform a solid-liquid separation of large volumes of slurry or sludge.

In a second aspect, the invention relates to a flocculation control system through the addition of flocculating reagent to a flow of slurry or sludge in a slurry or sludge treatment plant which uses the flocculation control device according to the first aspect of the invention.

In particular, according to the second aspect, a flocculation control system is provided by means of the addition of flocculating reagent to a flow of slurry or sludge, which is characterized in that it comprises:

- a flocculation control device according to the first aspect of the invention adapted to quantify the time elapsed when a sample of said flow passes between at least two consecutive probes each one disposed in a different position in the device containing a filter, and adapted to provide a signal indicative of said time change determined, said flocculation control device being downstream of the introduction of the flocculating reagent to the flow of slurry and upstream of a solid-liquid separation station,

- and, an automatic processor equipped with a ratio of the time interval elapsed when the sample passes between at least two consecutive probes of the flocculation control device to analyse the degree of flocculation and compare it with a predetermined value which indicates the quantity of flocculating reagent present in said sample only in accordance with said signal, and adapted to receive said signal, to process said signal according to said ratio, and to provide another signal in the flocculating reagent feed source to increase or reduce the quantity of flocculating reagent to introduce in the flow of slurry or sludge, said flocculating reagent feed source being upstream of the flocculation control device.

Advantageously, with the system of the present invention, the quantity of liquid is reduced in the solid-rich fraction after the solid-liquid separation, it adapts in real time to the variations of solids in the inlet flow of slurry or sludge to be treated, it is independent of the type of flocculating reagent used and it corrects with improved precision the excess or demand of flocculating reagent to be mixed in the flow of slurry or sludge which is being treated. When "real time" is mentioned, it is clear that a certain delay time may exist, in particular, where a short integration time is necessary or in probes where the calculation of a parameter takes place.

Advantageously, with the system according to the second aspect of the present invention it is possible to improve the degree of flocculation of the solids in suspension of a flow of slurry or sludge since the system is designed to easily and quickly modify the quantity of flocculating reagent to be added to the flow of slurry or sludge to be treated which makes it possible to correct the concentration fluctuations of the solids in suspension of the inlet flow of slurry or sludge in the system and thus provide a solid-rich fraction with the degree of dehydration desired.

Also advantageously, with the system according to the second aspect there is saving in the consumption of flocculating reagent which is added to the flocculation process as it has a more accurate and more reliable control of the demand or excess of flocculating reagent to be mixed in a flow of slurry or sludge which has pre- established a set point of flocculating reagent to introduce in the flocculation process for the treatment of a slurry or sludge.

Another aspect of the present invention is to provide an improved flocculation process for the treatment of a flow of slurry or sludge containing the admixed flocculating reagent therein, upstream of a solid-liquid separation station. The flocculation process is based on the control of the degree of the flocculation in said flow of slurry or sludge containing the admixed flocculating reagent, upstream of solid-liquid separation station.

The process according to this aspect of the invention comprises:

- analysing the flocculation degree of a flow of slurry or sludge having the mixed flocculating reagent and comparing with a preset flocculation degree, and

- if the flocculation degree analysed does not correspond with the preset flocculation degree, then correcting by adding or reducing the quantity of flocculating reagent to be mixed at the flow of slurry or sludge.

The degree of flocculation which initially is preset depends on the degree of dehydration desired in the solids obtained downstream of the station solid-liquid separation.

The flocculation process of the flow of slurry or sludge is performed upstream of the station of solid-liquid separation which is commonly equipped with band filters, filter presses, centrifugal separators, filter basket or any other equipment known to those skilled in the art suitable to perform solid-liquid separation.

The flocculation process in a flow of slurry or sludge flow containing the mixed flocculating reagent, upstream of a station solid-liquid separation, is characterized in that it comprises:

i) analyse the flocculation degree of a flow of slurry or sludge flow having the mixed flocculating reagent therein by:

- i-1 ) conducting a sample of sludge or sludge flow having the mixed flocculating reagent through a flocculation control device according to the first aspect of the invention equipped with a container with at least two probes disposed consecutively and each one in a different position in the container and a filter, the container whereof by one end comprises means for connecting to said flow of slurry or sludge having the mixed flocculating reagent to receive a sample of said flow of slurry or sludge, and by the other end comprises means for opening and closing the container to give an outlet to said sample, the filter being disposed between said two ends, where each one of said at least two probes provides a signal indicative of the presence or absence of sample in each one of said positions,

- i-2) measuring the elapsed time for filtering the sample between said at least two probes disposed consecutively,

- calculate the degree of flocculation of the sample as a function of the elapsed time of filtering the sample through the filter between said at least two probes disposed consecutively, and compared with a preset degree of flocculation, and

ii) if the flocculation degree analysed does not correspond with the preset degree of flocculation, then:

- ii-1 ) when the degree of flocculation is less than the preset degree, then increase the quantity of flocculating reagent to add to the flow of slurry or sludge upstream of the flow of slurry or sludge having the mixed flocculating reagent, and when the degree of flocculation is greater than the preset degree, then decrease the quantity of flocculating reagent to add to the flow of slurry or sludge upstream of the flocculation control device,

and

- ii-2) for a new control of the flocculation of a sample, clean the container prior to fill it again for a new filtering of a sample.

Brief description of the figures

Other advantages, and objects of the invention shall become apparent from the detailed description of the invention below when considered in combination with the accompanying figures, which are diagrammatic and do not have the intention of limiting their scaling.

Although not all the drawings include the numerical reference for each component represented therein, it is understood that the same component has the same numerical reference in all the figures where in it is depicted.

Figure 1 is a diagrammatic drawing of the flocculation control device (A) comprising a container (1 ), in this embodiment of non-conductive material, with conductor probes (2, [L1 , L2,...,LL1 , LL2,..]) disposed consecutively and each one at a different height in the container (1 ) and a filter (3) in a position such that the filter (3) divides the container (1 ) into two parts. One end (1 1 ) of the container (1 ) has a valve (51 ) which makes it possible to receive inside the container (1 ) a sample of the flow of slurry or sludge having the mixed flocculating reagent whereto the device (A) is connected, and the other end (12) comprises a valve (41 ) to give an outlet to said sample and empty the container (1 ). In said figure 1 , the filter (3) is shown in a working position, preferably in a horizontal position when the container (1 ) is disposed in a vertical position, so that the filter (3) divides the container (1 ) into two parts. Figure 2 shows another embodiment of the device (A) according to the first aspect of the invention. Different to Figure 1 , in said Figure 2, the filter (3) is shown in a cleaning position, i. e. in a vertical position with respect to the vertical position of the container (1 ) which is substantially elongated, so that the filter (3) does not divide the container (1 ) into two parts so that the sample may flow through the control device to exit by the end (12) of the container (1 ).

Figures 3A and 3B show other different embodiments of the positions of the probes in the device (A) according to the first aspect of the invention. Figure 3A shows probes (2, [L1 , L2,...]) disposed upstream of the filter (3), whilst Figure 3B shows probes (2, [LL1 , LL2,...]) disposed downstream of the filter (3). Figure 3A further shows in dashed lines an inlet (6) to the device (A) of air or water pressurized to force and facilitate the passage of the sample of slurry or sludge through the device (A), said inlet (6) being arranged next the entrance of the sample of slurry or sludge to the container (1 ).

Figure 4 shows a diagrammatic flow diagram of the flocculation control system by means of the addition of flocculating reagent to a flow of slurry or sludge to be treated, upstream the solid- liquid separation represented by a press filter (8), according to the second aspect of the invention. Said Figure 4 depicts the direction of the circulation of the flow of slurry of sludge to be treated from a sludge tank (7), which does not contain mixed flocculating reagent, to the entrance of the press filter (8), which contains the mixed flocculating reagent. The slurry or sludge feed pump (9), the flocculating reagent feed pump (10), the flocculation control device (A), and the flocculating reagent tank (15) are also shown.

Said Figure 4 also diagrammatically depicts the transmission of information to the automatic processor (1 1 1 ), flow of slurry or sludge controller (1 12), flow of flocculating reagent controller (1 13), signal from each probe of the device (A), or inlet pressure (14) to press filter (8), and the actuation of the automatic processor (1 1 1 ) on the slurry or sludge pump (9) or the flocculating reagent pump (10).

Figure 5 shows schematic device (A) according to the first aspect of the invention. The device (A) comprises a container (1 ) with probes (2, [L1 , L2,...,L9]) disposed consecutively and each one at a different height in the container and a filter (3). The container (1 ) comprises in one end (1 1 ) a valve (51 ) which makes it possible to receive inside the container (1 ) a sample of the flow of slurry or sludge having the mixed flocculating reagent whereto the device (A) is connected, and further comprises in the other end (12) a valve (41 ) to give an outlet to said sample and empty the container (1 ). In said Figure 5, the filter (3) is disposed inside the valve (41 ) dividing the container (1 ) into two parts. In this embodiment, the device (A) is equipped with two inlets (6) for entering optionally air and/or water pressurized inside the container (1 ) which force and facilitate the passage of the sample of slurry or sludge through the device (A). In this alternative embodiment, represented by Figure 5, means for vent (16) are included in the device (A) to easily maintain the pressure inside the container (1 ) when a sample of slurry or sludge having the admixed flocculating reagent therein is gravity filtered through the filter (3). Detailed description of the invention

In the present invention "flow of slurry or sludge" is understood as any waste flow which may contain solids in suspension such as a sludge, liquid slurry, semi-solid system, or a liquid containing solids or containing suspended components such as that, for example, the waste flow from a municipal wastewater plant, from a water treatment plant, from a septic tank, from an industrial process, or similar. The solid content may be of any concentration.

"Solid-liquid separation station" is understood as the solid-liquid separation that takes place in belt filters, press filters, centrifugal decanters, basket or candle filters, among the most typical.

The term "filter" is understood as any element susceptible to allow filtering a suspension of solids. The filter may be removable. The filter may be disposed in a filtering position, disposed in an horizontal position with respect to the direction of the flow of slurry or sludge into the container, and in a cleaning position, disposed in the same position as the direction of the flow of slurry or sludge, to give an outlet to the sample of slurry or sludge. The filter may be disposed inside the means for opening and closing the container.

The term "container" is understood as a recipient substantially elongated through whom a sample of flow of slurry or sludge is traversed. The container contains at least two probes disposed each one in a different position along the container in order to take measurements of the presence or absence of the sample of the slurry or sludge in that position.

In the present invention "probe" is understood as an instrument which can generate a digital or analogue signal of any magnitude of the flow of slurry or sludge which has the mixed flocculating reagent, said digital or analogue signal being an indirect reading for the calculation of the time elapsed between at least two of said probes disposed each one in a different position along the container in accordance with the degree of flocculation of the flow of slurry or sludge which has the mixed flocculating reagent. The probes may be disposed inside the container or outside the container. The magnitude to be analysed may be mass, pressure, flow intensity, light intensity, or any other magnitude which may generate a signal which indicates if there is or not sample in the position where the probe is located. The measurement and quantification of said magnitude in the flow of slurry or sludge which has flocculating reagent is not an object of the present invention, instead its use as a function of the presence or absence of the sample of flow of slurry or sludge at this position. Said probe can be selected from conductivity, ultrasound, pressure, membrane, a transducer, a photocell, a floater or a pneumatic cylinder probe or any probe capable of providing a digital or analogue signal indicative of the presence or absence of sample in the position where the probe is located.

The device and system according to the aspects of the present invention have application in any process where one wants to treat a flow of slurry or sludge by means of the addition of a flocculating reagent before the solid-liquid separation, for example, in the filling of press filters, in process with belt filters, decanters, thickeners, candle, basket filters, among others.

Advantageously, the number of probes is any number greater than two, so that at least two readings can be taken when it is filtered a sample of slurry or sludge containing the mixed flocculating reagent therein which make it possible to calculate the time elapsed between said at least two probes disposed in different positions in the container, being the probes installed inside or outside of the container.

The container can be made of any commercially available material, which does not interfere with the reading of the probe used. Thus, for example, if conductivity probes are used, the container material must be a non-conductor; if light probes are used, the container material must be transparent or translucent, etc...

The flocculating reagent, which is added and mixed to the flow of slurry or sludge, may be any flocculating and/or coagulating agent, which allows or facilitates the separation or aggregation of the solids in suspension in said flow. The type of flocculating reagent does not form part of the object of the present invention; what is more, according to the aspects of the invention the type of reagent varies neither the operation of the device nor the operation of the flocculation control system.

The coagulation or flocculation is a destabilization process of the electrical charges of the suspensions. The solids are maintained in suspension producing turbidity in the water, due to the electrostatic repulsion, which is produced between particles of the same sign, since around each one of them an alternation of electrical charges is generated, which generates the ZETA potential. It is necessary to break the zeta potential or electrostatic repulsion. To break the ZETA potential a flocculating reagent is added, which by means of aggregation or adsorption mechanisms cancels out the repulsive forces. As the repulsive forces are cancelled out it allows the aggregation of the particles in others of greater size and it is this increase in size, which favours its precipitation and subsequent separation of the liquid in filters designed for said purpose.

Thus, the flocculating and/or coagulating agents cause the aggregation of certain materials of a waste flow in solid aggregates. In this way, the aggregates may be eliminated in the later so I id- liquid separation process. Any flocculating reagent may be used. Examples of suitable flocculating and/or coagulating agents include PERCOL™ 757, available from Ciba, polyamine-alkyl methacrylates, polyamine-alkyl methacrylates and their copolymers, polyacrylesteracrylamide copolymers, polyamines, polyethyleneimines, dicyandiamide, chitosans, polyacrylamides, polyethylene oxides, sodium polyacrylates, acrylamide-sodium acrylate copolymers or carboxymethylcelluloses, among the most typical.

Thus, the present invention provides a flocculation control device in a flow of slurry or sludge which has the mixed flocculating reagent, before a solid-liquid separation station, which is characterized in that said device is equipped with a container with at least two probes disposed consecutively and each one in a different position in the container and a filter capable of dividing the container into two parts, the container whereof by one end is capable of connecting to a flow of slurry or sludge which has the mixed flocculating reagent to receive a sample of said flow of slurry or sludge, and by the other end is equipped with opening and closing means to give an outlet to said sample, where each one of said at least two probes is configured to provide a signal indicative of the presence or absence of sample in each one of said positions, allowing the difference in position of each one of said at least two consecutive probes to calculate the degree of flocculation of the sample in accordance with the time elapsed between each signal indicative of the presence or absence of sample provided by each one of said at least two probes in the filtered of the sample.

When the sample is filtered through the filter included into the container, the sample level within the container is moving down, so that a first signal from the first probe is given when the sample crosses the position wherein it is disposed the first probe, and a second signal from the second probe is given when the sample crosses the position at which it is disposed the second probe, being the time elapsed between the two signals a function of the degree of flocculation of the flow of slurry or sludge containing the admixed flocculating reagent therein.

It is preferable that the filter is removable.

To clean the container, the removable filter passes from a position wherein it divides the container into two parts to another position wherein it does not divide the container.

Advantageously, the device according to the first aspect of the invention may include probes upstream of the filter (Fig 3A and Fig 5), downstream of the filter (Fig 3B) or upstream and downstream of the filter (Fig 1 and Fig 2). The device according to the first aspect of the invention may also operate in horizontal position or in any another position, requiring according to the position of the device the additional components necessary for the filling of the device.

In each one of these embodiments, the signals generated by the probes may be compared with a previously established ratio to provide an indirect reading of the degree of flocculation of the sample under analysis.

Even more advantageously, the device comprises a connection, pipe or inlet adapted to introduce air, water or another fluid inside the container, with or without pressure, so that the flocculation control of the sample under analysis can be accelerated. Thus, it is possible to inject pressurized air to a container which, on the one hand, forces the passage of the sample through the container in less time and, in consequence, it can analyse a greater number of samples and, on the other hand, when there is no sample to analyse in the container, it can be cleaned with pressurized air. Water or another fluid can be introduced through the same pipe with the same purpose.

The stages that are carried out according to the second aspect of the present invention to control the quantity of flocculating reagent to be introduced in a flow of slurry or sludge before entering a solid-liquid separation station is schematized below:

- Experimentally determine the set point of the quantity of flocculating reagent to be added to the flow of slurry or sludge which is in accordance with the quantity of solids in suspension and the degree of humidity or dryness desired, said determination taking place in the flow of slurry or sludge which has no flocculating reagent;

- Generate one or several signals which are indicative of said set point;

- provide said signal(s) to an automatic processor;

- establish in said automatic processor a ratio of the quantity of flocculating reagent to be introduced in said flow to reduce the level of solids in suspension to the degree of humidity or dryness desired only in accordance with said signal;

- generating a control signal from said automatic processor, said control signal being based on said automatic processor which processes said signal according to said ratio;

- provide said control signal to a flocculating reagent feed source which provides said flocculating reagent to said flow; and

- operate said flocculating reagent feed source in response to said control signal to modify the quantity of said flocculating reagent introduced from said flocculating reagent source to said flow of slurry or sludge.

Description of a preferred embodiment

A practical embodiment is included below of an embodiment according to the present invention. This embodiment is represented by Fig 4, wherein the device (A) has the configuration represented in Fig 3A.

In first place, the preset degree of flocculation was determined in function of the quantity of flocculating reagent to be added to the flow of sludge in accordance with the degree of dryness or humidity desired in the solid-rich fraction of the flow of sludge to dehydrate. Next, this preset degree was sent to the automatic processor 1 1 1 as set point value, and a ratio of the quantity of flocculating reagent to be introduced in said flow was established to reduce the level of solids in suspension at a determined value only in accordance with said signal, and a control signal was generated from the processor 1 1 1 , so that the automatic processor provided a signal to the flocculant feed pump 10 connected to the flocculant tank 15 to add a quantity of said flocculating reagent to said flow according to said ratio.

In this embodiment, a set point value was determined of the quantity of flocculating reagent to introduce in said flow to obtain the degree of flocculation desired and it determined that the time elapsed of a sample with said degree of flocculation between two consecutive probes L1 and L2 in the device A was 10 seconds.

To determine said time elapsed, which corresponded to the set point value, the following was performed: valve 41 was closed and valve 51 was opened to fill container 1 . The sample of slurry was gravity filtered through the filter 3, with the solid being retained in the filter 3, decreasing the sample level within the container 1 which generated a signal from probe L1 which was collected in the processor 1 1 1 starting a timer which recorded the time elapsed until receiving a second signal from probe L2. The reading of said time elapsed was taken as the ration of time with the degree of flocculation desired in the processor 1 1 1 .

Throughout treatment of the slurry stored in the tank 7, samples were taken with device

A of the flow of slurry which has flocculant downstream of the introduction of flocculating reagent and upstream of the inlet of said flow to the press filter 8. Readings were taken of the time elapsed between two consecutive probes, for example, L1 and L2, disposed at a different height within the container 1 , so that when the time ratio was greater than that desired it means a demand of flocculating reagent in the system, and the processor 1 1 1 which received said signals compared the time elapsed between them with the ratio initially established to act on the flocculating reagent pump 10 increasing the flow of flocculating reagent which was controlled through the flow controller 1 13. Likewise, when the ratio of time was less than that desired it meant an excess of flocculating reagent in the system, and the processor 1 1 1 which received said signals and compared them with the time elapsed between them with the initially established ratio, acted on the flocculating reagent pump 10, decreasing the flow of the flocculating reagent in the system acting on the flocculating reagent pump 10. This control of demand or excess of flocculating reagent in the system could also be performed acting on the slurry feed pump 9 in the system or acting at the same time on the slurry feed pump 9 in the system and on the flocculating reagent feed pump 10 in the system. Once the treatment has finalized of all the slurry stored in the slurry tank 7, the device A was cleaned by means of the introduction of pressurized water through the pipe 6, after variation in the position of the filter 3 to a vertical cleaning position as shown, for example, in Figure 2.

In an alternative embodiment, during the sample taking in the flocculation control device, pressurized air was introduced through the pipe 6 inside the container 1 with the aim of forcing the passage of the sample through the filter 3 and performing the control with a shorter time. In this embodiment, the ratio of time of the processor 1 1 1 was adapted to that corresponding to the forced passage of the sample.

In yet another embodiment and with the sample to analyse in the container 1 , the part of the container 1 downstream of the filter 3 was subject to vacuum so that the liquid filtered more quickly, with the probes, for example, L1 and L2 also providing a signal indicative of a time and a ratio of the time elapsed between said consecutive probes.

Despite the fact that reference has been made to a specific embodiment of the invention, it is evident for a person skilled in the art that the device 2 described is susceptible to numerous variations and modifications and that all the details mentioned can be replaced by other technically equivalent ones, without departing from the scope of protection defined by the attached claims.