MOBILE SYSTEM AND METHOD DESIGNED FOR RECYCLING WATER FROM SLUDGES , IN PARTICULAR FOR SERVICE VEHICLES FOR CLEANING DRAINS , WELLS , AND THE LIKE

Field of the invention

5 The present invention relates to a method for recycling water from sludges sucked in from drains, wells, and the like, of a mobile system, in particular designed to be installed on service vehicles for purging drains, wells, and the like. The invention also relates to a vehicle equipped with said system. Prior ART

10 For cleaning wells and drains, it is common practice to use mobile equipment installed on vehicles, said equipment usually comprising one or more cisterns, if need be, high-pressure pumps, pumps or compressors for intake of the sludges. In fact, intake of the sludges is in general obtained by setting a cistern or one of its compartments in negative pressure so that the sludges are sucked in directly

15 through a purposely provided pipe, even though other methodologies are possible. The cisterns mainly have two purposes: supplying a reserve of water useful for washing wells or pipes, in general by means of high-pressure pumps; and receiving the sludges sucked in. To increase the efficiency of the operations, and hence the operating autonomy of the vehicle, the attempt is made to reuse also 0 part of the water that is entrained by the sludges sucked in. For example, the water can be extracted from a certain level of a cistern or compartment so as to enable a certain settling of the sludges on the bottom and hence a minimum separation. In the case where a number of compartments or cisterns are present, it is also possible to proceed to a coarse filtration. For example, sludge can be 5 sucked in from a compartment by means of a recycling pump, causing the sludge to traverse a coarse filter. The water recovered can be sent into a purposely provided compartment ready for use. This can be followed by a passage through other filtering systems or through a cyclone, from which the depurated water is collected, as has been seen previously, and the thickened portion is sent back into 0 the compartment from which it arrived. This increases the amount of water available and improves the quality thereof. With the methods and equipment according to the known art, however, the

operating autonomy of a vehicle used for the services referred to above is still rather limited, in general to a small number of cleaning cycles. Then, it becomes necessary for the vehicle to go back to the operating centre for discharge of the sludges collected and supply of new clean washing water. It would consequently be desirable to increase the operating autonomy of the vehicle, without, however, further increasing the volume of the cisterns on board, which is already considerable, or the number of the compartments.

In addition, it would be desirable to improve the quality of the washing water available in a whole series of cleaning operations, the aim being to increase the service life and reduce maintenance of the pumps on board, in particular the high- pressure ones used for washing. Furthermore, in many countries, more severe legal requisites have been envisaged on the quality of the water used for certain operations. In the case of wells, for example, after cleaning it is necessary to fill the water siphon so as to create a hydraulic guard that will prevent any possible contaminants spilt on the road surface from reaching the drains, and that, in any case, will isolate the latter from outside. It is clear that the quality of said water is important for preventing drawbacks, such as bad smells, and delaying the need for new purging operations. In addition, a greater recovery of water would reduce the volume of sludges to be disposed of, given the same number of cleaning operations performed. Summary

The problems set forth above have now been solved by means of a mobile system, in particular for a vehicle, for cleaning and purging drains, wells, and the like, said system comprising: a sludge-collection tank; and a recycling line, which connects said sludge-collection tank to a separator; said system being characterized in that it comprises means for introduction of a flocculant in said line upstream of said separator.

Preferably a line for the thickened sludge connects said separator to said sludge- collection tank; in addition, a line for the depurated water connects said separator to a tank for the depurated water. The invention relates to a vehicle equipped with said system.

The invention moreover relates to a method for recycling the water from sludges, comprising pumping of the sludges from a sludge-collection tank into a recycling line, and the subsequent passage of the sludges into a separator, preferably of a mechanical type, said method being characterized in that it envisages, prior to passage into the separator, introduction of a flocculating agent.

According to one aspect of the invention, the water purified by the separator is collected in a depurated-water tank, for a subsequent use, whereas the thickened part is reintroduced into the sludge-collection tank. By "tank" is meant, where not otherwise specified, a cistern or a compartment thereof, or the like, forming part of a mobile system for cleaning drains, wells or the like.

A particular object of the invention is represented by the contents of the annexed claims. List of figures The present invention will now be illustrated by means of the detailed description of preferred, but non-exclusive, embodiments provided purely by way of example, with the aid of the attached Figure 1 , which is a schematic illustration of a system according to the present invention. Detailed description of an embodiment Represented schematically in Figure 1 is a mobile system, in particular a system installed on a service vehicle. Present thereon is a cistern 1 , divided into a number of compartments. The two compartments 2 and 3 are designed for receiving sludges sucked in from drains, wells or the like. The water compartment 4 is designed for collection of recycled water for subsequent reuse. It is understood that, as occurs normally in mobile systems of this sort, the various compartments can be used differently if need be. For example, it is common practice, whenever the vehicle is to go out, to charge all the compartments of the cistern with clean water. Bit by bit the water is used, whilst the compartments 2 and 3 are filled with the sludges sucked in, according to an appropriate operating scheme. According to a possible embodiment, the compartments 2 and 3 are separated by the mobile wall 20 so as to vary the volume of the compartments accordingly during the various operations.

As has been said, the first sludge compartment 2 is designed to receive sludges sucked in; for example, a vacuum may be created in said compartment by means of a purposely provided compressor, designed to create a vacuum or pressurize the various compartments by means of an appropriate system of connections. The pressurization of the various compartments may for example be in the region of 0.5 - 2 bar. According to one procedure, the intake pipe, through the valve 5 is connected to the second sludge compartment 3, which communicates with the first sludge compartment 2 through the by-pass 6, equipped with a valve. Once the predefined maximum level is reached in the first sludge compartment 2, it is possible to close the by-pass and carry out suction directly in the second sludge compartment 3.

The first sludge compartment 2 is connected to a recycling line 7, equipped with a recycling pump 8. There may be set on said line, if deemed appropriate, a pre- separator 24, which can be a coarse filter and can be located at the inlet on the line that can be set at an adequate level in the first sludge compartment 2, preferably towards the bottom thereof. A separator 9 is preferably positioned downstream of the recycling pump, and has one outlet for the depurated water 10 and one outlet 1 1 for the thickened suspension. Said separator can be of any appropriate type, for example a cyclone or an inertial separator. According to a preferred aspect, it is a cyclone separator equipped with mobile parts, such as a blading kept in rotation by a purposely provided motor, for example a hydraulic motor. The blading increases the degree of separation thanks to the centrifugal force. Devices of this or another type, adequate for the purpose, are known and do not require any further description herein. According to a preferred aspect, the line 10 for the depurated water is connected to the water compartment 4, where the depurated water is collected, whilst the line 1 1 takes the thickened suspension back into the first sludge compartment 2. In this way, it is possible to thicken the sludge collected and obtain water that can be used for cleaning operations and filling drain wells. The cleaning operations can be performed with high-pressure nozzles, taking water from the water compartment 4, whilst the operations of filling can be performed by pressurizing the water compartment 4 by means of the compressor and taking water with a purposely provided pipe 19, which is

connected to the sludge-intake and water-discharge pipes through the valve 26. It has been noted that the quality of the water is not always satisfactory. Furthermore, given the normal mode of operation, the quality is extremely variable over a series of operations. The water in the water compartment 4 can be used as washing water, with high-pressure nozzles, above all where external water sources are not available. For this purpose, a line with high-pressure pumps can be provided on the vehicle. As usually occurs, high pressure can be supplied to one of the pipes used also for intake or discharge of the tanks, to which a device comprising the nozzle can be applied. The system according to the present invention envisages means for introduction of a flocculant into the recycling line. The introduction is obtained preferably upstream of the separator. The means can comprise a reservoir, for example a tank 12 of flocculant, and a mixer 13 for generation of a flocculant mixture. Said mixer can be a simple tank, of appropriate volume, which can have, for example, a capacity of 5 or 10 litres and may possibly be equipped with a line 14 and a pump 15 for recycling or other means designed to promote mixing. In fact, it is desirable for the pure flocculant to be mixed with water prior to introduction in the water to be treated. By way of example, from one litre of flocculant 100 litres of flocculant mixture are generated, which, in turn are enough for approximately 50 000 litres of treated water. This as regards what is defined a degree of "average flocculation", taking into account that the proportions can be varied considerably, according to the requirements. Taking into account that a cistern such as the one of Figure 1 can be typically between 5 and 20 m ³ in all, it is clear that a tank of flocculant of small dimensions can be used for a number of working days without there being any problems due to the need to store large amounts of flocculant on the vehicle. It is instead preferable to generate the mixture directly on the vehicle. For this purpose, it is possible to use the depurated water coming from the water compartment 4 or directly from the separator 9 by means of a purposely provided line 16. In this way, the discharge head of the pump 8 can be exploited. The introduction line 17 connects the mixer 13 to the recycling line 7. Preferably, the point of introduction is set upstream of the recycling pump 8, which favours mixing of the mixture in the recirculated water. The pump 18 can be designed for

overcoming the pressure that can exist in the recycling line, for example on account of the hydrostatic head in the first sludge compartment 2. Pumps and valves can be used for dosage of the components (such as, for example, the dosing pump 25). According to a possible aspect of the invention, it is possible to perform steps of recycling with or without introduction of flocculant even when other operations are not performed, for example, when the vehicle is travelling. All the operations can be performed manually, upon request of the operator or can be managed by an on-board computerized system. There can be provided level sensors for enabling control of the various operations. It is possible, if so desired, to transfer the contents of the second sludge compartment 3 into the first sludge compartment 2 through the by-pass to obtain sludges to be subjected to the recycling process for obtaining water or reducing the volume of the sludges. The line 23 can be used for introducing flocculant into the second sludge compartment 3, if so desired. It is, in fact, possible to take water from said compartment in the case where the sludges deposited there are not very thick, on account of the abundance of water in the drains. Said technique enables increase in the efficiency of the operation of suction of the sludges. As flocculant any known product having characteristics of an appropriate type can be used. Examples are the products marketed under the trade names BASF Sedipur CL Series®, or else Flonex ® or AQUAFLOC ® F 410 CL, F 430 CL. It has been found that the system according to the present invention, in addition to providing washing and filling water of excellent quality, makes it possible to increase the operating possibilities of a service vehicle, with considerable increase in the number of possible operations without having to go back to the operating centre for discharge of the sludges and charging of clean water. Also the consumption of clean water is reduced, with increase in the fraction of recovery from the sludges.