It is known that the disposal of urban waste is one of the most serious problems with which the administrative authorities are confronted every day.

Basically, waste disposal presents problems in relation to the amount of waste to be disposed of, to the disposal costs and, above all in relation to the sites designated or to be designated for waste disposal.

Considerable progress has been made in recent- years in improving waste disposal plants, particularly with regard to the installation of apparatus for treating emissions (fumes) resulting from the incineration of the waste.

However an ever increasing sensitivity of the population with regard to the protection of health, as well as the inevitable corresponding decline in the urban areas designated for disposal, unavoidably leads to certain rejection of any project which aims to provide new waste collection and disposal sites.

Over the years, the concept has emerged of using mobile disposal plants, particularly plants

installed on ships, so that the operation of incinerating the waste and the subsequent treatment of the ash are performed whilst under way.

It is known, for example, to provide, on board a ship, a waste disposal plant having a loading hopper for the collection of the waste, connected to incinerator apparatus in which the waste can be reduced to ash.

A plant for the disposal of waste on board a ship of the type mentioned above is described in United States patent No. 5,067, 425.

However, in disposal plants of the type mentioned, the loading hopper is supplied with waste with the use of suitable devices which can deposit the waste directly into the hopper.

Clearly, the presence of this additional apparatus for the loading of the waste onto the ship leads to many disadvantages of the disposal plant.

In fact, it is necessary to provide for extensive use of dock labour to operate the devices for loading and unloading the waste.

Moreover, tearing of the wrappers containing the waste is encountered, resulting in scattering of the waste onto the quay and onto the deck of the ship, a decline in port hygiene and sanitary conditions, emission of unpleasant odours, and inevitable protests by dock

workers.

Finally, the need for long periods of time for loading the waste onto the ship, with a consequent notable increase in disposal costs, is clear.

It is also known to provide, on board the ship, adequate spaces for the arrangement of containers in which the waste is collected. These containers, which are put on board by cranes or similar means, are manipulated by handling vehicles such as tractors to enable the waste they contain to be discharged into the waste-loading hopper with which the ship is provided.

A disposal plant having the characteristics given above is described in United States patent No.

5,967, 063.

However, disposal plants of the type described above clearly have the disadvantage of requiring long periods of time for the loading of the containers onto the ship, vehicles in movement on the deck whilst the ship is under way (often obstructed or hindered by sea conditions) for discharging the waste from the containers into the hopper, as well as long periods of time for unloading the empty containers onto land when the ship returns to port, before a new set of containers full of waste is loaded.

There is therefore a need to provide apparatus

for the disposal of waste on board a ship which can be supplied with waste quickly and efficiently, limiting the emission of unpleasant odours and the scattering of waste in dock areas and at the same time reducing the time required to load the waste onto the ship. There is also a need to make the waste-disposal process as economical as possible.

The problem underlying the present invention is that of devising apparatus for the disposal of waste on board a ship, which apparatus has structural and functional characteristics such as to satisfy the above- mentioned needs and at the same time to overcome the problems mentioned with reference to the prior art.

This problem is solved by a disposal plant according to Claim 1.

Moreover, the disposal plant can implement the waste-disposal method according to Claim 15.

Further characteristics and the advantages of the disposal plant according to the present invention and of the waste-disposal method which can be implemented thereby will become clear from the following description of a non-limiting embodiment of the plant, in which Figure 1 is a diagram of a waste disposal plant that cooperates with waste-transporting vehicles.

With reference to the appended drawing, a waste

disposal plant particularly for the disposal of solid urban waste, or comparable waste, and for the disposal of hospital waste, is wholly indicated 1.

The plant 1 comprises waste-disposal apparatus 2 and a ship 4 suitable for housing the apparatus. The ship should be watertight, constructed and maintained in accordance with the regulations of the classification institution, and capable of navigating in the open sea.

In one embodiment, the disposal apparatus 2 is an apparatus for the thermal destruction of the waste.

The plant 1 also comprises a gangway 6 suitable for vehicles, which is at least partially housed in-the ship 4 and which can provide access to the ship 4 for at least one waste-transporting vehicle 8 and can allow the waste to be discharged into the disposal apparatus 2.

The waste-transporting vehicle 8 is suitable for discharging the waste into the disposal apparatus 2 and is preferably composed of a waste-collection device 8'and a tractor unit 8''which can move the collection device 8'.

The vehicle 8 is also preferably suitable for the collection of the waste as well as for its transportation. By way of example, the vehicle 8 is a truck provided with a crusher of the type conventionally used, for example, in urban centres for collecting waste

from bins.

The vehicle 8 is, for example, a truck with a truck body, a truck with a tipping body, a compactor, or a railway carriage provided with an end opening and moved by a tractor and/or propulsion means supplied by the ship.

The vehicle gangway 6 preferably comprises at least one access ramp 10 which provides access to the ship 4 from a quay B to which the ship is moored in port.

In one embodiment, the ship 4 has a bow door of the type used in ferries which, when open, forms the access ramp 10 between the mooring quay B and the ship 4, preferably affording access to a below-deck compartment 12 of the ship.

In one embodiment, the vehicle gangway 6 also comprises at least one lifting platform 14 which, in its lowered position, is disposed in the vicinity of the end portion of the access ramp 10.

In a preferred embodiment of the disposal plant 1, the apparatus 2 has two lifting platforms 14, preferably disposed side by side.

The lifting platform 14 is operatively connected to translation, rotation and inclination devices (not shown).

The translation devices are suitable for

lifting the platform from the lowered position, in which it is at the level of the access ramp 10, to a raised position, in which it is substantially at the level of the deck of the ship 4. Naturally, the devices are reversible and enable the platform 14 to descend to the lowered position, as well as enabling the platform to stop in the raised position.

The rotation devices can bring about a rotation of the platform, preferably through 180°, about a vertical axis X-X perpendicular to the platform.

The inclination devices can incline the platform, preferably by up to 45°, by means of a pivoting movement about an axis perpendicular to the vertical axis X-X, to facilitate the discharge of the waste from the vehicle 8 into the disposal apparatus 2 by gravity.

The translation, rotation and inclination devices comprise electric and/or oleodynamic motors as well as handling members of known type such as pistons, telescopic arms and the like.

The lifting platform 14 preferably has stop hooks (not shown) for securing the vehicle 8 on the platform 14 even in unstable conditions such as when the platform is inclined or during lifting or rotation.

The access ramp 10 and the lifting platform 14 preferably have rail portions along which railway cars,

moved by tractors and/or propulsion means, can travel.

As far as the structural and functional characteristics of the structure for access to the ship 4 by vehicles 8 is concerned, the ship 4 is substantially of the"roll-on/roll-off"type, commonly known as the "ro-ro"type, similar to a ferry.

The lifting platform 14 renders the waste disposal apparatus 2 accessible to the vehicles 8.

The disposal apparatus 2 has at least one collecting hold, known as a hopper 16, for holding the waste. The hoppers are arranged so as to be accessible from one of the lifting platforms and there are preferably at least three hoppers.

In one embodiment of the plant 1, the hopper 16 has a feed opening 18 for the loading of the waste into the hopper 16, and an output opening 20.

The feed opening 18 of the hopper 16 is preferably disposed in the vicinity of the deck of the ship 4 or at least is arranged in a manner such as to render the hopper 16 accessible from the deck, preferably to the vehicles 8 disposed on the lifting platform 14.

Control points 22 for monitoring radioactivity and detecting ferrous masses are preferably arranged in the vicinity of the feed opening 18.

The output opening 20, on the other hand, is

disposed in the vicinity of the bottom 24 of the hold of the ship 4, known as the bottom boards.

In one embodiment of the plant 1, the hopper 16 has a"funnel-shaped"bottom 26 the output opening 20 of which represents the end nearest to the bottom boards 24 of the ship 4.

In other words, the bottom 26 of the hopper 16 has a frusto-pyramidal, frusto-conical, or similar shape, formed in a manner such that the smaller base of the bottom is disposed in the vicinity of the bottom boards 24 of the ship 4.

In the vicinity of the output opening 20 of the hopper 16, in one embodiment, the disposal plant 1 has at least a first conveyor belt 28 or a screw feeder which can transport the waste, which emerges from the hopper 16 through the output opening 20, towards a crusher 30.

Further points 32 for monitoring radioactivity and detecting ferrous masses are preferably arranged along the conveyor belt 30.

The crusher 30 receives the waste coming from the hopper 16, performs a crushing operation, and reduces the waste to crushed waste which passes through an opening provided in the crusher to reach a second conveyor belt 34 which supplies a drier 36.

In one embodiment, a grating 37, which may be

continuous or in separate portions, is disposed beneath the output opening 20 of the hopper 16, the first conveyor belt 28, and the crusher 30, in order to filter out the run-off liquids which are then collected in a double bottom of the ship 4.

The drier 36 is connected to a third conveyor belt 38 which can transport the crushed and dried waste to an incinerator furnace 40 which can reduce the waste to incinerated residues.

The incinerator furnace 40 is preferably in communication with a belt press 42 for sludges, through a duct 44 for the expulsion of the incinerated residues.

At least one ash sprayer 46 is preferably disposed along the duct 44 for the expulsion of the incinerated residues and can wet the burnt residues which pass through the expulsion duct before they reach the belt press 42.

The belt press 42 is connected to a screw feeder 48 for transferring the incinerated and pressed residues to the forward hold 50.

In one embodiment, the incinerator furnace 40 is connected to a hot-effluent flue 52 which connects the incinerator furnace to the drier 36 and to a heat exchanger 54.

The effluents of the heat exchanger 54 and well

as the effluents of the drier 36 are preferably transported by means of the duct 52 to effluent-treatment apparatus 56.

The effluent-treatment apparatus is also connected to an expulsion duct 58, chimney or funnel, through which the cleaned effluents are dispersed into the atmosphere upon completion of the treatment process.

The composition of the fumes is constantly monitored by suitable pollutant-monitoring systems located at various points in the plant.

In one embodiment, the heat exchanger 54 is operatively connected to turbo-propulsion units and to turbo-generators (not shown).

The waste disposal plant 1 housed on board the ship 4 enables waste-disposal cycles which provide for at least four stages to be performed.

In a first stage of the disposal cycle, known as the waste-loading stage, the ship 4 is moored to the quay B of the port.

The access ramp 10 of the vehicle gangway 6 of the plant 1 is arranged between the ship 4 and the mooring quay B to enable vehicles 8 to enter the ship.

The bow door of the"ro-ro"4 is opened and arranged bearing partially on the quay of the port, thus constituting the access ramp 10 of the vehicle gangway,

and renders the lifting platform 14, and hence the entire disposal apparatus 2, accessible to the vehicles 8 from the port quay B.

The vehicles 8, provided with the collection apparatus 8' (truck body, tipping body, railway carriage or the like, or containers) containing the waste are moved by the tractor unit 8''and enter the ship 4 by means of the access ramp 10. The vehicles 8 reach the lifting platform 14 which is disposed in the lowered position, adjacent the access ramp 10.

For railway cars moved by tractors or propulsion means, movement takes place on the rails with which the access ramp 10 and the lifting platform 14 are provided.

Vehicles may equally well enter in"forward gear"or in"reverse gear".

When the vehicle has arrived on the lifting platform 14 and is secured in position by the activation of the stop hooks provided on the lifting platform, the translation motors move the platform, bringing it from the lowered position level with the access ramp 10, to the raised position substantially at the level of the deck of the ship 4.

The vehicle 8 can gain access to the feed opening 18 of the hopper 16 from the lifting platform 14

in the-raised position, preferably whilst remaining on the lifting platform 14.

The position of the vehicle 8 along the vehicle gangway 6, in which the waste carried by the vehicle 8 can be discharged into the hopper 16 by gravity, forms a waste-discharge station of the vehicle gangway 6.

In particular, a vehicle 8 constituted by a truck with a load platform carrying a container or by a railway car positioned on the platform 14 (suitably inclined, if necessary, by the operation of the appropriate devices) can discharge the waste transported into the hopper 16 by gravity, that is, avoiding any intervention by personnel or mechanical means such as cranes and the like, operated by personnel.

Similarly, a vehicle 8 constituted by a truck with a tipping body can discharge the waste after the tipping body has been raised.

The rotation devices connected to the lifting platform 14 also enable the platform to be rotated so as to turn the door of the apparatus holding the waste (the container or railway car) towards the feed opening 18 of the hopper 16. In one embodiment, the platform rotates through up to 180°.

During the discharge into the hopper 16, the waste is subjected to a first check for radioactivity and

for detecting ferrous masses by means of electromagnets.

Upon completion of the waste-discharge operations, the lifting platform 14 returns the vehicle 8 to the level of the access ramp 10 and the vehicle leaves the ship 4.

Upon completion of the first stage of the disposal cycle, after suitable loading of the hopper 16 by the discharge of the waste from the vehicles 8, the ship is made ready to sail and leaves port.

The ship 4 is taken a considerable distance from the coast, preferably into international waters and, in general, no less than 75/80 km from the nearest coast.

During a second stage of the cycle, known as the thermal destruction stage, the ship 4 is offshore, preferably still under way.

In any case, the ship 4 remains under way, maintaining sufficient distance from the coast to prevent the effluents returning towards the coast, even though they have been treated.

The waste accumulated in the hopper 16 is transferred to the crusher 30 by means of the first conveyor belt 28 and, in transit, is subjected to further monitoring for radioactivity and ferrous masses by the control points 32.

The waste is crushed and then transferred by

the second conveyor belt 34 to the drier 36 in order to evaporate the moisture contained in the waste by means of the hot effluents coming from the incinerator furnace 40.

Liquid run-off material coming from the hopper or from the crusher, and filtered through the grating 37 falls into the double bottom of the ship 4 in order to be purified and disposed of separately.

The dried waste is transported to the incinerator furnace 40 by the third conveyor belt 38 in order to be reduced to incinerated residues.

The incinerated residues, reduced to shovellable sludges by wetting by the sprays 46, are transported by the screw feeder 48, through the expulsion duct 58, towards the sludge belt press 42.

The press 42 reduces the ash sludges by pressure and expulsion of the water, to solid slabs or cubes to be used in building, after being rendered inert, or into granulate for use in road surfacing.

The slabs or granulate products are transferred, by means of a fifth conveyor belt 60, to the forward hold 50 of the ship 4 in which they are placed on devices suitable for facilitating their transfer to land, such as pallets or the like.

Upon completion of the second stage of the disposal cycle, when the waste-burning operations are

completed, the ship 4 can return to port and moor.

During a third stage of the cycle, known as the residue-discharge stage, the residual products of the waste disposal (slabs or granulate) are discharged from the ship. Upon-completion of this stage, a new disposal cycle can start with a further loading of waste into the hopper.

The hot effluents produced by the incinerator furnace 40 are transported through the hot-effluent flue 52 to the drier 36 for the crushed-waste drying process, and to the heat exchanger 54 to produce steam for use as an energy source in propulsion turbines, in turbo- generators for the production of the electricity necessary for the operation of the auxiliary apparatus (conveyor belts) and of services on board, and for the production of the hot water necessary for the high- pressure washing of the conveyor belts of the hoppers.

The effluents used by the heat exchanger 54 and by the drier 36 are conveyed to the effluent-treatment apparatus 56 in order to destroy pollutants in accordance with international laws in force, before they are dispersed into the atmosphere through the expulsion duct 58.

Unusually, the plant for the disposal of waste on board a ship is supplied with waste quickly and

efficiently, reducing the time required for loading the waste on board.

In fact, in the plant described, the vehicles for transporting the waste enter the ship without intermediate stages for handling containers or for transferring the waste on board by means of handling devices or cranes. In fact self-propelled vehicles such as trucks, with or without tipping bodies, compactors, or railway wagons and/or flatcars moved by tractors/propulsion means, gain access to the waste hopper directly by travelling along the vehicle gangway and deposit the waste in the hopper in the loading station.

Moreover, the disposal plant has the further advantage of avoiding the additional use of dock labour, thus rendering the waste-disposal process very economical. In fact, the waste-discharge operations take place directly from the transporting vehicles, which are driven onto the ship by their own drivers.

Finally, the disposal plant has the advantage of preventing the emission of unpleasant odours or the scattering of some of the waste in dock areas, since the waste is loaded directly from the vehicles into the hopper of the ship without handling by cranes on the quay or on the ship.

It is clear that, in order to satisfy contingent and specific requirements, a person skilled in the art may apply to the above-described waste disposal plant many modifications and variations all of which, however, are included within the scope of protection of the invention as defined by the appended claims.