WO2000063864A1

WO2000063864A1 - A waste collection monitoring system

Info

Publication number: WO2000063864A1
Application number: PCT/AU2000/000323
Authority: WO
Inventors: Peter Donald Parker
Original assignee: Peter Donald Parker
Priority date: 1999-04-15
Filing date: 2000-04-17
Publication date: 2000-10-26
Also published as: AUPP974899A0

Abstract

A waste collection monitoring system (70) for monitoring the collection of waste from a number of waste generation locations (11), each location (11) having identifying means (12) for identifying each said location. An operator of a waste collection vehicle (24) has a reader unit (27) for identifying and recording from the identifying means (12), the location from which waste is collected. At a waste receiving station (30), the information recorded in the reader unit (27) may be downloaded to identify that waste has been collected from a waste generation location. The waste collection vehicle (24) may also include a monitor (60) to monitor flow into the waste collection tank of the vehicle and a monitor (61) to monitor the level of liquid in the waste collection tank. A grease trap (40) having a level sensor (49) for sensing and alerting that the trap is required to be emptied is also disclosed.

Description

A WASTE COLLECTION MONITORING SYSTEM Technical Field

This invention relates to a waste collection monitoring system and components thereof.

Background Art Government regulations currently require waste liquids particularly toxic wastes to be collected at regular intervals from waste generators. Commercially, grease traps which are connected into a waste water or sewerage system, are provided at many locations such as at food preparation outlets or industrial food processing plants to receive liquid kitchen or other similar waste to intercept grease and other solid waste to prevent it from entering the waste water system. For efficient operation, and to comply with the regulations, it is necessary that grease traps and other waste liquid collection containers be cleaned at regular intervals to prevent grease or other solids passing through the container outlet and thus causing possible contamination of the waste water system. For example, if grease waste is allowed to enter the municipal sewerage system, the cost of maintaining the system is substantially increased. It is also desirable that the collection of waste liquids be accurately monitored and tracked to ensure proper and regular collection and environmental safeguards.

A further problem which arises with the collection of liquid waste is that of ensuring that the collected wastes are correctly discharged at an authorised receiver and not disposed of in any other manner.

It is also desirable that collection of hard wastes from commercial and industrial locations be monitored and collected regularly so that such products are not just simply dumped at any location. Summary of the Invention The present invention aims in a first aspect to provide a system wherein the collection of waste liquids and other waste from a number of locations can be monitored so as to comply with the requirements of regulating authorities. The present invention in a further aspect aims to provide a method of. and means for. monitoring liquid waste collection containers so as to reduce the risk of periodic blockage through build up of solid wastes or other collected materials. The present invention in a further preferred aspect aims to provide a method and means for alerting a waste collector of the need to collect certain wastes. The present invention in a further preferred aspect aims to provide an arrangement whereby collected wastes can be correctly monitored and not dumped or disposed of in an unauthorised manner. Other objects and advantages of the invention will become apparent from the following description. The present invention thus provides in a first aspect, a waste collection monitoring system whereby waste collection from a number of waste generation locations can be monitored, said system including identifying means at each location for identifying each said location, reader means associated with a waste collection vehicle for identifying from said identifying means, a said location and for recording said location from which waste is collected, and means at a waste receiving location for receiving downloaded information from said reader means to identify that waste has been collected from a said identified location. The vehicle may also include similar identifying means to enable it to be identified by the reader means.

The identifying means at the waste generator's location may comprise either non-volatile or read-only memory microchips. Similar identifying means may be located in the waste collector^'s transport vehicle to identify the collecting vehicle.

The read-only memory microchips suitably contain a unique factory entered and registered number. The non-volatile memories preferably also include a readonly memory suitably containing a unique factory entered number as well as non-volatile memory. A non-volatile memory has the advantage of allowing additional coding or data to be stored. The factory-entered registration numbers therefore provide identification of the waste generator's location, of the waste collection and transport vehicle and of the reader unit employed to transfer the data.

In order to ensure the integrity of the system, it is preferred that a government or private management organisation be required to maintain the system which as a minimum, extends to control of the issue and maintenance of the system hardware and software components and control of data encryption.

One form of commercially available non-volatile memory is packaged in a stainless steel button-si2»d casing which is in two parts hermetically sealed together, the parts forming the electrical contacts. Other forms are packaged in conventional plastic casings with protruding electrical connector pins intended for mounting on a printed circuit board. The known available read-only memory is also packaged in a conventional plastic casing. In the case of some commercially available read-only and non-volatile memories, the factory entered number can be customised so as to classify it as belonging to the system and to further sub-classify it as. for example, a generator, a transpoπ vehicle or a reader unit memory. Alternatively, the classification can be entered into non- volatile memory by the management organisation. Additional classification by the management organisation may identify the date of sale, the purchaser of the memory unit who will normally be a waste transporter, or any other relevant information. The classification data may be entered in encrypted form.

In an alternative arrangement the identification means may be a contactless memory identification unit such as a passive transponder.

A waste generator may purchase a memory identification unit directly, however it is preferred that transporters who adopt the system will supply the waste generators from whom they collect waste with the units and will register the waste generators with the waste receiver. The waste receiver will preferably enter the identification of the generator and relevant waste details into the database of a computer held at the receiver. The receiver need not know the actual identity of a generator if the transporter wishes to keep its client base confidential. The transporter will also advise the regulating authority of the generator's identification.

The identification means may be hand-held units or fixed units. A preferred feature of the units however is that none of them requires a power supply thus simplifying installation and maintenance. The reader means may also suitably comprise a hand-held reader unit which is self powered.

The hand-held identification unit may be used where a generator employee is required to be in attendance during the waste collection. It may comprise a small key- sized unit containing a button type non-volatile memory, a small plastic enclosure containing a pin-type memory or any other suitable device. The unit may be carried on a key ring by a designated generator representative or kept in a convenient location.

Where waste quantity is required to be known and where a suitable mass, volume etc. measuring system has been installed at the generator^'s premises or on the waste transpoπ vehicle, an additional identification unit with non-volatile memory may be installed and the non-volatile memory may be updated with the quantity data from the measuring system. Alternatively a single non-volatile memory unit can provide both the identification and waste quantity data. The quantity may be read both prior to and at the completion of each waste collection rather than a single measurement prior to collection so that pan pickups are detected.

A custom designed electronic interface unit may be provided by the management organisation to monitor quantity data and to update the non-volatile memory with encrypted quantity data when so commanded by a signal from a reader unit.

Where more than one type of 'attended' waste is generated at the premises the generator may optionally have separate hand-held units for each type of waste or alternatively may have a single unit. In the latter case, the employee is required to enter the waste code via a keypad on the portable reader unit. Waste quantity may also need to be entered via the keypad.

An alternative form of identification unit comprises a fixed identification unit where the attendance of a generator employee during waste collection is not required and may comprises an enclosure or housing which can incorporate either a button or pin type of memory described above. The button type of memory is suitably fitted externally on the enclosure. The enclosure or housing may be fixed to a wall or post adjacent to the waste collection point. Where a pin type of memory is used, it is preferably mounted inside the enclosure or housing and connected to an externally accessible connector. The reader unit is fitted with a suitable mating connector /s for whichever type/s of memory is/are employed. Suitable means may be provided to normally block or close a connector entrance into the enclosure or housing to prevent entry of vermin, insects or the like. The blocking or closing means is suitably formed so as to be movable to allow entry of the reader unit^'s mating connector into the enclosure or housing. Preferably, the blocking or closing means is moved by engagement of the connector of the reader unit. The fixed identification unit may include switch means such as a reed switch which is activated by a magnet on the reader unit when the identification unit is read. The reed switch may be connected to an indicator panel unit that is installed in a convenient location so as to alert the generator that the memory unit has been read and thus that the waste has been collected. Other types of switches, such as a microswitch. can be used for initiating operation of the indicator panel or contacts within the mating connectors may pass a signal directly from the reader unit to the indicator panel.

Communication of the fact of having read the identification unit to the indicator panel may also be accomplished by means of storing a message from the reader unit into non-volatile memory and then accessing the message by the indicator panel. In either case, a simple pair of signal wires is required to connect the indicator panel unit and identification unit.

The indicator panel, which may be installed at any suitable location, may alert generator personnel via an intermittently repeating audible and/or visual signal that a waste collection has been made. The panel may have a reset switch to cancel the aleπing signal. The panel may be battery powered but it can also be provided with a plug-in mains power pack or can be hard wired to mains power.

In an alternative arrangement, the fixed identification unit may comprise a contactless unit with which the reader unit associated with the transport vehicle which may comprise a read or read/write unit may be brought or moved into proximity with the identification unit to enable the fixed identification unit to be identified for example by pressing an "Enter" key on the read or read/write unit. The fixed identification unit suitably comprises a transponder which contains a unique and permanent identification number in a read only memory. Preferably, the transponder requires no internal or external power supply and can be fixed to a wall, tank or post or installed in or on the ground adjacent to the waste collection point. Where more than one type of waste is generated at the premises, fixed units with individual identifications may be located adjacent each collection point associated with each type of waste. The vehicle identification unit is suitably mounted on or in the cabin of the waste transpoπ vehicle. This unit may be similar to the fixed generator identification unit and may have either a button or the pin type of memory. Its memory suitably is coded to classify it as a vehicle identification. It is preferred that the vehicle identification be read at the beginning of each collection run before generator identification can be accepted by the reader unit. An audible and/or visual alarm signal is preferably issued by the reader unit if the vehicle identification is not read before attempting to read the first generator identification. As with the fixed generator identification unit, the vehicle identification unit may be interfaced to a vehicle installed waste quantity measuring device.

The portable hand-held reader unit may be normally carried in the waste transport vehicle but is detachable therefrom to enable it to be brought into register with the identifying means at the waste generator^'s location to identify the location and the quantity data from the memory units. The reader unit suitably transfers data to data storage means within the reader unit from which data mav be read into a receiver unit interfaced directly into a computer at the waste receiver site. Alternatively, this data may be simply downloaded by remote communication means such as by radio transmission.

The portable reader unit is suitably housed in a robust case which for example may be a plastic cradle mounted case designed to be carried in the cabin of the waste transpoπ vehicle. The unit is preferably battery powered and is suitably recharged from the vehicle battery, normally via the cigarette lighter socket.

The unit suitably comprises a data transfer device requiring no pre-entry of reference data such as a check list of vehicle or generator identification. It may be switched between read and write modes for reading identification units or for transfering data into the receiver^'s database or may have a suitable data transfer protocol which obviates such switching. The reader unit may read and store the generator^'s or vehicle^'s identification and the waste quantity when its connector is placed against a vehicle or generator identification unit. It may also record the date and time of the reading as given by its own internal clock. It may require an "Enter" key to be pressed to initiate the reading. An audible and/or visual signal may advise that data has been successfully read. The reader unit may also contain a magnet that activates a reed switch in the generator's identification unit or may mechanically operate a switch or may emit a signal for the indicator panel. The reader unit can also write a coded message into non-volatile memory in an identification unit, for example a code to be read by the indicator panel informing it that waste has been collected or a date/time stamp which could be accessed by a generator^'s computer.

The portable reader unit may reads and store the generator^'s identification, the waste quantity (if applicable) and the time as a single record. The records from a collection run may then be downloaded to the receiver^'s database at the receiver^'s waste site. The reader unit may incorporate a keypad and LCD display to enable waste quantity and waste code to be entered where applicable. Where the waste quantity is not measured electronically, it may then be entered manually by keying in the quantity through the keypad. The waste code may also be entered into the reader unit via the keypad when the particular waste is collected or via the receiver^'s computer keyboard when the waste is delivered.

In the case of automatic entry of waste quantity, one or two readings of the generator or vehicle identification unit, as applicable, are made by the reader unit, one prior to and/or one after collection of the waste. After entering the reading/s. the quantity is displayed on the LCD. The reading may remain displayed and not stored in memory until either the "Enter" key is pressed or, in the case of an on-vehicle quantity measuring device or of a hand-held generator^'s identification unit, the generator^'s identification unit is read. In the case of manual entry of waste quantity, the generator^'s identification unit is preferably read within a time-out period after the entry of quantity to cause the quantity, the generator's identification and the date/time to be stored as a single record. Where an eπor occurs in entering the quantity, re-entering it before reading the identifying unit will overwrite the previous entry. Re-entering the quantity after having read the identification unit requires the identification unit to be re-read by the reader unit. This then overwrites the complete record. For manual entry of waste quantity the generator^'s identification unit is normally a hand-held type to ensure that the generator employee is present, however where driver entry of the quantity is acceptable a fixed identification unit may be installed. An implementation of the system may require that for all generators, the waste-measuring device must have a separate (i.e. additional) identification unit. The procedure for recording the quantity may then effectively be the same no matter whether quantity is entered via the keypad, from a generator device or from a vehicle device, that is each time a quantity is entered, whether total quantity via the keypad or an initial or final quantity via an identification unit, the generator identification is read to record it into the reader memory.

The units of quantity (i.e. cubic metres, litres, kilograms, number, etc) are preferably not entered. The units suitably are ones that are acceptable to the regulator for the type of waste and that will have been agreed between or are customarily used by the transporter, the generator and the receiver. The relevant unit will have been recorded in the receiver^'s database when the generator^'s identification is registered with the receiver.

Where a waste code also needs to be entered into the reader unit, this may be effected in a similar manner to entering quantity and done within a time-out period before or after entering the quantity and before reading the identification unit in order for it to become pan of the record. If a waste code is entered and the identification read without an associated quantity being entered, no record is stored and an audible and/or visual aleπing signal is activated. The reader unit suitably is able to distinguish between a waste code and a quantity entry. Entry eπors are handled in the same way as for quantity. If the waste code is inadvertently not entered, it may still be entered via the computer keyboard at the receiver site.

Where the identification units are of the transponder type, the read/write units may be normally stored in a cradle within the cabin of the waste transpoπ vehicle. Preferably the cradle includes identification means similar to the generator identification unit to identify the vehicle. Each time the read/writer units are placed in the cradle, the vehicle identification is monitored. The cradle also includes a charging circuit to charge the battery within the read/write unit when the latter is inserted into the cradle.

The read/write unit may be a simple data reading, storing and writing device which when brought into proximity with the generators identification unit, may read and store the generators identification when say an "Enter" or equivalent key is pressed. Date and time of reading may be provided by an internal clock within the read/write unit. The unit may have an audible and or visual indicating means which operates to advise the operator when data has been successfully read and recorded. In an alternative configuration, the read/write unit may include a keypad and digital display which enables manual entry of waste quantity. Typically, a manual entry is made using the keypad such as an entry of 90 where 90 tyres, batteries, drums etc. are collected and the "Enter" key then pressed. The generator's identification is then read as before and the data stored. At the waste receiver^'s site, a connector of the read/write unit may be mated with a connector on a fixed receiver unit and the read/write unit's stored data is downloaded into the receiver^'s database. Alternatively, in the case of a contactless read/write unit, a cradle may be located at the waste receiver's site into which the read/write unit may be inserted to enable the information stored therein to be downloaded into a database for processing. Alternatively, as referred to above, this information may be downloaded via radio transmission from the unit or via other communication means. For this purpose, the read/write unit may include a suitable transceiver unit. Data downloaded includes collection times and date, quantities, waste codes, aπival time and date and the transporter vehicle^'s identification. The generator^'s identification, the waste origin code, the waste code, and any other required identification data for the generator or transporter will have been entered into the receiver's database when the generator was first registered with the receiver by the transporter. Where scheduled periodic collections of waste are required, the schedule details are entered into the receiver^'s database. Reports generated from the database suitably will highlight any missed collection. The various identifications as displayed in the database may be the actual numbers stored in the memory units or, for further security or easier identification, identification numbers derived from them using an algorithm which is known only to the management organisation. After downloading, the read/write unit^'s memory may be purged and the read/write unit reset for the next run or the records may just be tagged to provide for the waste transporter to download data into its computer at the end of a shift. Flagged records would be progressively overwritten with new data when the reader^'s memory was full.

At the time of purging or flagging, the read/write unit^'s date and time of day may overwritten with the receiver^'s date and time to ensure continued agreement of these parameters. An audible and/or visual signal may then be activated to aleπ the vehicle driver that valid transfer of data has taken place. In the event that a valid transfer has not occurred, an audible and/or visual eπor signal is activated. At the same time, a database message alerts the receiver of the eπor condition and advises the appropriate coπective action. Once valid data has been entered, an output may be provided to operate a boom gate where one is in place.

Where the quantity of waste collected from a generator is required to be known and is constant, the quantity can be entered into the receiver^'s database when the generator is registered. If the quantity of waste collected varies with each collection, the quantity will have been entered into the reader unit via the integral keypad or via a generator or vehicle identification memory unit.

The management organisation tracking system may also provide for quantity to be measured and entered into the receiver^'s database via the receiver^'s computer keyboard or automatically measured and entered via an interfaced weighbridge or other receiver measuring device.

Where more than one waste code is associated in the database with a generator identification (i.e. where the generator has a single hand-held identification unit for use with more than one waste type) and the code has inadvertently not been entered into the portable reader, the code will be required to be entered via the receiver^'s computer keyboard.

Where a generator has more than one identification unit, the identification of each is entered into the database as separate records. The receiver will not necessarily know that the identifications refer to the same generator if the transporter has not provided name/address details of the generator.

Where, from time to time, a transporter uses different receiver sites for a particular type of waste from a paπicular generator, it will be necessary to have that generator^'s identification registered with each receiver. Where a waste pickup has taken place from an unregistered site. e.g. illegally dumped waste, the portable reader unit will not be able to be used. However, the system may provide for an authorisation code to be entered manually into the database at the receiver site, along with details of the waste. The authorisation code will normally have been provided to the transporter on an appropriate document by a local authority.

The system may provide for the receiver to upload reports or data periodically to the waste regulator via a dial-up network or to mail/email the reports. The reports can be customised to the regulator^'s requirements. They may include exception reports to advise the regulator of any anomalies that might have occurred with regards to quantities or collection frequencies. The receiver may also provide reports, including exception reports, to transporters giving details of all waste products that are delivered by their vehicles. The database software may be customised to suit particular receiver or regulator requirements.

The tracking system may provide for a private repoπmg agency to download the data from various receivers and to upload or mail/email reports to the regulator and transporters on their behalf. Optionally, where data is handled by a repoπmg agency and where generator names and addresses have been provided to it. the software may provide for the agency to invoice the generator for the service on behalf of the transporter. Copies of invoices may be faxed/mailed/e-mailed to the transporter. The transporter is responsible for the collection of payment. The system does not require the transporter to provide name and address details of its generator clients to the receiver, or to a repoπing agency if invoicing is not required. The repoπing agency may also assist the regulator in overseeing the system.

For further tracking and monitoring of the waste collection vehicle. movement of the vehicle may be tracked by means of an on-board global positioning system. Information from a global positioning unit on the vehicle may be transmitted to the regulating authority. Alternatively, information derived from the global positioning system may be stored in a memory and subsequently downloaded to verify movement of the vehicle.

The present invention in a further aspect provides a method and means whereby automatic, on-demand, waste collection may be initiated by providing a liquid level or load sensor at the waste generator^'s location, the level sensor sensing when a waste liquid collection container such as a grease trap is full and/or requires emptying or the load sensor sensing when a waste collection bin is full and/or requires emptying. These sensors may be interfaced to a telephone network to alert the waste transporter that the container or bin requires emptying. For liquid level sensing, the sensor may be a commercially available float switch or transducer, a pressure switch or transducer, or other type of sensor. For grease traps, a float and reed switch unit constructed so as not to accumulate undue grease or solids and which can be readily cleaned is preferable.

For liquid waste collection, the present invention in a particularly preferred aspect, provides a method for monitoring a liquid waste collection container of the type having an inlet for liquid waste, an outlet, and means for collecting or trapping grease and other waste materials from said liquid waste to prevent or minimise the passage of said waste materials into said outlet, said method including the steps of sensing when the level of liquid in said container rises to or above a predetermined level and the period said level of liquid remains at or above said predetermined level, analysing said sensed time and period data and initiating an alarm when analysis of said data indicates that cleaning of said grease trap is required.

The period of time which the level of liquid remains at or above the predetermined level (or "dwell time") usually indicates the measure of resistance to flow through the outlet and thus the level of blockage or buildup in a filter or trap of the liquid collection container.

To discriminate between a sensed increase in liquid level due to normal usage of the trap and an increase due to excessive grease and waste build up in the trap: however, the method of the invention preferably involves the steps of continuously monitoring respective dwell times or periods. Increasing dwell times over an interval indicates increasing grease build up in the trap. When this trend increases to a predetermined set limit, the alarm is triggered.

Suitably the analysis is carried out by software programmed means which progressively calculates a cumulative mean dwell time which is stored and compared with a predetermined set limit suitably determined by calibration testing.

The method may further include the steps of transmitting an alarm signal to a remote location so as to aleπ persons at the remote location of the need to clean the liquid waste container. For this purpose, the method may include the step of the alarm actuating an auto-dialler of a telephone in a telephone network for transmitting an alarm signal to a remote location. Alternatively or additionally, the method may include the step of actuating a local alarm such as a visual and/or audible alarm.

The present invention in yet a further aspect provides apparatus for monitoring liquid waste containers of the type having an inlet for liquid waste, an outlet. and means for collecting or trapping grease or other waste materials, said apparatus including means for sensing when the level of liquid in said container rises to or above a predetermined level, means for monitoring the period of time said level remains above said predetermined level, and analysing means for analysing said monitored periods of time and initiating an alarm when the periods of time monitored exceed predetermined limits.

Preferably, the analysing means includes means for progressively calculating and storing a cumulative mean dwell time, that is the time which the liquid level remains at or above the predetermined level, and comparing the means dwell time with a predetermined dwell time. The liquid level sensing means may comprise any known liquid level sensing means. For example, it may comprise a float, which floats on. or adjacent the level of liquid in the waste container with means provided to sense the vertical position of the float. In this form, the float may carry a magnet such as rare earth magnet and the means to sense the vertical position of the float and thus the liquid level may comprise a switch such as a reed switch which is actuated by the rare earth magnet for example when the float rises a predetermined amount consequent upon a rise in the level of liquid in the container. The monitoring means also sense or monitor, by the period for which the switch remains actuated, the time the liquid level remains at or above the predetermined level and thus the dwell time. In an alternative arrangement, the sensing means may comprise a mechanically actuated switch which is actuated by direct or indirect contact by the float.

Where a float/switch arrangement is provided to sense liquid level, it is preferably located within a chamber connected to the liquid inlet to the waste container so that the flushing action of liquid entering the inlet acts to minimise or reduce the risk of the float being exposed to. or becoming fouled by. solids such as grease in the container. Often, such a chamber of this form which is open at opposite ends and extends vertically and is connected intermediate its ends to the grease or waste trap inlet is provided in grease traps.

The float/switch are suitably provided in elongated housing means which in use projects veπically into the chamber from the top of the waste collection container. The housing means preferably comprises an outer hollow housing or cage in which the float is located and suitably trapped or constrained, the housing being open or having an opening at its lower end to communicate with liquid in the container. The length of the housing is suitably such that the lower end is located a substantial distance below the normal level of liquid in the container.

Located within the housing is an inner suppoπ for carrying the float sensing means and for positioning the float sensing means at a required level. Means may be provided at the lower end of the suppoπ to guide the float towards the sensing means such that the sensing means may be repeatedly or continuously triggered at a given liquid level. The guide means may be of a tapered configuration such as of a hollow conical configuration which tapers towards the sensing means. This ensures that reliable and accurate positioning of the float occurs at the correct level to avoid incorrect or spurious operation. The vertical position of the suppoπ may be adjusted so as to adjust the position of the sensing means relative to the normal liquid level in the grease or waste trap and enable calibration of the apparatus. For this purpose, the support may be threadably mounted to the housing whereby rotation thereof in opposite directions will move the support vertically in opposite directions. As stated above, somen designs of grease trap already incorporate a suitable inlet chamber in which to sense a surge. In other cases however, a suitable chamber is required to be fitted to the inlet either internally or externally. In most cases the required chamber is of a simple form and made for example from standard PVC fittings. The present invention in yet a further aspect provides a method and means for monitoring of a waste collection pump which pumps waste liquid into a collection tank of the waste collection vehicle to determine the volume of liquid waste collected or. where actual volume is not required, to verify that the pump did operate or operated for an appropriate length of time. Total volume may be measured by time integration of the pump output flow measurement. Typically flow may be measured directly via a flow transducer or indirectly via a differential pressure transducer and pre-mapping of pump pressure and flow. The total volume measured may be written to the vehicle^'s identification unit in which it is stored.

Simple verification of the pump's operation or of its time of operation can be effected by various means depending upon the installation. These means include use of a pressure transducer or pressure switch to sense pump pressure or to sense the pump engine^'s inlet or exhaust pressure, or by use of a Hall effect or other proximity' sensing transducer to sense pump rotation or rotation of the motor driving the pump, or by sensing exhaust temperature of the pump motor or any other appropriate parameter.

A flow monitoring unit for monitoring flow may be hard wired to the cradle in the vehicle such that the information collected thereby is downloaded into the reader or read/writer unit when the latter is placed in the cradle. The flow monitoring unit may be used not only in the system of the invention but in other systems where flow monitoring is required.

The present invention in yet a further aspect provides a method and means for continuous monitoring of calibrated liquid volume or uncalibrated liquid level of the liquid waste collected by the waste vehicle. The recorded volume or level changes may be stored in the on-vehicle identification unit either as raw volume/time or level/time data for rransfeπing into the hand-held reader and thence into the receiver^'s database for analysis, or analysed and stored in appropriate reduced form in the reader for rransfeπing into the receiver's database.

The analysis, whether party or fully within the vehicle identification unit, the reader or the database, will detect all increases and decreases in volume or level sustained for a pre-set minimum time interval. This interval suitably is larger than any transient variation due to vehicle movement. Multiple sensors enable mean volume or level to be determined regardless of vehicle attitude. This system enables unauthorised dumping of liquid waste during transportation to be detected. A level monitoring unit for monitoring liquid level may be hard wired to the cradle of the vehicle identification unit such that the information collected thereby is downloaded into the reader or read/ writer unit when the latter is placed in the cradle.

The level monitoring unit may be used not only in the system of the invention but in other systems where continuous liquid level monitoring is required. Brief Description of the Drawings

In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a prefeπed embodiment of the invention and wherein :-

Fig. 1 is a schematic view of the waste monitoring system according to one embodiment of the present invention;

Fig. 2 illustrates one form of fixed identifying unit for the monitoring means and associated housing; Fig. 3 illustrates the manner in which a receptor of a reader unit cooperates with the fixed identifying unit of Fig. 2;

Fig. 4 is a schematic cross sectional view showing a grease trap and monitoring means for the trap according to an embodiment of the invention;

Fig. 5 is a schematic sectional view of the monitoring means for the grease trap;

Figs. 6(a) and (b) illustrate schematically an on-vehicle liquid flow monitoring device and the signal derived therefrom:

Figs. 7(a) and (b) illustrate schematically an on-vehicle liquid level monitoring device and the signal derived therefrom: Fig. 8 illustrates the hardware of an alternative waste monitoring system according to the present invention. Detailed Description of the Embodiments

Refeπing to the drawings and firstly to Fig. 1. there is illustrated schematically the system 10 according to on form of the present invention for monitoring the collection of waste materials from a number of liquid waste generators 11 at different geographical locations. At each waste generation location, an identifying unit 12 is provided which identifies each location, the identifying unit 12 comprising, as shown more clearly in Figs 2 and 3. a fixed unit having housing 13 which is fixed say to a wall or post adjacent the waste collection point. Located within the housing 13 is a memory chip 14 which is connected to two terminals of a suitable connector 15 in this embodiment in the form of a stereo audio socket having a three terminals. The housing 13 is open at 16 at its lower end whilst the housing 13 is recessed to one side (or front or rear) as at 17 adjacent its open lower end 16. A ball 18 is located within the housing 13 and normally closes the opening 16 as shown in Fig. 3 to block the entrance into the housing 13. This ensures that entry of wasps or other vermin into the housing 13 is blocked.

The memory chip 14 within the housing 13 has a registration number permanently stored therein and which is unique to that chip so as to identify the location 11. More than one such unit 12 may be at the location of each generator where for example more than one type of waste is generated. The unit or units 12 may also be interfaced to a waste quantity measuring device at each location so as to enable reading of quantity of waste as well as location at which the waste is generated and collected.

If desired, an indicator panel 19 may be connected to two terminals of the connector 15 in the identifying unit 12. one terminal being common with the memory chip 14. the panel 19 being installed at a convenient location such as within a building. The indicating panel 19 may include visual and/or audible indicators 20 to aleπ the waste generator that the waste has been collected. A reset button or switch may be provided on the panel 19 to enable the waste-generator to cancel the aleπing signal. Suitably, the indicator panel 19 and identification unit 12 are battery powered however they may be provided with a mains power supply such as a plug in mains power pack.

The waste generator may additionally or alternatively also have, a hand held identification unit 22 which may be in the form of a hand held variant of the fixed unit or in the form of a small key-ring caπied unit which caπies an identifying memory unit such as that known as a Dallas key. This unit is used where an employee or other authorised personnel of the waste generator is required to be in attendance during the waste collection. Where more than one type of waste is generated at the premises, a single hand-held unit may be used and waste type entered manually into a reader or separate hand-held units may be provided for each type of waste or alternatively a combination of hand-held units and fixed units provided.

The waste generated at the respective locations 11 is collected by a waste collector indicated generally at 23 who has a vehicle 24. conventionally a vehicle which includes a liquid collection tank 25 where waste liquids are to be collected. The vehicle 24 includes a vehicle identification unit 26 which may be mounted in the cabin of the vehicle 24. This unit 26 includes a memory device which is coded to identify the vehicle and distinguish it as a vehicle identification unit. This unit 26 may be interfaced to a vehicle waste quantity measuring device as described further below.

The identification unit 26 may be incorporated in a cradle 27 within the waste collection vehicle 24 which is adapted to carry a portable reader unit 28. The unit 28 is suitably battery powered and recharged when placed in the cradle 27 from the vehicle battery normally via the cigarette lighter socket. The unit 28 is designed to read the data held in identification units 12 and/or 22 and transfer the data into a database within the unit 28. In one embodiment, the unit 28 includes a connector in the form of a probe 29 which may be placed into register with the units 12 and 22 to read the identification of that unit (and quantity where provided ). The unit 28 also records the time and date of the readings and an audible and/or visual signal is generated when the units 12 and 22 are read. The reader unit 28 reads and stores the identification, quantity and time as a single record.

The probe 29 is provided on its end with a plug 30 (see Fig. 3) which is adapted to cooperate with the socket connector 15. Leads from the plug 30 are connected to the reader unit 28 to transfer or download information from the memory chip 14 into the reader unit 28. As the probe 29 is inserted into the housing opening 16 as shown in Fig. 3. it will push the ball 18 to one side into the recess 17 to permit the plug 30 to connect to the socket connector 15. When the probe 29 and plug 30 are withdrawn the ball 18 will roll out of the recess 17 to close the opening 16 as in Fig. 2.

Embodiments of mating plug and socket other than the probe/plug 29/30 and the socket 15 shown in Figs. 2 and 3 may be employed and the employment of male and female parts on the reader and identification unit may be interchanged. The ball 18 may be incorporated into any embodiment involving a recess on the identification unit. In yet an alternative arrangement, the information in the memory 14 may be transfeπed directly into the reader unit 28 through a non-wired connection.

The unit 28 may include a LCD display which displays quantity of waste collected for visual confirmation. The unit 28 may also incorporate a keypad 31 which enables waste quantity to be entered manually. Waste quantity entered using the keypad 31 is preferably entered using predetermined units. Alternatively, the unit 28 may be of simple form without keypad as shown at 28' with information transfeπed into the reader unit 28' by simple depression of an "Enter" key. The waste materials collected by the vehicle 24 are conveyed to a receiving and waste disposal site indicated generally at 31 which includes a reader 32 through which the information stored in the reader unit 28 may be downloaded and stored in a database of a computer 33. The information downloaded into the database includes each waste generator^'s identification, the time and date that waste was collected from the generator, the quantity of waste collected and the waste code where applicable, time and date of the vehicle^'s arrival and the vehicle^'s identification and the reader^'s unit identification. The waste generator^'s identification, waste origin code and the waste code and any other required identification data for the generator or transporter is entered into the receiver^'s database when the generator is first registered with the receiver. If more than one waste code is associated in the database with a generator identification, for example where the generator has a single hand-held identification unit for use with more than one waste type and the code has not been entered into the reader, the code will be required to be entered via the receiver^'s computer keyboard.

If a generator has more than one identification unit, the identification of each is entered into the database as separate records. If a transporter uses different receiver sites for a particular type of waste from a paπicular generator, it will be necessary to have the generator's identification registered with each receiver. A weighbridge or other measuring device may be provided at the receiver site for measuring the quantity of waste delivered and its output can be interfaced with the computer 33 for recording in the database and for subsequent checking against the total quantity read from the reader unit 28. Alternatively, waste quantity as measured by the receiver can be entered manually via the computer keyboard. If waste pickup has taken place from an unregistered site, for example illegally dumped waste, the reader unit 28 will not be able to be used. The system however allows for an authorisation code to be entered manually into the database at the receiver site along with details of the waste. The authorisation code will normally have been provided to the transporter on an appropriate document by a local authority. When valid data has been recorded, the computer 33 at the receiver outputs its cuπent date and time to overwrite that held by the reader unit 28. All identification and collection time data records are then deleted in the reader unit 28 and the reader unit 28 is reset for a new collection run. This completes the transfer of data between the reader unit 28 and waste receiver 31 and activates an audible and/or visual signal in the reader unit 28 to aleπ the vehicle driver that a valid transfer of data has taken place. At the same time an output may be provided by the computer 33 to operate a boom gate where one is in place.

A selectable option for the reader unit 28 provides for data records to be tagged rather than deleted. The tagged records are then available for downloading by the transporter. They are overwritten by new records as the reader memory is filled. Only untagged records are read into the receiver^'s database.

Reports or data may periodically be provided by the receiver computer 33 to a waste regulator 34 via a dial-up network or the reports or data may be mailed/emailed.

A computer 35 may also be provided by the reporting agency to receive downloaded data from the computers 33 at the receiver site and to provide reports to computers at the regulator 34 and transporter 36 and if desired a local authority 37. Optionally, from the downloaded data, the generators may be invoiced for the serviced provided by the transporter.

Automatic on demand waste collection may be made available by providing at the waste generator, a liquid level or load sensor which senses and alerts automatically, through a telephone network, the transporter when the tank, grease trap. bin or other collection device is full or requires emptying. For use on liquid waste tanks, the arrangement shown in Figs. 4 and 5 may be provided which illustrates a conventional grease trap 40 including a liquid collection container in this embodiment in the form of a tank 41 having an inlet 42 and an outlet 43 below the inlet 42 and communicating with a grease filter 44 within the tank 41. the grease filter 44 having an inlet 45 at its lower end. In use waste water carrying grease or other solids passes through the inlet 42 and into the tank 41 to force the liquid already in the tank 41 into the inlet 45 of the filter 44 to pass therethrough to the outlet 43. with any grease or other solids being trapped in the filter 44 to prevent it passing into the outlet 43. The normal liquid level 46 in the tank 41 is thus at the lowermost level of the outlet 43. The tank 41 also includes an access hatch 47 to allow access to the interior of the tank 41 for cleaning of the filter 44 and a suction pipe 48 for removal of liquid and sediment from the tank 41.

As wastewater enters the tank 41 via the inlet 42. there will be a surge in the level of liquid until the filter 44 can handle the flow and the level again drops to the level 46. The height of the liquid surge will depend on the magnitude of the waste water flow into the tank, however as the grease filter 44 becomes increasingly blocked by collected grease and waste, there will be an increasing restriction to liquid flowing through the filter 44 which thereby results in an increasing mean surge level of liquid. Also, there is an increasing mean period of time before the liquid level returns to the normal level. For sensing the level of liquid in the tank 41. the grease trap 40 incorporates a sensor 49 which as also shown in Fig. 5 includes an outer hollow housing 50 in the form of an elongated tube which is substantially closed except at its lower end where it is open or provided with openings 51 to communicate with the liquid within the tank 41. The housing 50 is secured at its upper end to the tank 41 for example by being secured in an aperture in the top of the tank 41 whilst the length of the housing 50 is such that its lower end is well below the normal level 46 of liquid in the tank 41. This ensures communication with liquid rather than solids such as grease which floats at or adjacent the surface of the liquid. Arranged within the housing 50 is an elongated suppoπ 52 which caπies a switch 53. in this case a reed switch, at or adjacent its lower end. The suppoπ 52 is preferably threadably connected at its upper end to the housing 50 whereby upon rotation in opposite directions, the lower end of the suppoπ 52 is raised or lowered to adjust the vertical position of the switch 53. Located and constrained within the housing 50 is a float 54 which carries a magnet 55 at its upper end and which is self-righting so as to always present the magnet 55 on its upper side. The float 54 is of such a size as to reduce the risk of fouling with the wall of the housing. The suppoπ 52 also includes a guide 56 which is of tapered form, suitably of conical form, to guide the float 54 towards the switch 53 in use to ensure reliable operation. The guide 56 may be open or vented as at 57 to release trapped air and water as the float 54 rises and to ensure it is flushed so there is no grease build up.

To ensure that grease does not build up on the float 54 and other components of the sensor 49. a veπically extending chamber in the form of a duct 58 is connected to the inlet 12 if there is no suitable existing duct or chamber and the housing 50 of the sensor 49 projects substantially coaxially into the duct 58. Thus the sensor 49 and components thereof will be flushed each time liquid passes into the inlet 42 and there will be little or no grease build-up on the inner surface of the duct 58.

Connected to the switch 53 is suitable electronic circuitry which senses and monitors operation of the switch 53 and the time that the switch 53 remains on. The electronic circuitry also includes means to generate an alarm signal. At most times, any liquid entering the inlet 42 will cause a rise in the level 46 of liquid in the tank 41 and a consequent rise of the float 54 and triggering of the switch 53. With increasing build up of grease within the filter 44. each time waste water enters the inlet 42 there will be an increasing time that the switch 53 remains on because there is an increasing resistance in the filter 44 to liquid flow through the outlet 43. The electronic circuitry is software programmed to monitor the progressive mean dwell time, that is the time the switch 53 remains on, and when this goes beyond predetermined parameters to provide an alarm signal.

The alarm signal may be used to operate a visual and/or audible alarm at the trap 40 and or initiate transmission of an alarm to a remote location say to a cleaning contractor to indicate the necessity of cleaning the trap. The alarm may be transmitted to the remote location by any suitable means such as by initiating the dialing of a cellular or cordless phone to use existing communication networks. Of course any other remote signaling means may be used.

In one prefeπed form, the electronic circuitry may be located within a sealed housing in the suppoπ 52 so that the apparatus is self-contained.

Whilst in the embodiment described, the float is shown to cooperate with a reed switch, the reed switch may be replaced by any other suitable sensing means for the float.

In yet a further arrangement, the level sensing means may comprise a tethered float carrying a level sensing switch such as a mercury operated switch which switches on when the float reaches a predetermined level in the tank. The electronic circuitry may be of any suitable form however it most preferably includes a programmed microprocessor for analysing the signals indicative of liquid level and time signals for comparison with stored data.

The system of the invention may also include a monitor 58 for monitoring a waste collection pump 59 which pumps liquid wastes into the collection tank of the transpoπ vehicle 24 to determine the volume of liquid waste collected or alternatively for verifying that the pump was operated for an appropriate length of time (see Figs. 1 and 6).

Total volume may be measured by time integration of the pump output flow measurement. Typically, pump flow is measured directly by a flow transducer or indirectly via a differential pressure transducer and pump pressure mapping. The total volume is stored in the vehicle^'s identification unit 25 to be read by the reader unit 26.

Verification of the pump^'s operation or time of operation may be measured by a pressure transducer or pressure switch to sense pump pressure (as indicated by the graph in Fig. 6(b)) or to sense the pump^'s engine inlet or exhaust pressure or alternatively by the use of proximity sensing transducers to sense pump engine rotation or by sensing pump engine exhaust temperature or other appropriate parameter.

The system may additionally include a monitor 60 (see Figs. 1 and 7) for continuously monitoring calibrated liquid volume or uncalibrated liquid level. By such means, the recorded volume or level changes are stored in the vehicle identification unit 26 either as raw volume/time or level/time data (as indicated by the graph in Fig. 7 (b)) for transfeπing into the hand-held reader unit 28 and thence into the receiver^'s database in the computer 33 for analysis, or analysed and stored in appropriate reduced form for transfeπing into the reader unit 28. The analysis whether partly or fully within the monitoring unit, the reader or database, will detect all increases and decreases in volume or level sustained for a preset minimum time interval larger than any transient variation due to vehicle movement. Multiple liquid level sensors of known type are provided within the collection tank on the vehicle to enable mean volume or level to be determined regardless of vehicle attitude and enable unauthorised dumping of waste during transportation to be detected.

Such an aπangement may of course be used in any form of waste collection system other than that described to detect unauthorised dumping of waste. Similarly the aπangement described in Fig. 4 and 5 may be used in waste collection systems other than that described with reference to Fig. 1. Refeπing now to Fig. 8 there is illustrated the hardware of an alternative form of waste monitoring system 61 according to the invention in which like components to the components of Fig. l have been give like numerals. In this case the waste generator's site 11 includes a fixed identification unit 12 in the form of a passive transponder which contains in a memory (ROM) an identification number. The unit 12 is fixed adjacent the waste collection point and where more than one type of waste is collected, units 12 may be located adjacent each collection point. The waste generator's site 11 may also include a hand-held unit 22 of similar form to the fixed unit but being portable so as to enable it to be easily carried such as on a key ring.

The units 12 and 22 are capable of being read by a reader 28 or 28'. The units 28 and 28' comprises a data reading, storing and writing device which when brought into proximity to one of the identification units 12 or 22 is capable of reading and storing the identification of each unit by for example pressing an "Enter" key together with the time and date of reading. The units 28 and 28' are battery powered and when not in use it is caπied in a recharging cradle 27 in the cabin of the waste collection vehicle 24 for recharging the battery. When in the cradle 27, the unit 28 or 28' monitors the vehicle's identification. If the vehicle identification is different to an assigned identification, the unit 28 or 28' will be disabled and the driver will be alerted. When placed in the cradle 27 at the commencement of the waste collection run. the unit 28 or 28' reads and assigns to itself that vehicle's identification for the duration of that run until information stored therein is downloaded at the waste receiver's site.

In Fig. 8, the reader unit 28 includes a keypad 31 to enable waste quantity to be manually input into the unit 28. This unit 28 however may also be used in the same manner as the unit 28'. Each unit 28 and 28' may also be provided with a telephone transmitter/receiver circuit and a dedicated communications key which when depressed causes the transmitter/receiver to dial over a telephone network the waste collection coordinator or other information provider to enable the waste collector to check details of a paπicular connection. The cradle 27 is hard wired to a flow monitor 58 and/or a level monitor 60 of the type described above. When the unit 28 or 28' is placed into the cradle 27. it will read and record waste quantity or other waste monitoring parameters registered by the flow monitor 58. Thus any details of a paπicular waste collected from a waste generator's site 11 can be recorded in a unit 28 or 28'. For individual quantities to be recorded against each generator by a reader unit 28 or 28'. the unit 28 or 28' must be replaced in the cradle 27 after each individual collection.

At the waste receiver's site 31. a reader unit 32 is provided being typically located on a post or wall adjacent to the entrance into the receiver's site 31. The unit 32 is interfaced to a computer 33 container a database. The unit 30 includes a cradle 62 into which a reader unit 28 or 28' may be placed when enables all data stored in a unit 28 or 28' to be downloaded into the database for processing or forwarding to regulators or other bodies as described previously. Thus a record is held of all waste collections from paπicular sites and of the time and date of each collection to enable complete monitoring. This information however may also be downloaded from the unit 28 or 28' by simple transmission of data in for example serial form by any suitable communication arrangement such as by radio communications.

The unit 28 or 28' may also record any unauthorised dumping by using the level monitor 60 information from which is stored in the unit 28 or 28' and also downloaded at the receiver's reader unit 32. Alarm means may also be provided in the vehicle cabin associated with the level monitor 60 and/or flow monitor 58 to aleπ the driver as to a loss of volume or pressure in the case, for example, of a spillage. The alarm means may be a visual or audible alarm. A vehicle motion sensor may also be associated with the vehicle and the level monitor 60 such that level is only monitored when the vehicle stops to detect unauthorised dumping when stopped. This then may eliminate the need for constant monitoring of the level.

It will be appreciated that the reader units 28 may be of many different configurations provided that they are capable of reading data from the waste generator's site and vehicle identification unit and transfer that data to the waste receiver. Reading and transfer of data can occur by any suitable communication system. The system of the invention is suitable for tracking waste of many different types including liquid and solid wastes.

Whilst the above has been given by way of illustrative embodiment of the invention, all such modifications and variations to the invention as would be apparent to persons skilled in the an are deemed to fall within the broad scope and ambit of the invention as defined in the appended claims.

Claims

1. A waste collection monitoring system whereby waste collection from a number of waste generation locations can be monitored, said system including identifying means at each location for identifying each said location, reader means associated with a waste collection vehicle for identifying from said identifying means, a said location and for recording said location from which waste is collected, and means at a waste receiving location for receiving downloaded information from said reader means to identify that waste has been collected from a said identified location.

2. A waste collection monitoring system according to Claim 1 wherein said vehicle includes identifying means to enable it to be identified by the reader means.

3. A waste collection monitoring system according to Claim 1 wherein said identification means comprises a contactless memory identification unit.

4. A waste collection monitoring system according to Claim 1 wherein said identification means comprises a self powered hand-held unit.

5. A waste collection monitoring system according to Claim 4 wherein separate hand- held units are associated with each type of waste to be collected.

6. A waste collection monitoring system according to Claim 4 wherein said hand held unit includes a keypad for entering waste type and quantity.

7. A waste collection monitoring system according to Claim 1 wherein said identification means comprises a fixed identification unit.

8. A waste collection monitoring system according to Claim 7 wherein said fixed identification unit comprises a contactless unit and wherein said reader means may be brought into proximity with said fixed identification unit to identify that unit.

9. A waste collection monitoring system according to Claim 7 wherein where more than one type of waste is generated at a waste generation location, fixed identification units with individual identifications are located adjacent each collection point associated with each type of waste.

10. A waste collection monitoring system according to Claim 2 wherein the vehicle identification unit is mounted m the cabin of the waste transpoπ vehicle.

11. A waste collection monitoring system according to claim wherein said reader unit includes audible and/or visual alarm means for issuing an audible and/or visual alarm if the vehicle identification means is not read before attempting to read the location identifying means.

12. A waste collection monitoring system according to Claim 2 wherein said vehicle identification unit is interfaced to a vehicle installed waste quantity measuring device.

13. A waste collection monitoring system according to Claim 1 wherein said reader means includes a portable hand-held reader unit normally caπied in the waste transpoπ vehicle but being detachable therefrom to enable it to be brought into register with the identifying means at the waste generator^'s location to identify the location and the quantity data from the memory units.

14. A waste collection monitoring system according to Claim 13 wherein at said waste receiving location, said reader unit may download data derived from said waste generation locations to data storage means.

15. A waste collection monitoring system according to Claim 14 wherein said reader means is adapted to read and store the waste generator^'s identification, the waste quantity and the time as a single record for downloading to the receiver^'s database at the receiver^'s waste site.

16. A waste collection monitoring system according to Claim 15 wherein said reader unit includes a keypad and display to enable waste quantity and waste code to be entered manually.

17. A waste collection monitoring system according to Claim 1 and including means at a waste generator's location for aleπing said system of the need to collect waste.

18. A waste collection monitoring system according to Claim 17 wherein said aleπing means includes a liquid level sensor for sensing when a liquid waste collection container is full and/or requires emptying

19. A waste collection monitoring system according to Claim 17 wherein said aleπing means includes load sensor means for sensing when a waste collection bin is full and/or requires emptying.

20. A waste collection monitoring system according to Claim 1 wherein waste at a waste generation location comprises liquid waste collected in a grease trap.

21. A method for monitoring a liquid waste collection container of the type having an inlet for liquid waste, an outlet, and means for collecting or trapping grease and other waste materials from said liquid waste to prevent or minimise the passage of said waste materials into said outlet, said method including the steps of sensing when the level of liquid in said container rises to or above a predetermined level and the period said level of liquid remains at or above said predetermined level, analysing said sensed time and period data and initiating an alarm when analysis of said data indicates that cleaning of said grease trap is required.

22. A method according to claim 21 and including the steps of continuously monitoring respective said periods and initiating said alarm when said increase in said periods reaches a predetermined set limit.

23. A method according to claim 22 wherein and including the step of progressively calculating and storing a cumulative mean said periods and comparing said stored mean with a predetermined set limit.

24. The method of claim 21 wherein said alarm initiation includes the step of transmitting an alarm signal to a remote location so as to aleπ persons at the remote location of the need to clean the liquid waste container.

25. Apparatus for monitoring liquid waste containers of the type having an inlet for liquid waste, an outlet, and means for collecting or trapping grease or other waste materials, said apparatus including liquid level sensing means for sensing when the level of liquid in said container rises to or above a predetermined level, monitoring means for monitoring the periods or time said level remains above said predetermined level, and analysing means for analysing said monitored periods of time and initiating an alarm when the periods of time monitored exceed predetermined limits.

26. Apparatus according to claim 25 wherein said analysing means includes means for calculating and storing cumulative mean periods and comparing said stored mean periods with a predetermined period.

27. Apparatus according to claim 25 wherein said level sensing means comprises a float, which floats on, or adjacent the level of liquid in the waste container and means for sensing the vertical position of said float.

28. Apparatus according to claim 27 wherein said float carries a magnet and the means to sense the vertical position of the float and thus the liquid level comprises switch means adapted to be actuated by said magnet when said float rises a predetermined amount consequent upon a rise in the level of liquid in the container.

29. Apparatus according to claim 28 wherein said sensing means further sense by the period which said switch remains actuated, said period the liquid level remains at or above said predetermined level.

30. Apparatus according to claim 29 wherein said float is located within a chamber connected to the liquid inlet to the waste container so that the flushing action of liquid entering the inlet acts to minimise or reduce the risk of the float being exposed to. or becoming fouled by. solids such as grease in the container.

31. Apparatus according to Claim 30 wherein said float and sensing means are provided in elongated housing means which projects vertically into the chamber from the top of the container.

32. Apparatus according to Claim 31 wherein said housing means comprises an outer hollow housing or cage in which the float is located, said housing being open at its lower end to communicate with liquid in the container and wherein the length of the housing is such that the lower end thereof is located a substantial distance below the normal level of liquid in the container.

33. Apparatus according to Claim 32 wherein said sensing means is supported on an inner support located in said housing and wherein means may be provided at the lower end of the suppoπ to guide the float towards the sensing means such that the sensing means may be repeatedly or continuously triggered at a given liquid level.

34. A waste collection monitoring system according to Claim 1 wherein said waste collection vehicle includes a waste collection pump and including means associated with said waste collection vehicle for monitoring said waste collection pump to determine the volume of liquid waste collected or for verifying operation of said pump.

35. A waste collection monitoring system according to Claim 34 and including means for measuring volume of liquid collected by said vehicle by time integration of the pump output flow measurement.

36. A waste collection monitoring system according to Claim 1 wherein said vehicle includes a liquid waste collection container and including means for continuously monitoring and recording the liquid volume or liquid level of the liquid waste in said collection container for detecting unauthorised dumping of liquid waste.