TECHNICAL FIELD

The present concerns an apparatus for measuring the turbidity of a fluid and use thereof with liquid-solid separators. BACKGROUND

Fluid turbidity is caused by solids suspended in the fluid resulting in a cloudy or hazy appearance. Turbidity may be measured for various reasons such as, for example, determining water quality or identifying a fluid. Turbidity measurement may be useful during maintenance of a septic tank. Septic tanks are well known and used to contain waste water, which, after it enters the septic tank, separates or decants into a bottom layer of settled waste, or sludge; a middle layer of water and impurities in suspension, or supernatant; and a top layer of floating waste, or scum.

Septic tank maintenance is generally performed using a waste collection vehicle such as a vacuum truck. In some examples, vacuum trucks are provided with a liquid-solid separator, an example of which is disclosed in U.S. Patent 6,790,368. The liquid-solid separator allows waste water to be extracted from the septic tank. The liquid-solid separator includes a valve assembly used to direct extracted scum and sludge into a first reservoir and extracted supernatant into a second reservoir, to be filtered and returned to the septic tank. The extracted sludge and scum may then be transported to a disposal site without having to also transport the supernatant, thereby substantially reducing the cost associated with the maintenance of the septic tank.

To selectively direct the supernatant, the sludge and the scum into the appropriate reservoir, a number of solutions have been suggested. According to one solution, the waste water is extracted through an extraction conduit, a portion of which is translucent to allow the operator to visually assess a level of turbidity of the extracted waste water and manually activate the valve assembly according to this level of turbidity. However, visual assessment of the level of turbidity is largely inaccurate and may vary between operators carrying out the assessment. Further, this solution inconveniently requires the operator to constantly observe the extracted waste water during maintenance of the septic tank.

Another solution uses a turbidity measurement apparatus, which is coupled to the valve assembly. The turbidity measurement apparatus includes a pipe with a restricted portion located between a pair of planar walls. An aperture is provided in each wall, and a glass panel is provided over each of the apertures. An emitter and a receiver are positioned behind the glass panels and are in alignment with each other to allow a light beam emitted by the emitter to be transmitted through fluid flowing through the pipe, to be received by the receiver and to be converted to a value representing the level of turbidity of the fluid. To measure the turbidity of the fluid with sufficient accuracy, the planar walls are spaced apart at a predetermined distance. Unfortunately, since this distance is usually smaller than the diameter of the pipe, the restricted portion may restrict the flow of fluid flowing through the pipe, which limits the maximum flow of fluid in the pipe. Furthermore, the glass panels are exposed to debris which may be carried by the fluid flowing in the pipe. The debris may damage the panels upon contact, which may then need costly and time consuming repairs or replacement. Also, the damaged panels may distort the light beam emitted by the emitter and therefore distort the measurement of the turbidity of the fluid. The debris can also prevent the emitted light beam from being received by the receiver, which may further distort the measurement of the turbidity of the fluid. Thus, there is a need for an improved turbidity measurement apparatus. BRIEF SUMMARY

In one aspect, there is provided an apparatus for monitoring the turbidity level of a fluid, the apparatus comprising:

- a fluid passageway for a fluid, the fluid flowing along a main flow pathway in the passageway;

- a chamber located in fluid communication with the fluid passageway, a portion of the fluid being deviated away from the main flow pathway such that it flows through the chamber; and

- a turbidity monitor connected to the chamber for monitoring the turbidity of the fluid flowing through the chamber, the turbidity monitor being capable of transmitting a signal into the chamber to monitor the turbidity level of the fluid flowing through the chamber.

In one example, the chamber includes an inner sidewall having first and second spaced apart angled sidewall portions, and a roof portion interconnecting the angled sidewall portions. In another example, the first angled sidewall portion is angled away from the main flow pathway and the second angled sidewall portion is angled towards the main flow pathway. The inner sidewall is generally trapezoidal in cross section.

In one example, the fluid passageway has a first internal fluid volume and the chamber has a second internal fluid volume that is smaller than the first internal fluid volume.

In another example, the fluid passageway is a truncated pipe having a sidewall opening for sealingly receiving therein the chamber. In one example, the chamber includes a lower rim that is sealingly connected to the sidewall opening. The sidewall opening is generally rectangular.

In another example, the chamber has four exterior sidewalls, and a first port hole located in one of the exterior sidewalls and a second port hole located in an opposing exterior sidewall, the port holes being aligned with each other and located in the sidewalls such that the fluid flowing through the chamber passes between the port holes. In one example, the turbidity monitor includes a signal emitter connected to the exterior sidewall adjacent the first port hole to permit the transmission of the signal into the chamber and through the fluid flowing through the chamber, and a signal receiver connected to the exterior sidewall adjacent the second port hole to receive the signal. First and second translucent panels are located adjacent respective port holes and between the respective signal emitter and the signal receiver. The first and second translucent panels are made from a translucent material selected from the group consisting of: glass, poly(methyl methacrylate), and polycarbonate.

In one example, the signal is a light beam. In one example, the light beam is an infra-red light beam.

In another example, two of the exterior sidewalls are separated by a distance that is smaller than the diameter of the fluid passageway.

In one example, the chamber is cuboid.

According to another aspect, there is provided a flow deviation chamber for use with a fluid passageway having a fluid flowing along a main pathway therein, the chamber comprising:

- an inner sidewall having first and second spaced apart angled sidewall portions, and a roof portion interconnecting the angled sidewall portions, the chamber locatable in fluid communication with the fluid passageway, a portion of the fluid being deviated away from the main flow pathway such that it flows through the chamber; and - a turbidity monitor connected to the chamber for monitoring the turbidity of the fluid flowing through the chamber, the turbidity monitor being capable of transmitting a signal into the chamber to monitor the turbidity level of the fluid flowing through the chamber In one example, the inner sidewall is generally trapezoidal in cross section.

According to another aspect, there is provided a liquid-solid separator for collecting waste from a waste tank, the separator comprising:

- a waste collection tank; and - the apparatus according to any one of claims 1 through 7, the apparatus being connected between the tanks.

In one example, the waste tank is a septic tank. In another example, the waste tank is a grease trap. The waste tank contains solid waste including sludge and/or scum. According to another aspect, there is provided a waste collection vehicle comprising a liquid-solid separator, as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the discovery may be readily understood, embodiments are illustrated by way of example in the accompanying drawings, in which:

Figure 1 is a perspective view of a turbidity measurement apparatus; Figure 2 is an exploded perspective view of the turbidity measurement apparatus shown in Figure 1 ;

Figure 3 is another exploded perspective view of the turbidity measurement apparatus shown in Figure 1 showing a deviation chamber;

Figure 4 is a perspective view of the deviation chamber; Figure 5 is a worm's eye perspective view of the deviation chamber;

Figure 6A is a cross-section view taken along line VI-VI of Figure 1 ; Figure 6B is the cross-section view shown in Figure 6A showing with flow lines of a fluid pathway;

Figure 7 is a cross-section view taken along line VII-VII of Figure 1 ;

Figure 8 is a perspective view of a bracket and an emitter of a turbidity sensor; Figure 9 is a top perspective view of a solid-liquid separator showing the turbidity measurement in use with a waste tank and a septic tank; and

Figure 10 is a detailed view of area X of Figure 9 showing the location of the turbidity measurement apparatus.

DETAILED DESCRIPTION

In the following description, references to the accompanying drawings are by way of illustration of an example by which the discovery may be practiced. It will be understood that other embodiments may be made without departing from the scope of the discovery.

Referring now to Figures 1 and 2, an apparatus for monitoring the turbidity level of a fluid is shown generally at 00. The apparatus 100 includes a fluid passageway 102, a deviation chamber 104, and a turbidity monitor 106. The deviation chamber 104 is connected to the fluid passageway 102 and is in fluid communication with the passageway 102, and extends outwardly therefrom. The fluid passageway 102 is typically a truncated pipe in which a fluid flows along a main flow pathway 103. When the fluid flows along the fluid passageway 102 (hereinafter "pipe"), a portion of the fluid 105 is deviated away from the main flow such it flows through the chamber 104.

The turbidity monitor 106 is connected to the chamber 104 for monitoring the turbidity of the fluid as it flows through the chamber 104. The turbidity monitor 106 is capable of transmitting a signal into the chamber 104 so as to monitor the turbidity level of the fluid that is flowing through the chamber 104, which will be described in more detail below.

The apparatus 100 is particularly well adapted to measure the turbidity of flowing sewage or of flowing fluid that carries debris and solid matter, such as rocks, wood pieces and the like, which are susceptible to cause damage to the turbidity sensor 106 and induce errors in the measurement of turbidity, since its configuration avoids contact between the turbidity sensor 106 and larger debris, as will be explained in greater details below.

Still referring to Figure 1 , the pipe 102 has an inlet end 108, an outlet end 110 and a curved wall 112 extending therebetween. First and second flanges 118, 120 are respectively connected to the inlet and outlet ends 108, 110 of the pipe 102 and extend outwardly from an outer surface 116 of the curved wall 1 2. The first and second flanges 118, 120 may be secured to the outer surface 116 using known assembly techniques, such as welding. A plurality of holes 122 and 124 are evenly spaced on the respective first and second flanges 1 8, 120, to accommodate fasteners (not shown) for attaching each of the first and second flanges 118, 120 to a corresponding flange of inflow and outflow pipes (not shown). This configuration allows the pipe 102 to be easily connected to corresponding flanged pipes in an existing fluid circuit. Annular grooves 126, 128 are located on the first and second flanges 118, 120 respectively. The annular grooves 126, 128 each define a weld joint to aid welding of the flanges 118, 120 to the pipe 102. The annular grooves 126, 128 may further be configured to receive O-ring seals (not shown) to prevent leakage of fluid when the apparatus 100 is connected to inflow and outflow pipes. Gaskets may also be located between the first and second flanges 18, 20 and the corresponding flange of the inflow and outflow pipes connected thereto to eliminate fluid leakage.

The pipe 102 is connectable via the inlet end 108, to an inflow pipe (not shown) to communicate fluid into the pipe 102 and via the outlet end 110, to an outflow pipe (not shown) for the fluid to exit the pipe 102. The pipe 102, inflow pipe and outflow pipe form a fluid circuit, which may include additional fluid circuit elements, such as valves, filters, or any other fluid circuit elements.

The pipe 102 typically has a diameter of 3 inches, and can be connected to other 3- inch pipes. 3-Inch pipes are generally used for applications described herein, but pipes of other diameters can also be used, such as those between 2 inches and 12 inches. The first and second flanges 18, 120 each typically have an inner diameter of about 3 1/2 inches. Typically, the inner diameter is between 3 1/2 inches and 13 inches. Referring now to Figure 3, a generally rectangular sidewall opening 300 is defined in the curved wall 1 12 to allow fluid communication between the pipe 102 and the deviation chamber 104. The opening 300 extends longitudinally relative to the pipe 102 and is defined by front and back arcuate edges 306, 308 and a pair of side edges 310, 312 extending therebetween. The sidewall opening 300 is sized and shaped to sealingly receive the deviation chamber 104 so as to connect the chamber 104 to the portion 102.

The pipe 102 is linear and has a longitudinal axis AL. The pipe 102 may have a curved configuration or an elbow configuration, depending on various considerations such as the shape and size of a structure supporting the pipe 102, or the position and orientation of inflow and outflow pipes.

Now referring to Figures 4, 5 and 6A, the deviation chamber 104 includes an inner sidewall which defines a cavity 550, which is in fluid communication with the pipe portion 102. The deviation chamber 104 is generally cuboid. In the example illustrated, the chamber is a rectangular box having an outer planar surface defining a lower rim 552 surrounding the cavity 550, the lower rim 552 is sealingly connected to the sidewall opening 300. The body 400 includes exterior side walls, a pair of side walls 500, 502, a front wall 503 and a back wall 505. When the apparatus 100 is assembled, the lower rim 552 of the deviation chamber 104 rests on the side edges 310, 312 of the opening 300, and the front and back walls 503, 505 abut the front and back arcuate edges 306, 308 respectively, and is sealed thereto to allow fluid communication between the pipe 102 and the deviation chamber 104. The deviation chamber 104 is welded to the pipe 102 to substantially reduce or essentially eliminate leaks of fluid.

The cavity 550 is defined by the first and second sidewalls 500, 502 and a third wall (inner sidewall) 504 extending between the first and second sidewalls 500, 502. The first and second walls 500, 502 are spaced apart and generally parallel to each other. The inner sidewall 504 is generally trapezoidal when viewed in cross-section and has a pair of spaced apart front and back sidewall portions 600, 602 angled inwardly relative to the outer surface 552 of the deviation body 400. A top roof portion 604 interconnects the front and back portions 600, 602. The angled sidewall portion 602 is angled away from the main flow pathway 103, whereas the angled sidewall portion 600 is angled towards the main flow pathway 103. This configuration provides a substantially smooth path of travel for fluid entering the cavity 550 from the pipe 102.

A person skilled in the art will appreciate that the inner sidewall 504 is trapezoidal, other shapes may include a curved sidewall in a semicircular or parabolic configuration, to provide a smooth path of travel for fluid entering the cavity 550 of the deviation chamber 104.

The first fluid passageway (the pipe 102) has a first internal fluid volume, wherein deviation chamber 104 has a second internal volume that is smaller than the first internal fluid volume. As best illustrated in Figure 7, the first and second side walls 500, 502 comprise first and second circular apertures (portholes) 260, 262, respectively. The first and second circular apertures 260, 262 are aligned and share a common axis Ai to allow a signal (a wave or a beam of light) to be transmitted through the cavity 550 between the first and second circular apertures 260, 262. While the first and second apertures 260, 262 are circular, they could have a different shape provided they are aligned with the axis Ai. Referring to Figures 2 and 7, the turbidity monitor 106 includes a signal emitter 250 and a signal receiver 252, which is connectable to an input/output device (not shown), such as an analyzer, a visual or sound indicator, a display device or a controller which will activate an actuator, such as a valve, in response to a predetermined level of turbidity measured by the turbidity monitor 106. The emitter 250 emits a signal (or wave), which is transmitted through the portion of the deviated fluid 105. The transmitted wave is then received by the receiver 252 and converts this signal into an indication relative to a characteristic of the transmitted signal, which is then processed by the input/output device.

The emitted signal is a light beam. In one example, the light beam is an infrared light beam, which is transmitted through the portion of the deviated fluid 105, and received by the receiver 252. The receiver 252 provides a value indicative of the intensity of the transmitted light beam, which may then be converted into a level of turbidity of the deviated fluid portion. In one example, the turbidity sensor 106 is an E3S-CT66™ sensor manufactured by Omron Corporation (Kyoto, Japan). Referring now to Figures 2, 7 and 8, the emitter 250 and the receiver 252 are connected to the exterior of the deviation chamber 104 using first and second brackets 200, 202, respectively, which hold the emitter 250 and the receiver 252 respectively over the first and second circular apertures 260, 262 so that the light beam emitted by the emitter 250 is oriented along the axis Ai of the first and second apertures 260, 262 so as to be received by the receiver 252.

Referring now to Figure 8, the turbidity monitor 106 may alternatively include a unitary emitter/receiver secured by the first bracket 200 over the first aperture 260 and a reflector secured by the second bracket 202 over the second aperture 262. In this embodiment, the emitter/receiver transmits a light beam towards the reflector. The light beam is first transmitted through the portion of deviated fluid 105 and is then reflected by the reflector back towards the emitter/receiver. The light beam is transmitted through the deviated fluid portion a second time and is received by the emitter/receiver.

Since the first bracket 200 and the second bracket 202 are identical only the first bracket 200 will be described in detail with reference to Figure 8. The first bracket 200 includes a generally rectangular outer panel 800 and a mounting portion 802 for mounting the emitter 250 to the first bracket 200. The mounting portion 802 extends away from the panel 800. A first plurality of holes 806 are provided in the planar end portion 804 for receiving a corresponding plurality of fasteners (not shown) to fasten the emitter 250 to the mounting portion 802. A second plurality of holes 210 are located in the panel 800 for fastening the first bracket 200 to the deviation chamber 104 using fasteners 212 (best shown in Figure 2).

A first panel 204 of translucent material is located between the emitter 250 and the first circular aperture 260, while a second translucent panel 206 is located between the receiver 252 and the second aperture 262. The first and second translucent panels 204, 206 are respectively sandwiched between the first and second brackets 200, 202 and the deviation chamber 104.

In the illustrated example, the first and second translucent panels 204, 206 have a pentagonal shape and are sized such that when they are installed between the first and second brackets 200, 202 and the chamber 104, they prevent leakage. Additionally, to prevent leakage of fluid from the first and second apertures 260, 262, gaskets (now shown), sized and shaped to extend along the perimeter of the first and second translucent panels 204, 206, or sealant, such as silicone sealant, may also be provided. The first and second translucent panels 204, 206 allow the light beam to be transmitted between the emitter 250 and the receiver 252 through the deviation chamber 104, while preventing fluid and debris from contacting the emitter 250 and the receiver 252. It will be appreciated that if the fluid contains material typically found in waste water, the turbidity monitor 106, which does not come in contact with the fluid, will remain essentially uncontaminated.

The first and second translucent panels 204, 206 are made of glass, or alternatively other translucent materials, such as poly(methyl methacrylate), or polycarbonate.

As best illustrated in Figure 7, the first and second sidewalls 500, 502 of the deviation chamber 104 are spaced apart by a distance Di, which is less than the diameter of the pipe 102. This configuration advantageously allows large debris to pass through the pipe 102 while preventing the large debris from entering the cavity 550 of the deviation chamber 04 and damaging the turbidity monitor 106. The emitter 250 and the receiver 252 are further spaced from a distance corresponding substantially to the distance Di, which obtains an accurate reading of turbidity of the deviation fluid portion 105. In one example, the distance Di is less than 3 inches. In an another example, the distance D-i measures 1 inch.

It will be appreciated that debris and solid particles which may be carried by the flowing fluid usually tend to travel between the inlet and outlet ends 108, 110 through the pipe 102 without entering the cavity 550 of the deviation chamber 104. By locating the turbidity monitor 106 away from the pipe 102, it advantageously prevents debris and solid particles from contacting and potentially damaging the turbidity monitor 106. In this configuration, the debris and solid particles are prevented from passing between the emitter 250 and the receptor 252, and therefore from distorting the measurement of the level of turbidity of the deviated fluid portion 105. It will also be appreciated that the turbidity monitor 106 is not located inside the cavity 550 of the deviation chamber 104 and therefore does not affect the flow of fluid through the turbidity measurement apparatus 100. While the deviation chamber 104 and the pipe 102 are a unitary structure, it may be advantageous to provide an existing fluid circuit with a similar turbidity detection apparatus. Accordingly, the deviation chamber 104 could be mounted to an existing pipe by cutting into a sidewall of one existing pipe and mounting the deviation chamber 04 to the cut pipe, over the opening, and securing it thereon using known assembly techniques such as welding. Alternatively, the deviation chamber 104 may be provided with a base which may be fastened to the sidewall of the cut pipe using threaded fastener to facilitate maintenance of the turbidity monitor 106.

In another example, the deviation chamber 104 may be configured differently. For instance, the deviation chamber 104 may comprise a pair of spaced apart side plates and a curved plate extending between the side plates to define a hollow, thin- walled compartment which may be mounted to the pipe 102. Alternatively, the deviation chamber 104 may be a bulging portion of the pipe 102, on which the first and second apertures 260, 262 are defined. In this embodiment, the deviation chamber 104 and the pipe portion 102 would form a monolithic structure, which would prevent leaks of fluid from the pipe 102. It will be appreciated that the deviation chamber 104 and the pipe 102 may be made according to various configurations, as long as the cavity 550 of the deviation chamber 104 defines a substantially smooth path of travel for fluid deviated into the deviation chamber 104, allows the turbidity monitor 106 to be mounted thereon.

Operation

The operation of the apparatus 100 will now be described with reference to Figures 6B and 7. Fluid enters the pipe 102 through the inlet end 108 and flows along the main pathway 03 to the outlet end 0, a portion of fluid 105 is diverted into the deviation chamber 104. The deviated fluid portion enters the cavity 550 of the deviation chamber 104 through the opening 300 of the pipe 102 near the inlet end 108, flows along a path by the inner sidewall 504, between the first and second apertures 260, 262, and exits through the opening 300 near the outlet end 1 0. The emitter 250 emits the light beam, which is transmitted through the deviated fluid portion 105 and is received by the receiver 252. In one example, the receiver 252 is operatively connected to a valve mounted to the outflow pipe for directing the fluid to a first location or a second location depending on the measured level of turbidity of the fluid. In an alternative example, the receiver 252 is connected to an indicator which provides a signal, such as a sound or a light signal, when the measured level of turbidity is within a predetermined range or under/over a predetermined value. Alternatively, the receiver 252 may be connected to an analyzer which converts the measured level of turbidity into another quantity, a data recorder which would record the level of turbidity in a database, a display device which would display to a user the measured level of turbidity or any other devices known to those skilled in the art. Liquid Solid Separator

Referring to Figures. 9 and 10, there is shown a liquid-solid separator, 900, for maintenance of a septic tank 950. Septic tanks are well known in the art and usually contain waste water, which, after entering the septic tank 950, separates into a bottom layer of settled waste (i.e. sludge) 962, a middle layer of water and suspended impurities (i.e. supernatant) 964, and a top layer of floating waste (i.e. scum 966). It will be appreciated that the term "septic tank" is used herein to broadly describe a container used for treatment of waste and may alternatively include any container containing waste fluids configured in layers, such as a grease trap or the like, in which the layers have different levels of turbidity.

The liquid-solid separator 900 is mounted on a truck 908 to form a waste collection vehicle. Alternatively, the liquid-solid separator 900 is mounted on a trailer attached to a motor vehicle, or on any other suitable vehicle.

The truck 908 includes a waste collection tank 912 which is mounted on a subframe (not shown) secured to the frame of the truck 908 and configured for supporting the tank 912. Alternatively, the truck 908 may comprise a bed and the tank 912 may be mounted on the bed of the truck. A separation 930 is provided in the tank 912 to divide the tank 912 into a first compartment, or supernatant reservoir 932, for receiving extracted supernatant 964 from the septic tank 950 and a second compartment, or waste reservoir 934, for receiving and storing scum 966, sludge 962 and/or impurities extracted from the septic tank 950.

The liquid-solid separator 900 includes an extraction conduit 902 and a pump (not shown) for extracting waste water from the septic tank 950. The extraction conduit 902 includes a first end 920 positionable in the septic tank 950 and a second end 922 operatively coupled to a valve assembly 904. The valve assembly 904 allows the extracted waste water 970 to be selectively routed towards the supernatant reservoir 932 (supernatant 964) or the waste reservoir 934 (sludge 962 and scum 966), based on turbidity measurement.

The turbidity measurement apparatus 100 is operatively coupled to the extraction conduit 902, upstream of the valve assembly 904, for measuring the turbidity of the extracted waste water 970 and thereby determining whether the extracted waste water 970 includes scum 966 and/or sludge 962 or is supernatant 964. A person skilled in the art will understand that the scum 966 and sludge 962 have a substantially higher level of turbidity than the supernatant 964. The turbidity measurement apparatus 100 is further connected to the valve assembly 904 via a controller (not shown) which operates the valve assembly 904 to selectively direct extracted waste water 970 towards the supernatant reservoir 932 or towards the waste reservoir 934 according to the level of turbidity of the extracted waste water 970, as measured by the turbidity measurement apparatus 100. The supernatant and waste reservoirs 932, 934 are operatively coupled to the extraction pipe 902 via the valve assembly 904. The supernatant reservoir 932 is further coupled to a filtering device 914, which allows the extracted supernatant 964 to be filtered and returned to the septic tank 950.

The valve assembly 904 includes a plurality of valves which may be used for directing extracted waste water 970 towards a desired location. A first valve 916 is provided between the turbidity measurement apparatus 100 and the supernatant reservoir 932, while a second valve 918 is provided between the turbidity measurement apparatus 100 and the waste reservoir 934. The first and second valves 916, 918 are configured for selectively allowing and preventing extracted waste water 970 from entering the supernatant reservoir 932 and the waste reservoir 934, respectively. The first and second valves 916, 918 are actuated by the controller, which is configured for directing extracted waste water 970 towards the supernatant reservoir 932 upon measurement of a level of turbidity which is below a predetermined value and towards the waste reservoir 934 upon measurement of a level of turbidity which is above the predetermined value.

To perform maintenance of the septic tank 950, the truck 908 is first positioned near the septic tank 950. The first end 922 of the extraction conduit 902 is placed in the layer of supernatant 964 of the septic tank 950 and the pump is activated to create a vacuum inside the supernatant and waste reservoirs 932, 934. This vacuum urges the supernatant 964 in the septic tank 950 to be extracted from the septic tank 950 through the extraction conduit 902 and into the turbidity measurement apparatus 100. When the extracted supernatant 964 passes through the turbidity measurement apparatus 100, the turbidity sensor 106 measures a level of turbidity which is lower than the predetermined value. Upon measurement of the level of turbidity of the extracted supernatant 964, the controller positions the first valve 916 in an open position and the second valve 918 in a closed position. In this configuration, the vacuum in the supernatant reservoir 932 urges extracted supernatant 964 into the supernatant reservoir 932 while preventing supernatant from entering the waste reservoir 934.

As supernatant 964 is extracted from the septic tank 950, the layer of scum 966 tends to move downwardly towards the layer of sludge 962 at the bottom of the septic tank 950. When the extraction conduit 902 reaches the layer of sludge 962 and/or the layer of scum 966, waste is extracted from the septic tank 950 through the extraction conduit 902. When the extracted waste passes through the turbidity measurement apparatus 100, the turbidity monitor 106 measures a level of turbidity which is higher than the predetermined value. The controller then positions the first valve 916 in a closed position and the second valve 918 into an open position. The controller may further emit a signal such as a light signal and/or a sound to indicate to the user that waste is being extracted from the septic tank 950. In this configuration, the vacuum in the waste reservoir 934 urges extracted waste into the waste reservoir 934 while preventing waste from entering the supernatant reservoir 932, until the septic tank 950 is substantially empty. If desired, the interior of the septic tank 950 may then be cleaned using a pressure washer or other washing devices, and the extracted supernatant 964 may be filtered and returned to the septic tank 950. The extracted waste in the waste reservoir 934 may be transported to and discharged at the disposal site by moving the truck 908 to the disposal site. It will be appreciated that during maintenance of the septic tank 950, impurities suspended in the supernatant 964 may tend to distort the measurement of the turbidity of extracted supernatant 964. For instance, if large debris, such as pieces of paper, clothing, discarded diapers, plastic particles or rocks or the like, were to pass between the emitter 250 and the receiver 252 of the turbidity monitor 106, the turbidity monitor 106 may measure a higher level of turbidity than the actual level of turbidity of the extracted supernatant 964. In this configuration, the debris passes in the pipe 102 of the turbidity measurement apparatus 100 without entering the deviation chamber 104, and thus does not pass between the emitter 250 and the receiver 252 of the turbidity monitor 106. This configuration prevents extracted supernatant 964 from being directed into the waste reservoir 934 and stored therein, which avoids adding unnecessary weight into the waste reservoir.

Furthermore, the turbidity monitor 106 or, as in the embodiment described hereinabove, the first and second translucent panels 204, 206 respectively protecting the emitter 250 and receiver 252 of the turbidity monitor 106 may be damaged from contact with solid debris, such as rocks, metallic items or the like, carried by the extracted waste water 970. As described above, such solid debris are carried by the extracted waste water 970 through the pipe chamber 102 of the turbidity measurement apparatus 100 without entering the deviation chamber 04 on which is mounted the turbidity monitor 106. The turbidity monitor 106 and/or the first and second translucent panels 204, 206 respectively disposed over the emitter 250 and receiver 252 are therefore advantageously protected in this configuration. This may substantially reduce the cost associated with replacement of the turbidity monitor 106 and/or of the first and second translucent panels 204, 206. One skilled in the art will further recognize that a damaged turbidity monitor and/or damaged translucent panels may distort the measurement of turbidity of the extracted matter. By protecting the turbidity monitor and/or translucent panels, this configuration advantageously enhances the accuracy of the measurement of turbidity and thus, the efficiency of the septic tank maintenance process.

Although the above description relates to a specific embodiment as presently contemplated by the inventor, it will be understood that the discovery in its broad aspect includes mechanical and functional equivalents of the elements described herein.