Patent Description:
Substantial advances have been made in the last dozen years, as exemplified by the Trapzilla line of grease traps sold by Thermaco, Inc. of Asheboro, North Carolina. Information about Trapzilla grease traps is available at http:/thermaco. com/trapzilla and Trapzilla technology is disclosed in <CIT><CIT><CIT><CIT>.

While achieving substantial commercial success and industry recognition, those devices still permit small quantities of FOG to go downstream with the grey water, so there is room for improvement. In some examples, the improvement disclosed herein may be added to structures disclosed in the patents disclosed above, and this disclosure should be deemed, in some examples, to cover combinations of those structures with any structures disclosed herein.

<CIT> discloses a buoyant component separator for removing floating contaminants from fluids. <CIT> discloses a grease trap for separating waste from waste water that includes grey water and FOG.

The inventions of the present disclosure fulfill one or more of these needs in the art by providing a grease trap for separating waste from waste water, as defined in claim <NUM>. The tank may be roto-molded plastic and may be provided with a lid covering the tank.

The first and second baffles may diverge so waste water entering the tank between the baffles encounters an enlarging volume. The first baffle may be conical with a downward apex and the second baffle may also be conical, with an upward apex. The hole in the first baffle is at a downward apex and the hole in the second baffle is at an upward apex. The first and second baffles may each substantially span the interior volume of the tank. The baffles may be connected to one another by a joining peripheral wall sized and shaped to nest in the tank. The peripheral wall preferably has an indentation for the inlet invert and an indentation for the outlet invert.

The first baffle may include a vertical baffle extending downward and positioned to shield the drain end of the outlet invert. Similarly, the second baffle may include a vertical baffle extending downward and positioned to shield the discharge end of the inlet invert.

The invention may also be considered as a method of separating FOG and solids from grey water, as defined in the appended claim <NUM>. The method includes discharging effluent having FOG, solids and grey water into a tank between an upper and a lower baffle, the lower baffle comprising a wall with a hole, allowing the grey water and heavy solids to descend in the tank through the hole in the lower baffle and the grey water to exit the tank along an upward path to an exit above the upper baffle, and allowing the FOG to float through a hole in the upper baffle where the FOG is protected from entrainment in flows of grey water exiting the tank. Discharging effluent having FOG and grey water into a tank between an upper and a lower baffle may include baffling the path of the effluent as it enters the tank before the effluent encounters the upper and lower baffles so the effluent progresses toward the lower baffle while leaving a path for FOG to float to the upper baffle. Allowing the grey water to exit the tank may include baffling the path of the grey water after it descends through the hole in the lower baffle to lengthen the path the grey water traverses to exit the tank. Discharging effluent having FOG and grey water into a tank may include discharging solids in the effluent so the solids traverse with the grey water as the grey water descends in the tank through the hole in the lower baffle.

The invention will be better understood by a reading of the Detailed Description of the Examples of the Invention along with a review of the drawings, in which:.

The improved grease trap disclosed herein may be considered an improvement of the grease trap disclosed in <CIT>, which has enjoyed considerable commercial success, sold as the Trapzilla line of grease traps by Thermaco, Inc. of Asheboro, North Carolina. Before discussing specifically some examples of the improved grease trap, an example of which is shown in <FIG>, the following discussion with reference to some aspects of <FIG> of portions of the structure and operation of the grease traps generally should be helpful to those of ordinary skill in understanding the improvement, its operations and differences.

<FIG> shows a FOG trap <NUM> for separating solids and FOG from waste water. The FOG trap <NUM> includes an outer tank <NUM> with a bottom <NUM> that is conical with its apex downward, as seen in <FIG>. The bottom may be shaped like an inverted pyramid, bowl shape, slanted plane, or the like, can be used. Preferably, the lowermost portion of the bottom is centrally located, but that is not critical. As seen in <FIG>, an inlet invert <NUM> is provided for connecting to a waste water source, such as a kitchen sink drain, allowing waste water to flow into the outer tank <NUM>. The FOG trap also <NUM> includes a tank lid <NUM>. The tank lid <NUM> includes an outlet port <NUM> provided with a removable closure <NUM>. The outlet port <NUM> allows for the connection of a pipe through which solids and FOG may be sucked out of the grease trap <NUM>. Other outlet ports may be provided to vent gases, selectively remove heavy solids from the <NUM>, or selectively remove FOG trapped in the upper chamber <NUM>, as seen in <FIG>.

<FIG> shows an exploded view. The grease trap <NUM> includes an outer tank <NUM> with a bottom <NUM>. An inner tank <NUM> is inserted into the outer tank <NUM> such that there is very little space, if any, between the walls 14a of the inner tank <NUM> and the walls 12a of the outer tank <NUM>. Other shapes for the perimeter of the trap such as pentagonal, trapezoidal, triangular, or even free form could be used.

The inner tank <NUM> has a bottom <NUM>, as best seen in <FIG> when in the shape of an inverted pyramid, so that the bottom <NUM> of the inner tank <NUM> and the bottom <NUM> of the outer tank <NUM> diverge. The bottom <NUM> divides the outer tank <NUM> into an upper chamber <NUM> where lightweight FOG collects, and a lower chamber <NUM> where heavy solids may settle.

As effluent made up of water, solids, and FOG flows into the tank through the inlet invert <NUM>, its velocity slows as the separation between the bottom <NUM> and the bottom <NUM> increases, where the cross-sectional area that the effluent current encounters increases. This concept of increasing residence time and enabling greater separation by a greater cross-section is disclosed in <CIT> to Batten. The slower the effluent, the greater the probability that the lightweight FOG can separate from the water. The separated FOG rises to the apex of the bottom <NUM> and through the central hole <NUM> in the bottom <NUM>. After passing the position of greatest divergence, the effluent (generally depleted of its FOG) can increase in speed as it makes its way from the center to the outlet invert <NUM>.

Preferably, and in some embodiments, the inner tank <NUM> and the outer tank <NUM> are roto-molded plastic. In some cases, the inlet invert, outlet invert, and outer tank are can be molded as one piece. However, the grease trap <NUM> may be made of metal, and the parts may be welded together or joined by other fasteners.

As seen in <FIG>, in a cylindrical embodiment, the inlet invert may include a vent <NUM> for venting gases from the grease trap <NUM> and acts as an anti-siphon. The vent <NUM> may be hooked up to an external ventilation system to prevent odors from escaping the grease trap <NUM> into interior areas if the grease trap is installed in a building.

The inner tank <NUM> as best seen in <FIG>, is roto-molded such that the inner tank <NUM> slides into place over the inlet invert <NUM> and the outlet invert <NUM> that lead into and out of the outer tank <NUM>. As such, the inner tank <NUM> can be removed without disturbing the invert pipes leading in and out of the grease trap <NUM>.

The walls of the inner tank <NUM> help support the bottom <NUM>, as seen in <FIG> and <FIG>. The cylindrical shape for the tank is stronger than the rectangular shape, but the grease trap may also be square, rectangular, or other shapes.

In a preferred embodiment the exit port end of the inlet invert <NUM> needs to be as high as possible to maximize the storage space in the bottom <NUM>. If the inlet invert <NUM> is not above the level of the solids layer, the solids layer may be disturbed as wastewater flows into the lower chamber <NUM> via the inlet invert <NUM>.

As seen in <FIG> and <FIG>, a pipe <NUM> may be inserted to extend from the outlet <NUM> in the lid <NUM> through the upper chamber <NUM> of the inner tank <NUM>, and extends through the hole <NUM> in the bottom <NUM> of the inner tank <NUM>. Preferably, the pipe <NUM> has a smaller diameter than the hole <NUM> so that lightweight FOG may flow into the inner tank <NUM> through the space between the hole <NUM> and the pipe <NUM> inserted therein.

In operation, waste water enters the grease trap <NUM> via the inlet invert <NUM>. The water flows into the diverging space between the bottom <NUM> and the bottom <NUM>. Since the bottom <NUM> and the bottom <NUM> diverge from the edge of the tank to the center of the tank, as waste water flows into the diverging area, the velocity of the water flow slows, allowing the FOG to rise under the influence of gravity, since it is less dense than the water. Heavy solids settle on the bottom <NUM>. Lightweight FOG gather at the bottom <NUM> and float through the central hole <NUM> into the inner tank <NUM> as seen in <FIG>. Since the lightweight FOG accumulates at a location outside of the flow path for the effluent between the inlet invert and the outlet invert, less FOG is re-entrained in the effluent, so it does not pass back out of the grease trap via the outlet invert <NUM>. The bottom <NUM> provides a barrier that sequesters the FOG that has become trapped above the bottom in the inner tank <NUM>, protecting the FOG from the flow of grey water from the inlet <NUM> to the outlet <NUM>. Thus the grey water current does not entrain the sequestered FOG and sweep it out of the grease trap via the outlet invert <NUM>.

The heavy solids collected on the bottom <NUM> may be pumped out through the pipe <NUM>. Continued pumping draws water from the tank <NUM>, and pulls the FOG back down to the lower chamber and out through the pipe <NUM>. The pipe <NUM> need not be strictly vertical, but could be slanted or have horizontal elements, as long as it leads from the lower chamber <NUM> to enable pumping of solids and FOG.

<FIG> shows one example of an improved grease trap <NUM>. It includes an outer tank <NUM> and inner tank <NUM>. The outer tank <NUM>, in some examples, differs from the tank <NUM> in that it includes its own outer tubing to make the inlet invert <NUM>, but a separate inlet invert construction can be used. In either case, the inlet invert is somewhat shorter than in the earlier shown grease trap of <FIG>, having its opening into the grease trap between the walls <NUM> and <NUM> of the inner tank <NUM>. Walls <NUM> and <NUM> substantially span the width of the inner volume of tank <NUM>. The inner tank has an indentation to allow fit around an outlet invert <NUM>. Constructions that incorporate the outlet invert as unitary with the inner tank are within the scope of the current disclosure.

The walls <NUM> and <NUM> diverge to make a volume of increasing cross section as effluent flows from the inlet invert <NUM> to the outlet invert <NUM>, and each of the walls <NUM> and <NUM> is provided with a hole, preferably at its apex. The diverging volume allows the flow to move without hitting walls. The slope upper wall allows the grease to easily rise to the upper chamber, and the sloped lower wall allows solids to easily roll to the bottom of the tank. The walls can be conical, pyramidal, bowl shaped, slanted planes or other non-flat-and-level shapes. The holes are typically in the middle of the respective walls <NUM> and <NUM> but need not be.

The wall <NUM> is spaced above the bottom <NUM> of the outer tank, leaving a substantial volume between them in which solids can collect and still allow flow of grey water from the hole in wall <NUM> to the outlet invert <NUM>. The wall <NUM> is lower than the bottom of the horizontal portion <NUM> of the outlet invert <NUM>. The horizontal portion of the outlet invert typically is connected to a sewer line and defines the static water level in the tank <NUM>. FOG collecting above the grey water in the tank <NUM> will rise slightly above the static water level because FOG has a specific gravity less than water, so the FOG can collect to a greater thickness than the water it displaces. The wall <NUM> is preferably at a height sufficient to allow a substantial amount of FOG to accumulate above the wall <NUM>, so grease trap pumping need not be particularly frequent.

The bottom of wall <NUM> has a depending baffle <NUM> that aligns with the inlet <NUM>. The baffle <NUM> diverts the incoming effluent circumferentially in the space between the walls <NUM> and <NUM> to slow the effluent, as the diverging walls <NUM> and <NUM> also slow the effluent. FOG in the slowed effluent rises toward the wall <NUM> and through its hole <NUM>. FOG above the wall <NUM> is sequestered from the effluent traveling from the inlet <NUM> to the outlet <NUM>, preventing re-entrainment of the FOG in the effluent. Solids and grey water descend through hole <NUM> in the wall <NUM> and are again slowed by the widening space below the wall <NUM> and a baffle <NUM> positioned to block direct flow to the outlet invert <NUM>. Residual FOG in the effluent still has time to migrate back through the hole <NUM> and hole <NUM>. Other residual FOG may find its way up the outside of the outlet invert and through the hole <NUM> to the space above wall <NUM>, where it is protected from fast effluent flows.

The walls <NUM> and <NUM> may be joined by a peripheral sidewall that fits inside the peripheral sidewall of the tank <NUM>, with additional molded configurations for the inlet invert <NUM>, outlet invert <NUM> and baffles <NUM>, <NUM>. This provides the advantage that the combined parts can be made in one molding operation. Walls <NUM> and <NUM>, peripheral sidewall, inlet invert <NUM>, outlet invert <NUM> and baffles <NUM>, <NUM> can all be made as one piece by rotomolding. Alternatively those parts can be assembled from separate pieces.

A lid like the lid <NUM> can be provided, having a hole that can be capped. The hole can be uncapped so the solids and FOG can be pumped out, as described above.

An alternate embodiment is shown in <FIG>, with <FIG> showing an insert component <NUM> for the assembled grease trap of <FIG>. In <FIG> the two walls <NUM> and <NUM> are molded as indentations in a peripheral wall <NUM>, so that the indentations define holes <NUM> and <NUM>. <FIG> show the location of a molding feature <NUM> to receive the inlet invert and a molding feature <NUM> to receive the outlet invert.

The grease trap shown in <FIG> has an outer tank <NUM>, an insert <NUM> as shown in <FIG> and a tube element <NUM> that helps to complete the inlet <NUM>. The tube element <NUM> closes the back opening in the rotomolded insert component <NUM>. Interlocking molded items <NUM> in the tube element <NUM> and the insert <NUM> hold the tube element in place, wedged against the outside wall of the tank <NUM>. The trap includes a vent pipe <NUM> acts as an anti-siphon.

The grease trap can be equipped with additional elements such as a sensor for detecting FOG, water or solids levels in the tanks. Examples are shown in <CIT> and <CIT>, separate solids collectors as shown in <CIT>, increased capacity shapes as shown in <CIT>, monitoring of grease trap operation as shown in International Patent publication <CIT>.

In operation FOG may be separated from grey water in effluent. The effluent having FOG and grey water is discharged through the inlet <NUM>, <NUM> into the tank <NUM>, <NUM> between an upper wall or baffle <NUM>, <NUM> and a lower wall or baffle <NUM>, <NUM>, allowing the grey water to descend in the tank through a hole <NUM>, <NUM> in the lower wall <NUM>, <NUM> and exit the tank along an upward path through the outlet <NUM>, <NUM> to an exit <NUM> above the upper wall <NUM>, <NUM>. FOG floats through hole <NUM>,<NUM> in the upper wall <NUM>, <NUM> where the FOG is protected from entrainment in flows of grey water exiting the tank. Solids in the effluent traverse with the grey water as the grey water descends in the tank through the hole <NUM>, <NUM> in the lower wall <NUM>, <NUM>, and collect there or are swept to the outlet <NUM>, <NUM>.

In the embodiment of <FIG>, as the effluent enters the tank <NUM> (before the effluent encounters the upper and lower walls <NUM> and <NUM>) it encounters baffling at <NUM> so the effluent progresses toward the lower wall <NUM> while leaving a path for FOG to float to the upper baffle <NUM>. As the grey water moves to exit the tank it encounters baffling at142 to lengthen the path the grey water traverses to exit the tank.

The second baffle or wall between the sequestered FOG and the exiting grey water further enhances the operation, leading to near-complete removal of FOG from the effluent. Standard ASME A112. <NUM> Grease Interceptor Rating Tests show <NUM>% removal of FOG (<NUM>% cumulative and <NUM>% incremental) for nearly <NUM> times longer than conventional units (and in some examples, <NUM> times improvement as evaluated by drop number).

Claim 1:
A grease trap (<NUM>) for separating waste from waste water comprising
an outer tank (<NUM>) having a bottom (<NUM>);
an inlet invert (<NUM>) having a discharge end for directing waste water into the outer tank;
an outlet invert (<NUM>) having a drain end for directing water from the outer tank (<NUM>);
an inner pair of horizontal baffles each comprising a wall (<NUM>, <NUM>) having a hole (<NUM>, <NUM>), an upper one of the baffles (<NUM>) being above the discharge end and a lower one of the baffles (<NUM>) being below the discharge end and above the drain end, so the baffles divide the outer tank (<NUM>) into upper, middle and lower chambers; and
wherein the lower baffle (<NUM>) slopes downwardly to a downward apex at the hole (<NUM>) of the lower baffle, and the upper baffle (<NUM>) slopes upwardly to an upward apex at the hole (<NUM>) of the upper baffle,
whereby FOG and solids may separate from the waste water within the middle chamber such that grey water and heavy solids fall through the hole (<NUM>) in the lower baffle (<NUM>) to the lower chamber and FOG rises to enter the upper chamber through the hole (<NUM>) in the upper baffle (<NUM>) and is sequestered by both baffles from currents flowing to the outlet invert (<NUM>), thereby inhibiting later mixing of sequestered FOG into the grey water exiting the grease trap.