WO2001031251A1

WO2001031251A1 - Odor and noise control system for use in servicing sewage holding tanks

Info

Publication number: WO2001031251A1
Application number: PCT/US2000/029731
Authority: WO
Inventors: Donald Emerson
Original assignee: Donald Emerson
Priority date: 1999-10-26
Filing date: 2000-10-26
Publication date: 2001-05-03
Also published as: AU1105001A

Abstract

An apparatus and process for servicing sewage holding tanks while reducing odor and noise is disclosed. The apparatus includes a vacuum tank (12), a vacuum pump (24) having an inlet port (23) and an exhaust port (25), the inlet port (23) being connected to the tank (12) so that the vacuum pump (24) can draw air out from an interior of the tank (12), and a conduit having one end connected to the exhaust port of the vacuum pump (24) and having its other end connected to an air intake of an engine (16). The process includes extracting air from a tank to create a vacuum therein which will draw sewage into the tank through a hose, routing the air removed from the tank into an air intake of an engine, and combusting the air from the tank to remove the odor therefrom.

Description

ODOR AND NOISE CONTROL SYSTEM FOR USE IN SERVICING SEWAGE

HOLDING TANKS

FIELD OF THE INVENTION The invention relates to odor and noise control systems for sewage treatment, and more particularly to an odor and noise control system for use on a sewage treatment and servicing truck.

BACKGROUND

Portable toilets, affectionately known as "Porta-potties," "Johnny-on-the-spots," "Honey Buckets" and other names, are commonly found in places where there is no fixed bathroom, such as construction sites and large outdoor gatherings. They are also found in places where there is a bathroom, but it is too small to handle the number of users. These portable toilets are usually self-contained units having, among other things, a compartment for the persons using it and a holding tank to hold all the waste collected from the users. The holding tanks are usually small enough that, if the portable toilet gets a heavy amount of use, it will need to be serviced often. Servicing a portable toilet involves, among other things, pumping waste out of the holding tank.

The usual method of servicing these portable toilets, or other sewage collection facilities, is by using a service truck which vacuums the sewage out of the holding tank. A typical service truck has a large tank on the back which is partitioned into a fresh water side and a waste product side. To clean out the holding tanks, a hose is connected between the waste side of the tank and the holding tank of the portable toilet. A vacuum pump sucks air out of the waste side of the tank, thus creating a vacuum in that portion of the tank which draws the waste out of the holding tank. When all the waste has been removed from the holding tank, a separate hose is attached between the fresh water side of the tank and the holding tank, and the holding tank is then filled with water and deodorant and is ready to be used again.

Existing service trucks, and the method by which they clean portable toilets, have two important disadvantages: they produce a lot of odor and are noisy. As the vacuum pump extracts air from the tank, it must exhaust the air removed. Existing service trucks vent the exhaust from the vacuum pump straight into the atmosphere, meaning that noxious odors and fumes from the inside of the tank are spread into the air surrounding the truck. This creates quite an unpleasant experience for anyone near the truck when it is operating, and if the holding tank being serviced is near a lot of people it creates an unpleasant experience for many. In addition to ejecting all the fumes and noxious odors, the vacuum pump makes a great deal of noise, particularly when it is vented directly to the atmosphere. Thus, the service trucks produce a unpleasant noise environment in addition to the already noxious smell environment.

Given the problems and disadvantages of existing service trucks, there is a need in the art for an apparatus and method to service portable toilets, or other sewage collection devices, while eliminating odor and minimizing noise.

SUMMARY OF THE INVENTION

An apparatus and process for servicing sewage holding tanks while reducing odor and noise is disclosed. The apparatus comprises a vacuum tank, a vacuum pump having an inlet port and an exhaust port, the inlet port being connected to the tank so that the vacuum pump can draw air out from an interior of the tank, and a conduit having one end connected to the exhaust port of the vacuum pump and having its other end connected to an air intake of an engine. The process comprises extracting air from a tank to create a vacuum therein which will draw sewage into the tank through a hose, routing the air removed from the tank into an air intake of an engine, and combusting the air from the tank to remove the odor therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic depiction of an embodiment of the apparatus of the present invention.

Figure 2 is a schematic depiction of a second embodiment of the apparatus of the present invention.

Figure 3 is an illustration of the embodiment of the apparatus schematically described in figure 2, showing its implementation on a service truck.

DETAILED DESCRIPTION OF THE INVENTION

Described below are three embodiments of the present invention. The embodiments illustrate ways m which the present invention can be implemented. In the descπptions that follow, like numerals represent like elements in all figures. For example, where the numeral 10 is used to refer to a particular element in one figure, the numeral 10 appearing in any other figure refers to the same element.

Figure 1 schematically illustrates a first, simplified embodiment 10 of a sewage treatment apparatus with odor and noise control. The apparatus comprises a vacuum tank 12, a suction and filtration system 14 connected to the tank, and an engine 16 connected to the suction and filtration system. The suction and filtration system 14 is connected to the tank 12 via a conduit 18. The elements in the suction and filtration system are also connected to each other via the conduit 18.

The vacuum tank 12 is typically a cylindrical vessel with convex ends, and is designed to support the load created by atmospheric pressure when a vacuum is drawn inside the tank. The tank has connected thereto a hose 20 which, when in use, is plugged into the holding tank 22 from which sewage is to be extracted; neither the hose 20 nor the holding tank 22 are part of the invention. The holding tank 22 will usually be the holding tank of a portable toilet, but may be another type of sewage holding tank as well.

The suction and filtration system 14 comprises a vacuum pump 24 connected to the tank 12 and, optionally, a filter 26 connected to the vacuum pump. The vacuum pump has an inlet port 23 and an exhaust port 25. The inlet port 23 is connected to the tank 12 via the conduit 18 and is in fluid communication with the interior of the tank, so that the vacuum pump can draw air out of the interior of the tank. The exhaust port 25 is connected to the filter 26, so that the air extracted from the tank 12 through the inlet port 23 is routed out the exhaust port and into and through the filter. The optional filter 26, if present as shown, is connected to the air intake of an engine 16, so that air passing through the filter is routed into the engine. If the filter 26 is not present, the air is filtered solely by the engine's own air filter (not shown). When it enters the engine 16, the air extracted from the tank 12 is combusted, so that any odors in the air are removed. After combustion inside the engine, the air removed from the tank is exhausted into the atmosphere along with other exhaust from the engine.

In operation of the apparatus 10, the vacuum pump 24 draws a vacuum inside the tank. Since the pressure inside the tank is then lower than atmospheric pressure, the atmospheric pressure pushes the sewage from the holding tank 22 up through the hose 20 and into the tank 12. As the vacuum pump 24 removes air from inside the tank, it routes the air into and through the optional filter 26 so that any particulates are removed, thus preventing damage to the engine 16. After filtration, the air is routed into the air intake of the engine 16, where it may also be filtered by the engine's own air filter. Once the air is combusted in the engine, it is vented into the atmosphere along with the other exhaust created by the engine.

Use of the apparatus in this way has some important advantages. One of the most common complaints about servicing sewage holding tank is the unpleasant odor created during servicing in the vicinity of the holding tank. With the present apparatus and method, the odor is removed from air removed from the vacuum tank by combusting it in an engine. Another common complaint is the noise associated with servicing the holding tanks. With the present apparatus and method, noise is substantially reduced by routing the exhaust from the vacuum pump into and through the filter and then into the engine.

Figure 2 schematically illustrates a second, more complex embodiment 30 of the present apparatus. The apparatus 30 comprises a vacuum tank 12 and a suction and filtration system 32. The suction and filtration system is connected to the vacuum tank 12 via the conduit 34. The conduit 34 also connects elements of the suction and filtration system to each other. The vacuum tank 12 of the apparatus 30 is identical to the tank in the apparatus 10; the differences between apparatus 10 and the apparatus 30 relate to the suction and filtration system 32.

The suction and filtration system 14 comprises a pressure relief valve 36, a dryer 38, a vacuum pump 40, an oil remover 42 and an engine 44, all connected to each other in series. The pressure relief valve 36 is shown interposed in the conduit 34 between the tank 12 and the dryer 38, but it could be positioned anywhere between the vacuum pump 40 and the tank. The pressure relief valve prevents the pressure inside the tank from becoming too low, causing the higher atmospheric pressure acting on the outside of the tank to crush the tank. This could happen if, for example, the hose 20 becomes clogged while the vacuum pump is running.

The dryer 38 is interposed in the conduit 34 between the pressure relief valve 36 and the vacuum pump 40 to extract moisture from air extracted from inside the tank. Drying the air extracted from the tank improves its combustion in the engine, and also prevents problems such as corrosion in components downstream of the dryer. The vacuum pump 40 is interposed in the conduit 34 between the dryer 38 and the oil catcher 42. The vacuum pump has an inlet port 39 and an exhaust port 41. The inlet port 39 is connected to the tank 12 by the conduit 34 and is in fluid communication with the interior of the tank, so that the vacuum pump can draw a vacuum in the interior of the tank. The exhaust port 41 is connected via the conduit 34 to the oil catcher 42, so that the air drawn out of the tank 12 and through the pressure relief valve 36 and the dryer 38 is then routed to the oil catcher 42, which reduces noise and removes any oil injected into the flow by the vacuum pump.

The engine 44 is positioned at the end of the conduit 34. The conduit routes the air from the oil catcher into the air intake 46 of the engine. Preferably, the air is injected into the air intake upstream of the engine's air filter 48, where it undergoes additional filtration before being injected into the engine. Once injected into the engine, the air extracted from the tank is combusted and released into the atmosphere through the engine's exhaust 50, along with any other exhaust produced by the engine.

The apparatus 30 operates nearly identically to the apparatus 10, except that the air undergoes drying, oil removal and filtration before being injected into the air intake of the engine 44.

Figure 3 illustrates third embodiment of the apparatus 60. The apparatus 60 is essentially the apparatus 30 applied to a service truck for servicing sewage holding tanks. The apparatus consists of a tank 12 mounted on the bed of a truck 62, a suction and filtration system connected to the tank, and an engine (not shown) to which the exhaust from the suction and filtration system is routed.

The tank 12 is cylindrical with convex ends and its size is matched to the size and carrying capacity of the truck. Preferably, the tank has a capacity between 475 and 650 gallons and the truck has a weight rating between 14,500 and 18,000 pounds. A trap 64 is attached to the top of the tank and is in fluid communication with the interior of the tank. The trap is designed to prevent large particles or other matter from entering the suction and filtration system.

The suction and filtration system is attached to the trap 64 and, through the trap, is in fluid communication with the interior of the tank. The suction and filtration system comprises a dryer 66, a pressure relief valve 68, a vacuum pump 70, and a collector 72. The suction and filtration system is attached to the trap, and the elements of the suction and filtration system are attached to each other, by a conduit 72. The conduit 72 also extends between the suction and filtration system and the air intake 74 of the truck 62. After the air removed from the tank exits the suction and filtration system, it is carried by the conduit 72 to the air intake 74 of the truck, where it is injected into the engine upstream of the engine's air filter 76. The conduit 72 may be connected to the air intake by any means. The conduit is preferably made of rubber vacuum hose upstream of the vacuum pump, and regular rubber hose downstream.

The function of each of the elements in the suction and filtration system is explained above in connection with the apparatus 70. For the system to work properly, the flow capacities of the elements must be matched so that a smooth flow through the system is obtained. Usually, the capacity of the vacuum pump 70 is matched to the size of the tank 12, and the remaining components are them matched to the capacity of the vacuum pump. For tanks 12 with a capacity of 475 to 650 gallons, a vacuum pump having a capacity of about 160 cubic feet of air per minute is preferable.

Three embodiments of the present invention have been described. A person skilled in the art, however, will recognize that many other embodiments are possible, including combinations of the embodiments presented. For this reason, the scope of the invention is not to be determined from the description of the embodiments, but must instead be determined solely from the claims which follow.

Claims

1. An apparatus for servicing sewage holding tanks comprising:

a vacuum tank;

a vacuum pump having an inlet port and an exhaust port, the inlet port being connected to the vacuum tank so that the vacuum pump can extract air from an interior of the tank; and

a conduit having a first end and a second end, the first end being connected to the exhaust port of the vacuum pump and the second end being connected to an air intake of an engine.

2. The apparatus of claim 1 wherein the vacuum tank is cylindrical and has convex ends to support drawing a vacuum in the tank.

3. The apparatus of claim 1 further comprising a filter interposed between and connected to the vacuum pump and the air intake of the engine.

4. The apparatus of claim 1 further comprising a dryer interposed between and connected to the tank and the vacuum pump.

5. The apparatus of claim 1 further comprising an oil catcher interposed between and connected to the vacuum pump and the air intake.

6. The apparatus of claim 1 further comprising a pressure relief valve interposed between and connected to the tank and the vacuum pump.

7. The apparatus of claim 1 wherein the conduit connects to the air intake upstream of an air filter on the engine.

8. A truck for servicing sewage holding tanks comprising: a vacuum tank positioned on a bed of the truck;

a vacuum pump having an inlet port and an exhaust port, the inlet port being connected to the vacuum tank so that the vacuum pump can extract air from the interior of the tank; and

a conduit having one end connected to the exhaust port of the vacuum pump and having its other end connected to an air intake of an engine of the truck.

9. The apparatus of claim 8 wherein the vacuum tank is cylindrical and has convex ends to support drawing a vacuum in the tank.

10. The apparatus of claim 8 further comprising a filter interposed between and connected to the vacuum pump and the air intake of the engine.

11. The apparatus of claim 8 further comprising a dryer interposed between and connected to the tank and the vacuum pump.

12. The apparatus of claim 8 further comprising an oil catcher interposed between and connected to the vacuum pump and the air intake.

13. The apparatus of claim 8 further comprising a pressure relief valve interposed between and connected to the tank and the vacuum pump.

14. The apparatus of claim 8 wherein the conduit is connected to the air intake upstream of an air filter on the engine.

15. A process for servicing sewage holding tanks comprising:

extracting air from a vacuum tank to create a vacuum therein, wherein the vacuum draws sewage from the holding tank into the vacuum tank through a hose;

routing the air extracted from the tank into an air intake of an engine; and combusting the air extracted from the tank in the engine to remove the odor therefrom.

16. The process of claim 15 further comprising relieving the pressure in the tank when an external pressure outside the tank exceeds an internal pressure inside the tank by a selected value.

17. The process of claim 15 further comprising drying the air extracted from the tank.

18. The process of claim 15 further comprising removing oil from the air extracted from the tank.

19. The process of claim 15 wherein routing the air extracted from the tank into an air intake of an engine comprises routing the air into the air intake upstream of an air filter of the engine.

20. The process of claim 15 further comprising filtering the air removed from the tank to remove particulates.