Shipboard human waste treatment for removing solids

[0001] This invention relates generally to a method and system for use on a ship for the removal of human waste and, in particular, to a method and system for the separation, treatment and removal of solid human waste and other solid materials found in the shipboard black water sanitary waste system, thereby significantly reducing the biological oxygen demand (BOD) loading on any shipboard advanced marine sanitation device.

[0002] In recent times, large ships, such as ocean-going cruise liners, have experienced difficulties in meeting the local environmental black water discharge standards of certain bodies of water around populous ports and any areas within the twelve-mile territorial limit of the United States because of increased pollution problems caused by overflow or discharge of human waste. This results from the large amount of human waste black water effluent generated by hundreds or even thousands of passengers aboard each ship. Many states and the federal government have passed environmental protection laws to prohibit large ships from discharging any effluent within the twelve-mile limit. Additionally, the dumping of plastics at sea is illegal. What is needed is a low cost, non-complex system that addresses the problems caused by human waste treatment aboard ship. The present invention provides a method and system that separates solids in black water effluent and dewaters the solids so that the solids can be either stored for later removal as landfill or burned in the ship incinerator.

[0003] A method and system for treating human waste aboard ship, which includes a human waste solid-liquid separator that can be maintained under a vacuum, a collection tank that collects the separated waste solids while the separated liquids are directed to the shipboard advanced marine sanitation device (AMSD) liquid treatment system generally using a vacuum pump, and a solid waste compacter that allows the solid waste products to be compacted into a non-liquid, easily storable and removable solid material for later removal as landfill or burned in the ship incinerator.

[0004] The system includes a first large separating tank that receives all human waste and debris (liquid and solids) directly from the vacuum toilet systems aboard ship. Note that this waste would also include plastic items or other undesirable items that are flushed periodically down a toilet. The large separating tank includes at least one internal screen that allows virtually all solids to be separated from the liquids that flow through the screen into removal conduits that have vacuum pumps for effluent stream transfer. Removal of these solids significantly reduces the load and wear on the vacuum pumps in the shipboard waste treatment system so that the vacuum pumps do not clog, run more efficiently and maintain functionality longer. The solids and the liquids that are the input from the toilet system are received into the large separation tank which is maintained under vacuum. Once separated, the solid waste output from the separation tank goes directly into an interim built-in storage tank for the solid waste that is separated from the separation tank by an upper first valve that is immediately closed whenever the built-in interim tank is full of solid waste in order to maintain the vacuum in the separating tank. The interim storage tank that contains waste solids also is connected directly through a second lower valve to the input of a waste compactor that has a motor-driven helical screw, which compresses the solid waste into a very compact, dewatered material with liquids being entirely removed during the compacting process. The waste storage tank output leads directly into the compactor input through a valve that allows the transfer of the solid waste materials into the compactor at particular times when the valve is opened without breaking the vacuum. When the valve is closed, the compactor is turned on and the materials are compressed into a large receiving tube that contains the compressed waste materials and is inclined vertically. The receiving tube is angled at approximately 45 degrees vertically and includes a reversal tube at its open end that allows the compressed, non-liquid waste materials to be dumped directly into combustible storage bags, such as plastic bags.

[0005] The compaction process is continuous wherein the toilet system is connected directly to the separation tank and is continuously admitting waste materials into the separation tank. The separation tank is maintained under negative pressure by the ship's black water vacuum. The bottom of the separation tank has outlet conduits connected to the vacuum pump that allow the liquids separated by the filter screens inside the separation tank to be removed and discharged from the separation tank on a continuous basis. A series of air and liquid jets are also used with the separation screen for automatically clearing any accumulated buildup of waste or debris from said separation screen.

[0006] The compactor has an electric motor that has automated or manual power switches. The electric motor shaft is connected to a helical blade. A gear may be used to provide more torque and compressive force to the helical blade. The helical blade is mounted in a very solid elongated tube, which may include discharge holes to allow liquids to be squeezed out of the solid waste material into a surrounding housing during compaction. Because of the vertical incline, the compacted waste material is pulled by gravity which aids in compacting the solid waste material. The discharge tube connected to the output of the compact helical blade may be four or five feet long and a foot in diameter. The process may be turned on and off as needed as solid waste collects in the storage tank.

[0007] An object of this invention is to provide an improved shipboard human waste treatment for separating solids that include human waste and other deleterious materials placed in the toilet system.

[0008] Another object of this invention is to provide a simple, low cost, efficient system for significantly reducing the loading on the shipboard black water treatment system by safely processing, storing, and removing virtually all of the solids out of the human waste stream aboard ship.

[0009] Still another object of this invention is to provide a system for processing, storing, and removing wastes aboard ship, which preserves the vacuum pumps that are a component of the shipboard waste treatment system and reduces the load on the existing shipboard waste treatment plant.

[0010] In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings.

[0013] Referring now to FIG. 1 and FIG. 2, the present invention is shown generally at 10 schematically comprising a solid waste separation and compaction system that is connected to a shipboard toilet system 12. The toilet system 12 uses vacuum toilets that connect through valve 14 and has an outlet into a solid waste separation tank 16. The system is maintained under vacuum by a vacuum pump 16a connected directly into said separation tank 16. The vacuum pump 16a receives the liquid waste while solid wastes are diverted into the solid waste separation tank 16. By removing all of the solid wastes upstream of the vacuum pump, the vacuum pump 16a functions longer with far less maintenance, and therefore, more efficiently. Separation tank 16 may be a large, inclined stainless steel tank that includes a liquid/solid separating screen 18 disposed across its entire width so that waste solids coming from the toilet system 12 through valve 14 will be separated and maintained apart from all liquids that will pass through screen 18 into a removal conduit 22 which contains liquid only. The solids will continue down through conduit 20 and through valve 24 into a solid waste interim storage tank 26. Thus, waste materials that pass through separation tank 16 include liquid and solid human waste and other objects that are thrown into the toilet system that can be solid or liquid. By using the full screen 18, only solid materials are received into the solid waste interim storage tank 26. The effluent solids in the interim storage tank 26 may still contain a substantial amount of absorbed liquid. When interim tank 26 is full, valve 24 closes. A control valve 28 opens. The control valve 28 separates the interim solid waste storage tank 26 from the compaction chamber 30. The compaction chamber 30 includes a helical compaction blade 34 connected to an electric motor 32 and includes a liquid collection tank 36 that has a liquid output conduit 38. The compacted waste storage tube 40 (outfall chute) has an outlet end 42 and is shown at a 45-degree angle vertically emanating at the end of the compaction screw 34. The interim solid waste storage tank 26 allows solid waste to pass into the compaction chamber 30 when valve 28 is open and valve 24 is closed. During compaction, valve 28 is open and the helical blade 34 is rotated by motor 32 which may include a gear for increased torque. As the solid waste is compacted, it is forced upward into the outfall chute/compaction tube 40. The compaction chamber 30 also includes drain holes through which excess liquid from the compacted solid waste may drain into tank 36. As the material is compacted and pushed upward through the storage tube 40, the compacted waste can be removed through the open end 42 directly into bag 44 for later removal as landfill or to be burned in the ship incinerator.

[0014] The primary use for the present invention shown herein is to process large amounts of human waste and other debris flushed down toilets, which accumulates aboard a cruise ship in a short amount of time, into a highly compacted small volume of waste that has been dewatered and that can be either incinerated at sea or taken ashore in compact bundles. Using the method in accordance with the present invention, the human waste is received into the standard shipboard toilet system where it passes into a solid waste separation tank so that all of the solids and liquids are separated at this point using one or more separating screens to capture solid wastes while allowing liquids to drain through. The solids continue to pass into a solid interim storage tank while the liquids are diverted into the existing vacuum pumps for further shipboard treatment. By using a full screen disposed across the entire width of the separation tank, the only materials that pass into the interim storage tank are the solids that are to be removed and dewatered. Next, a substantial amount of additional liquid is removed from the recovered solids using a compactor. Said compactor includes a helical blade and electric motor in a storage tube that is used to further compress the residual waste to extract more moisture and water from the solid waste. By using an inclined storage tube, which includes a reversal outlet end, the dewatered compacted waste can be deposited into storage bags for burning or removal from the ship.

[0015] Using the present system, which itself is quite compact, the efficiency of removal and elimination of the black water solids aboard ship significantly reduces vacuum pump and screen maintenance while simultaneously substantially increasing the performance of the existing advanced marine sanitation device (existing waste treatment system).

[0016] The instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment. The applicant recognizes, however, that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to a person skilled in the art.