Liquid purification or separation – Processes – Separating
Reexamination Certificate
1999-10-07
2001-03-27
Popovics, Robert (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S744000, C210S650000, C210S104000, C210S167050, C210S416100
Reexamination Certificate
active
06207065
ABSTRACT:
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
BACKGROUND OF THE INVENTION
The present invention relates to the processing of waste material, more particularly processing waste material generated aboard marine vessels.
Environmental regulations have increasingly restricted the discharge of ship-generated wastewaters overboard. It is anticipated that future discharges of untreated blackwater (e.g., urinal and water closet wastes), graywater (e.g., shower, sink, galley, and laundry wastes) and oily wastewater will be prohibited in many areas of the world.
Shipboard liquid wastewater has been generally classified as either non-oily waste or oily waste. The non-oily fractions include blackwater and graywater. Bilgewater and waste oil make up the shipboard oily waste. Blackwater (or sewage) is the waste that is generated by water closets and urinals. Typically, blackwater consists of feces, urine, wipes, and flushing water. Graywater is wastewater generated by sinks, showers, laundry equipment and galley and scullery equipment. Typically, graywater consists of water, dirt, detergents, food particles, hair, lint, and numerous other contaminants.
Bilgewater originates as seal and equipment leaks, condensation, evaporator dumps, and fuel strippings. Typically, bilgewater consists primarily of water (usually greater than 99 percent) with small amounts of fuel oil, lubricating oil, detergents, particulate matter, corrosion products, and other contaminants. Waste oil is a mixture of oil and water separated from the bilgewater. The fraction of water contained in the waste oil can vary by as much as 10 to 90 percent. The fraction of waste oil contains predominantly fuel and lubricating oils (greater than 90 percent of the bulk oil), with smaller amounts of detergent and emulsified water. The bulk oil can have associated therewith a recoverable heating value.
On large ships, current practice involves storing the liquid wastes onboard when the ship is in transit or is moored in restricted waters, until such time as when the liquid wastes can be off-loaded to shore facilities or to a barge. Certain ships are designed to have sufficient storage capacity to retain liquid wastes for a maximum of 6 hours. If suitable off loading facilities are not available, such ship must alter its schedule in order to discharge at sea beyond coastal waters. Other concerns involve the high disposal costs when off-loading liquid wastes to barges, operational security concerns when off-loading to shore facilities in hostile ports, and safety and accidental discharge concerns associated with barging.
As a result of increasingly stringent water quality standards being imposed under state, national, and international regulations, wastewater offload and disposal costs in domestic and foreign ports and harbors continue to increase.
In view of the foregoing, it is an object of the present invention to provide a system for treating liquid wastes aboard ship, thereby obviating the need for discharging ship-generated wastewaters overboard.
SUMMARY OF THE INVENTION
The present invention advantageously affords maritime vessels the capability to treat liquid wastes aboard ship, thereby maximizing shore independence and minimizing waste off-load costs. By processing all liquid waste streams generated onboard ship, the present invention enables the maritime vessels to navigate global waters without restrictions imposed by current and future wastewater discharge regulations.
Typical embodiments of the present invention feature the disposal of all non-hazardous liquid wastes, accomplished through the combination of liquid waste concentration and thermal incineration. The concentrating of liquid waste into dense sludge reduces the necessary size of the thermal incineration unit in which the sludge is to be burned so as to render the apparatus associated with the present invention especially suitable for applications wherein space is at a premium, such as shipboard installations.
The present invention represent s a unique methodology for treating and reducing the blackwater, graywater, bilgewater and waste oil which are generated aboard ship by combining volume reduction and thermal incineration technologies to treat and eliminate virtually all shipboard liquid waste, and effectuates an over-arching strategy for managing shipboard liquid wastes involving integration of membrane filtration and thermal incineration technologies.
The present invention features three distinct elements or constituents, viz., (i) non-oily liquid waste treatment, (ii) oily liquid waste treatment and (iii) incineration. Each of the two waste treatment elements (i.e. non-oily liquid waste treatment and oily liquid waste treatment) has associated therewith two different types of liquid waste streams. Non-oily liquid waste treatment encompasses a blackwater waste stream and a graywater waste stream. Oily liquid waste treatment encompasses an oily wastewater (or “oily waste”) stream and a waste oil stream.
The wastewater discharges to be concentrated and/or directly combusted include: sewage (blackwater), graywater, bilgewater, waste oils, fuel-compensated ballast water strippings and fuel tank strippings. Both the oily wastewater stream and the waste oil stream derive from the aggregate of the various forms of bilgewater to include fuel-compensated ballast water strippings and fuel tank strippings. Oil/water separation means separates bulk oil (which is directed to the waste oil tank) from the oily wastewater (which is directed to the oily wastewater tank). The terms “bilge waste” and “bilgewater waste” are sometimes meant to be distinguished from fuel strippings (e.g., fuel-compensated ballast water strippings and fuel tank strippings). Unless otherwise indicated herein, the terms “bilge waste” and “bilgewater waste” refer to liquid waste which consists primarily of water (usually greater than 99 percent) and which contains small amounts of contaminants such as fuel oil, lubricating oil, detergents, particulate matter, corrosion products, and/or other contaminants. Hence, according to the present invention, four different liquid waste streams are individually treated, and then either discharged overboard in an acceptably clean effluent form, or subjected to incineration. Four separate treatment subsystems, each corresponding to a particular waste stream, ultimately direct treated waste to a central incineration apparatus. Two or three of the four treatment subsystems (i.e., those pertaining to graywater waste and to oily wastewater, and possibly that pertaining to blackwater waste) also direct overboard, via discharge lines, a sufficiently clean portion of the treated waste. One of the four treatment subsystems (i.e., that pertaining to waste oil) leads to incineration but permits retention for possible use in helping to fuel such incineration.
Therefore, the subsystems referred to herein produce: (i) a clean effluent that can be discharged overboard; and, (ii) concentrated wastewater streams which can be thermally incinerated by one of the subsystems. An underlying premise of the present invention is to minimize each of the waste streams so that shipboard thermal incineration technologies can process the volume of waste. The present invention not only incorporates the hardware to process the different waste streams, but also incorporates the control logic necessary to handle the various generation rates and peak loads.
According to typical embodiments of the present invention, the three constituents (viz., non-oily liquid waste treatment, oily liquid waste treatment and incineration) operate basically as follows:
A. Non-oily liquid waste treatment. Ultrafiltration technology and other minimization techniques are used: (i) to concentrate the volume of non-oily liquid waste; and (ii) to discharge clean water overboard. Graywater is treated so that a portion thereof is concen
Forrest John
Popovics Robert
Shuster Jacob
The United States of America as represented by the Secretary of
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