Bleaching and dyeing; fluid treatment and chemical modification – Fluid treatment – Manipulation of liquid
Reexamination Certificate
1998-04-08
2001-03-06
Popovics, Robert (Department: 1723)
Bleaching and dyeing; fluid treatment and chemical modification
Fluid treatment
Manipulation of liquid
C068S0180FA, C068S902000, C210S650000, C210S780000, C210S791000, C210S805000, C210S388000, C210S652000
Reexamination Certificate
active
06195825
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to the general field of water purification and recovery. In particular, it provides a new method and apparatus for the reclamation and reuse of waste-water effluent from wash cycle of laundry operations.
2. Description of the Prior Art
Normally, water usage results in its contamination and the resulting waste water is no longer useful for most applications. Therefore, waste waters from domestic and industrial users have been the subject of treatment and purification for a long time in order to remove toxic contaminants, bad odors and suspended solids. The waste water is typically treated by various means of filtration and chemical reaction designed to accomplish specific purification goals, as needed by particular users. The most common systems involve passing the water through layers of filtering media to remove solid particles and through chemically active media to reduce the water's hardness, improve its pH, and extract undesirable contaminants.
Accordingly, water purification agents are generally categorized in terms of their function as filters, when designed to eliminate larger size suspended solids; clarifiers, when intended to remove smaller size particles and reduce opacity; softeners, to remove calcium and magnesium ions and reduce water hardness; and refiners, to extract chlorine, iron and organic compounds. Both anion and cation exchange resins are used to perform a multiplicity of these functions.
The separation of solutes from water by means of selectively permeable membranes is also an effective and economical method of water purification. The processes of reverse osmosis, ultrafiltration, nanofiltration and electrodialysis all involve the use of membranes that have the ability to prevent the migration of most dissolved and suspended solids while allowing the passage of water through their pores.
This invention is directed to the use of a novel combination of these known methods of water purification in a new application for treating waste-water effluents from commercial laundries. In particular, it discloses a closed-loop system for reusing the hot waste-water effluent from the washing cycle of a laundry operation.
During conventional laundry operations, the waste water from each cycle is typically disposed of to the sewer after use and fresh water is fed to the washer machines through cold and hot feed systems to completely replace each load. The cold water feed is drawn directly from a utility supply, while the hot water feed is first heated and stored in a tank at about 150 to 180° F. As the washer machines process laundry, they call for both hot and cold water from these sources in order to provide the water utilized in the wash process. In most operations, the proportion of hot to cold water usage is about fifty/fifty. The resulting waste water is typically at 120° F. and laden with detergent and softening chemicals, in addition to dirt and pollutants. Therefore, when waste water is drained to a sewage system or otherwise discarded, useful chemicals and valuable heat are also wasted with it. In addition, the contaminants left in the water often require downstream water treatment before the effluent can be released to the environment.
Thus, conventional laundry operations involve large water usage, high fuel consumption for water heating, and wasteful disposal of active chemical ingredients in the waste-water effluent, all of which affect the efficiency and operating costs of a laundry.
Therefore, it would be very desirable to improve commercial laundry processes by minimizing these problems.
In U.S. Pat. No. 4,441,340 (1984), Kaplan discloses a system for recycling water from the rinse cycle of a commercial laundry. The water is combined with heated or fresh make-up water, as necessary to reach the required operating temperature, and is then used in the next wash cycle of the laundry system. By so doing, the invention also recovers the heat content present in the water after the rinse cycle is completed. Only rinse water is used because it is relatively clean and can, therefore, be reused as wash water maintaining the quality of washing during the second and subsequent cycles.
Since commercial laundries use relatively cold water for rinsing purposes, the heat recovery afforded by this invention is modest. In addition, no prior art system has been able to recycle wash water effectively and recover not only its energy content, but also its unused active chemicals. Thus, the purpose of this invention is to address this objective by reusing at least a portion of the hot waste water produced during the wash cycle of conventional laundry processes.
SUMMARY OF THE INVENTION
One of the objectives of this invention is the reduction of fuel consumption in the hot-water feed system of a commercial laundry operation.
Another objective of the invention is the reduction of water consumption in a commercial laundry operation.
Yet another objective is the reduction of waste water disposed to a sewage system from a commercial laundry operation.
Another goal of the invention is the full utilization of the active chemicals in laundry water for the purposes of the laundering operation before it is discarded as waste water.
Still another goal is the reduction of chemicals and other pollutants released to the environment from commercial laundry operations.
A final objective is the easy and economical implementation of the process of the invention according to the above stated criteria. This is achieved by using commercially available apparatus, materials and processes, modified only to the extent necessary to fit the requirements of the invention.
Therefore, according to these and other objectives, the present invention consists of a waste-water treatment and recycling process for reducing water, energy and chemical consumption in commercial laundry operations. A portion of the warm waste water from each wash cycle is first passed through a vibrating shaker screen to remove particles larger than 70 microns and then filtered through a 1-5 micron medium in a tubular filtration unit. The clear-water filtrate is then heated to operating temperature and recycled to the wash cycle of the process through the hot-water feed system. Only unheated fresh water is used for the rinse cycle, which also provides the water make-up for the process. For operations requiring low total dissolved solids, a nanofiltration unit is added downstream of the tubular filtration unit.
Various other purposes and advantages of this invention will become clear from its description in the specifications that follow, and from the novel features particularly pointed out in the appended claims. Therefore, to the accomplishment of the objectives described above, this invention consists of the features hereinafter illustrated in the drawing and examples, fully described in the detailed description of the preferred embodiment and particularly pointed out in the claims. However, such drawing and description disclose but one of the various ways in which the invention may be practiced.
REFERENCES:
patent: 4441340 (1984-04-01), Kaplan
patent: 5207922 (1993-05-01), McFarlan et al.
patent: 5329659 (1994-07-01), Reinert
Durando Antonio R.
Popovics Robert
Wastewater Resources Inc.
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