Patent Application
20070056134
The present invention relates to a cleaning arrangement for a sedimentation tank, such as a water or wastewater treatment tank and, more particularly, to a cleaning device that utilizes a mechanized rotary brush arrangement to effectively remove algae and other debris from various surfaces of the tank.
A typical wastewater treatment facility includes clarifiers or settling tanks to accomplish separation of solids from liquid. The settled solids are removed from the bottom of the tank as sludge and the clarified liquid above is discharged into an effluent trough or launder. Tank geometries and configurations vary widely but are most commonly circular with the continuous flow of influent water entering near the center of the tank and the discharge of clarified effluent water occurring near the tank periphery. Effluent troughs and launders are generally equipped with weirs to control the flow of the clarified supernatant. In tanks where surface scum is prevalent, scum baffle plates are often provided adjacent to the weirs and the displaced water is forced to flow under a baffle plate that blocks floating scum. Once over the weir, the water flows in an effluent trough or launder to a discharge pipe and on to the next unit in the treatment process. Ultimately, the clean effluent water is disinfected and made sufficiently safe to discharge into a river or stream.
As is known in the art, the outdoor exposure of the treatment tanks in direct sunlight encourages the unwanted growth of algae. This growth is most prevalent one the baffle, weir, spillway and clean water flow channel areas of the treatment tank. Disadvantageously, algae growth on these members inhibits the flow of clean water from the tank. Further, the algae can be carried in thick masses and high concentrations in the clean water being discharged from the final treatment tank. When this occurs, large concentrations of chlorine are required to kill the algae. Since chlorine is relatively expensive, it is preferred to prevent the buildup of algae.
Removing the algae from the baffle, weir, spillway and clean water flow channel has primarily been accomplished in the past by scrubbing the tank structure by hand with long-handled brushes. Since the final treatment tanks are usually quite large, such a cleaning process becomes considerably tedious and labor-intensive.
One prior art apparatus for improving algae removal is disclosed in U.S. Pat. No. 4,830,748 issued to Ford W. Hall on May 16, 1989. The Hall cleaning apparatus comprises a series of rectangular cleaning brushes that are attached through support arms to a main frame member. The main frame member is attached to a conventional skimmer blade. Since the skimmer blade is designed to slowly revolve, the cleaning brushes will also move around the tank. Thus, instead of a worker manually scrubbing algal growth surfaces with a broom, an automated set of brooms essentially moves around the surfaces of the tank. A self-propelled version of this apparatus (for use in arrangements without a skimmer blade) is the subject of U.S. Pat. No. 4,978,447, issued to Ford W. Hall on Dec. 18, 1990. A remaining problem with both of these arrangements, however, is that the brushes are non-mechanized (i.e., a “static” brush design), and a significant amount of algae and other debris may build up on the brush surfaces, thus lessening the cleaning ability of the system. Moreover, the rectangular brush design is not considered as the most effective cleaning arrangement.
Thus, a need remains in the prior art for a mechanized arrangement for effectively cleaning algae and other debris from water and wastewater treatment tanks.
The need remaining in the prior art is addressed by the present invention, which relates to a cleaning arrangement for a sedimentation tank, such as a water or wastewater treatment tank and, more particularly, to a cleaning arrangement that utilizes a mechanized rotary brush arrangement (i.e., a “dynamic brush”) to effectively remove algae and other debris from various surfaces of the tank.
In accordance with the present invention, a sedimentation tank cleaning apparatus comprises a single rotary brush or a series of rotary brushes attached to a support arm. Each brush is mechanized (either individually or as a group) to rotate at a speed sufficient to effectively remove algae and other debris from the various surfaces within the tank structure. Different sizes of brushes may be used along various surfaces, as need be. Moreover, different rotation speeds may be used for different brush locations. For example, a faster rotation may be used along the baffle and weir, where a larger amount of algae and debris will collect. More aggressive scrubbing in these areas will serve to prevent a significant amount of algae and debris from crossing the spillway into the launder area.
Other and further embodiments and advantages of the present invention will become apparent during the course of the following discussion and by reference to the accompanying drawings.
Referring now to the drawings, where like numerals represent like parts in several views:
Prior to describing the improvements in the cleaning of water or wastewater treatment sedimentation tanks in accordance with the present invention, it is considered helpful to review the state-of-the-art cleaning apparatus. In particular,
Water treatment tank 20 (which is nominally circular in form, with only a portion being illustrated in
In operation of prior art apparatus 10, a first set of brushes 32 is provided to scrub/clean baffle 22 and weir 24, including individual brushes to clean the inner surface of baffle 22, the outer surface of baffle 22 and the inside surface of weir 24. A second set of brushes 34 is used to clean the outer surface of weir 24 and spillway 26, including a brush mounted in a sloping position to clean sidewall 28 of spillway 26. Lastly, a third set of brushes is used to scrub clean water channel 30, with separate brushes for the sidewalls and bottom surface of channel 30. As mentioned above, while a degree of improvement is achieved with this prior art apparatus (as compared to manual cleaning processes), various amounts of algae and other debris may be lodged against the static brushes, resulting in ineffective cleaning.
It is to be understood that the inclusion of motor 120 on brush 100 is exemplary only. Various other arrangements may be used that include the provision of a single, centralized motor that is coupled to each separate bristle assembly through an interconnection, such as a pulley system. While more efficient in terms of the reduction of motors and power required, the single-motor embodiment lacks the ability to modify the rotational speed of the individual brushes. However, either arrangement may be used in accordance with the present invention.
With this understanding of the particular brush assembly, it is possible to understand the operation of the present invention by reference to
In accordance with the present invention, the necessary power and control signals are fed along first support member 44 and into the individual motors 120 of each brush assembly 100. Elements 110, 120 and 130 of an exemplary brush (as discussed above in association with
Second support member 46, as shown in
The cut-away side view of
Thus, in accordance with the present invention, the application of electrical, pneumatic or hydraulic power signals along first and second support members 44, 46 energizes the individual motors associated with each of the illustrated rotary brushes. Upon activation, the bristle assembly will rotate at a predetermined speed to provide efficient cleaning. In one embodiment, a common control/power signal is used for the entire combination of brushes. Alternatively, different brushes may be coupled to separate power/control leads so as to separately adjust the rotational speed of each brush and tailor the scrubbing ability of each brush for its particular use (i.e., scrubbing the weir vs. scrubbing the clear water channel).
While this invention has been described fully and completely with special emphasis upon preferred embodiments, it should be understood that various modifications and alterations may be made to the particular brush and/or support mechanism and remain within the spirit and scope of the present invention. Since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, and fall within the scope of the invention.
