Clarifier cleaning apparatus

The apparatus of the present invention is a cleaning system to be employed in the clarifier. A track is mounted to opposing sides of the clarifier. A scraping blade spans the two rails. A mechanism connects the two ends of the blade to the tracks and provides for stepwise movement of the blade bidirectionally within the clarifier. Movement of the blade over slots found in the clarifier bottom results in displacement of sludge from the clarifier back into the orbital ditch. The moving mechanisms are preferably located adjacent the clarifier floor. The scraping blade moves in stepwise motion over each of the slots, displacing sludge through such slots. At the same time a suction header, with inlets on both sides of the blade, allows some of the sludge to be suctioned from the bottom of the clarifier and removed from the orbital ditch system.

FIELD OF THE INVENTION 
This invention relates to a system for treating water, wastewater and other 
liquid-solid solutions where a clarification step is to be employed in an 
oxidation ditch, with a clarifier may be incorporated within the ditch 
confines. The invention relates to a cleaning apparatus mounted therein. 
BACKGROUND OF THE INVENTION 
Domestic sewage and industrial wastewater often contain impurities which 
include materials such as sugars and other carbohydrates and proteins and 
other forms of nitrogen. Many of these impurities or pollutants are 
decomposable by microorganisms, and there are various types of systems to 
remove the impurities from wastewater by action of microorganisms. One 
type of wastewater treatment system is known as an orbital system, 
sometimes referred to as an oxidation ditch system. 
Orbital wastewater treatment systems include an elongated tank having two 
sidewalls and at least one partition wall mounted vertically in the tank 
substantially parallel to the two sidewalls and spaced apart from the ends 
of the tank. The tank and partition wall together form an endless, 
circuitous channel to contain a stream of mixed liquor. An orbital 
wastewater treatment system also includes means to cause the liquid to 
flow through the channel and an aerating means to introduce air into the 
liquid to provide oxygen for the microorganisms. Various mechanisms can be 
used for such purposes including a surface aerator, a rotary perforated 
disc-type aeration mixer, or a rotating brush aerator. Orbital wastewater 
treatment systems are taught, for example, in U.S. Pat. Nos. 3,510,110 and 
3,846,292. According to U.S. Pat. No. 3,846,292, influent wastewater is 
introduced into the tank and driven to flow around the endless, circuitous 
channel. A stream of treated liquid, less than the total flow in the 
channel, is removed from the channel and transferred into a solid-liquid 
separator, or clarifier, spaced apart from the orbital system. In the 
separator, solid particles form sludge which settles, and part of the 
sludge is returned to the orbital system to mix with the wastewater to 
form mixed liquor. Clarified liquid is transferred from the separator to a 
stream or other body of water or sent to further treatment. The purpose of 
returning sludge to the orbital system is to maintain a predetermined 
concentration of microorganisms in the mixed liquor, thereby to accomplish 
biological removal of pollutants from the wastewater. 
The construction of a conventional orbital system such as taught in the 
above patents requires that the circuitous channel be constructed and that 
a separate sludge separation system also be added. Additionally, a system 
of pipes and pumps must be installed to permit diversion of wastewater 
from the orbital system to the separator and for return of sludge from the 
separator to the orbital system. 
As discussed in U.S. Pat. No. 4,303,516 (Stensel, et al.) assigned to a 
predecessor of applicants' assignee and as practiced in 1981 at a 
wastewater treatment plant at Campbellsville, Kentucky, and later at 
Owensboro, Kentucky, a rectangularly shaped clarifier is disposed in an 
orbital channel between a channel wall and partition with a frontal top 
weir to receive a portion of the overall mixed liquor flowing through the 
orbital channel. The mixed liquor portion passed down the clarifier 
co-currently with the main orbital channel flow into a clarifier quiescent 
zone. Biological sludge is settled in the clarifier for removal through 
ports in the clarifier bottom back in to the orbital channel mixed liquor 
flow and clarified liquor removed by overflow into effluent troughs 
alongside the partition wall and extending over a substantial length of 
the top of the clarifier. In the '516 patent, one embodiment employs a 
dipped orbital channel portion so that the orbital channel flow has 
substantially the same cross-sectional area throughout its length. In the 
Campbellsville installation, the clarifier was installed over the same 
channel floor elevation as the remainder of the orbital channel, and thus 
the remaining orbital channel flow at that location had less of a 
cross-sectional area than the remaining areas of the channels. 
U.S. Pat. Nos. 4,362,625; 4,383,922; 4,457,849; and 4,780,206 to Beard also 
show intra-channel clarifiers which involve a boat-shaped structure 
positioned in a channel with its bow directed into the wastewater flow and 
providing a stern or rear inlet for entry of a portion of the wastewater 
flow, with that portion being flowed in the clarifier counter-currently to 
the channel flow at the bow of the clarifier structure. Sludge is settled 
in the clarifier and flows back into the channel between rows of vertical 
plates or through tubes. An effluent launder is positioned in a forward 
bow section of the clarifier structure. 
Various other types of intra-channel clarifiers, including modifications of 
the Stensel, et al., patent and the Beard boat structure, are shown and 
discussed in an article entitled "Assessment of Design Trade-offs When 
Using Intrachannel Clarifiers" by Jon H. Bender of the U.S. Environmental 
Protection Agency, published in the October 1987 issue of the Journal WPCF 
volume 59, number 10, pages 871-876. As set forth in the article, an 
intra-channel clarifier must not negatively impact the mixed liquor flow 
velocity in the orbital channel. All intra-channel clarifiers restrict the 
circulating flow of mixed liquor in the aeration channel to a certain 
degree. Such restrictions must be minimized to maintain adequate channel 
velocities without requiring additional power to the aerator or other 
propelling means for the mixed liquor. The capability of the aeration 
device to overcome headlosses in the channel also must be considered. 
The article also indicates that consideration must also be given to the 
effect of aerator channel and clarifier maintenance in an intra-channel 
clarifier system. Proper adjustment of sludge return flows from the 
clarifier to the orbital channel are also a factor. Paramount to any 
intrachannel clarifier is the cost-effectiveness in terms of original 
cost, operational (power) costs, operational manpower costs, maintenance 
cost, and longevity. 
SUMMARY OF THE INVENTION 
The invention disclosed herein results in a waste water or other 
liquid-solids treatment system involving a clarification operation which 
minimizes diminution of mixed liquor flow velocity and the headloss in the 
orbital channel(s) due to the presence of an intra-channel clarifier 
therein. The disclosed system is of a type which substantially minimizes 
the amount of concrete and labor required in constructing the system and 
utilizes the mixed liquor flow in the channel to positively force inlet 
flow by providing an inlet in one-half of the clarifier bow facing forward 
into the channel mixed liquor flow. Further, the clarifier inlet ensures 
that there is a diminished slower positive flow of influent in the 
intraclarifier vessel. Likewise, settled sludge removal is positive since 
its flow rate can be controlled by the amount of mixed liquor forcibly fed 
into and entering the clarifier inlet over and above the flow of settled 
effluent. 
The particular intra-channel configuration disclosed and its location 
relative to the sidewalls and elongated partition of an orbital channel 
treatment system results in a clarifier of suitable surface area and 
volume, while only encroaching on well less than half the full 
cross-sectional area of the orbital channels in which it is mounted. In 
one embodiment, the cross-section of the intra-channel clarifier is about 
72 sq.ft. in about a 242-sq.ft. channel, thus providing only about a 30 
percent encroachment, thus greatly minimizing the restriction of mixed 
liquor flow in a channel. It is believed that prior art intra-channel 
clarifiers which are placed in one channel only block out over 50 percent 
of the mixed liquor flow in the channel by cutting the open 
cross-sectional area more than 50 percent. 
The above desirable results are obtained by providing an elongated 
top-facing notch or series of notches in the center partition between two 
sidewalls of the orbital ditch and positioning the clarifier in the 
notch(es) so that, in effect, the outer sidewalls of the clarifier 
function as the flow partition wall as an extension of the partition wall 
into the orbital channel. It is thus seen that there is an inherent saving 
in concrete and construction costs of the resultant smaller central 
partition. This construction leaves a ma]or amount of each flow channel, 
particularly the outer periphery thereof, completely unimpeded by the 
intra-channel clarifier. 
The intra-channel clarifier occupies only a relatively small fraction of 
the oxidation ditch channel cross-sectional area as compared to prior art 
devices. This causes the mixed liquor flow velocity in the channel to 
increase, in the area of the intra-channel clarifier, only slightly above 
what it is in other portions of the tank. For example, in one embodiment 
of the invention, the increase in velocity has been calculated as 0.3 
ft/sec., whereas in prior art intraclarifiers, the increase of velocity 
may well be over 1 ft/sec. This aspect of the invention substantially 
reduces the headloss in the channel caused by the intra-channel clarifier 
(headloss is proportional to the square of the velocity), resulting in a 
reduced consumption of energy (in the form of aerator horsepower) to 
overcome the headloss. 
The intra-channel clarifier actually straddles a lowered section of the 
center partition of the orbital ditch so that the respective opposite 
longitudinal sidewalls and a longitudinal bottom half of the clarifier 
each extend in cantilevered fashion from the center partition the same 
distance into opposed channels of the orbital ditch; i.e., the 
intrachannel clarifier is disposed essentially symmetrically across the 
central partition of the orbital ditch adjacent a midpoint of the 
partition. 
The apparatus of the present invention is a cleaning system to be employed 
in the clarifier. A track is mounted to opposing sides of the clarifier. A 
scraping blade spans the two tracks. A mechanism connects the two ends of 
the blade to the tracks and provides for stepwise movement of the blade 
bidirectionally within the clarifier. Movement of the blade over slots 
found in the clarifier bottom results in displacement of a selected amount 
of sludge from the clarifier back into the orbital ditch. The moving 
mechanisms are preferably located adjacent the clarifier floor. The 
scraping blade moves in a stepwise motion over each of the slots, 
displacing a selected amount of sludge through such slots. At the same 
time a suction header, with inlets in close proximity to the blade, allows 
some of the sludge to be suctioned from the bottom of the clarifier and 
removed from the orbital ditch system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The orbital system 210 shown in FIG. 1 includes an elongated mixed liquor 
holding tank 211 which has two vertical sidewalls 212 and 214 and two 
curved vertical or otherwise configured end walls 215 and 216 connected 
between opposed ends of sidewalls 212 and 214. The tank 211 has a floor 
shown as channel bottom 217a in a first channel reach and a channel bottom 
217b in a second return channel reach. The tank is mounted normally on 
ground level 209. A vertical curvilinear turning wall 218 may be utilized 
to guide the flow of mixed liquor between the various channels. The 
invention may be used in various configurations of one or more orbital 
channels or in a freestanding clarifier or similar piece of equipment. A 
vertically disposed partition in the form of a wall 220 is mounted 
approximately equidistant between and substantially parallel to sidewalls 
212 and 214 and with the partition wall ends spaced from end walls 215 and 
216 so that an endless, circuitous channel 221 is formed in the tank. An 
inlet conduit 222 is connected to the tank to permit a wastewater mixed 
liquor influent to fill the tank to a desired level 223 (FIG. 2). 
In the event an orbital system as taught by U.S. Pat. No. 3,510,110 is to 
be employed, a vertically disposed surface aerator 224 and associated 
drive motor (not shown) is mounted on a walkway 225 at one end of the tank 
adjacent curved end wall 216. The aerator includes a rotating impeller 
with a plurality of blades extending radially from a vertical shaft and 
located slightly below the wastewater surface level so that as the 
impeller rotates, the mixed liquor in the channel is driven to move as 
indicated by the FLOW arrows and the mixed liquor is agitated so that the 
liquor is aerated. Other means for moving and aerating the mixed liquor 
may be employed such as by horizontal rotating brushes positioned across a 
channel or bottom-mounted diffusers or standard draft tube aerators. 
The clarifier C is mounted preferably in a top-facing notch (FIG. 3) of the 
partition 220 so that the clarifier C straddles across the partition. The 
clarifier can also be freestanding. Clarifier C is formed as an elongated 
vessel having vertical sidewalls 231 and 232, sludge exit ports 240, a bow 
section 235, and a closed stern section 236. One side 237 of the bow 
section facing into the mixed liquor flow contains a pair of vertically 
movable gates (FIG. 4) which are operable to control the flow of a portion 
(shown by arrows 238) of the mixed liquor in the circuitous channel 221 
into the clarifier. 
The clarifier influent portion is conducted into the clarifier at the bow 
section side 237 and after distribution in the clarifier (FIG. 5), flows 
concurrently with the mixed liquor in the return reach of channel 221. The 
remaining mixed liquor in the channel passes to sludge exit ports 240 and 
past the outside of the clarifier vessel. 
Clarification of the portion of mixed liquor takes place in the clarifier, 
with sludge settling out as the clarifier influent portion moves down the 
clarifier. A series of clarifier effluent troughs 241, as also seen in 
FIG. 3, are provided at the downstream end of the clarifier to remove 
clarified liquor through an effluent outlet 242. Scum and floating 
material in the clarifier may be removed by a scum system such as shown in 
U.S. Pat. Application 07/326,143, filed 3/20/89, and fully incorporated by 
reference as if actually forth herein. The sludge exit ports 240 may be 
cut out on three sides and the cut metal or plastic bent down as a flap to 
direct sludge flow into the same direction as the mixed liquor flowing 
therebeneath. Other types of sludge ports, such as tubes or circular 
bottom apertures or open troughs, may be employed. The clarifier bow 
section 235 includes an internal baffle 246 having spaced apertures 247 
which aid in directing the mixed liquor portion flow into the main volume 
of the clarifier and in arresting the mixed liquor portion flowrate. 
Normally, the flowrate of the mixed liquor in the channel 221 is about 1.0 
ft/sec., while the increased flow velocity across section 2--2, for 
example, will be in the range of about 1.2 to about 1.4 ft/sec. 
The clarifier C is mounted on the top 248 of one or more notches in 
partition 220. Suitable truss or other support structures 249 may extend 
from the partition 220 to the sidewalls 231 and 232 so as to support and 
stabilize the clarifier. 
The bow end of the clarifier C is seen in FIG. 4, including a pair of inlet 
gates 251 and 252 which are vertically movable into a full open or closed 
or intermediate position by movement of a standard screw-raising mechanism 
253. The gates may comprise a flat closure plate which slides up and down 
within vertical retaining lips on the exterior of that part of the bow 
section facing the flow of mixed liquor in the channel 221. The gates 251 
and 252, providing in a typical embodiment a two-foot by two-foot opening, 
are preferably spaced about one foot below the water level 223 so as to 
minimize the entry of scum or other floating matter into the clarifier. 
The gate maximum open area will depend on the clarification capacity of 
the clarifier vessel. The amount of flow coming into the vessel is 
approximately equal to the flow velocity of the mixed liquor times the 
inlet gate(s) inlet cross-sectional area. Gate 251 feeds the half of the 
clarifier which faces channel wall 212 while gate 252 feeds the other half 
of the clarifier facing channel wall 214. It is to be noted that partition 
220 in FIG. 4, forward of the bow section toward channel end 215, extends 
at full height from the channel bottom floor to above the mixed liquor 
level 223 in the channel 221. Inwardly of the clarifier, the partition is 
notched so that there is essentially freedom of flow of the portion of the 
mixed liquor being clarified across the length and breadth of the 
clarifier. 
FIG. 5 illustrates the distribution of the influent portion of mixed liquor 
entering the clarifier 230 through the gates. Influent entering gate 251 
passes into a chamber 256, and influent entering gate 252 passes into a 
chamber 255. The chambers are separated by a vertical wall 254. Each 
increment of mixed liquor passes through spaced apertures in a vertical 
baffle plate 257 into downstream chambers 258 and 259, respectively, in 
opposite halves of the clarifier. The partition is notched between the 
chambers 258 and 259 to allow crossflow. The increments of influent then 
pass through similar apertures 247 in parallel-spaced baffle 246, the 
apertures in the respective baffles being staggered so as to provide a 
tortuous flowpath to permit arresting the clarifier influent flowrate in a 
prescribed amount as discussed above. The baffles 246 and 257 extend 
across the width of the vessel and from the vessel bottom to above the 
liquid level in the vessel. The arrows show the clarifier influent flow 
movement into the settling zone 260 of the clarifier. In notching the 
partition 220, more appropriately in pouring a concrete partition, 
upstanding pylons 261 are formed in the partition for mounting the truss 
structure 249. The longitudinal bottom of the clarifier is anchored 
against the partition at 248 as seen in FIGS. 2, 3, and 8. 
The apparatus A of the present invention comprises moving means M and 
driving means D, connected to the moving means M to drive the moving means 
in a stepping manner, as defined by movement of a portion of said driving 
means D relative to another portion of said driving means D (see FIG. 3). 
As shown in FIGS. 3 and 6, driving means D comprises a track 32 as 
described below. Body 24 is movably mounted to track 32. As shown in FIG. 
3, track 32 is disposed on opposing walls of a clarifier. Body 24 is 
movably mounted to track 32 on both sides of the clarifier. The two bodies 
24 are connected by a structural member shown generally as 300, which 
spans at least a portion of the clarifier C. It should be noted that only 
one drive means D can be used with a roller idler on the opposite track 
32, but use of a pair of drive means is preferred. The structural member 
300 can vary in design, depending upon the spans involved and the amount 
of sludge (not shown) anticipated to settle at the bottom of clarifier C. 
FIG. 3 illustrates a truss-type structural member, but other designs may 
be used without departing from the spirit of the invention. Connected to 
the underside of structural member 300 is plow 302. While FIG. 6 shows the 
plow to be mounted directly below structural member 300, alternative 
mounting methods can be employed for the plow 302. The plow 302 can be 
flexibly mounted to structural member 300 without departing from the 
spirit of the invention. The importance of structural member 300 is to 
give plow 302 sufficient structural rigidity as it pushes the sludge (not 
shown) toward sludge exit ports 240 located at the bottom 304 of clarifier 
C. Plow 302 moves in a stepwise manner by virtue of the drive means 
located within body 24. The operation of drive means D is described in 
more detail below. As a result of the operation of drive means D, plow 302 
moves across all the sludge exit ports 240 which span bottom 304 of the 
clarifier C. In the preferred embodiment, the sludge exit ports 240 are 
open troughs which extend longitudinally over the short dimension of the 
clarifier, and the plow 302 is disposed in a plane parallel to all the 
sludge exit ports 240. Drive means D has a reversing feature which allows 
plow 302 to traverse the entire length of the clarifier C and then return 
in the opposite direction. Plow 302 is structurally mounted to support 
member 300 so that it is effective in plowing the sludge, regardless of 
the direction that the plow 302 is driven. 
As shown in FIG. 6, the clarifier C can have transverse support members 249 
which give structural integrity to the clarifier C shell. The track 32 is 
necessarily mounted below structural crossmembers 249. As shown in FIG. 6, 
track 32 does not extend the entire length of clarifier C. The gap 306 
allows each body 24 to be mounted to and taken off track 32. In the 
preferred embodiment, track 32 is mounted within the clarifier C. If 
structural members 249 are used for reinforcing, then track 32 is mounted 
between the bottom 304 and structural members 249. Preferably, track 32 
should be mounted high enough so that it is above the zone of sludge 
accumulation. However, as described below, portions of drive means D in 
contact with track 32 act as a wiping mechanism to wipe off any 
accumulated sludge which might deposit on track 32 during the operation of 
the clarifier C. As shown in FIG. 3, a pair of tracks 32 and drive means D 
operate in tandem, with structural member 300 connected therebetween. 
Structural member 300 can be built of tubular members with ends sealed off 
so that it has some buoyant properties. Any inherent buoyancy of 
structural member 300 reduces the downwardly exerted loads on drive means 
D due to the weight of structural member 300 and moving means M. 
Alternatively, to decrease the downwardly extending loads on drive means 
D, additional buoyancy can be provided in the form of ballast tanks (not 
shown) which create an upwardly extending force to counteract the weight 
of the structural member 300 and the plow 302 attached thereto. 
As will be discussed below, a suction header 308 is preferably attached to 
the structural member 300. Suction line 310 leads from suction header 308 
to a vacuum source 312, which is generally labeled as V on FIG. 3. The 
vacuum source can be a vacuum pump or a self-priming centrifugal pump, 
depending on the application. Depending upon the design of the clarifier 
C, more than one suction header 308 can be used (see FIG. 3), in which 
case additional suction lines 310 are employed to connect to vacuum source 
312. 
Alternatively, a multiplicity of vacuum sources 312 can be used. As shown 
in FIG. 6, if structural members 249 are employed within the clarifier C, 
suction line 310 must be sufficiently long to allow housing 24 to traverse 
both ends of track 32 without getting snagged on suction line 310. It 
should be noted that the use of structural members 249 is optional and 
depends upon the structural design of the clarifier. Preferably, the 
clarifier walls will be constructed of sufficient rigidity or will have 
sufficient external bracing so that the use of structural members 249 can 
be avoided. However, if structural members 249 are used, the length of 
suction line 310 in effect doubles over itself below structural members 
249 when the housing 24 is in the position shown in FIG. 6. Flotation 
devices may be attached to line 310 to control its position as plow 302 
moves. 
It should be noted that suction header 308 preferably extends for 
substantially the entire length of structural member 300. Header 308 has a 
plurality of outlets 314 on one side of plow 302 and a plurality of 
outlets 316 on the opposite side of plow 302. 
The number, size, and spacing of outlets 314 and 316 depend upon the 
configuration of clarifier C and the expected rate of sludge accumulation. 
Outlets 314 and 316 serve as means to remove sludge from the clarifier C 
by the selective operation of vacuum source 312. With outlets provided on 
both sides of plow 302, sludge can be removed with the plow 302 traversing 
from left to right or from right to left. Optionally, valving mechanisms 
can be provided to ensure that outlets 316 are blocked off when outlets 
314 are open. It will be appreciated by those skilled in the art that, as 
an alternative, a pair of headers 308 can be employed, with one header 
connected to outlets 314 and the other to outlets 316. Each of the headers 
308 in that event would be connected to vacuum source 312 with appropriate 
valving at the vacuum source to apply vacuum selectively to one header 308 
or the other, depending upon the direction of movement of plow 302. 
In applications using an orbital ditch with a clarifier built in, it may 
not be desirable to always return all of the accumulated sludge back into 
the orbital ditch through sludge exit ports 240. It may be desirable to 
purge some of the sludge from the system during the operation of the 
orbital ditch. Accordingly, the vacuum source 312 can be employed in 
conjunction with suction header 308 and outlets 314 or 316 to pick up 
sludge from clarifier C and move it to a location separate from the means 
to receive sludge located below sludge exit ports 240. Sludge can then be 
sucked out of clarifier C while it is also being plowed out through ports 
240. Both rates can be simultaneously controlled by regulation of the 
speed of drive means D and the amount of vacuum applied to suction header 
308. Those skilled in the art will also appreciate that vacuum source 312 
can be either built to pass sludge sucked out of the bottom 304 of 
clarifier C, or suitable separating equipment will need to be placed on 
suction line 310 to prevent the sludge from getting into vacuum source 312 
if it is of the style that cannot pass such materials. 
It should be noted that the stepwise movement of housing 24, described 
below, also acts to shake any accumulated sludge off of structural member 
300. 
Placing track 32 within clarifier C has advantages over previous scraping 
designs employed in the prior art. Previously, the support mechanisms for 
the plow have been necessarily located outside of the clarifier C, with a 
purposeful intent of avoiding contact between the driving mechanism for 
the plow and the clarified media or the sludge. One of the reasons for 
locating the drive equipment for a scraper outside of the clarifier C is 
due to the presence of electrical and mechanical components and the need 
to keep such components from getting fouled by the clarified liquid or 
sludge. The placement of the drive mechanism for a scraper blade outside 
of the clarifier made it more difficult to solidly support any scrapers 
along the bottom of the clarifier. As a result, such scrapers could tend 
to get hung up if confronted with fairly severe sludge accumulations. The 
nature of the superstructure, connecting the driving mechanism for the 
scrapers located outside of the clarifier C to the scraper moving along 
the bottom, limited the amount of force which could be transmitted to such 
scrapers. This concept is illustrated in U.S. Pat. No. 4,303,516, which 
shows the scrapers supported by flimsy structural members solely at one 
end, with what amounts to a knee brace to try and lend support to the 
outer fringes of the blade. Alternatively, massive support structures for 
the plow were used, requiring extra concrete and reinforcing in the 
clarifier walls to support railroad-type rails at the top of the clarifier 
and the aggregate weight of the blade support superstructure and the 
mechanisms to drive it. 
The cleaning mechanism of the present invention eliminates this inherent 
design weakness by giving support to plow 302 along substantially its 
entire length and at a point close to its point of contact with the 
sludge. The plow is also driven from both ends in tandem by driving means 
D, with an interconnecting structural member 300. Accordingly, the plow 
302 can be made of a somewhat more flexible material to allow it to pass 
over irregularities in the bottom 304 of the clarifier, but at the same 
time have sufficient structural rigidity to substantially move the 
required amount of the accumulated sludge through sludge exit ports 240. 
It should be noted that with the use of the cleaning mechanism as shown, 
any deflecting panels below sludge exit ports 240 can be eliminated. These 
deflecting panels used in the prior art have served to constrict the 
bottom openings with the intended function of directing sludge flow 
direction. They sometimes caused plugging. Those skilled in the art can 
appreciate that fouling of the sludge exit ports 240 can result in 
accumulation of sludge build-up on bottom 304 and cause a shutdown of the 
clarifier. 
The apparatus of the present invention, as described in more detail below, 
has a drive means D which positively engages track 32 to provide for 
improved traction along track 32 and a greater force transmitted to plow 
302 to push accumulated sludge through the sludge exit ports 240. 
Additionally, drive means D is operable in a completely pneumatic design 
and, therefore, can be easily built to be installed submerged completely 
in liquid. This, again, is a departure from prior designs where it has 
been advantageous to locate drive mechanisms out of the clarified liquid 
for maintenance and explosive hazards. Locating the drive means D within 
the clarifier C also permits the use of smaller components since the 
driving force generated by drive means D is that much closer to the plow 
302. 
It is within the spirit of the invention to use the vacuum source 312 
without plow 302 to selectively purge sludge from the clarifier to some 
separate location other than a receiving container under sludge exit ports 
240. To do this, plow 302 would require a retraction means (not shown) to 
pull it away from ports 240 as it is driven across the clarifier. 
Alternatively, the vacuum source 312 can be employed in tandem with the 
plow 302 to suck up sludge from the bottom 304 of clarifier C and return 
the sludge back to a receiving container mounted below sludge exit ports 
240. Finally, plow 302 can be used without vacuum source 312. 
While it has been shown to use the clarifier C in an orbital ditch by 
mounting it on a central wall, it is within the purview of the invention 
to use the cleaning apparatus for the clarifier in a clarifier which is 
mounted in a flow channel of an orbital ditch or in a stand-alone 
clarifier. 
As shown in FIGS. 8 and 9, drive means D further includes a housing 34, 
first body member 36, second body member 38, and third body member 40. The 
housing 34 surrounds and contains the three body members 36, 38, and 40. 
The first body member 36 includes a cross member 42 and a slide member 44 
integrally joined to the cross member 42, as seen in FIG. 9. Similarly, 
the third body member 40 includes a cross member 46 and a slide member 48 
integrally joined to the cross member 46. Positioned between first and 
third body members 36 and 40 is the second body member 38, comprising 
frame members 50 and 52 and slide member 54. The slide member 54 
interconnects the two frame members 50 and 52. The slide members 44 and 48 
are connected to the midportions of the cross members 42 and 46, while the 
slide member 54 is connected to the midportions of frame members 50 and 
52. 
First body member 36 is joined to second body member 38 by an 
interconnecting mechanism including a pair of cylinders 56 and 58. First 
cylinder 56 extends between frame members 50 and 52, and is attached 
thereto at opposite ends of first cylinder 56. First cylinder 56 has a 
pair of piston rods 60 and 62. Each piston rod 60 and 62 is retractable 
within the first cylinder 56, as well as extendable out of an end of first 
cylinder 56. The outer end of piston rod 60 is fastened to cross member 42 
of first body member 36 adjacent a first side of the cross member 42. The 
outer end of the piston rod 62 is fastened to cross member 46 of third 
body member 40 adjacent a first side of cross member 46. The inner ends of 
the piston rods 60 and 62 are connected to a common piston (not shown) 
contained within first cylinder 56. 
Likewise, second cylinder 58 extends between frame members 50 and 52 and is 
attached to the sides of the frame members 50 and 52, opposite those sides 
to which first cylinder 56 is connected. The second cylinder 58 has a pair 
of piston rods 64 and 66. Each piston rod 64 and 66 is retractable within 
the second cylinder 58, as well as extendable out an end thereof. The 
outer end of the piston rod 64 is fastened to cross member 42 of first 
body member 36 adjacent a second side of the cross member 42. The outer 
end of the piston rod 66 is fastened to cross member 46 of third body 
member 40 adjacent a second side of the cross member 46. The inner ends of 
the piston rods 64 and 66 are connected to a common piston (not shown) 
contained within second cylinder 58. 
Fixably fitted within the hollow interior of each of the slide members 44, 
48 and 54 is a contact member 68, which the track 32 engages as the 
collecting device moves along the track 32. The contact member 68 
contained within slide member 44 is depicted in FIG. 10 while the contact 
member 68 of third body member 40 is shown in FIGS. 11 and 12. The contact 
member 68 is typically made of a strong plastic and is held against two of 
the inner walls of a slide member. Securely connected to each slide member 
44, 48 and 54 is also a pressure brake line 70 which is received in a 
brake opening 72 formed in each slide member 44, 48 and 54, as represented 
in FIG. 13. The pressure brake line 70 carries pressurized fluid to its 
corresponding brake opening 72, as will be subsequently discussed. Each 
pressure brake line 70 is of sufficient length so that the assembly is 
movable along the entire extent of the track 32. 
In addition, a track clamping mechanism is positioned within each slide 
member 44, 48 and 54. Each clamping mechanism includes a rigid, generally 
rectangular bar 74 surrounded by a diaphragm 76. The bar 74 has a threaded 
opening. Correspondingly, the diaphragm 76 has an opening aligned or 
coaxial with the bar opening. A threaded end of the pressure brake line 70 
is tightly held in the threaded bar opening to connect the pressure brake 
line 70 to the clamping mechanism. 
The clamping mechanism further includes a brake pad 78 held adjacent the 
diaphragm 76 within each slide member 44, 48 and 54 for engagement with 
the diaphragm 76. The pressure brake line carries pressurized fluid so 
that the fluid can exit into the diaphragm 76. As illustrated in FIG. 11, 
pressurized fluid is contained in the diaphragm 76. As a result, the 
diaphragm 76 expands and pushes against the brake pad 78. In turn, the 
brake pad 78 engages the track 32 so that the slide member 48 is thereby 
clamped or braked on the track 32, for purposes to be discussed later. 
FIG. 12 illustrates the workings of the clamping mechanism when the 
pressurized fluid is no longer present in the diaphragm 76. As can be 
seen, the track 32 is no longer clamped between the brake pad 78 and the 
contact member 68. Consequently, the slide member 48 is free to move along 
the track 32 when the collecting device is driven. 
The operation of the sediment-collecting device is illustrated 
diagrammatically in FIG. 13. As stated previously, the device is capable 
of a reciprocating, stepping movement. A description of the stepping 
movement in a first direction (illustrated by the solid line arrow of FIG. 
13) is given first. For explanation purposes, it is assumed that the first 
body member 36 is immediately adjacent second body member 38 so that the 
piston rods 60 and 64 are retracted within first cylinder 56 and second 
cylinder 58, respectively. In order to move first body member 36 away from 
second body member 38 or in the direction illustrated by the solid line 
arrow, no pressurized fluid is provided to the clamping mechanisms of 
slide member 44 and 48. The clamping mechanism of slide member 54 is then 
activated by providing pressurized fluid through pressure brake line 70 
and brake opening 72 to the diaphragm 76 housed therein. As a result, the 
second body member 38 is held fixed or braked upon the track 32. Next, 
pressurized fluid is provided to both first and second cylinders 56 and 58 
through pressure drive line 79 and drive openings 80 and 82. Pressure 
drive line 79 carries pressurized fluid to the cylinders 56 and 58 for use 
in driving the device. Drive openings 80 and 82 are formed in the 
cylinders 56 and 58 at first ends thereof adjacent frame member 52 of 
second body member 38. The pressurized fluid against the pistons within 
the cylinders 56 and 58 forces the piston rods 60 and 64 outwardly of the 
cylinders 56 and 58, while the second body member is held fixed to thereby 
move or slide first body member 36 along the track 32 relative to and away 
from the second body member 38. Since piston rods 62 and 66 are connected 
to the common piston to which piston rods 60 and 64 are also connected, 
third body member 40 moves in a direction towards second body member 38. 
After the piston rods 60 and 64 have reached their fullest outer extent 
with respect to the second body member 38 or where third body member 40 is 
immediately adjacent second body member 36, the clamping mechanisms of 
slide members 44 and 48 are activated by means of the application of 
pressurized fluid thereto through their respective pressure brake lines 70 
and brake openings 72. The clamping mechanism of slide member 54 is 
released. Next, pressurized fluid is provided to both cylinders 56 and 58 
through drive line 83 and drive openings 84 and 86. Pressure drive line 82 
carries pressurized fluid to the cylinders 56 and 58 for use in driving 
the device. Drive openings 84 and 86 are formed in the cylinders 56 and 58 
at second ends thereof adjacent frame member 58 of second body member 38. 
The pressurized fluid against the pistons in the cylinders 56 and 58 
through these drive openings 84 and 86, while first body member 36 and 
third body member 40 are clamped to the track 32, results in a force which 
pulls second body member 38 in the direction of the first body member 36 
to retract piston rods 60 and 64 within their respective cylinders 56 and 
58, while moving second body member 38 along the track 32 relative to and 
towards first body member 36. Second body member 38 moves until it 
contacts first body member 36. The piston rods 62 and 66, connected to 
third body m ember 40, are extended outwardly from their respective 
cylinder ends during this movement of the second body member 38. 
After the second body member 38 is immediately adjacent the first body 
member 36, that is to say, the piston rods 60 and 64 are retracted within 
the cylinders 56 and 58, the foregoing process just described is repeated. 
The movement of the collecting device in the first direction continues for 
a predetermined time, normally, until the collecting device reaches a wall 
of the vessel 16. In order to move the collecting device in a second 
direction, opposite the just described first direction, a similar 
operation is used. Assuming that second body member 38 is immediately 
adjacent first body member 36 and first body member 36 is essentially 
adjacent the vessel wall, the clamping mechanisms of slide member 44 and 
48 are activated to hold first and third body members 36 and 48 fixed to 
the track 32. Pressurized fluid is removed from the clamping mechanism of 
the second body member 38. Pressurized fluid is then provided through 
pressure drive line 79 and drive openings 80 and 82 to the first and 
second cylinders 56 and 58. The force against the piston in the two 
cylinders 56 and 58 moves the second body member 38 along the track 32 in 
a second direction or towards third body member 40. 
After second body member 38 is moved immediately adjacent third body member 
40, the clamping mechanisms of slide members 44 and 48 are disengaged by 
removal of the pressurized fluid applied thereto. The clamping mechanism 
of slide member 54 is activated by means of pressurized fluid. 
Subsequently, pressurized fluid is provided through pressure drive line 83 
and drive openings 84 and 86 of first and second cylinders 56 and 58. 
Force of the fluid moves the piston rods 62 and 66 outwardly of the 
cylinders 56 and 58 while piston rods 60 and 64 are retracted within the 
cylinders 56 and 58. 
After the piston rods 62 and 66 have reached their fullest outer extent 
with respect to the second body member 38 or where first body member 36 is 
immediately adjacent second body member 38, the foregoing described 
process is repeated until the collecting device is moved for a 
predetermined time in the second direction. 
The state or condition of the pressurized fluid sent to the slide members 
44, 48 and 54 and cylinders 56 and 58 for proper working operation of the 
device is provided adjacent the pressure brake lines 70 and pressure drive 
lines 79 and 83 depicted in FIG. 13. ON indicates that pressurized fluid 
is being applied, while OFF indicates that pressurized fluid is not being 
applied. The first column of the first pair of columns represents the 
state of the pressurized fluid when the first body member 36 and the third 
body member 40 are being moved in the first direction (solid line arrow). 
The second column of the first pair of columns represents the state of the 
pressurized fluid when the second body member 38 is being moved in the 
first direction (solid line arrow). 
The first column of the second pair of columns represents the state of the 
pressurized fluid when the third body member 40 and first body member 36 
are being moved in the second direction (dashed line arrow). The second 
column of the second pair of columns represents the state of the 
pressurized fluid when the second body member 38 is being moved in the 
second direction (dashed line arrow). 
Referring to FIGS. 14-15, different embodiments of the clamping mechanism 
of the present invention are provided. In FIG. 14, a cable 88 is 
substituted for the track 32. Unlike the slide members 44, 48 and 54, 
slide member 90 has no opening formed at its bottom to receive a track 32. 
The cable is supported within the clarifier to be received within the 
hollow interior of the slide member 90. Pressure brake line 92 is 
connected to the slide member 90 and carries pressurized fluid to a 
bellows 94. Upon delivery of pressurized fluid, the bellows 94 expands and 
forces brake show 96 against the cable 88. The cable 88 then also engages 
brake shoe 98 so that slide member 90 is clamped to the cable 88. In the 
absence of pressurized fluid, the bellows 94 retracts and slide member 90 
is no longer clamped to the cable 88 and is capable of movement 
therealong. 
The clamping mechanism embodied in FIG. 15 includes a pair of cams 100 and 
102 connected to a slide member 104 for pivotal movement about pivot pins 
106 and 108, respectively. The cams 100 and 102 are positioned on opposite 
sides of the bottom opening of the slide member 104. The cams 100 and 102 
are joined together by an interconnecting piece 110. A spring 112 attached 
to the interconnecting piece 110 urges the cams 100 and 102 toward the 
track 32. A solenoid 114 having a solenoid head 116 is positioned within 
the slide member 104 so that the solenoid head 116 can engage the 
interconnecting piece 110 when the solenoid 114 is energized. 
In operation, the slide member 104 is capable of movement in the direction 
identified by the solid line arrow of FIG. 15. However, the slide member 
104 cannot move in the direction of the phantom or dotted line arrow 
inasmuch as the cams 100 and 102 grip the track 32 when the slide member 
104 is attempted to be moved in that direction. Once it is desirable to 
move the slide member 104 in the direction of the phantom line arrow, the 
solenoid 114 is energized s that the solenoid head 116 drives the 
interconnecting piece 110 and the cams 102 and 102 pivot in a 
counterclockwise direction away from the track 32. 
The foregoing disclosure and description of the invention are illustrative 
and explanatory thereof, and various changes in the size, shape and 
materials, as well as in the details of the illustrated construction, may 
be made without departing from the spirit of the invention.