Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS FOR SOLID PARTICLE REDUCTION
~ 5 CROSS REFERENCE TO RELATED CASES
This application claims the benefit of U.S. P~uvi~iollal Application No. 601014,743,
filed March 28, 1996, hl.,o,~ cd herein by lef~"~,ncc.
TECHNICAL ~IELD
This invention relates to the p,oce~ g of a ~.a~lc~.alcl stream to reduce solids to a
size acc~lable for L~cal~l~elll in a dO..l~ calll wastewater plant.
BACKGROUND OF THE INVENTION
In a conventional screening device, large solid material is removed from a
Wa~tc~.dtcl stream for disposal, de~,~ia~i"g the loading on a WaStl,~.alcl plant. However, the
nnfligeS~d solids removed from the ~.~h~ 4t~,- stream must be handled and disposed of and
create an odor problem. U.S. Patent No. 4,812,231, for example, describes an a~)p~luS that
5 filters particles larger than 0.5 mm from a water stream by means of a series of pivot members
~u~ ing an assembly of spaced apart straight links forming endless loop sections. These
sections move in an elliptical path along the interior of the water filter apparatus receiving
chamber.
Instead of removing large solids, some facilities employ a screen to separate large
10 solids from a wastewater stream, deliver the large solids to a grinder, then return the ground
solids to the wa~c~ er stream. See, U.S. Patent Nos. 5,061,380 (Stevenson) and 5,333,801
(Chambers, Sr. et al.). However, grinder systems described for this purpose are very large and
tA~naive, since the entire ~ c~atc. flow must pass through small openings in the grinder
system. U.S. Patent No. 5,102,536 (Wi~ ,) provides a smaller, less e~.lai~., a~lJal~lu~.
SUMMARY OF THE INVENTION
A wa~ .al.,. Ircdllll~nla~dluS includes a co..~; ....~u~ly rotating elongated drum-
type filter screen and a grinder suitable for reducing solid debris to a size suitable for processing
by a dO~ .a~t~ ,eal",~.ll facility.
The drum screen includes a continuous loop of closely spaced link members. The
front end of the drum is open to allow the waste effluent to flow into an inner drum chamber
defined by the drum screen. Part of the water moves out through the sides and bottom of the
drum chamber after passing between the links. Particles that are too large to pass through the
links are trapped on or between the links and are carried upwards by the drum screen as the links
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rotate in an elliptical pattern. These large-sized particles are dislodged from the top of the drum
screen by a water flushing system.
In one emho-lim~nt, the lliclo-lg~d solids fall back into the inner chamber. The rest
of the water, together with solid waste, passes through an outlet in the rear of the drum into a
grinder unit that Illaceldt~,~ the solid waste and discl.a~ s the .~lace~d~d solids to rejoin the
dt~,. which passed through the drum screen. The drum screen is oriented so that the flow
path to the grinder is straight and unobsl-u~ ,d.
In another emhoflim~nt of the present invention, solids dislodged from the top of the
drum screen by the water flushing system are directed into a macerator/grinder. Macerated solids
10 which leave the ,..aceldlor/grinder are directed into a de~.dte.i..g screw compactor and are
C~ ,d away from the filter screen appaldlus, by the d~ hlg screw compq~tor~ for disposal.
The invention may be best understood by ~~ e to the following detailed
description when considered in coJIjun~ with the accoll-~,~lying drawings.
BRIEF DESCRIE~ION OF THE DRAWINGS
FIG. 1 is a p~ C.,live view of an a~lJa dlUS for reducing the size of solids in a
stream of water.
FIG. 2 is a top plan view of the apparatus of FIG. 1 with a portion cut away to
show interior detail.
FIG. 3 is a front elevational view of the top portion of the apparatus of FIG. 1 with
the cover plate of the filter screen portion removed.
FIG. 4 is a right side elevation view of the al)lJalalu~ of FIG. 1.
FIG. S is a sectional view of the a~aldlus of FIG. 1, taken along line 5-5 of FIG.
4, showing a loop section and a driving chain.
FIG. 6 is a front elevational view of another a~a dlu~ for reducing the size of
solids in a stream of water.
FIG.7 is a sectional view of the a~paldlus of FIG. 6, taken along line 7-7 of FIG.
6.
FIG. 8 is a front elevational view of another a~alalu~ for reducing the size of
30 solids in a stream of water, which a~palaluS employs two grinders side-by-side.
FIG. 9 is a top s ~ ;r view showing a~Jaldus for securing a filter screen
alJ~,aldlu~ to a grinder, the top of the filter screen a~l~alaluS being cut away to show interior
detail.
FIG. 10 is a top s~h~m~ti~ view showing another ap~aldu~ for reducing the size of
35 solids in a stream of water.
FIG. 11 is a top plan view showing another a~l,a dlus for reducing the size of solids
in a stream of water, with a portion broken away to show internal detail.
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FIG. 12 is a sectional view of the a~JpalduS of FIG. 11, taken along line 12-12 of
FIG. 11.
FIG. 13is a sectional view of the a~pdlaLu~ of FIG. 11, taken along line 13-13 of
FIG. 12.
S FIG. 14 is an enlarged front elevational view of the top portion of the a~)~Jaldtus of
FIG. 11, taken along line 13-13 of FIG. 12.
FIG. 15 is an enlarged side elevational view of the co"~ye. of the a~lJaldLus ofFIG. 11, taken along line 12-12 of FIG. 11.
DETAILED DESCRIPIION
Throughout the following detailed dcs, ~ flon of the c.l.bodi~ of FIGS. 1-10,
the same l~f~.. ,nce llulllc~als refer to coll~;i",ol.dil.g elements in all figures. A different
,.. l-.. i"g system is used for the embodiment of FIGS. 11-15.
FIGS. 1-5 show a self-cleaning filter screen/grinder a~JpalaLus S according to one
15 c.--bodi~,-l of the i~,.Lion. The filter screen/grinder S co-.l~,ises a filter screen a~pdldLus 10
mounted within an interior portion of a su~,~c,. Li..g housing which includes a frame 11. The filter
screen/grinder is located in a wastewater effluent channel 12 with a weir 14 on each side of an
opening 16 into the water filter screen a~J~alaLus 10. The opening 16 serves as an inlet for
receiving a liquid stream, CO.~ ;.,g water and solids, from the channel 12.
The screen a~d~d1u:~ includes a CC~ n~'1Y rotating screen assembly 26 which
includes two cylindrical, endless-loop filter sections 2X of generally elliptical cross-section. The
filter sections 28 are formed from multiple spaced-apart links 32 as shown in FIG. 3. The screen
assembly 26 defines a drum chamber or l-mgitn-lin~l bore 18 poci~i~n~d to receive a stream of
~.a~t~,~.àl~.~ A rear baffle wall 20 defines an end outlet 98, the path from the inlet 16 to the
outlet 98 being ~ .a~ lly straight and ul-ob~L~u~t~. The screen assembly has an axis of
rotation 33 that is s ~ lly parallel to the direction of flow of the liquid stream into the inlet
16.
A first portion 29 of the water and small-sized solid material can exit radiallythrough the bottom 22 or sides 24 of the filter screen a~ aLus 10, such bottom 22 or sides 24
thus serving as a first outlet from the chamber 18 and the housing. Debris that is too large to
pass through the screen either is C.l~lainC;I on the inner surface of the screen or between links of
the screen assembly or travels with a second portion 31 of the water directly through the chamber
18 and outlet 98. The outlet 98 thus serves as a second outlet from the chamber 18 and the
housing.
The multiple links 32 are su~ J-t~,d by rods 34 COII~ g to a pivot member 36 on
each side. The pivot members move within a guide track 30. Each pivot member 36 as shown
in FIGS. 3 and 5 has a top surface co..~ .g notch 42. The links 32 and the support rods 34
together with the chains and other metal fittings are made from stainless steel to retard rusting
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and all exterior surfaces of the housings are painted to protect the surfaces from rusting. The
pivot member 36 is p,~,f~ bly made from a high strength polymer, such as a polyamide or
po~ all~o~lale.
In each screen assembly section 28 the bottom surface of the pivot member 36 is
proximal to the interior of chamber 18 with a foot 58 on each link 32 protruding below the pivot
member 36 so as to face inwardly in chamber 18. The notch 42 of pivot member 36 is engaged
by a lug 60 mounted on a bottom surface of an endless loop gear chain 62 as seen in FIG. 3.
The endless loop transfer chain 65 is engaged at one end to gear 66 and another end
to a drive gear 64. The drive gear 64 drives shah 52 as seen in FIG. 3. Shaht 53 is directly
c."mc~t.,d to a gear reducer 68 that is driven by a drive motor 70 mounted on the top of the water
filter screen appàldlus 10. Rotation of chain 62 by gear 74 driven by shaft 52 causes the lugs 60
to engage within the notch 42 of the pivot member 36 and causes the entire screen assembly 26 to
move in a clockwise direction. At least two lugs are always in Pngagr-,.f ,l with adjacent pivot
members 36 while the screen assembly is moving.
As seen in FIG. 5, an a~ljU~ gear 72 moves in response to drive gear 74 and
together with idler gear 76 supports chain 62. Shah 75 connects all three idler gears 76. This
all - ~g..--~..l adjusts tension on the screen assembly 26. Terlsion is manually adjusted on gear 72
to desired levels by "I~,~.",..,.lt of a bolt on tension adjusting bracket 73.
The filter screen/grinder ~p-~ includes a water flushing system for screen
llnloq~ing. The water flushing system includes an inlet pipe 92 leading to spray headers 94, 96
which flush the top of the screen assembly 26 as seen in FIGS. 1-5, thereby p,~ i"g solid
material from building up on the screen assembly 26. Alt. ll,ati~cly, solid material can be
removed from the screen assembly 26 by alt.,."alive solids dislodg~ n;~..,c, e.g., a cam
ll~f. ~ that drives solid pieces of plastic into the gaps between links 32, scrapers, syucegces,
brushes, an air stream, vibration, and the like.
In one emho~limfnt according to the invention, the drum chamber 18 has a depth of
about thirty-two inches and a width of thirty-six inches and can handle about twenty million
gallons of water per day.
Further details of the filter screen portion of the apparatus, particularly
arrngfnn~ntc of screen links, are as shown in U.S. Patent No. 5,102,536 (WirC~
h~culyOlal~d herein by l~f~,.,ce. Such a~J~aldus are co"m,~l, ;ally available in 24", 36", 48",
60" and 72" widths to treat ~ flows from below 20 million gallons per day ~mgd) to
over 100 mgd (WIESE-FLO~ se,~.".irlg systems, Whcclab Water Te~,h"ologics Inc.,
Sturbridge, MA).
Solid material that is too large to pass through the sides or bottom of the filter
screen apparatus is urged by the wa~t ~ er flow to exit the drum chamber 18 via outlet 98,
together with a portion of the ~.a~t~_~.aLtr, into a grinder 100. The grinder 100 includes two
parallel shafts 102, 103, mounted with cutter teeth 104, which rotate in opposite senses. The
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shafts are rotatably driven by drive motor (not shown), which is mounted above the grinder 100.
A number of existing grinders, such as Wi~s~ ... Macerator/Grinder model W24CH
~ (Wi~Sr .. ~ Products, Sturbridge, MA3, which is c~ rl~:A with hydraulic drive motor, speed
reducer, and cutters, are suitable for use in the present hl~ ivn. The macerated solids, which
are also referred to as "fines, and the second portion 31 of the water are ~lisch~,ed through a
grinder outlet 108.
The fines typically include both fecal matter and non-biode~;ladàbl~ material such as
plastic and rubber. These fines and the accv~ a lying second portion 31 of water are returned
directly to the stream 29 of wa~ e/ that has passed through a side or the bottom of the screen
assembly 26. In the e-.-l o~ of FIGS. 1-10, the fines and both portions of water are
cvlllI~incd in a common vessel 109, which is a du..ll~ alll portion of the channel 12 in the
illustrated ~ ...ho~ ... r.lc. Alt~,.lldti~ly, non-biode~,ladable material can be removed from the
ll~ce,a~td solids by coll~ ional means. Or, as de~.,libed below, oertain large solids can be
diverted and llall~lJuli~d to a location for plV~ essillg separate from the wa~ ...t~l stream.
It is helpful to provide a fastener system which joins the filter screen a~alatUS 10
and the grinder 100 d.,tachal.ly. The duwll~LI~alll side of the baffle wall 20 can be provided with
brackets or tracks 112 which define channels as shown in the elllbodillle,ll of FIG. 9. The
grinder 100 can have opposed flanges 113 which mate with the brackets 112 so that the grinder
100 can be slid vertically into place and easily removed, by raising the grinder vertically, for
servicing without l~lluvhlg the filter screen 10 as well. The grinder 100 can also be attached to
the rear baffle wall 20 by a hinged ...~ - 114, as shown in FIG. 7, to allow the grinder 100
to be swung away and allow WaSl~..dt~,l to bypass the grinder 100 in e.ll~,.ge.,~y con-litionc. The
illustrated hinge m.~rh~-nigm has a vertical hinge axis 115so that the grinder 100 rotates
horizontally.
It is desirable recycle the solids captured by the screen. This can be accvllll,lished
by dislodging the solids from the screen and carrying the dislodged solids into the grinder by the
dropping the solids into water at a location U~ alll of the grinder, most errl.,;en Iy into the
second portion 31 of water which is traveling through the center of the chamber 18. Some
embodiments of the invention include a baffle system which extends ul)~LI~alll from the wall 20
and which can be used to assist the rh~nnl~ling of recycled solids to the grinder 100. As shown in
FIGS. 6-7 and 9, the system can include multiple vertically-oriented baffles 110 which define a
region 111 u~Lr~;alll of the opening 98 to the grinder 100. The baffles channel a center portion
116 of the liquid stream into the grinder 100 and divert side portion 118 of the wastewater flow
away from the grinder 100 and toward the filter screen 10. In the alm-~g. . "~ shown in FIGS.
6-7 and 9, the side portion 118 cvll~_~n-ls tO the first portion 29 of water, and the center
portion 116 cvll~vnds to the second portion 31 of water. Other baffle all~ could be
used; for example a U-shaped baffle (not shown), generally conce,ltlic and CC/Il~ullllillg to the
sides 24 and bottom 22 of the screen, could extend from the wall 20. For ~frlciency, it is best
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for the baffle system to be open at the top and for one or both of the spray headers 94, 96to be
po,;~ d at an elevation above the baMe system at a location such that at least a portion of the
solids flushed from the top of the screen fall into the region 111, for example between the baffles
110, or into the center portion of the liquid stream ul,aLI~;all. of the baffle system. This feature is
particularly suitable for larger filter screen/grinder a~J~alduaes with coll~ olldillgly large flow
rates.
The flow rate of a larger filter screen/grinder apparatus can be iul~,lo~ed by
including two (or more) grinders 100 side-by-side on the baMe wall 20, as shown in FIG. 8. An
example filter screen/grinder a~alalua with two grinders has a capacity of about 90 mgd.
This filter screen/grinder design offers hll~ullalll advantages over previous designs.
The axis of rotation of the screen assembly 10 is a~ba~ iqlly parallel to the Waat~.dt~l flow path
through the screen assembly 10, the outlet 98, and the grinder 100. (By "5~ 5t-qnti~ly parallel" is
meant an angle of no greater than ap~ 'y 15~ from the parallel.) There are no
Oballu~liolls in the flow path to the grinder, and the entire volume of the liquid stream is
15 ~ -Ied directly toward the grinder. The force of the Waat~.dlUI stream thus carries c.lllaille~
solid debris directly into the grinder 100, together with a portion of the water flow. Another
portion of the water flow exits the a~alatuS radially through the screen assembly 26, but large
solids do not escape by this route. The ~paldlUa is ci~.ir,. --~lly more compact than other
collll~illaliOIl filter/grinders.
The filter screen 10 and grinder 100 are rotatably driven by a hydraulic drive and
chain-linkage ~--f- 1~'--;'--- A variety of conventional drive and linkage Illf- ~ c, including,
direct drives, can also be used.
In order to service the filter screen/grinder al)paldlua, the channel 12 leading to the
unit being serviced or the outlet 98 can be closed off. All~llldlh,~ly, the entire filter
25 screen/grinder a~ aldlU5 can be removed from the channel 12, or one can remove either the
screen ~I)p~ ,.c 10 or grinder 100 il fl- pf .~ 1y If the alJIJalalUa is e.luil~ped as shown in FIG.
9, a solid plate or sheet of bar screen (not shown) can be slid into the channels provided by tracks
112, after the grinder 100 is removed, to cover the opening 98so that flow can continue through
the filter screen 10 and through the bar screen, if any.
The filter screen/grinder a~ udlUa 5 includes a water flushing system for screenllnloq~ing. The illustrated water flushing system includes an inlet pipe 92 leading to spray
headers 94, 96 which flush the screen unloading area 124 located at the top of screen assembly
26, as seen in FIGS. 5,to prevent the buildup of solid material on the screen assembly 26.
Preferably, the spray headers 94, 96 have spray outlets that are spaced lol-gi~ lly to provide
35 overlapping coverage of the screen unl~q~ling area 124. Alt~.lla~ ,ly, solid material can be
removed from the screen assembly 26 by other "~ , e.g., a cam lI-f~ "~ that drives
solid pieces of plastic into the gaps between links 32, scrapers, sllueegees, brushes, an air stream,
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vibration, and the like. Solids AicloAged from the screen assembly 26 are directed back into the
liquid flow stream that travels toward the grinder 100.
Since ~~ ~t~,~. flows often vary, reaching a peak flow of as much as two or moretimes the average flow, the use of multiple units in parallel allows a facility to bring qAAitinnql
~ 5 standby ~l~P- ~n~ units "on line" to handle peak flows. Moreover, the use of multiple units in
parallel allows for c~ fd operation while one unit is being serviced. Not all of the units in
parallel need be e~ .ptd with grinders. As shown in PIG. 10, large solids captured by a filter
screen 120 lacking a grinder (of the type shown in U.S. Patent No. 5,102,536) can be conveyed
via a screw CCJ~ -, 122 or other conventional means (or allowed to passively migrate) to filter
screen/grinder alJIJ~du~ S accoldhlg to the present i.l~ ion. Solids from the screen 120 are
deposited in front of a device 5 so that they will flow to the grinder 100. Alt~.,ldli~ely, a single
filter screen ~p~d~ can deliver large solids to two or more grinders in series (not shown), i.e.,
deliver large solids a first grinder, which in turn delivers the resulting smaller solids to a second
grinder. Other config,~ldtiùns will be apparent to those of ordinary skill in the art.
FIGS. 11-15 show a self-cleaning filter screen/grinder app~ualus 200 according to
another emhoAim~nt of the invention. The filter screen/grinder 200 cullll,liscs a filter screen
aldtus 210 which includes a ~u~ullhlg frame 212 located within a ..~L~ dt~,l effluent channel
214 with a weir 216 on each side of an opening 218 into the water filter screen ~I'P~ 210. A
drum chamber 220 receives ~.~t~at~r from the channel 214.
The filter screen app~udlu~ 210 is similar in design and operation to filter screen
~ ,aldtu~ 10 dcsc~;hcd above, except that a rear baffle wall 222 has no opening and thus deflects
water so that it must exit through the bottom 224 or sides 226 of the filter screen apparatus 210.
The drum chamber 220 is enclosed by a rotating screen assembly 230 formed by two endless loop
filter sections as de,. libcd above. Debris that is too large to pass through the screen either is
cllLldillcd on the inner surface 232 of the screen assembly 230 or between links (not shown).
The filter screen/grinder a~ .Lus 200 includes a water flushing system or other
means for screen lmln~ing ec~enti~lly as described above. The water flushing system includes
spray headers 234 that provide overlapping coverage to err~ i. Iy flush the top of the screen
assembly 230. Solid material Ai~'oAg~d from the screen assembly are carried by the water spray
and gravity into a chute 238, which directs the solid material into a ~llacc.. llor or grinder 240.
The grinder 240 includes two parallel shafts 242, 244, mounted with cutter teeth 246, which
rotate in opposite senses. The shafts are rotatably driven by drive motor 248.
Macerated solids which leave the grinder 240 fall by gravity through a chute 250into a d~.dt~,.hlg screw cc. ~ o- 252 to dewater and compact the macerated solids. The
35 cc,.ll~,a.,lol 252 acts as a screw cull~ l to carry the fines to a location away from the screen
assembly for further plU~.e~;~illg or disposal. The screw compactor 252 has a closed tubular body
254 ~ .,A;,,g from an inlet end 256 located under chute 250 to an outlet end 258. A helical
augur screw 260 is centrally disposed within the body 254 and driven by a motor 266. The inlet
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end 256 is attached to the ~ "li"g frame (not shown) for support; q~ onql support may be
provided at the outlet end 258 and/or at other points between the inlet end 256 and outlet end 258
by conventional hangers or other supports. As needed, standard length sections may be coupled
together to form the body of the screw co...~ or 252. Movement of the solid material in the
screw co,.~,a ~ol 252 is from the inlet end 256 to the outlet end 258, thereby carrying the solid
material away for disposal.
The inlet end 256 has a wall or inner sleeve 262 and outer sleeve (not shown), one
of which may be less than a complete cylinder, that are rotatable or slidable with respect to each
other. The inner sleeve 262 and the outer sleeve each define a plurality of openings 270. The
openings of each sleeve are arranged in patterns such that openings in one sleeve register with
openings in the other sleeve when the sleeves are in proper ~lienmPnt Thus, rotation or sliding
of the inner and outer sleeves, relative to each other, adjusts the rate of dewatering by regulating
water flow and the size of particles which can pass through the openings. For most efficient
operation, the co"~ r is pGc;~ n~ so that water which escapes through the openings 270is
returned to the liquid stream in the channel 12,u~LIca~u or d-,~. u;~Llcalll of the filter screen
~pal~us 210. This can be acco.~ l,ed by positioning the openings 270 over the channel 12so
that the escaping water can simply fall by gravity into the channel.
The screw c~ ol 252 can be can be operated at a sllhst-qnti-ql angle of
inrlin~tion or ~eclin~inn- Best results are achieved with the screw co",~a~lor 252 inclined during
op~"~LiOn at an inrlin~ir n of about S to 30 degrees from the hori7f ntq1. The screw compactor
252 can be oriented to extend either u~llc~ll or du ~ C~U~- from the chamber 220 of the filter
screen/grinder 200.
Multiple filter screen/grinder a~ uDes or various configurations of screen
assemblies and grinders in series or in parallel may be; , lo;ed, if desired. A single filter
screen àppal~lLu~ can employ more than one grinder, side-by-side or in series, if nccesja.y to
acco.. - d ~ large flow rates.
Having illustrated and described the i . ' of the invention in pl.,f~ ,d
~ .~ho~ it should be apparent to those skilled in the art that the invention can be modified
in al, --~B~ and detail without dc~ i,lg from such ~, r~
