CA1113616A - Method and apparatus for sludge treatment - Google Patents
Method and apparatus for sludge treatmentInfo
- Publication number
- CA1113616A CA1113616A CA306,076A CA306076A CA1113616A CA 1113616 A CA1113616 A CA 1113616A CA 306076 A CA306076 A CA 306076A CA 1113616 A CA1113616 A CA 1113616A
- Authority
- CA
- Canada
- Prior art keywords
- sludge
- dewatering
- press
- solids
- transferring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
- C02F11/125—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering using screw filters
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Treatment Of Sludge (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The disclosure is of a method and apparatus for dewatering waste water or liquid carrying waste solids, and, in particular, waste sludges such as sewage and industrial sludges. The method comprises conditioning the sludge for optimal mechanical dewatering, dewatering the conditioned sludge and recovering the sludge cake and pressate. The apparatus comprises a mean for particlizing the sludge where necessary, a means for injecting conditioning agents and a (particularly advantageous) water extracting press. The apparatus and method of the invention are advantageous in that they provide a system for sludge processing requiring low energy consumption. The system is characterized by high efficiency, minimal maintenance requirements, small space requirements, (the apparatus can be made compact and portable), adaptability to a wide variety of waste water and adaptability to automatic control.
The disclosure is of a method and apparatus for dewatering waste water or liquid carrying waste solids, and, in particular, waste sludges such as sewage and industrial sludges. The method comprises conditioning the sludge for optimal mechanical dewatering, dewatering the conditioned sludge and recovering the sludge cake and pressate. The apparatus comprises a mean for particlizing the sludge where necessary, a means for injecting conditioning agents and a (particularly advantageous) water extracting press. The apparatus and method of the invention are advantageous in that they provide a system for sludge processing requiring low energy consumption. The system is characterized by high efficiency, minimal maintenance requirements, small space requirements, (the apparatus can be made compact and portable), adaptability to a wide variety of waste water and adaptability to automatic control.
Description
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BACKG~OUND OF TflE~ INVl:NTION
_ __ : 1. Field of the Invention ____ _ The invention relates to methods and apparatus for the processing of waste water or waste liquid carrying solids or particulate matter in any proportion, waste sludge and more particularly relates to the dewatering of sewage, raw sewage and industrial sludge.
BACKG~OUND OF TflE~ INVl:NTION
_ __ : 1. Field of the Invention ____ _ The invention relates to methods and apparatus for the processing of waste water or waste liquid carrying solids or particulate matter in any proportion, waste sludge and more particularly relates to the dewatering of sewage, raw sewage and industrial sludge.
2. Brief Descrip-tion of the Prior Art .. ._ Waste sludges are the residue oE p~imary and secondary waste water treatments and co~prise mixtures of waste solids and up to 99 5% by weigh-t of water. Included also are digested sludges of up to 95~ by weight of water. Sludges are potential environmental pollutants and pose a disposal problem for municipal governments, industry and even on occasion the small business man whose business activity may produce a sludge.
The primary goal of sludge processing has been to remove as much of the water content as possible. This facilitates handling, shipping and dispersal o residue solids. A commonly employed prior art method of dewatering sludges comprises spreading the sludge on open beds of sand and gravel and allowing it to dry. After 7 to 14 days of drying, the residue is removed and used as land fill. One skilled in the art will appreci~te the extensive land areas reguired by this method of dewatexing.
Other prior art methods of dewatering sludges include apparatus employing vacuum filters, plate and frame arrangements, centrifuges, belt presses (see U.S. Patent 4,019,431) and the il '` ~ I
like. In cJeneral~ the~e rn~thods and clevices are not comple-tely satisf~ctory in that t}ley require high initial cost~, high operating costs, various deyrees of supervision b~ operatiny personnel or are of limited efficiency.
The apparatus and me-thod of the present invention utilize mechanical principles to dewater wasté water of all types. Minim~lm space requirements are a distinct advan-kage.
The method and appara-tus of the invention are inherently more efficient than prior art me-thods and apparatus. The apparatus and method of the invention require relatively little power or energy consumption and minimal maintenance. Both apparatus and method are adaptable to automatic control (requiring minimal supervision) and will function to process a wide variety of waste and sludges. The apparatus requires only moderate capital .
L5 ¦ investment and moderate operating costs.
Representative of other prior art disclosures is that of U.S. Patent 3,319,897.
SU~RY OF THE INVENTION
The invention comprises apparatus for dewatering waste water, and, in accordance with the disclosed successful embodi-ment, comprises; a sludge particlizer; a reaction vessel; means for transferring particlized sludge from said particlizer to said vessel; means for injecting a sludge conditioning agent P
into the particlized sludge; a dewatering press; and means for ~-transferring the conditioned sludge from said vessel to said press.
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The invention a:Lso compxises a rnethod of dewa-tering waste water such as was-te sludge, which comprises; particLizing said sludge; conditioning the particlized sludge for optimal mechanical dewatering; and dewatering -the condi~ioned sludge.
The term "waste water" as used throughout the specification and claims means any combination or mixture of waste liquids and solids or particulate matter such as industrial, municipal and commercial waste. In addition, the term "waste sludge" as used throughout the specification and claims means municipal sewage sludges including digested and non-digested primary and secondary sludges, industrial sludges such as paper and asbestos fiber plant waste sludges, like waste sludges and mixtures thereof.
BRIEF DESCRIPTION OF THE D~WINGS
. . .
Figure 1 is a schematic diagram showing the components of a successful embodiment apparatus of the invention.
Figure 2 is an isometric view of a successful embodi-ment apparatus of the invention.
Figure 3 is a schematic diagram of the apparatus of ~20 Figure 2 and shows the flow process of the invention.
Figure 4 is a cross-sectional-in~part side elevation of a successful extractor component of the apparatus of the invention. ~j Figure 5 is a cross-sectional end view of the successful screw component of the extractor shown in Figure 4.
Figure 6 is a schematic diagram of embodiment electrical circuits and controls or the apparatus of Figure 2.
Il ~l d L~ 9 ~
¦i ~icJ~Ir~ 7 is c, clraph deyicting thc~ y~centaye of solids in sludcJe cakes Eorm~d from p~;mary sludges oE varying solid con-tents, at vario~ls feed rates.
Fiyure 8 is a graph depicting -the percentage of solids content in sludge cakes formed rom 1:1 mixtures of pr,,mary and secondary municipal sludges (having varying solids contents) at varying flow rates~
Figure 9 is a graph dep:icting the pe~centage of solids in sludge cakes formed from 2:1 mixtures of primary and secondary municipal sludges (of varying sol:ids contents) at varying flow rates.
Figure 10 is a graph depicting optimum feed rates for sludges of varied solids con-tent.
DETAILED DESCRIPTION
..
Figure 1 is a schematic diagram of an embodiment ; apparatus of the invention and shows an initial feeding of waste sludge to a receiving or hol~ing tanX 10 from sludge feed line 12.
The feed line 12 is controlled by a valve 14 controlled from control panel 16 so that a metered flow of waste sludge may be '~20 delivered to tank 10. Sensing devices 18 and 20 may be located in association with tank 10 to monitor the high tl8) and low t20) levels, respectively, of sludge in the tank 10 and to activate solenoid means of opening and closing the valve 14. Tank 10 generally receives sludges having a water content of from about ~:
93 percent to about 99 percent by weight of water. Tank 10 should be constructed of sufficient dimensions to handle at least twice the flow of sludge anticipated in a 10 minute period.
A grinder 22 receives sludge from tank 10 and is controlled to , - S
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~¦ operate from contro:l panel 16 when ther~` is suf~icient sludge ¦¦ in tank 10. Grinder Z2 ensures that rags and other items deleterious to operation of the apparatus of the inven-tion are particlized and uniforrnly homogenized. It should be underskood, that in handling and processing cerkain peculiar and special types of waste waters where mechanical reduction of particle size is unnecessary a grinder need not be utilized. The grinder 22 when utilized may be of a type capable of reducing solids to pumpable dimensions for the process of the invention, i.e.; on the order of abou-t 7/16 inch or less. In this connection, a grinder may embrace a comminuter, pulper, shredder or any device capable of particlizing or reducing particle size of khe solids being handled.
; The ground or particlized sludge is transferred b~ a sludge pump 24 through transfer conduits 26, 28 to a reactor vessel 30. Pump 24 is preferably a positive displacement pump, supplying moti-vation of the sludge throughout the entire system to be described more fully hereinafter. The pump 24 is preferably driven at variable speeds, controlled by control panel 16 as will be ¦ described in greater detall hereinafter. During transfer, the sludge may be injected with one or more chemical conditioning agents from storage vessel 32. The agent is pumped directly into conduit 28 by pump 34 from conduit 36 for admixture with the sludge. The proportion of agent injecked may be controlled by activation and inactivation of pump 34 through control panel 16, as will be described in greater detail hereinafter. Pump 34 ~':
is preferably a positive displacement pump whose speed may be varied and controlled. Reactor vessel 30 is rekention vessel .
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to hold the condition~d sludge for an optimum residence time to permit reaction or cuxing of the sludge with the conditioning agent or agents. For example, certain flocculating agents, as will he described more fully hereinafter, may be added to the sludge to condition the sludge and facilitate dewatering and the capture of fine par-ticles. In the reactor vessel 30, the flocculating (conditioning) agent causes growth of fine sludge particles into clus-ters called floc. The quasi-static, time retention conditions of reactor vessel 30 promote the formation of floc. The floc should not be exposed to sheer forces which would disrupt it, but a low speed agitator 38 can be added for gentle mixing if required to assure further admixture of con-ditioning agent and sludge. The conditioned sludge is then gently extruded to the dewatering or extraction press 40 through conduit 42. Extraction press 40 is operated from control panel 16 and separates the conditioned sludae into a dry sludge cake delivered from its upper end and a liquid pressate delivered ` - to a pressate collection vessel 44 by conduit 46. The pressage may be delivered by pump 48 to any desired point for reclamation, and is operated from control panel 16 by solenoids, directed by a level sensor 50. The sludge cake may be delivexed to conveyor or like handling means for disposal.
Figure 2 is an isometric view of a successful emhodi-ment apparatus of the invention. In Figure 2, components like .
those seen in Figure 1 bear the same numeral identification.
The illustrated apparatus comprises a single receiving tank 10 ~; and a single conditioning agent holding tank 32. All of the .
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~ rem3~irlin~ components are provided in cluality, i.e.; grinders 22 ¦ (only one seen in Figure 2), cJrinder operating mo-tors 23, gear trains 25, reactor vessels 30, extractiorl presses 40 and all ~he associated conduits, pumps, etc. The e~odiment apparatus of Figure 2 has the advantage of operational reliability and con-tinuity. Thus, one of the dual process lines may be operated while maintenance is performed on the other process line. One line may be shut down if the load of sludge does not require both lines or one process line may be a reserve line for use when there is a surge o~ sludge ~or treatment. Further details of the depicted embodimen-t apparatus of Figure 2 may be seen in Figure 3 a schematic diagram of the embodiment apparatus of the invention, showing the process flow.
It will be appreciated that a critical component o~ the apparatus of the invention is the extraction press 40. In the illustrated embodiment apparatus of the invention, the press is a screw press extractor of particular design and construction.
Figure 4 is a cross-sectional side elevation of such an extractor press 40. As can be seen in Figure 4, press 40 comprises a cylindrical shell or housing 60 defining a central conduit 62 ; holding a tubular filter screen 64 and a screw 66 having helicoid flights 68. The screen 64 i5 actually a split screen having different size apertures in different sections or portions. The lower portion 64A of the screen has a hole size within the range of from about .010 inches to about .045 inches diamet~r while the ~:
upper screen 64B has a hole diameter of from about .045 inches to about .093 inches. Obviously, these sizes and limits will vary depending on the application of the system and solids being handled.
1.
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ii .3~i11.6 Press 40 is position~l ve.rtically with sludg~ beiny E~ in~ ~ lower e~t70 cmd ca~ried upward throuc~h ~e central ~rt oE the cen~al conduit 62 by screw 66. The center portion of central conduit 62 acts as a collect~n chamber where de~atered sludge is transported via screw 66 through to a plug 80 formed by the dewa-tered sludge and then is carried on to the chute 71. The outer or periphery channel 72 of cen-tral conduit 62, on the outside of the screen 64 collects the water after it passes through the screen 64. When sludge is first introduced . into the center of central conduit 62, and as a result of the flow pressure, a film of sludge solids lS distributed on the inside surface of the screen 64. This film, along with the screen 64 acts as the filter media for sludge dewatering. Ex-cessive sludge collected along the walls of the screen 64 is : continuously removed by the action of the screw 66. In effect, r extractor press 40 acts as a continuous wash filter.
As long as the filtering film described above has de-- . veloped on the inside surface of screen 64, dewatering of sludge . is achieved. When sludge is first introduced, the percent solids . is generally low, i.e.; in the area of 1 to 5 percent by wéight and thus, for the rapid formation of filtering film, the screen : 164 openings are relatively small, to trap the solids and form the ¦filtering film. In the successful design,a screeen 64A is located - . at the end 70 of press 40 and preferably has hole diameter of . 0.031 inch. As water filters throughthe 0.031 inch screen and :
;- ~5 the sludge becomes thicker, the sludge particles become larger ~:
; and form a film on the screen 64 with different properties;
therefore a scree:n 64B is located near the top of the press 40, :.
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¦having hole ~iam~ters of preferably 0.062 inches. Sludge cle-wateriny usiny the above descxibecl arrangement with split screens 64A and 62B takes advantage of the combination of two physical ¦phenomena. These phenomena are the flow pressure to effectively Idewater the sludge and the s-traininy action of the filtering fi~n ¦of sludye which traps solids within its voids and produces a ¦superior filter per~ormance. As ]ong as the integrity of fhe ¦filtering sludge film is maintained, filtering action proceeds Iwith the only limita-tion being the pressure head loss through the filtering sludge film and the screens 64 as the rate of sludge - application increases. As previously men~ioned, water (pressate) drains by gravity down the outside of screen 64 and into periphera collection channel 72 while the solids are propelled upward. The ~
pressate is carried to the vessel 44 (see Figure 1). As previously mentioned, pressure is also a factor for dewatering sludge, aside from gravit~. Thus, the effluent or discharge end 74 of press 40 is relatively restricted in comparison to influent end 70. The sludge, propelled toward end 74 by screw 66 is pressured against screen 64 to squeeze liquid through screen 64. The compacting of a solids plug 80 in the ~one 76 of the press 40 also forms a back pressure on the underlying sludge in central conduit 62. Pre-ferably screw 66 has nylon fiber or like tipped flights 68 which clean the inner surface of screen 64 simultaneously with movement of the sludge toward dewatering; see Figure 5 a cross- .
sectional end view of the preferred screw 66.
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The method of the invention is carried out by con-ditioning the sludc~e for optimal ~echanical dewatering, dewater-ing and recovering the separa-te solids and liquids. Conditioning of the sludge is carried ou-t by first mechanically reducing par-ticulate matter and artiEac-ts -to a pumpable size, i.e.; on the order of about 7/16 inch diameter (maximum). As previously stated, in special instances mechanical reduc-tion maynot be necessary. This is conveniently accomplished with a conventional ¦ grinder 22 as previously described. Although the object of processing the sludge is to dewater it, at the initial stacJes of processing a low viscosity, low solids content is desired.
Ideally, the sludge will comprise from about 90% to about 99~
by weight water or other solvent/suspension medium and will have - pumpability. Water may be added if necessary to condition the sludge and ideally pressate at the end of the process may be employed when required to reduce the need for better quality waters, i.e~, potable or plant water. Prior to water extraction in the extrac-tion press 40 it may be desirable to treat the sludge further with chemical conditioning agents such as stabi~
lizers, precipitating agents and the like. Advantageously, the sludge is conditioned with a flocculating agent to bring abou~ an aggregation of fine particles in the sludge. The flocculated sludge is retained better to form the film on the screen 64.
Representative of flocculating agents are cationic, anionic and nonionic polymers, ferric chloride, and the like. Theproportion ~; of flo~ating agent used will depend on the agent selec~ed and the sludge being processed but in general will be less than about 0.3 percent by weight of the slud~e. The process of the invention ¦ may be carriecl out uncler ~ wide v~riety of -temperature conditions, ¦ i.e.; on the order of Erc~n between about 5C. to about 90C. being a ¦ practical range. I-t is not generally necessary-to heat the sLudge to be dewatered. The pressure on the sludge as it passes through the apparatus of the invention is generally not critic~l and will be within the range of frcm about 1 to abou-t 10 psig. Residence time of sludge within the apparatus of the invention is of co~se dependent on -the flow rate which may be within the range of frcm about 10 -to about 30 gallons per minute per process line.
The residence time of the sludge within reaction vessel 30 may be varied according to the conditioning treatmen-t being efEected. Advantageously, vessel 30 will afford a residence time of at leas-t about 5 minu-tes for the sludge when it is being conditioned with a flocculating agent. As will be ¦ appreciated by those skilled in the art, flow rate will vary with the ¦ diameter of the screw of the hydroextractor. With this in nind these limits I will vary depending on the size of the hydroextractor employed. Other factors will also vary flcw rate, pressure, residence time etc. The control o the residence and flow of sludge in the apparatus of the invention may be effected through control panel 16 which controls the opening and closing of valves, the activation and inactivation of pumps and the energizing and de-energizing of electrical circuits. Figure 6 shows a schematic diagram of embodiment circuits and controls for the apparatus shcwn in Figure 2. In Fig.
; 6, the following symbols and their meaning are used:
FS - float switch WL~R - water level control relay PB - push button .
M - motor st~rter TR - timer A ~ R - colored lam~s CRM- rotor control reL~y I
l .' SOL - so:lenoid CR - control relay OL - overload LT - light Upon startup, sludge valve 14 opens to admit sludge to tank 10, sensor 20 having signaled the opening of valve 14. When tank 10 is full, sensor 18 signals the! closing of valve 14 and actuates grinders 22 and sludge pumps 24. Upon s-tartLng the system, air vent 31 opens to allow vessel 30 to fill. Simultaneously pump 34 is energized to inject conditioning agents and stirrer 38 starts up for : agita-tion of the sludge and the agent. At this point the extractor press 40 drive will start and the syste~ can then be adjusted with respect to polymer addition and sludge feed rates. When the sludge level in tank 10 reaches a pre-de!termined high level, sensed by sensor 18, valve 14 closes until the level falls to the level sensed by sensor 20. If the level continues to fal~, the press 40 is de-energized, vent 31 opens and the s~stem fills again as described ab~ve. For shutdown, the fe d sludge 14 valve closes and is not ; reopened when the sludge level is dropped to its nu~LDn~m in t~nk 10. Once the lcw level is reached, an automatic flush system can be actuated to thin the remaining sludge prior to dumping (draining) the system.
The follcwing examples describe the manner and process of making and using the invention and set forth the best ~de contemplated by the inventor of carrying out the invention, but are not to be construed as limiting. .;
Apparatus according to that shcwn in Figure 2 was provided. The extractor press 40 :in each instance was 48" long and had a screw diameter of 9 inches. A 0.031 inch holed screen was employed at the influ~nt end and a 0.062 inch holed screen at the effluent end.
The effective size of the screen was 44" long and 9" in ;`' I .
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l~ diarneter, (one i~lal.~ of the ~c:re~n len~Jt}~ hear:i.rlc3'the 0.031 inch ¦ holes and one half bearinc3 the 0.062 inch holes) ~:ie:Ldinc~ a total area o.E approximately 8~7 square feet. Ilo~ever, effect:ive area for dewatering was estimated to be in the vicinity oE 5.5 square feet with the remaining area 76 for plug formation and further densification of the ca~e.
Example 1 Employing the above described apparatus, primary munici .
: ¦ pal sludges of various solid contents were dewatered at various feed rates employiny various proportions of a flocculating agent to condition the sludge. The sludge cakes obtained were of high solids content suitable for incineration or other disposal .
. methods... Table 1 below shows the various runs made, with the .. feed rates, dosage of flocculating agent (Calgon WT-2640; a 1 polymeric cationic polyelectrolyte; Bull. 12-58A, Calgon Corpor-ation, Pittsburgh, Pa.), solids content of the feed sludge and the solids content of the resulting sludge cakes together with the solids content of pressate. As shown in Table 1, the percent ..
solids in the sludge cake prove to be independent of the p rcent .
solids in the feed. This is clearly seen in Figure 7 a graph de-picting the.percentage of solids in the sludge cake obtained with employment of primary sludges of varying solids content, under : varying feed rates. Feed rates up to 30 gallons per minute con-. sistently produced ca]ces of high percentage. solids.
~ .~61~ k . , ~
~ _ . . _ R, J ~ . 3 ~BI,E 1 Prim~ry MunicLpal Slud~e .
Flocculating Agent Dose, Percent Solids Feed Rate, gpm GPH (5~ Solution) Feed Cake Pressate ! lo ~2.5 ~.4 31.0 1.5 42.5 4.2 39.0 1.5 25.5 3.1 31.2 .9 25.5 3.4 28.9 .9 25.5 4.4 30.4 .3 25.5 4.2 30.4 .3 25.5 4.1 2~.3 1.2 25.5 3.6 25.9 1.2 25.5 2.6 31.4 1.1 25.5 2.5 30.8 1.1 25.5 5.5 32.3 1.1 25.5 5.8 29.6 1.1 25.5 7.6 Z4.3 1.4 25.5 7.3 23.~ 1.4 25.5 2.9 23.5 .2 25.5 2.9 21.4 .2 25.5 1.9 43.5 .7 25.5 1.9 42.1 .7 63.8 3.7 28.8 1.
63.8 3.5 30.3 1.4 , 25 17.0 6.3 19.7 *
17.0 6.3 19.7 *
~3.8 5.3 25.8 1.7 63.8 5.3 25.6 1.7 34.0 4.1 27.0 1.0 34.0 4.0 26.2 1.0 34.0 3.2 26.1 .8 34.0 3.6 27.3 .8
The primary goal of sludge processing has been to remove as much of the water content as possible. This facilitates handling, shipping and dispersal o residue solids. A commonly employed prior art method of dewatering sludges comprises spreading the sludge on open beds of sand and gravel and allowing it to dry. After 7 to 14 days of drying, the residue is removed and used as land fill. One skilled in the art will appreci~te the extensive land areas reguired by this method of dewatexing.
Other prior art methods of dewatering sludges include apparatus employing vacuum filters, plate and frame arrangements, centrifuges, belt presses (see U.S. Patent 4,019,431) and the il '` ~ I
like. In cJeneral~ the~e rn~thods and clevices are not comple-tely satisf~ctory in that t}ley require high initial cost~, high operating costs, various deyrees of supervision b~ operatiny personnel or are of limited efficiency.
The apparatus and me-thod of the present invention utilize mechanical principles to dewater wasté water of all types. Minim~lm space requirements are a distinct advan-kage.
The method and appara-tus of the invention are inherently more efficient than prior art me-thods and apparatus. The apparatus and method of the invention require relatively little power or energy consumption and minimal maintenance. Both apparatus and method are adaptable to automatic control (requiring minimal supervision) and will function to process a wide variety of waste and sludges. The apparatus requires only moderate capital .
L5 ¦ investment and moderate operating costs.
Representative of other prior art disclosures is that of U.S. Patent 3,319,897.
SU~RY OF THE INVENTION
The invention comprises apparatus for dewatering waste water, and, in accordance with the disclosed successful embodi-ment, comprises; a sludge particlizer; a reaction vessel; means for transferring particlized sludge from said particlizer to said vessel; means for injecting a sludge conditioning agent P
into the particlized sludge; a dewatering press; and means for ~-transferring the conditioned sludge from said vessel to said press.
Il . I
The invention a:Lso compxises a rnethod of dewa-tering waste water such as was-te sludge, which comprises; particLizing said sludge; conditioning the particlized sludge for optimal mechanical dewatering; and dewatering -the condi~ioned sludge.
The term "waste water" as used throughout the specification and claims means any combination or mixture of waste liquids and solids or particulate matter such as industrial, municipal and commercial waste. In addition, the term "waste sludge" as used throughout the specification and claims means municipal sewage sludges including digested and non-digested primary and secondary sludges, industrial sludges such as paper and asbestos fiber plant waste sludges, like waste sludges and mixtures thereof.
BRIEF DESCRIPTION OF THE D~WINGS
. . .
Figure 1 is a schematic diagram showing the components of a successful embodiment apparatus of the invention.
Figure 2 is an isometric view of a successful embodi-ment apparatus of the invention.
Figure 3 is a schematic diagram of the apparatus of ~20 Figure 2 and shows the flow process of the invention.
Figure 4 is a cross-sectional-in~part side elevation of a successful extractor component of the apparatus of the invention. ~j Figure 5 is a cross-sectional end view of the successful screw component of the extractor shown in Figure 4.
Figure 6 is a schematic diagram of embodiment electrical circuits and controls or the apparatus of Figure 2.
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¦i ~icJ~Ir~ 7 is c, clraph deyicting thc~ y~centaye of solids in sludcJe cakes Eorm~d from p~;mary sludges oE varying solid con-tents, at vario~ls feed rates.
Fiyure 8 is a graph depicting -the percentage of solids content in sludge cakes formed rom 1:1 mixtures of pr,,mary and secondary municipal sludges (having varying solids contents) at varying flow rates~
Figure 9 is a graph dep:icting the pe~centage of solids in sludge cakes formed from 2:1 mixtures of primary and secondary municipal sludges (of varying sol:ids contents) at varying flow rates.
Figure 10 is a graph depicting optimum feed rates for sludges of varied solids con-tent.
DETAILED DESCRIPTION
..
Figure 1 is a schematic diagram of an embodiment ; apparatus of the invention and shows an initial feeding of waste sludge to a receiving or hol~ing tanX 10 from sludge feed line 12.
The feed line 12 is controlled by a valve 14 controlled from control panel 16 so that a metered flow of waste sludge may be '~20 delivered to tank 10. Sensing devices 18 and 20 may be located in association with tank 10 to monitor the high tl8) and low t20) levels, respectively, of sludge in the tank 10 and to activate solenoid means of opening and closing the valve 14. Tank 10 generally receives sludges having a water content of from about ~:
93 percent to about 99 percent by weight of water. Tank 10 should be constructed of sufficient dimensions to handle at least twice the flow of sludge anticipated in a 10 minute period.
A grinder 22 receives sludge from tank 10 and is controlled to , - S
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~¦ operate from contro:l panel 16 when ther~` is suf~icient sludge ¦¦ in tank 10. Grinder Z2 ensures that rags and other items deleterious to operation of the apparatus of the inven-tion are particlized and uniforrnly homogenized. It should be underskood, that in handling and processing cerkain peculiar and special types of waste waters where mechanical reduction of particle size is unnecessary a grinder need not be utilized. The grinder 22 when utilized may be of a type capable of reducing solids to pumpable dimensions for the process of the invention, i.e.; on the order of abou-t 7/16 inch or less. In this connection, a grinder may embrace a comminuter, pulper, shredder or any device capable of particlizing or reducing particle size of khe solids being handled.
; The ground or particlized sludge is transferred b~ a sludge pump 24 through transfer conduits 26, 28 to a reactor vessel 30. Pump 24 is preferably a positive displacement pump, supplying moti-vation of the sludge throughout the entire system to be described more fully hereinafter. The pump 24 is preferably driven at variable speeds, controlled by control panel 16 as will be ¦ described in greater detall hereinafter. During transfer, the sludge may be injected with one or more chemical conditioning agents from storage vessel 32. The agent is pumped directly into conduit 28 by pump 34 from conduit 36 for admixture with the sludge. The proportion of agent injecked may be controlled by activation and inactivation of pump 34 through control panel 16, as will be described in greater detail hereinafter. Pump 34 ~':
is preferably a positive displacement pump whose speed may be varied and controlled. Reactor vessel 30 is rekention vessel .
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1'.' :
~ $~
to hold the condition~d sludge for an optimum residence time to permit reaction or cuxing of the sludge with the conditioning agent or agents. For example, certain flocculating agents, as will he described more fully hereinafter, may be added to the sludge to condition the sludge and facilitate dewatering and the capture of fine par-ticles. In the reactor vessel 30, the flocculating (conditioning) agent causes growth of fine sludge particles into clus-ters called floc. The quasi-static, time retention conditions of reactor vessel 30 promote the formation of floc. The floc should not be exposed to sheer forces which would disrupt it, but a low speed agitator 38 can be added for gentle mixing if required to assure further admixture of con-ditioning agent and sludge. The conditioned sludge is then gently extruded to the dewatering or extraction press 40 through conduit 42. Extraction press 40 is operated from control panel 16 and separates the conditioned sludae into a dry sludge cake delivered from its upper end and a liquid pressate delivered ` - to a pressate collection vessel 44 by conduit 46. The pressage may be delivered by pump 48 to any desired point for reclamation, and is operated from control panel 16 by solenoids, directed by a level sensor 50. The sludge cake may be delivexed to conveyor or like handling means for disposal.
Figure 2 is an isometric view of a successful emhodi-ment apparatus of the invention. In Figure 2, components like .
those seen in Figure 1 bear the same numeral identification.
The illustrated apparatus comprises a single receiving tank 10 ~; and a single conditioning agent holding tank 32. All of the .
~ ' , ': I
~ rem3~irlin~ components are provided in cluality, i.e.; grinders 22 ¦ (only one seen in Figure 2), cJrinder operating mo-tors 23, gear trains 25, reactor vessels 30, extractiorl presses 40 and all ~he associated conduits, pumps, etc. The e~odiment apparatus of Figure 2 has the advantage of operational reliability and con-tinuity. Thus, one of the dual process lines may be operated while maintenance is performed on the other process line. One line may be shut down if the load of sludge does not require both lines or one process line may be a reserve line for use when there is a surge o~ sludge ~or treatment. Further details of the depicted embodimen-t apparatus of Figure 2 may be seen in Figure 3 a schematic diagram of the embodiment apparatus of the invention, showing the process flow.
It will be appreciated that a critical component o~ the apparatus of the invention is the extraction press 40. In the illustrated embodiment apparatus of the invention, the press is a screw press extractor of particular design and construction.
Figure 4 is a cross-sectional side elevation of such an extractor press 40. As can be seen in Figure 4, press 40 comprises a cylindrical shell or housing 60 defining a central conduit 62 ; holding a tubular filter screen 64 and a screw 66 having helicoid flights 68. The screen 64 i5 actually a split screen having different size apertures in different sections or portions. The lower portion 64A of the screen has a hole size within the range of from about .010 inches to about .045 inches diamet~r while the ~:
upper screen 64B has a hole diameter of from about .045 inches to about .093 inches. Obviously, these sizes and limits will vary depending on the application of the system and solids being handled.
1.
''.
ii .3~i11.6 Press 40 is position~l ve.rtically with sludg~ beiny E~ in~ ~ lower e~t70 cmd ca~ried upward throuc~h ~e central ~rt oE the cen~al conduit 62 by screw 66. The center portion of central conduit 62 acts as a collect~n chamber where de~atered sludge is transported via screw 66 through to a plug 80 formed by the dewa-tered sludge and then is carried on to the chute 71. The outer or periphery channel 72 of cen-tral conduit 62, on the outside of the screen 64 collects the water after it passes through the screen 64. When sludge is first introduced . into the center of central conduit 62, and as a result of the flow pressure, a film of sludge solids lS distributed on the inside surface of the screen 64. This film, along with the screen 64 acts as the filter media for sludge dewatering. Ex-cessive sludge collected along the walls of the screen 64 is : continuously removed by the action of the screw 66. In effect, r extractor press 40 acts as a continuous wash filter.
As long as the filtering film described above has de-- . veloped on the inside surface of screen 64, dewatering of sludge . is achieved. When sludge is first introduced, the percent solids . is generally low, i.e.; in the area of 1 to 5 percent by wéight and thus, for the rapid formation of filtering film, the screen : 164 openings are relatively small, to trap the solids and form the ¦filtering film. In the successful design,a screeen 64A is located - . at the end 70 of press 40 and preferably has hole diameter of . 0.031 inch. As water filters throughthe 0.031 inch screen and :
;- ~5 the sludge becomes thicker, the sludge particles become larger ~:
; and form a film on the screen 64 with different properties;
therefore a scree:n 64B is located near the top of the press 40, :.
!l I
~3~
¦having hole ~iam~ters of preferably 0.062 inches. Sludge cle-wateriny usiny the above descxibecl arrangement with split screens 64A and 62B takes advantage of the combination of two physical ¦phenomena. These phenomena are the flow pressure to effectively Idewater the sludge and the s-traininy action of the filtering fi~n ¦of sludye which traps solids within its voids and produces a ¦superior filter per~ormance. As ]ong as the integrity of fhe ¦filtering sludge film is maintained, filtering action proceeds Iwith the only limita-tion being the pressure head loss through the filtering sludge film and the screens 64 as the rate of sludge - application increases. As previously men~ioned, water (pressate) drains by gravity down the outside of screen 64 and into periphera collection channel 72 while the solids are propelled upward. The ~
pressate is carried to the vessel 44 (see Figure 1). As previously mentioned, pressure is also a factor for dewatering sludge, aside from gravit~. Thus, the effluent or discharge end 74 of press 40 is relatively restricted in comparison to influent end 70. The sludge, propelled toward end 74 by screw 66 is pressured against screen 64 to squeeze liquid through screen 64. The compacting of a solids plug 80 in the ~one 76 of the press 40 also forms a back pressure on the underlying sludge in central conduit 62. Pre-ferably screw 66 has nylon fiber or like tipped flights 68 which clean the inner surface of screen 64 simultaneously with movement of the sludge toward dewatering; see Figure 5 a cross- .
sectional end view of the preferred screw 66.
.1 . I
The method of the invention is carried out by con-ditioning the sludc~e for optimal ~echanical dewatering, dewater-ing and recovering the separa-te solids and liquids. Conditioning of the sludge is carried ou-t by first mechanically reducing par-ticulate matter and artiEac-ts -to a pumpable size, i.e.; on the order of about 7/16 inch diameter (maximum). As previously stated, in special instances mechanical reduc-tion maynot be necessary. This is conveniently accomplished with a conventional ¦ grinder 22 as previously described. Although the object of processing the sludge is to dewater it, at the initial stacJes of processing a low viscosity, low solids content is desired.
Ideally, the sludge will comprise from about 90% to about 99~
by weight water or other solvent/suspension medium and will have - pumpability. Water may be added if necessary to condition the sludge and ideally pressate at the end of the process may be employed when required to reduce the need for better quality waters, i.e~, potable or plant water. Prior to water extraction in the extrac-tion press 40 it may be desirable to treat the sludge further with chemical conditioning agents such as stabi~
lizers, precipitating agents and the like. Advantageously, the sludge is conditioned with a flocculating agent to bring abou~ an aggregation of fine particles in the sludge. The flocculated sludge is retained better to form the film on the screen 64.
Representative of flocculating agents are cationic, anionic and nonionic polymers, ferric chloride, and the like. Theproportion ~; of flo~ating agent used will depend on the agent selec~ed and the sludge being processed but in general will be less than about 0.3 percent by weight of the slud~e. The process of the invention ¦ may be carriecl out uncler ~ wide v~riety of -temperature conditions, ¦ i.e.; on the order of Erc~n between about 5C. to about 90C. being a ¦ practical range. I-t is not generally necessary-to heat the sLudge to be dewatered. The pressure on the sludge as it passes through the apparatus of the invention is generally not critic~l and will be within the range of frcm about 1 to abou-t 10 psig. Residence time of sludge within the apparatus of the invention is of co~se dependent on -the flow rate which may be within the range of frcm about 10 -to about 30 gallons per minute per process line.
The residence time of the sludge within reaction vessel 30 may be varied according to the conditioning treatmen-t being efEected. Advantageously, vessel 30 will afford a residence time of at leas-t about 5 minu-tes for the sludge when it is being conditioned with a flocculating agent. As will be ¦ appreciated by those skilled in the art, flow rate will vary with the ¦ diameter of the screw of the hydroextractor. With this in nind these limits I will vary depending on the size of the hydroextractor employed. Other factors will also vary flcw rate, pressure, residence time etc. The control o the residence and flow of sludge in the apparatus of the invention may be effected through control panel 16 which controls the opening and closing of valves, the activation and inactivation of pumps and the energizing and de-energizing of electrical circuits. Figure 6 shows a schematic diagram of embodiment circuits and controls for the apparatus shcwn in Figure 2. In Fig.
; 6, the following symbols and their meaning are used:
FS - float switch WL~R - water level control relay PB - push button .
M - motor st~rter TR - timer A ~ R - colored lam~s CRM- rotor control reL~y I
l .' SOL - so:lenoid CR - control relay OL - overload LT - light Upon startup, sludge valve 14 opens to admit sludge to tank 10, sensor 20 having signaled the opening of valve 14. When tank 10 is full, sensor 18 signals the! closing of valve 14 and actuates grinders 22 and sludge pumps 24. Upon s-tartLng the system, air vent 31 opens to allow vessel 30 to fill. Simultaneously pump 34 is energized to inject conditioning agents and stirrer 38 starts up for : agita-tion of the sludge and the agent. At this point the extractor press 40 drive will start and the syste~ can then be adjusted with respect to polymer addition and sludge feed rates. When the sludge level in tank 10 reaches a pre-de!termined high level, sensed by sensor 18, valve 14 closes until the level falls to the level sensed by sensor 20. If the level continues to fal~, the press 40 is de-energized, vent 31 opens and the s~stem fills again as described ab~ve. For shutdown, the fe d sludge 14 valve closes and is not ; reopened when the sludge level is dropped to its nu~LDn~m in t~nk 10. Once the lcw level is reached, an automatic flush system can be actuated to thin the remaining sludge prior to dumping (draining) the system.
The follcwing examples describe the manner and process of making and using the invention and set forth the best ~de contemplated by the inventor of carrying out the invention, but are not to be construed as limiting. .;
Apparatus according to that shcwn in Figure 2 was provided. The extractor press 40 :in each instance was 48" long and had a screw diameter of 9 inches. A 0.031 inch holed screen was employed at the influ~nt end and a 0.062 inch holed screen at the effluent end.
The effective size of the screen was 44" long and 9" in ;`' I .
' ii . ~ .
l~ diarneter, (one i~lal.~ of the ~c:re~n len~Jt}~ hear:i.rlc3'the 0.031 inch ¦ holes and one half bearinc3 the 0.062 inch holes) ~:ie:Ldinc~ a total area o.E approximately 8~7 square feet. Ilo~ever, effect:ive area for dewatering was estimated to be in the vicinity oE 5.5 square feet with the remaining area 76 for plug formation and further densification of the ca~e.
Example 1 Employing the above described apparatus, primary munici .
: ¦ pal sludges of various solid contents were dewatered at various feed rates employiny various proportions of a flocculating agent to condition the sludge. The sludge cakes obtained were of high solids content suitable for incineration or other disposal .
. methods... Table 1 below shows the various runs made, with the .. feed rates, dosage of flocculating agent (Calgon WT-2640; a 1 polymeric cationic polyelectrolyte; Bull. 12-58A, Calgon Corpor-ation, Pittsburgh, Pa.), solids content of the feed sludge and the solids content of the resulting sludge cakes together with the solids content of pressate. As shown in Table 1, the percent ..
solids in the sludge cake prove to be independent of the p rcent .
solids in the feed. This is clearly seen in Figure 7 a graph de-picting the.percentage of solids in the sludge cake obtained with employment of primary sludges of varying solids content, under : varying feed rates. Feed rates up to 30 gallons per minute con-. sistently produced ca]ces of high percentage. solids.
~ .~61~ k . , ~
~ _ . . _ R, J ~ . 3 ~BI,E 1 Prim~ry MunicLpal Slud~e .
Flocculating Agent Dose, Percent Solids Feed Rate, gpm GPH (5~ Solution) Feed Cake Pressate ! lo ~2.5 ~.4 31.0 1.5 42.5 4.2 39.0 1.5 25.5 3.1 31.2 .9 25.5 3.4 28.9 .9 25.5 4.4 30.4 .3 25.5 4.2 30.4 .3 25.5 4.1 2~.3 1.2 25.5 3.6 25.9 1.2 25.5 2.6 31.4 1.1 25.5 2.5 30.8 1.1 25.5 5.5 32.3 1.1 25.5 5.8 29.6 1.1 25.5 7.6 Z4.3 1.4 25.5 7.3 23.~ 1.4 25.5 2.9 23.5 .2 25.5 2.9 21.4 .2 25.5 1.9 43.5 .7 25.5 1.9 42.1 .7 63.8 3.7 28.8 1.
63.8 3.5 30.3 1.4 , 25 17.0 6.3 19.7 *
17.0 6.3 19.7 *
~3.8 5.3 25.8 1.7 63.8 5.3 25.6 1.7 34.0 4.1 27.0 1.0 34.0 4.0 26.2 1.0 34.0 3.2 26.1 .8 34.0 3.6 27.3 .8
3~.0 3.2 29.0 1.4 34.0 3.1 29.9 1.4 * Not Reported Note: On Fig. 7, the feed rate values are charted as follows:
o 10 GPM
a 15 GPM
~ 25 GPM
X 30 GPM ~, . .~
.
. , .
~ ~3~3.~j ~
¦ Example 2 l Mixtures of 50~ by volume primary and 50~ by volume ¦ secondary municipal sludges were fed to the apparatus described ¦ above at various feed rates and with varying proportion of the flocculating agent (Calgon 2640; supra.). ~he feed rates employed, the proportion oE flocculating agent, the solids content of the feed and the solids content of the resulting sludge cake are given in Table 2, below along with the quantity of pressate recovered. The results shown in Figure 2 are given graphically in Figure $. It is evident from Figure 8 that the maximum application rate for this particular mixture is about 15 gallons per minute. Higher application rates give cakes of lower percent solids.
~.' l ,' l "
~ . .
' ' ,:
~ 3 Table 2 ___ Mixture 1 Primary: 1 Seconclary Polymer Dose Percent Solids Feed Rate, qpm GPH ~5~ Solution) FeedCake Pressate - -~
25.5 3.6 15.6.30 25.5 3.5 15.~.30 25.5 3.2 17.2.7 25.5 3.1 17Ø7 25.5 4.2 19.3.3 25.5 ~.3 21.3.3 25.5 2.3 15.
25.5 2.2 16.01.~
25.5 2.9 16.81.3 25.5 2.9 16.81.5 25.5 3.1 9.61.2 25.5 3.2 10.01.2 25.5 3.0 18.2.2 25 5 3.0 17.~.3 63.8 3.2 15.22.2 63.8 3.1 11.82.2 63.8 3.5 13.92.3 63.8 3.~ 14.12.2 25.5 4.9 13.6.8 25.5 5.1 13.2.8 Note: On Fig. 8 the feed rate values are charted as follows:
.
n 20 GP~
.
Example ~
~ Iixtures of 67~ primary and 33~ by volume secondary municipal sludyes were fed at various rates to the above described apparatus with conditioning by various proportions of flocculating agent (Calgon 2640, supra.). The feed rates ¦employed, dosage of flocculating agent, solids content of the feed and solidscontent of the resulting sludge cakes together with pressate recovered are given in Tabel 3 below. The results are also sho~n graphically in Figure 9. It will be observed that the maximum application rate for this mix-ture is about 25 gallons per minute. Higher application rates give cakes a lower percent solids.
~ ~'L~
il . ' , ¦ Table 3 Mixt ~
_p GPH (5~ Solutiog/ Percent Sollds 0 25,:~ 4.2 28.6 1 1 25.~) 4.8 25v7 --- *
25.~ 2.8 25.8 --- *
*
- 20 255 55 2 6 18 8 .7 ~~
2~ ~' 5 5'7 I4.8 _'4 : ~ 20 25 5- 3 4 2ll 44 1.6 * Not Reported Note: On Fig. 9, the feed rate values are charted as follows:
O 20 GP~I , : ~ 30 GPM
1:
1 ~ 13~;1.6 ¦ It is reasonable to assume that the sludge film ¦ deposited on the screen in the above examples is densest in case I of processing primary sludges and decreases in density as the ratio of secondary to primary sludge in the mixture increases;
therefore, the li~uid portion causing the wash out of the filter-ing film can break through the sludge film easier when processing ` mixtures oE sludges ~here the secondary sludge portion is higher than when processing mixtures with a lower portion of secondaxy sludge.
It may also be observed from the above examples that when using mixtures of primary and secondary sludges in equal proportions, a maximum application rate OL 1.75 gallons per , minute/square feet based on the total screen area of 8.7 square ¦ feet represents the upper limit beyond which there was more "
~¦ water in the feed than could pass through the screen. This ex-cess water was transported by ~he screw along with the sludge thus resulting in sludge cakes of lower percent solids. When ¦ using mixtures of primary and secondary munlcipal sludges in the ratio of 2:1, the maximum rate of application of 2.9 gallons per minutejsquare ~eet based on the total screen area of 8.7 square feet represented the upper limit beyond which there was more water in the feed than can pass through the screen. This water ~- was transported by the screw along with the sludge thus resulting in sludge cakes of lower percent solids.
In dewatering primary sludge, thickened secondary ~:
sludge nd mixtures of p~imary and secondary sludges, our obser-_ 20 _ - ~
I . ' ; ., 34i ~ ~
,, I
vation has been tha-t the theoretical application rate based on the percent solids in the feed may be determined by reference to Fiyure 10, a graph depicting t:he ideal application rate, de-pendent upon the concentration of solids in the feed sludge.
Those skilled in the art will apprecia-te that many modifications may be made to the above described apparatus and method without departing from the spirit and scope of the inven-tion. Ideally, the apparatus will be constructed of simple and conventionally available materials to maintain a low initial capital cost.
.'''. Il .
, I
o 10 GPM
a 15 GPM
~ 25 GPM
X 30 GPM ~, . .~
.
. , .
~ ~3~3.~j ~
¦ Example 2 l Mixtures of 50~ by volume primary and 50~ by volume ¦ secondary municipal sludges were fed to the apparatus described ¦ above at various feed rates and with varying proportion of the flocculating agent (Calgon 2640; supra.). ~he feed rates employed, the proportion oE flocculating agent, the solids content of the feed and the solids content of the resulting sludge cake are given in Table 2, below along with the quantity of pressate recovered. The results shown in Figure 2 are given graphically in Figure $. It is evident from Figure 8 that the maximum application rate for this particular mixture is about 15 gallons per minute. Higher application rates give cakes of lower percent solids.
~.' l ,' l "
~ . .
' ' ,:
~ 3 Table 2 ___ Mixture 1 Primary: 1 Seconclary Polymer Dose Percent Solids Feed Rate, qpm GPH ~5~ Solution) FeedCake Pressate - -~
25.5 3.6 15.6.30 25.5 3.5 15.~.30 25.5 3.2 17.2.7 25.5 3.1 17Ø7 25.5 4.2 19.3.3 25.5 ~.3 21.3.3 25.5 2.3 15.
25.5 2.2 16.01.~
25.5 2.9 16.81.3 25.5 2.9 16.81.5 25.5 3.1 9.61.2 25.5 3.2 10.01.2 25.5 3.0 18.2.2 25 5 3.0 17.~.3 63.8 3.2 15.22.2 63.8 3.1 11.82.2 63.8 3.5 13.92.3 63.8 3.~ 14.12.2 25.5 4.9 13.6.8 25.5 5.1 13.2.8 Note: On Fig. 8 the feed rate values are charted as follows:
.
n 20 GP~
.
Example ~
~ Iixtures of 67~ primary and 33~ by volume secondary municipal sludyes were fed at various rates to the above described apparatus with conditioning by various proportions of flocculating agent (Calgon 2640, supra.). The feed rates ¦employed, dosage of flocculating agent, solids content of the feed and solidscontent of the resulting sludge cakes together with pressate recovered are given in Tabel 3 below. The results are also sho~n graphically in Figure 9. It will be observed that the maximum application rate for this mix-ture is about 25 gallons per minute. Higher application rates give cakes a lower percent solids.
~ ~'L~
il . ' , ¦ Table 3 Mixt ~
_p GPH (5~ Solutiog/ Percent Sollds 0 25,:~ 4.2 28.6 1 1 25.~) 4.8 25v7 --- *
25.~ 2.8 25.8 --- *
*
- 20 255 55 2 6 18 8 .7 ~~
2~ ~' 5 5'7 I4.8 _'4 : ~ 20 25 5- 3 4 2ll 44 1.6 * Not Reported Note: On Fig. 9, the feed rate values are charted as follows:
O 20 GP~I , : ~ 30 GPM
1:
1 ~ 13~;1.6 ¦ It is reasonable to assume that the sludge film ¦ deposited on the screen in the above examples is densest in case I of processing primary sludges and decreases in density as the ratio of secondary to primary sludge in the mixture increases;
therefore, the li~uid portion causing the wash out of the filter-ing film can break through the sludge film easier when processing ` mixtures oE sludges ~here the secondary sludge portion is higher than when processing mixtures with a lower portion of secondaxy sludge.
It may also be observed from the above examples that when using mixtures of primary and secondary sludges in equal proportions, a maximum application rate OL 1.75 gallons per , minute/square feet based on the total screen area of 8.7 square ¦ feet represents the upper limit beyond which there was more "
~¦ water in the feed than could pass through the screen. This ex-cess water was transported by ~he screw along with the sludge thus resulting in sludge cakes of lower percent solids. When ¦ using mixtures of primary and secondary munlcipal sludges in the ratio of 2:1, the maximum rate of application of 2.9 gallons per minutejsquare ~eet based on the total screen area of 8.7 square feet represented the upper limit beyond which there was more water in the feed than can pass through the screen. This water ~- was transported by the screw along with the sludge thus resulting in sludge cakes of lower percent solids.
In dewatering primary sludge, thickened secondary ~:
sludge nd mixtures of p~imary and secondary sludges, our obser-_ 20 _ - ~
I . ' ; ., 34i ~ ~
,, I
vation has been tha-t the theoretical application rate based on the percent solids in the feed may be determined by reference to Fiyure 10, a graph depicting t:he ideal application rate, de-pendent upon the concentration of solids in the feed sludge.
Those skilled in the art will apprecia-te that many modifications may be made to the above described apparatus and method without departing from the spirit and scope of the inven-tion. Ideally, the apparatus will be constructed of simple and conventionally available materials to maintain a low initial capital cost.
.'''. Il .
, I
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A portable apparatus for dewatering waste sludge, which comprises:
a sludge particulizer;
inlet means on the particlizer for delivering sludge therein;
a reaction vessel;
means for transferring particlized sludge from said particlizer to said vessel;
means for injecting a sludge conditioning agent into the particlized sludge;
a dewatering press;
transfer means for transferring the conditioned waste water from said conditioning means to said press;
a chassis;
mounting means for mounting particlizer, vessel, press and transfer means on the chassis; and the entire apparatus being of a size and constructed and arranged that it is capable of being transferred from one dewatering site to another.
a sludge particulizer;
inlet means on the particlizer for delivering sludge therein;
a reaction vessel;
means for transferring particlized sludge from said particlizer to said vessel;
means for injecting a sludge conditioning agent into the particlized sludge;
a dewatering press;
transfer means for transferring the conditioned waste water from said conditioning means to said press;
a chassis;
mounting means for mounting particlizer, vessel, press and transfer means on the chassis; and the entire apparatus being of a size and constructed and arranged that it is capable of being transferred from one dewatering site to another.
2. The apparatus of claim 1, which additionally comprises a holding tank for sludge, inlet means on the holding tank for receiving sludge therein, and outlet means on the holding tank for feeding sludge to the particlizer.
3. The apparatus of claim 1, wherein said means for transferring particlized sludge comprises conduits and a sludge pump.
4. The apparatus of claim 1, wherein said means for injecting comprises a reservoir tank for conditioning agent connected by conduit to the means for transferring particlized sludge and a pump for transferring agent to the latter means.
5. The apparatus of claim 1, wherein said means for transferring conditioned sludge comprises closed conduits.
6. The apparatus of claim 1, which further comprises, dual and separate sludge particlizers, reaction vessels, means for transferring, means for injecting and presses, all joined by a common source of sludge for treatment.
7. A portable apparatus for dewatering waste water containing solids, which comprises:
a solids conditioning means;
a dewatering press;
transfer means for transferring the conditioned waste water from said conditioning means to said press;
a chassis;
mounting means for mounting the solids conditioning means, dewatering press and transfer means on the chassis; and the entire apparatus being of a size and constructed and arranged that it is capable of being transferred from one dewatering site to another.
a solids conditioning means;
a dewatering press;
transfer means for transferring the conditioned waste water from said conditioning means to said press;
a chassis;
mounting means for mounting the solids conditioning means, dewatering press and transfer means on the chassis; and the entire apparatus being of a size and constructed and arranged that it is capable of being transferred from one dewatering site to another.
8. The apparatus of claim 7, wherein the solids conditioning means includes a reactor vessel for receiving the waste water and treating it in order that the solids are in condition for capture by the dewatering/press.
9. The apparatus of claim 8, wherein means for introducing a thickening agent is associated with the reactor vessel to facilitate the removal of the solids from the waste water by the dewatering press.
10. The apparatus of claim 8, wherein a particle reducing means is adapted to receive waste water and reduce the size of certain of the solids and means for transferring the waste water from the particlizer to the reactor vessel.
11. A portable apparatus for dewatering waste sludge, which comprises:
a reaction vessel;
means for transferring sludge from said vessel;
means for injecting a sludge conditioning agent into the sludge;
a dewatering press;
transfer means for transferring the conditioned waste water from said conditioning means to said press;
a chassis; and the entire apparatus being of a size constructed and arranged that it is capable of being transferred from one dewatering site to another.
a reaction vessel;
means for transferring sludge from said vessel;
means for injecting a sludge conditioning agent into the sludge;
a dewatering press;
transfer means for transferring the conditioned waste water from said conditioning means to said press;
a chassis; and the entire apparatus being of a size constructed and arranged that it is capable of being transferred from one dewatering site to another.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US84487177A | 1977-10-25 | 1977-10-25 | |
| US844,871 | 1977-10-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1113616A true CA1113616A (en) | 1981-12-01 |
Family
ID=25293841
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA306,076A Expired CA1113616A (en) | 1977-10-25 | 1978-06-23 | Method and apparatus for sludge treatment |
Country Status (10)
| Country | Link |
|---|---|
| JP (2) | JPS5465170A (en) |
| AU (1) | AU524927B2 (en) |
| CA (1) | CA1113616A (en) |
| DE (1) | DE2838899A1 (en) |
| FR (1) | FR2407174B1 (en) |
| GB (1) | GB1603681A (en) |
| IT (1) | IT1105397B (en) |
| MX (1) | MX4206E (en) |
| NO (1) | NO783595L (en) |
| SE (1) | SE7810232L (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DK152015B (en) * | 1979-08-02 | 1988-01-25 | Voest Alpine Ag | DEVICE FOR DEVICING AURAL SUSPENSIONS AND SLAMS WITH A SEBAND PRESSURE AND SPALTESI |
| ZA822382B (en) * | 1981-04-07 | 1983-08-31 | Schmidt Mfg | Improved physical-chemical waste treatment method and apparatus |
| US4481176A (en) * | 1983-10-03 | 1984-11-06 | Stauffer Chemical Company | Treatment for phosphorus-containing waste material |
| DE3346834C1 (en) * | 1983-12-23 | 1985-05-15 | Allied Colloids Manufacturing GmbH, 2000 Hamburg | Process and plant for dewatering sludge |
| GB8419035D0 (en) * | 1984-07-26 | 1984-08-30 | Water Res Centre | Dewatering solids suspensions |
| NL1014310C2 (en) * | 2000-02-08 | 2001-08-09 | Witteveen & Bos B V | Sludge thickening or dewatering process, uses combination of sludge weight and solids content measurements and disposal and operating cost values to optimize a total cost value |
| US6808305B2 (en) | 2002-03-25 | 2004-10-26 | Sharpe Mixers, Inc. | Method and apparatus for mixing additives with sludge in a powered line blender |
| DE102007055563A1 (en) * | 2007-11-20 | 2009-06-10 | J. F. Knauer Industrie-Elektronik Gmbh | Method and device for treating sludge |
| CN113666600A (en) * | 2021-09-15 | 2021-11-19 | 中铁工程服务有限公司 | Portable slurry treatment test system and test method thereof |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3426677A (en) * | 1966-09-20 | 1969-02-11 | Wascon Systems Inc | Screw press |
| DE1658097A1 (en) * | 1967-11-30 | 1970-03-26 | Metallgesellschaft Ag | Process for the dewatering of Klaer and industrial slaughter, especially fresh and lazy slaughter, with the addition of flocculants and warming |
| US3549010A (en) * | 1968-07-01 | 1970-12-22 | Black Clawson Co | Methods and apparatus for disposing of waste materials |
| US3695173A (en) * | 1972-01-28 | 1972-10-03 | Clyde Harold Cox | Sludge dewatering |
| NL7214504A (en) * | 1972-10-26 | 1974-05-01 | ||
| DE2343323C2 (en) * | 1973-08-28 | 1975-08-21 | Albert 6683 Elversberg Baehr | Mixing tank for the continuous addition and mixing of flocculants to sludge, especially sewage sludge |
| JPS5418751Y2 (en) * | 1974-09-09 | 1979-07-13 | ||
| JPS51121473A (en) * | 1975-04-17 | 1976-10-23 | Reshiku Shisutemusu Inc | Method of treating inorganic and organic waste materials |
| JPS52103853A (en) * | 1976-02-26 | 1977-08-31 | Morita Tokushu Kiko | Sludge dewatering vehicle |
| DE2656299A1 (en) * | 1976-12-11 | 1978-07-27 | Iplan Dr Ing Stefan Schulz Ing | Drainage channel cleaning unit - sucks out sludge, adds flocculant, filters mixt. and returns filtered water to drain |
| DE2656362A1 (en) * | 1976-12-13 | 1978-06-15 | Rolf Flach | METHOD AND DEVICE FOR DETERMINING WASTE WATER |
-
1978
- 1978-05-25 AU AU36463/78A patent/AU524927B2/en not_active Expired
- 1978-05-26 GB GB23141/78A patent/GB1603681A/en not_active Expired
- 1978-06-23 CA CA306,076A patent/CA1113616A/en not_active Expired
- 1978-07-03 JP JP7984778A patent/JPS5465170A/en active Pending
- 1978-08-02 FR FR7822861A patent/FR2407174B1/en not_active Expired
- 1978-08-07 IT IT50630/78A patent/IT1105397B/en active
- 1978-08-24 MX MX787352U patent/MX4206E/en unknown
- 1978-09-06 DE DE19782838899 patent/DE2838899A1/en not_active Ceased
- 1978-09-29 SE SE7810232A patent/SE7810232L/en unknown
- 1978-10-24 NO NO783595A patent/NO783595L/en unknown
-
1983
- 1983-04-25 JP JP1983060888U patent/JPS5979299U/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB1603681A (en) | 1981-11-25 |
| IT7850630A0 (en) | 1978-08-07 |
| SE7810232L (en) | 1979-04-26 |
| FR2407174A1 (en) | 1979-05-25 |
| NO783595L (en) | 1979-04-26 |
| JPS5979299U (en) | 1984-05-29 |
| JPS5465170A (en) | 1979-05-25 |
| IT1105397B (en) | 1985-10-28 |
| MX4206E (en) | 1982-01-27 |
| AU3646378A (en) | 1979-11-29 |
| AU524927B2 (en) | 1982-10-14 |
| DE2838899A1 (en) | 1979-04-26 |
| FR2407174B1 (en) | 1985-06-28 |
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