Patent Publication Number: US-3876157-A

Title: Method for treating organic and inorganic waste material

Description:
United States Patent Mclntire et al. Apr. 8, 1975 [54] METHOD FOR TREATING ORGANIC AND 3.549.092 lI/lT/U Baxter. .lr. 241/15 INORGANIC WASTE MATERIAL i r l 1 1 3mg 1m 1 i 1 1 i i H [76] Inventors: Ray G. Mclntire. 8% Blac f t T 3.613540) 1 1972 Brewer 241m Jamestown. Ohio 48335; David M. 2045&#39; Primur E.rumi1wrGranville Y. Custer. Jr. 531 5 2 g g g il I 7 Allurm&#39;y. Agent. or FirmGleim and Tritle t t.. out t eters urg. a. 33707 7 [57I ABSTRACT 2 3 l l Flled Jan 18 Flhrous matenal having UIlllK) in the production ofnu- [2l Appl. No; 324.671 merous and differing products is produced from refuse Relaed US. Application Data by a continuous process after separation and removal q 3 of undesirable consutuents such as dirt. glass. ferrous l63l g z lq7land non-ferrous metals from the refuse. Individual remaining particles are then reduced in size and suspended in a water slurry. The slurry is then subjected v a 1 i v 4 l 24l/l7&#39; i fit to centrifugal acceleration to remove any glass. metallic or other relatively dense particles that may remain 2g i i k&#39; ig i j therein. The resulting slurr is sterilized by continuous ll 0 l 2 cooking to thermally destroy all major pathogens and- /or parasitic organisms. The solids content is then ins6 R f d creased and additives introduced into and mixed with l e &#34;mugs the solids following which the mixture of solids and UNlTED STATES PATENTS additives is rolled to produce granules of a desired size 2108,07 4 5/1955 Hosklns 2-11/l7 and the resulting product is dried. 3,477.64) ll/l969 Dalherg et al. 24l/24 3.524.594 8/l970 Anderson et al. 241/24 x 10 Clalms- 7 Drawmg Figures PATENTEDAPR 8 975 SHEET 2 5 INVENTORS lF/W a. MINT/Rs PJV/D A4. COLD BY 4 THUR M- M0452? PMENIEDAPR 8191s 3.876.157  
 SREET 5 Bf /Z4- o 11 23 o L- PAY 6. McINT/RE DAVID M- COLD ARTHUR M- MOLE)? MW d I METHOD FOR TREATING ORGANIC AND INORGANIC WASTE MATERIAL This is a continuation of application Ser. H0332. filed Mar. -l. 1971. now abandoned.  
 BACKGROUND The disposal of solid waste or refuse has been a wry troublesome problem primarily because refuse is gcnerated in enormous quantities. For ewmple. it has been estimated that refuse. as it comes from garbage containers. would cover approximately 100.000 acres to a depth of about 2V2 feet each year. Within the past l to years many cities have replaced open garbage trucks with closed \ehicles designed specifically for refuse collection. Such vehicles tend to eliminate litter. dust and odors. and they also compact the refuse to 2 to 3 times its uncompacted density. This increases the weight carried per truck. reduces the number of trips to the disposal site. and thereby increases the efficiency of collection.  
  Disposal of the refuse still presents difficult problems. Heretofore such material has been disposed of at dumps but dumps are now considered an unsatisfactory method ofdisposal. In some cases the dumps have been converted to sanitary landfills where the refuse is dumped and then covered with dirt. Landfill facilities tend to reduce nuisance. pollution. and health hazards. as long as suitable fill is available and some open space is maintained downwind to dissipate odors.  
  Additionally. where the nature ofthe refuse material permits. incineration disposal methods have been employed successfully to very substantially reduce volume and weight of refuse. This method of disposal is advantageous in that it leaves a residue that is unattractive to pests and permits disposal of the residue in open dumps or as fill material. However, most incineration methods. as currently practiced. do not meet the advanced standards of air pollution control authorities. since combustion contributes particulate matter. opacifying matter. and oxides of nitrogen to the atmosphere Accordingly. a principal object of the present invention is to provide improved means and methods for obviating the above noted difficulties and to provide for the satisfactory and efficient disposition of refuse material. as well as the salvaging of useful material such as metals. and the recycling of organic materials to conserve natural resources.  
 SUMMARY These and other objects are achieved by the present invention by a process that converts the organic matter in refuse to a useful product or to a disposable material that is substantially odorless and unattractive to pests. After salvageable and non-grindable materials have been removed. the refuse is ground and continuously fed by suitable conveyor means. Water is added and the water with the ground material suspended therein is continuously cooked to destroy pathogens and para sitic organisms. If desired. nutrients or other additives may be added. following which the water is eliminated to convert the refuse to a dry useful product or a dry disposable material.  
 DESCRIPTION Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings in which:  
  FIG. I is a flow chart illustrating diagrammatically various types of apparatus employed in the practice of the present invention:  
  FIG. 2 is a view illustrating a typical layout ofthe apparatus of FIG. I;  
  FIG. 3 is a flow chart illustrating the method of the present in\ ention;  
  FIG. 4 is a cross-sectional view illustrating separator apparatus;  
  FIG. 5 is a diagrammatic iew show ing additional details of the separator and portions of the conveyor means:  
 FIG. 6 is a cross-scctional \ic\\ of shredding apparatus&#39;.  
  FIG. 7 is a cross-sectional view ofthe sterilizing apparatus.  
  As noted above. municipal refuse contains a mixture of many different things such as bottles. cans. grass. other small objects. waste paper. news print. cartons and the like. In accordance with the present imcntion it is contemplated that after collection ofsuch refuse by refuse collection trucks. these trucks will discharge their load directly into apparatus which recebes and separates the material according to the characteristics of the various constituents. For example. the material is separated or classified according to whether the ob jects are relatively large or small. or \ery fine. into objects that are salvageable. rejectable. or useable in the process ofthe present invention. For example. salvageable items include ferrous and non ferrous metals as well as glass objects. Material processed according to the present invention includes fibrous material and/or food wastes which are convertible into a number of products of different types. For example. the method and product produced thereby according to the present invention may be useable to produce paper pulp. fibers for board production. fibers for roofing felt. fertilizer base. fibers for hydraseeded land reclamation. and a cattle feed supplement.  
  In the drawings. the apparatus employed in practicing the present invention is indicated generally at I0. Refuse is discharged from a refuse collection truck into a separator II which includes a hopper l2 and a plurality of spaced-apart rotating drums I3 having a plurality of spikes I4 projecting outwardly from the periphery of the drum. The drums are caused to rotate by motor means (not shown). The refuse material falls under the influence of gravity through the hopper portion and through the rotating drums. As the drums rotate. the revolving spikes operate to tear open bags and cartons and expose the contents thereof for separation along with other constituents of the refuse. Separator II also includes screens 15. I6 and an inclined pan feeder 17. as is best shown in FIGS. 4-5. The refuse falling between the rotating drums is received on a vibrating screen 15 of relatively coarse mesh. for example. nine inches. thereby allowing bottles. cans. grass and small objects to fall through the screen and onto a second vibrating screen 16 having a smaller mesh. for example. three inches. Material such as grass. dirt and fine objects falls through the second screen 16 onto an inclined pan feeder 17.  
  Material which is retained on the top side of screen I5 such as paper products including bags. news print. cartons. and the like pass from the vibrating screen 15 onto a conveyor 18. Similarly. the material which re mains on the upper side of screen 16 such as cans. bottles and the like passes from screen If) to a ballistic flinger l) which separates such objects according to their density by centrifugal action similar to that of a cream separator. After passing through flinger [9 any remaining desirable material such as paper products or portions thereof are picked up and returned to cor \eyor 2U \ia conveyor a. Material from the pan feeder l7 also discharges onto the pneumatic conveyor system 20 which comeys desirable material to a shredder 23. and all undesirable materials are collected and remov ed by a reject comeyor 22.  
  The shredder 23 recei\ es material from conveyors l8 and 20. The shredder comprises a housing hzoing a hopper or feed portion 23a and a reject chute portion 24. Within the housing is a rotor 25 having connected thereto and projecting outwardly from the periphery thereof a plurality of hammers 2b. Rotor 25 is journaled for rotation within the shredder housing and is caused to rotate by any desirable dri\ ing means such as an electric motor (not shown). Directly below rotor 25 and closely spaced from and adjacent the outer ends of hammers 26 is a screen 27. A comb 28 is connected to the screen to provide a rubbing and/or wiping action relati\e to the hammers 26 as they rotate past the comb thus tending to clear the hammers 26 relative to rags and or material such as plastic material that may tend to stick or otherwise adhere to the hammers.  
  Also journaled within the shredder housing for rotation therein is a star wheel 29 having teeth 30 that mesh with the hammers 26 as is best seen in FIG. 6.  
  The pneumatic or air blast conveyor system 21 is dis-- posed directly below screen 27 to receive material that passes through the screen. and the air blast passing over the surface of the screen exerts a scrubbing action which removes material particles which might otherwise tend to adhere to the screen.  
  As material is received into the feed or hopper por tion 23a of the shredder. rotation of rotor 25 and hammers 26 operates to reject metal objects and wood ob jects ballistically, the impact of hammers 26 serving to dri\e such objects upwardly for dischzfrge through the reject chute portion 24. The meshing between the teeth 30 of the star wheel 29 and hammers 26 tears paper and cartons and other like material passing through the revolving star wheel and swing hammers. and material falling below the axis of rotor 25 toward screen 27 is subjected to a grinding action by the hammers 26 and the surface of screen 27 thereby sizing the particles that fall through the screen and are picked up by the pneumatic conveyor 21.  
  After shredding the shredded material is conveyed by a pneumatic conveyor 21 to a pulper which introduces water to form a slurry having a composition of about lU i to 25% solids The slurry with the shredded material suspended therein discharges from a pulper 31 and passes to a liquid cyclone 32 which removes any glass or metal particles that may have escaped the earlier separation procedures. The liquid cyclone discharges into a decanter 33 which removes some of the water from the slurry and raises the solids content thereof to about 50%. The excess water is returned to the pulper through a line 34. The slurry now containing approximately 50% solids discharges from the decanter into a continuous cooker 35.  
  As best shown in FIG. 7, the cooker includes a retention vessel 36 having an inlet opening 37. A screw conveyor 38 extends partially into the retention vessel and includes a housing 3) connected to said vessel through which the slurry is pumped for discharge to the next step in the operation. The housing 39 and the vessel 36 are jacketed at 40. Preferably. the dimensions of the screw conveyor housing 39 and those of the retention vessel 36 are sized so as to provide a retention time of about two hours from the time that incoming material is received into the vessel until it is discharged from the conveyor 38. During such retention time. steam is admitted into the space between housing 30 and jacketing 40 and the temperature of the slurry is maintained at about 212F for the entire retention time. thereby thermally destroying all major pathogens and parasitic organisms and the slurry and its constituents are thereby sterilized.  
  The slurry thus removed from the retention vessel and discharged by the conveyor 38 is discharged into a centrifuge 41 where more water is removed from the slurry and the solids content thereof raised to about The water thus removed is returned to the pulper through a line 42. The slurry with 70% solids content then discharges into a pug mill 43.  
  If it is desired to produce a product that will have util it in a particular market, suitable additives are introduced into the pug mill and mixed with the slurry. For example. if it is desired to produce a product having utility as a cattle feed supplement. such additives may include proteins and/or other nutrients and/or minerals; a flame retardant additive will be added if the product is intended for use as an insulation board material; an additive for a fertilizer will include plant nutrients and minerals; and an additive for a hydraseeding material will include fertilizer and grass seed.  
  The material is discharged from the pug mill into a granulator 44 where the product is reduced to desired size following which the product is discharged into a dryer 45 which removes moisture and reduces it to proper level. The product is then discharged onto a screen classifier 46 from which the preferably sized product is removed. The oversized and undersized product particles are recycled and reintroduced into the pug mill by a line 47.  
  The foregoing is intended to be exemplary and illustrative of the apparatus and method of the present invention and not limiting. Similarly, as noted above, the apparatus and process ofthe present invention are useful in producing products having utility in differing markets some examples of which have been indicated heretofore. The following examples are intended as exemplary and illustrative only, and not limiting. in connection with certain products resulting from the practice of the present invention regarding the effects of variations in pressure. temperature, cooking time, initial composition. and certain additives.  
  Four batches of material consisting of paper, grass, and food wastes were prepared by initial grinding, thorough mixing, and subsequent feeding into a garbage disposal unit with water running through the unit con stantly thus producing pulped material in a wet state. This pulped material was then placed in a vessel and cooked for a period of time at an elevated temperature. Following the cooking step. half of the batch was removed from the cooking vessel, dried and then finish ground. The other half of each batch remaining in the cooking vessel was immediately treated by adding urea at the rate of 1 lb. of urea per 20 pounds of dry material. After stirring, and being allowed to set for a few minutes. this mixture was dried and finish ground in the same manner as the other half of the batch. Samples were taken from each half of each batch and analyzed. In each of the examples enumerated below. the odd numbered samples contained no urea additive and the even numbered samples are those to which the urea addition was made.  
 EXAMPLES Examples 1. 2. 5 and 6 were prepared from material consisting of bli &#39;1 paper. 3U&#34;; grass and Ill? food waste. Examples 1 and 2 were cooked at Ill pounds pressure for 45 minutes and then cooked for 1 hour and minutes at U pounds gage pressure. At pounds pressure. the temperature was Z5UF. and at pounds gage pressure. the temperature was 2l2F. ln examples 5 and 6 the material was cooked at 0 pounds gage pressure for 2 hours after the temperature had reached 212F.  
  The cooking treatment for examples 3 and 4 was identical with that of examples l and 2 but the batch material consisted of 43% paper. 43% grass and l4); food wastes. ln examples 7 and 8 the batch material consisted of 439% paper. 43% grass. and 149 food wastes. and the cooking procedure was identical with ill  3. Process according to claim and additionally granulating the mixture of said additive and the solids content of said slurry.  
  4. Process according to claim 3 and additionally including the step of removing the moisture from the 20 mixture resulting from said granulating step.  
  5. Process according to claim 4 including the additional steps ol&#39;size classifying the resulting granules. removing undesired granules. and reintroducing remain ing granules into the process prior to said granulating that employed In connection with 5 and 6. p&#39;  
  A summary of the analyses of the several examples is (a. Process according to claim 1 and including. follow as follows: ing the removing step and prior to the pulverizing step.  
 Sample No l I 3 4 5 h 7 S Analysis MOISTURE 3614 an. is 20.20 9.49 I054 15.85 9i 251m PROTEIN 3.5a I950 5.3x lsso sun 34.50 (1.44 271m FAT 2.II 1.9x s 415 n.75 (ms 370 4.35 FIBER 41mm 35.61) 5M2 49nd ShJtI 4025 Isis 401m Nlf-FREE-EXTRACT ltrl I 5.14 1x34 mm Ims .95 IN} l.l4 ASH 1.54 I57 2H4 2.25 I57 I.7I 1.83 L52 The foregoing analyses adjusted to dry weight of mathe additional step of reducing to a preselected size the terial is as follows: remaining pulverulent material.  
 Sample Nov 1 2 3 4 5 (I 7 K Analysis Protein 5.5 3.07 6.73 20.35 9.03 4 I. I3 8.69 36.53 Fat 3.3] 3.I I 4.48 4.57 7.56 7.95 5.03 5x7 Fiber 6374 55x9 h2.9II 53.9II 63.06 47.90 64.98 not) Nit-Free Extract 25.29 8.07 22.93 I827 I819 I.I3 18.80 I54 Ash 2.42 2.46 2.73 24s 1.76 2.03 2.47 ,05  
  While particular embodiments of the invention have 7. Process according to claim 1 and additionally in been illustrated and described. it will be obvious that cluding the step of subjecting said slurry to density clasvarious changes and modifications can be made withsiflcation and remaining undesired particles. out departing from the invention and it is intended in 8. Process according to claim 1 and also including. the appended claims to cover all such changes and after said classification and retaining step. the addimodifications that fall within the true spirit and scope tional step of removing some of the water from said of the invention. slurry and reintroducing said removed water into the What is claimed is: 55 process at said slurry forming step.  
 . 9. Process according to claim 1 and also including.  
  A Commuous process r WB mfube mm prior to said classification and retaining step. removal disposable pulverulent material comprising the steps of of some of the water from Said Slurry and reintroducing removing men] a glass fmm refube comlmmg said removed water into the process at said slurry form veru ent materials. ing Step mixing the resulting product with water to form a slurry having a solids content of about 50%.  
 causing a continuous inflow of said slurry into a re tention vessel.  
 retaining said slurry within said vessel for a period of time ranging from about 45 minutes to about 2 10. Process according to claim 1 and additionally including. removing water from said slurry before and after said classification and retaining step and reintroducing said removed water into the system at said