GB1604948A - Process for the preparation of fuel and nutrients from wastes - Google Patents

Description

(54) PROCESS FOR THE PREPARATION OF FUEL AND NUTRIENTS FROM WASTES (71) I, JOHN LESTER LANG, a citizen of the United States of America, of 1187 East Stewart Road, Midland, State of Michigan, United States of America, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a process for the combined production of a liquid fuel and a nutritive residue.

The problem involved in treatment for disposal of municipal waste concerns the "ultimate disposal" of the noxious material therein.

The ultimate disposal of liquid-containing wastes, especially municipal waste (or sewage) is a perplexing, expensive problem.

The present partial solutions to the problem include the primary treatment of such wastes, which involves merely the removal of the gross contaminants; and the secondary treatment involving a partial digestion of the contaminating solids, using air or even oxygen sparging to promote the metabolic process of aerobic microbes while suppressing the growth and/or reproduction of anaerobic species, such as the clostridii, which produce very toxic metabolic by-products. The product of such treatment processes may consist of 9699.5% water, but it is a grey suspension, susceptible to conversion to septic material in about twenty minutes, and is not only un-palatable but repugnant in appearance and odour.

The problem involved in the disposal of solid municipal waste (garbage) is presently solved by the so-called "sanitary landfill" method, by incineration, disposal in abandoned mines, merely dumping, etc.

These methods are wasteful, in terms of the loss of the energy content of such materials, the disseminaton of otherwise valuable resources, and in the cast of incineration, the loss of the energy stored as fixed nitrogen compounds represents a fearful waste, as these materials have to be resynthesized by either nature or man in order to provide the supply of foodstuffs available to the human race.

Several attempts have been made to recover at least a part of the energy values in such materials by rather exotic processes, e.g., the hydrogenation thereof under conditions of high temperatures and pressures, by direct gasification, by drying and burning them together with other fossil fuels in electrical power stations, etc. The disadvantages of such systems include high capital investments for special reactors, the production of considerable char instead of the primary fuel product, and the necessity for special flue-gas purification systems in order to meet air-purity standards.

Also, the fuel-fired drying and incineration process consumes fuels in such a way that no useful purpose is served in terms of the recovery of such energy requirements and the energy stored in the components being destroyed.

These conventional processes merely, in virtually every case, convert one form of nuisance into another form, and the problem of "ultimate disposal" in some harmless, or preferably useful, form remains largely unsolved.

In accordance with the present invention, there is provided a process for the combined production of a liquid fuel and a nutritive residue from solid-containing waste material comprising a biomass, which process comprises separating the biomass from the waste, comminuting the biomass, subjecting the biomass to acid hydrolysis at a temperature and pressure sufficient to render the organic portion of the biomass substantially watersoluble and to convert the said portion into fermentable sugars, and fermenting the resultant product to form alcohol and a nutritive residue, wherein the hydrolysis step is carried out in the presence of sulphurous acid as a hydrolysis catalyst, the fermented resultant product is filtered so as to separate out a filtrate and nutritive residue, and the filtrate is distilled so as to obtain a liquid fuel containing alcohol and a nutritive residue.

Preferably the separation step includes separating metallic materials in the waste material, separating the friable and nonfriable materials in the waste material the friable materials principally consisting of brittle plastics materials, bone and glass and containing the biomass, and the non-friable materials principally consisting of leather, paper, fabrics, gristle, films of plastics materi als and rubber, and separating the friable materials and the biomass by flotation in water; this separation step including steeping in water the hydrolyzable material of the biomass.

Desirably the separation step of the metallic materials comprises a magnetic separation step enabling magnetic metals in the waste material to be recovered, and the separation step of friable and non-friable materials comprises comminuting and then screening the waste material, the friable materials passing through the screen and the nonfriable materials not passing therethrough.

Preferably also the residue from the filtering of the fermented resultant product is subjected to sterilisation before being used to produce a nutritive product.

The present invention also provides both a liquid fuel containing alcohol and a plant or animal food consisting of or comprising a nutritive residue, wherein the said fuel or said residue is produced by a process in accordance with the present invention.

The steps of the process are comprised essentially of those outlined in Figure 1. The solid municipal waste I is passed through a magnetic separator, and the magnetically susceptible materials (A) therein removed for recovery by step 2, and the non-magnetically susceptible mixture sent to Primary Roll Crusher step 3, wherein friable materials are crushed, including certain plastics, bone and vegetable materials, and the non-magneti- cally susceptible metals, leather, tough plas- tics, etc., are merely flattened. The crushed mixture is put through Coarse Screening step 4, in which the crushed material passes through the screen thereof, and the tough materials do not. This step is arranged to separate the non-friable materials 6 from the mixture. The non-friable material in the solid waste is put through Flotation step 7, which separates the non-magnetically susceptible metals (5) for recover. The balance of the non-friable materials is subjected to Steeping (step 8) during which the hydrolyzable materials become preferentially heavier by absorption of water and sink, while the nonfriable plastic films, waxed paper, etc., do not absorb water and hence float. These materials are separated in Flotation step 9; the floating materials may be superficially dried and used as a Product solid fuel (10). The sinking material is sent to the Fine Grinding step 11. The material passing through the screen of step 4, is separated by Flotation step 12 into a heavier fraction containing crushed friable plastics, crushed bone. and crushed glass and a lighter fraction containing hydrolyzable materials which are sent to Fine Grinding step 11. The heavier fraction of friable materials (13) are processed by a Flotation step 14, wherein the specific gravity of the fluid is adjusted to so that the friable plastics float and the glass and bone fragments sink. The Recovered Plastic 15 results: the mixture of glass and bone fragments is then subjected to Flotation step 16, wherein the specific gravity of the fluid is adjusted so that the bone fragments float and the glass fragments sink, thus separating for recovery the Recovered Crushed Bone 17 and the Recovered Crushed Glass 18.

After the hydrolyzable materials of the original solid municipal waste from step 9 and 12 have passed through the Fine Grinding (step 11) they are forwarded to the Hydrolysis step 19, wherein a significant portion of the hydrolyzable materials are saccharified to fermentable sugars using sulphurous acid as a hydrolysis catalyst. This saccharified and optionally caramelized materials is filtered in step 20; the residue is optionally recycled to the hydrolysis step 19; the filtrate from step 20 is flash evaporated in step 21 to remove excess volatile substances, including the hydrolysis catalysts used in step 19, and concentrating the filtrate to the desired volume and/or solids content. This mixture is sent to fermentation step 22, where the appropriate addition of microoganisms and/or enzyme-containing materials and the maintainance of proper conditions of time, temperature of pH brings about the conversion of the fermentable sugars to the desired fermentation products, including alcohol.

After fermentation 22, the material is filtered in step 23; the residue is again optionally recycled to hydrolysis step 19 or to Excess Water Removal step 25, depending upon the work load of the hydrolyzer 19 or the supply/demand circumstances for product nutrient 27.

The filtrate is forwarded to Distillation step 24, and the overhead liquid fuel product 28 containing alcohol is collected for use.

The residue from distillation step 24 is sent to Excess Water Removal step 25, where it and the residue from Filtration step 23 are de-watered to a consistency suitable for use as animal and/or plant nutrients; partial dewatering giving a syrupy product suitable for use as a binder for other nutrients such as grains, peat moss, etc., and the resulting mixture flaked, pelletized or otherwise prepared for nutrient use as a Product Nutrient 27, or de-watered to a concentration suitable for use per se as Product Nutrient 27.

The water removed in Excess Water Removal step 25 is Distilled Water 26, a known marketable commodity.

The steps of the present process wherein sewage solids are used are comprised essentially of those outlined in Figure 2. The municipal waste water 1 is put through a primary screening step 2, being separated into Filtrate 3 and gross or large size solids 4.

The Filtrate 3 is then aerated by air or oxygen sparging or otherwise contacting therewith in Aeration step 5. The effluent from Aeration 5 is then passed to a Settling step 6, with or without addition of suitable settling agents, and the clear supernatant water separated into Decanted water 7 and the settled solids passed to fine mixing step 8, where they are recombined with the gross Solids 4 obtained from the Primary Screening step 2, and mixed until more or less uniform in flow character. The non-aqueous contaminants are then converted, at least partially, into sugars in the Saccharification step 9 using as a hydrolysis catalyst sulphurous acid. It will be realized that the mixing step 8 and the Saccharification step 9 can be carried out in the same vessel, or separately, as desired, and that the Saccharification step 9 can be carried out with the application of suitable heat and pressure. After proper saccharification, the pH of the molasses-like material is adjusted, and the composition adjusted suitably for fermentation by, e.g.

Saccharomyces cereiroiae, to form alcohol which process is carried out in Fermentation step 10. When a suitable degree of conversion of the fermentable sugars is obtained, the product of Fermentation step 10 is filtered in Filtration step 11, the residue passed to Excess Water Removal step 12.

The filtrate from the step 11 is charged to the Distillation unit of step 13, and the overhead liquid fuel product 14, containing alcohol collected for use. The residue from the Distillation step 13 is sent to the Excess Water Removal unit 12, here it and the residue from Filtration step 11 are dewatered to a consistency suitable for use as animal and plant nutrients; partial de-watering giving a syrupy product suitable for use as a binder for other materials as grains, peat moss, etc., and the resulting mixture flaked, pelletized, or otherwise prepared for nutrient use as the Product Nutrient 15. or de-watered to a concentration suitable for use per se as Product Nutrient 15.

The water removed in the Excess Water Removal step 12 may be used per se, if desired, as distilled water 18. or combined with water from step 6 after sterilization in Sterilization step 16, giving Product Water 17.

The hydrolysis and saccharification are hastened by proper adjustment of the temperature, the amount of the hydrolysis catalysts used, and the concommitant pressure required for maintainance of the temperature selected for use in the hydrolysis and saccarifcation step.

The following Examples are given merely to illustrate the invention.

EXAMPLE I A representative "synthetic" solid municipal waste was prepared by mixing fat, meat scraps, paper, cabbage leaves, carrot tops, potato peelings, bones, polyethylene film, aluminum foil, glass, tinned iron sheet metal, bottle caps and leather.

The synthetic solid waste, when passed through magnetic separator, results in removal of the magnetic materials therein for recovery. The non-magnetically susceptible materials thus separated, when passed through a roll crusher, results in considerable size reduction of the friable materials therein, including most of the materials derived from vegetable and animal sources, the brittle plastics, bones and glass; this roll crusher merely flattens the non-magnetically susceptible metals, the flexible plastic films, and the tougher components such as leather, gristle, etc. of the waste.

The crushed material, when passed through a coarse screen, is separated into a portion which contains the non-magnetic metals, flexible plastics, and the tough components such as leather, paper, etc. and another portion containing the softer animal and vegetable materials, friable plastics, bone, glass, etc.

The non-friable portion when subjected to brine flotation at a sp. gr. of 1.2 is separated into a sinking fraction which contains the non-magnetically susceptible metals, which are thereby recovered. The floating fraction is subjected to a stepping process for at least four hours; the water-susceptible materials, such as leather, paper, cloth, etc. absorb water and sink. A successive flotational separation thus separates the water-repellant materials such as plastic films, rubber, etc.

The floating fraction is used as solid fuel or recovered as desired, while the sinking portion is separated and contains the leather, gristle, paper, etc., which is put through a fine grinder of the chopper type.

The friable material from the roll crusher, ,after the screen separation thereof, when subjected to a flotation step using water, results in separation of a slurry of the main animal and vegetable parts (the biomass) of the original waste and a settled mixture of friable plastic, bone, glass, etc.

The slurry of animal and vegetable matter is sent to the fine grinder-chopper, while the sedimented material is gravity separation by flotation into recovered friable plastic granules. bone granules, and glass fragments.

After the fine grinding of this separated animal and vegetable material, this mixture was subjected to a hydrolysis step, using sulphurous acid as a hydrolysis catalyst.

The saccharified material was cooled and concentrated by passing throug a falling-film evaporator, operated so that the effluent temperature was 65'C and the organic solids content was about 30%. The pH was adjusted to a value of 3.4, and a small amount of enzymes, e.g., in the form of barley malt, was added. This enzyme-containing mixture was maintained at 65'C for 3 hours.

After cooling to 27 C and re-adjustment of the pH to a value of 3.4, yeast was added and the temperature and pH maintained until fermentation ceased. The fermented material was filtered, the residuum steam-sterilized and stored. The filtrate was distilled, using a four-foot column packed with porcelain chips, fitted with a take-off head which was regulated at a reflux-ratio of 20:1. The stillpot heating was regulated to maintain a temperature in the vicinity of 76 80 C in the still head.

Based upon an initial charge of 100 parts to the still-pot, the distillate was about 11 parts of ethanol-water mixture. The ethanol was, optionally, dried with calcium oxide, filtered and this product mixed 1:9 with gasoline. This liquid fuel mixture, after minor carburetor adjustment, was found to burn cleanly and well in a conventional internal combustion engine.

The filtered residuum from the fermentation step was recombined with the still-pot residuum, and the whole evaporated until a thick syrup was formed, distilled water being formed as a by-product. This syrup was combined with ground feed grains, the syrup acting as both a binder for pelleting same, as well as containing the sterilized, cooked nutritive values of the municipal waste and the nutritive values of the yeasts in the fermentation residuum, which yeasts multiplied, of course, during the fermentation step.

EXAMPLE II Municipal waste sludge was introduced after coarse screening and grinding into a corrosion-resistant pressure vessel, and the pressure increased by means of heat and air sparged therethrough, at a temperature of 200"C and a pressure of about 350 pounds per square inch to saccharify the organic materials in the sludge using sulphurous acid as a hydrolysis catalyst, during which process the organic materials are solubilized to a greater degree and the remaining insoluble materials are mainly inorganic in character.

At this stage, the saccharified product contains about 8-10% total solids, of which about 5-7% is organic materials, and the pH is about 6.

The saccharified material was cooled and concentrated by passing through a fallingfilm evaporator, operated so that the effluent temperature was 65'C and the organic solids content was about 30sub. The pH was adjusted to a value of 3.4, and a small amount of enzymes, e.g., in the form of barley malt. was added. This enzyme-containing mixture was maintained at 65'C for 3 hours.

After cooling to 27"C and re-adjustment of the pH to a value of 3.4, yeast was added and the temperature and pH maintained until fermentation ceased. The fermented materials was filtered, the residuum steam-sterilized and stored. The filtrate was distilled, using a four-foot column packed with porcelain chips, fitted with a take-off head which was regulated at a reflux-ratio of 20:1. The stillpot heating was regulated to maintain a temperature in the vicinity of 76-80"C.

Based upon an initial charge of 100 parts to the still-pot, the distillate was 11.5 parts of ethanol-water mixture. The ethanol was, optionally, dried with calcium oxide, filtered and this product mixed 1:9 was gasoline. This liquid fuel mixture, after minor carburetor adjustment, was found to burn cleanly and well in a conventional internal combustion engine.

The filtered residuum from the fermentation step was recombined with the still-pot residuum, and the whole evaporated until a thick syrup was formed, distilled water being formed as a by-product. This syrup was combined with ground feed grains, the syrup acting as both a binder for pelleting same, as well as containing the sterilized, cooked nutritive values of the municipal waste and the nutritive values of the yeasts in the fermentation residuum, which yeasts multipled, of course, during the fermentation step.

EXAMPLE III Eight gallons of partially de-watered, activated sludge, having a total solids of 8% was coarse screened and comminuted and placed in a corrosion-resistant pressure vessel fitted with an agitator, electrical heating element and thermocouple well. The pH of the sludge was lowered to a value of 1.5 by the addition of sulphurous acid. After sealing the reactor and beginning agitation, the electrical heating system was adjusted to maintain a temperature of 140'C, and heating and agitation continued for 3.5 hours.

The contents of the reactor were then discharged into an expansion chamber, and sparged with steam and the pH was adjusted to 3.4. After cooling to 65 C, enzymes in the form of barley malt, were added and these conditions of temperature and pH maintained for 4 hours. The temperature was lowered to 27'C, and the pH adjusted to 3.4.

Yeast was added and fermentation begun.

These fermentation conditions were maintained until the fermentation ceased.

The fermented material was filtered, and the nutritive residuum steam-sterilized and stored for use later. Distillation, per 100 parts of the filtrate gave 3.4 parts of ethanol water azeotrope containing 95% ethanol.

Mixture of this product at a ratio of 1:9 with ordinary gasoline burned well and cleanly in a conventional internal combustion engine, after minor adjustment of the carburetor. A nutritive distillation residue was also formed.

WHAT I CLAIM IS: 1. A process for the combined production of a liquid fuel and a nutritive residue from solid-containing waste material comprising a biomass, which process comprises separating the biomass from the waste, comminuting the biomass, subjecting the biomass to acid hydrolysis at a temperature and pressure sufficient to render the organic portion of the biomass substantially watersoluble and to convert the said portion into fermentable sugars, and fermenting the resultant product to form alcohol and a nutritive residue, wherein the hydrolysis step is carrid out in the presence of sulphurous acid as a hydrolysis catalyst, the fermented resultant product is filtered so as to separate out a filtrate and a nutritive residue, and the filtrate is distilled so as to obtain a liquid fuel containing alcohol and a nutritive residue.

Claim 2. A process as claimed in claim 1 wherein the separation step includes separating metallic materials in the waste material, separating the friable and non-friable materials in the waste material; and friable materials principally consisting of brittle plastics materials, bone and glass and containing the biomass, and the non-friable materials principally consisting of leather, paper, fabrics, gristle, films of plastics materials and rubber, and separating the friable materials and the biomass by flotation in water; this separation step including steeping in water the hydrolyzable material of the biomass.

Claim 3. A process as claimed in claim 2 wherein the separation step of the metallic materials comprises a magnetic separation step enabling magnetic metals in the waste material to be recovered.

Claim 4. A process as claimed in either claim 2 or claim 3 wherein the separtion step of friable and non-friable materials comprises comminuting and then screening the waste materials; the friable materials passing through the screen, and the non-friable materials not pass therethrough.

Claims 5. A process as claimed in any one of the preceding claims wherein the residue from the filtering of the fermented resultant product is subjected to sterilisation before being used to produce a nutritive product.

Claim 6. A process as claimed in claim I substantially as hereinbefore described with reference to the accompanying drawings.

Claim 7. A process as claimed in claim I substantially as hereinbefore described in any one of the Specific Examples.

Claim 8. A liquid fuel containing alcohol when produced by a process as claimed in any one of the preceding claims.

Claim 9. A plant or animal food consisting of or comprising a nutritive residue when produced by a process as claimed in any one of the preceding claims.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. water azeotrope containing 95% ethanol. Mixture of this product at a ratio of 1:9 with ordinary gasoline burned well and cleanly in a conventional internal combustion engine, after minor adjustment of the carburetor. A nutritive distillation residue was also formed. WHAT I CLAIM IS:

1. A process for the combined production of a liquid fuel and a nutritive residue from solid-containing waste material comprising a biomass, which process comprises separating the biomass from the waste, comminuting the biomass, subjecting the biomass to acid hydrolysis at a temperature and pressure sufficient to render the organic portion of the biomass substantially watersoluble and to convert the said portion into fermentable sugars, and fermenting the resultant product to form alcohol and a nutritive residue, wherein the hydrolysis step is carrid out in the presence of sulphurous acid as a hydrolysis catalyst, the fermented resultant product is filtered so as to separate out a filtrate and a nutritive residue, and the filtrate is distilled so as to obtain a liquid fuel containing alcohol and a nutritive residue.

Claim 2. A process as claimed in claim 1 wherein the separation step includes separating metallic materials in the waste material, separating the friable and non-friable materials in the waste material; and friable materials principally consisting of brittle plastics materials, bone and glass and containing the biomass, and the non-friable materials principally consisting of leather, paper, fabrics, gristle, films of plastics materials and rubber, and separating the friable materials and the biomass by flotation in water; this separation step including steeping in water the hydrolyzable material of the biomass.

Claim 3. A process as claimed in claim 2 wherein the separation step of the metallic materials comprises a magnetic separation step enabling magnetic metals in the waste material to be recovered.

Claim 4. A process as claimed in either claim 2 or claim 3 wherein the separtion step of friable and non-friable materials comprises comminuting and then screening the waste materials; the friable materials passing through the screen, and the non-friable materials not pass therethrough.

Claims

5. A process as claimed in any one of the preceding claims wherein the residue from the filtering of the fermented resultant product is subjected to sterilisation before being used to produce a nutritive product.

Claim 6. A process as claimed in claim I substantially as hereinbefore described with reference to the accompanying drawings.

Claim 7. A process as claimed in claim I substantially as hereinbefore described in any one of the Specific Examples.

Claim 8. A liquid fuel containing alcohol when produced by a process as claimed in any one of the preceding claims.

Claim 9. A plant or animal food consisting of or comprising a nutritive residue when produced by a process as claimed in any one of the preceding claims.