Method and apparatus for separation of chemical materials from feces

Abstract

A method and apparatus for treatment of feces is present in which usable organic and inorganic chemical compounds and substances are extracted from the fecal material for reuse. The process and apparatus includes receiving a mixture of fecal material from various sources, separating the liquid from the solids for further processing or disposal, mixing the solids with an acid and/or solvent solution to break down the solids into components to be extracted, filtering solids from the mixture, distilling the filtrate to remove remaining solvents, reacting the remaining solids with a metal hydroxide solution to yield fats, fatty acids, oils, alcohols, sugars, and other minerals, and further processing these materials to produce lubricants, grease, emulsifiers, biodiesel, fuels and/or fertilizers.

Description

FIELD

The present invention relates to a method and apparatus for treatment of feces, and more particularly, to a method and apparatus for the separation, reuse and recycling of various organic and inorganic chemical compounds found in feces.

BACKGROUND

Disposal and/or treatment of feces produced daily by humans and livestock is a growing problem. As the human population grows, existing treatment plants become overburdened or outdated and new treatment plants must be built. More livestock are raised to meet the growing food needs of the human population resulting in an increase in animal waste. Additionally, a current practice is to concentrate more livestock in smaller areas to improve efficiency and increase the profitability of the livestock operation. This concentration creates a greater burden on the waste control, removal and treatment system. This waste is a problem from the standpoint of cost associated with handling and disposing of so many tons per day. Many small cities faced with a growing local population are sometimes put in a position where they must either spend large amounts of money to increase their waste treatment facilities or run the risk of possible contamination to water supplies due to an overburdened system.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for the separation of chemical materials from feces (human, pig, cattle and fowl, for example). Raw feces is collected and an array of unit operations are performed in a specified manner to extract organic material from the feces. This allows for the capturing and reuse of certain chemical materials present in feces. All feces from all mammals are about the same in makeup. The differences are in the percentages of different chemical groups and the types of individual materials found. However, the treatment of the feces these sources will be the same for the others. The collection points may be from a municipal waste facility for human feces or from a farm feces collection area.

The above aim is reached by this combination of unit operations that allows separation of some of the chemical groups from other chemical groups in the organic portions present in feces.

There are many processes that can be used to separate some of this water from the solids although different methods and conditions will vary the amount of dewatering possible. Centrifugation, filtering and dehydration are all common and well known methods. All of these methods have different efficiencies and costs. In the present invention, the preferred method is pressure filtration which is utilized due to its efficiency and low cost. It has been used in sewerage waste treatment plants for many years is capable of producing a filtrate that is consistently less than 1% in solids and a filter cake that is at least 25% percent solids. The filtrate may be treated with enzymes and yeast to produce an alcohol.

In the raw mix tank the organic portion of the feces is mixed with an organic solvent such as aliphatic, ketone, ether or alcohol, for example. This allows a portion of the organic chemicals in the feces to dissolve. The mixture is then pumped or augured to a raw filter tank. Here the solids that did not dissolve in the organic solvent are separated from the liquid and sent to a washed raw solids holding tank for disposal or to be further processed.

The liquid from the raw filter tank is sent to a filtrate holding tank where it awaits the next step. The filtrate holding tank also serves as a serge tank to allow for the proper amount of liquid to be sent to the next unit operation which is the distillation unit.

In the distillation unit, the solvent is distilled from the solids and the solvent sent back to a solvent holding tank to be reused. The solids left after distillation are pumped or augured to the solids holding tank. This tank also acts as a surge tank to allow the proper amount of solid material to be sent to the next step, which is mixing with a metal hydroxide solution.

It's here that the solids are mixed with the metal hydroxide dissolved in water and agitated. Certain acidic components of the solids will react with the metal hydroxide to form the metallic salt of the acidic components. These will be in solution in the water stage with the excess metal hydroxide. There will also be some other organic materials that will not react or be affected by the metal hydroxide. These will stay in the organic phase and there will be a phase separation.

This material is then pumped to a separation tank. There are many ways of separating a two phase system. Centrifugation can be utilized. It's quite common and well known in the chemical industry. Another type of separation is settling, where the two components will separate due to their differences in polarity and density. In this case the nonpolar phase and other viscous liquids will float atop of the aqueous phase containing the unused metal hydroxide and acidic salts in solution.

The nonpolar phase and viscous liquids are then pumped or augured to the solids holding tank for shipping and the aqueous phase containing the metal hydroxide and acidic salts in solution are sent to another tank for shipping.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic illustration of the process and apparatus of the present invention for treatment of waste.

DETAILED DESCRIPTION

Referring to the FIGURE, a method and apparatus for separation of chemical materials from feces is generally indicated by reference numeral 10. Feces is brought into the plant and sent to a feces holding tank 100. At this point the fecal material may be from 4% to 50% solids as the remainder is water and water soluble minerals. From the feces or waste collection point 100 the feces is pumped 102 through a screen filter 104 or other commercially common filtering media to remove large objects and any large debris such as sticks, leaves, plastic bottles and cans, for example. The remaining water and solids are mixed either inline or in a mix tank 106 or other commercially common mixer including a mix tank with a motor driven shaft and impeller. From here the blended material is sent through a pressurized filter 108 to remove as much water as possible. This operation could be a belt press filter or other commercially available pressure filter that squeezes or somehow releases as much water or aqueous solution as possible from the solid material.

The water filtrate is pumped to an aqueous filtrate holding tank 110. The water may be processed further or disposed. Generally, the water is low in sugars but, depending on the source of the feces or waste, the water may be further processed to remove the sugars and carbohydrates to be fermented to produce ethyl alcohol. Additionally, the water filtrate typically includes nitrogen, phosphorus and amino acids, for example, which may be used as a fertilizer.

From here the dewatered solids may be sent to a dryer where almost all of the water is dehydrated from the solids, leaving the solids as a granular or powder material. To obtain the most surface area for the material it may be put through a grinder, ball mill or other commercially available unit operation to make smaller particles and increase reactive surface area. The solids are then delivered, either by pump or auger elevator or pneumatically 112 to a solids cake holding tank 114.

From here the material is delivered either by auger or pump 116 to a mix tank 118 where the solids are mixed with a small amount of acid 120 and solvent 122 mixture or solvent alone. Tank 118 is a closed mix tank where the solids are mixed with an acid solvent blend consisting of an acid where the pH may be between 0.0 and 6.5. Depending on the composition of the solids, the ratio of acid to solvent in the acid solvent blend may be one acid to 100 solvent by weight or may be 100 acid to one solvent. The solids may be mixed with either this acid solvent blend or with a pure solvent or a mixture of solvents without adding any acid. The solvent may be an aromatic, aliphatic, ketone, ether or alcohol, for example. The solvent may also be a mixture of the solvents mentioned. The ratio of the weight of acid solvent blend or solvent (now called the liquid to weight of dry solids) may be one to one or as high as one part dry solid to eighty parts liquid.

The mixture at this point may be heated to speed the reaction of the solids with the acid and/or solvent. At this point oxygen or other gases released from the mixture through the reaction with acid may be driven from the closed mix tank 118 by flushing with nitrogen or an inert gas, for example, or the gases be left in the tank. The mixture is stirred in the tank by a mixing device such as a motor with a shaft and propeller or by recirculating with a pump or by an inline pump. The time of mixing may be from one minute to twenty four hours depending on the reaction speed of the mixture. The fecal material can be mixed anywhere from one to four times with this liquid and allowing the mixture to rest between mix cycles, or a countercurrent continuous wash may be used.

After mixing, the material is filtered, either in the same mix tank, or a tank specifically designed for filtering. Pressure filtering or centrifugation may also be used. The mixture is pumped 124 to a filter tank 126 to filter out any material that is not in solution which is pumped or augured to a solids holding tank 128 for further processing or disposal. From here the liquid material is pumped or augured 130 to a liquids holding tank 132 for further processing. The liquid at this stage now contains the extracted material released from the feces during the mixing stage.

From here the liquid containing material extracted in solution from the feces is pumped 134 to a distillation unit 136 where the liquid can be separated from the material extracted from the feces. The extracted material is the product desired. Solvent is distilled off through a distillation line 138 to a solvent holding tank 140. The solvent is condensed and may be pumped 142 to the mix tank 118 for reuse in the cycle.

The solids left after distillation are pumped or augured to the solids holding tank 144. It should be understood that the solids may include viscous liquids or oils that have a higher boiling point than the distilled solvent, and thus remain with the solids. This tank also acts as a surge tank to allow the proper amount of solid material to be sent to the next step, which is mixing with a metal hydroxide solution. Solids from the solids holding tank are sent to a mix tank 146 to be mixed with the metal hydroxide dissolved in water. Certain acidic components of the solids will react with the metal hydroxide to form the metallic salt of the acidic components. These will be in solution in the water stage with the excess metal hydroxide. There will also be some other organic materials that will not react or be affected by the metal hydroxide. These will stay in the organic phase and there will be a phase separation.

After the reaction with the metal hydroxide, the material is pumped to a separation tank 148. There are many ways of separating a two phase system. Centrifugation may be utilized. Another type of separation is settling, where the two components will separate due to their differences in polarity and density. In this case the polar phase will float atop of the aqueous phase containing the unused metal hydroxide and acidic salts in solution.

The solids are then pumped or augured to the solids holding tank 150 for shipping or further treatment. The fats or fatty acids in the solids may be reacted with potassium to create a water soluble lubricant, for example, or reacted with magnesium or calcium to form a grease. The oils resulting from the reaction may be used as a lubricant or may be further reacted with sodium hydroxide, commonly known as lye, and methanol to create biodiesel. The aqueous phase containing the metal hydroxide and acidic salts in solution are sent to another tank 152 for shipping or further processing. The long chain alcohols remaining in the liquid may be used for fuel or emulsifiers, for example.

It is to be understood that while certain forms of this invention have been illustrated and described, it is not limited thereto, except in so far as such limitations are included in the following claims and allowable equivalents thereof.

Claims

1. A method for treating feces comprising:

a. receiving dehydrated solid fecal material,

b. mixing said dehydrated solid fecal material with an acid and/or solvent solution,

c. removing solids from the mixture to yield a filtrate,

d. distilling the solvent from the filtrate to yield a solid material,

e. mixing the solid material with a metal hydroxide solution to yield fats and/or fatty acids and a liquid, and

f. separating the fats and/or fatty acids from the liquid.

2. The method as set forth in claim 1 wherein step b includes mixing said dehydrated solid with an acid solvent blend wherein said blend is between one part acid to one hundred parts solvent and one hundred parts acid to one part solvent.

3. The method as set forth in claim 1 wherein step b includes a solvent solution selected from the group consisting of aromatic, aliphatic, ketone, ether and alcohol.

4. The method as set forth in claim 1 wherein step b includes mixing said dehydrated solid and an acid solvent blend for a period of up to about 24 hours.

5. The method as set forth in claim 1 wherein step b includes heating said mixture.

6. The method as set forth in claim 1 wherein step b includes mixing said dehydrated solid and said acid and/or solvent solution one to four times allowing the mixture to rest between mixing.

7. The method as set forth in claim 1 wherein the final pH of the liquid solution from step e is between 7.0 and 13.5.

8. The method as set forth in claim 1 further comprising:

g. separating oils from said liquid.

9. The method as set forth in claim 1 further comprising:

g. separating alcohols from said liquid.

10. A method for treating feces comprising:

a. receiving a mixture of a liquid and fecal material;

b. removing the liquid in step a from said fecal material;

c. dehydrating said fecal material to yield a dehydrated solid fecal material;

d. mixing said dehydrated solid fecal material with an acid and/or solvent solution,

e. removing solids from the mixture to yield a filtrate,

f. distilling the solvent from the filtrate to yield a solid material,

g. mixing the solid material with a metal hydroxide solution to yield fats and/or fatty acids and a liquid, and

h. separating the fats and/or fatty acids from the liquid in step g.

11. The method as set forth in claim 10 wherein step b further includes separating the liquid into a sugar containing solution and a nonsugar containing solution.

12. The method as set forth in claim 11 wherein said step b further includes fermenting said sugar containing solution to yield ethyl alcohol.

13. The method as set forth in claim 10 wherein step d includes mixing said dehydrated solid with an acid solvent blend wherein said blend is between one part acid to one hundred parts solvent and one hundred parts acid to one part solvent.

14. The method as set forth in claim 10 wherein step d includes a solvent solution selected from the group consisting of aromatic, aliphatic, ketone, ether and alcohol.

15. The method as set forth in claim 10 wherein step d includes mixing said dehydrated solid and an acid solvent blend for a period of up to about 24 hours.

16. The method as set forth in claim 10 wherein step d includes heating said mixture.

17. The method as set forth in claim 10 wherein step d includes mixing said dehydrated solid and said acid and/or solvent solution one to four times allowing the mixture to rest between mixing.

18. The method as set forth in claim 10 wherein the final pH of the liquid solution from step g is between 7.0 and 13.5.

19. The method as set forth in claim 10 further comprising:

i. separating oils from said liquid.

20. The method as set forth in claim 19 further comprising:

j. reacting said oil with sodium hydroxide and methanol to yield a biodiesel.

21. The method as set forth in claim 10 further comprising:

i. separating alcohols from said liquid in step h.

22. The method as set forth in claim 10 further comprising:

i. reacting said fat and/or fatty acids with potassium to yield a lubricant.

23. The method as set forth in claim 10 further comprising:

i. reacting said fats and/or fatty acids with magnesium or calcium to yield a grease.

24. An apparatus for treating feces comprising:

a solids holding tank for storing solid fecal material;

a first mix tank in communication with said solids holding tank for mixing said solid fecal material with an acid and/or solvent solution,

a pump in communication with said first mix tank for transferring a mixture from said first mix tank through a filter to remove solids from the mixture and transfer a remaining liquid solution to a distillation unit,

said distillation unit for distilling solvent from said liquid solution to yield a washed solid material,

a second mix tank in communication with said distillation unit for mixing said washed solid material with a metal hydroxide solution to yield fats, fatty acids, oils, and/or alcohols.

25. The apparatus as set forth in claim 24 further comprising:

a feces holding tank for receiving fecal material,

a first filter screen in communication with said feces holding tank for removing debris from said fecal material,

an inline mixer in communication with said first screen filter for blending said fecal material,

a pressurized filter in communication with said inline mixer for removing liquid from said blended fecal material to yield a solid fecal material, and

an augur for transferring said solid fecal material to said solids holding tank.

26. The apparatus as set forth in claim 25 further comprising a dehydrator for removing substantially all remaining water from said solid fecal material before transfer to said solids holding tank.

27. The apparatus as set forth in claim 25 further comprising a filtrate holding tank for receiving said liquid removed from said blended fecal material by said pressurized filter.

28. The apparatus as set forth in claim 24 further comprising a solvent holding tank for receiving solvent from said distillation unit.