CA2173085A1 - Process for the treatment of manure - Google Patents

Abstract

The process for treating slurry consisting of a liquid mixture of urine and faeces from domestic animals comprises the following steps: a) clarification by aeration of the slurry so as to obtain floating sludge over a liquid solution; b) purification of the liquid solution obtained in step (a) in a swamp of aquatic plants; c) recovering the sludge obtained in step (a) and mixing it with part of the aquatic plants mowed in the marsh of step (b) and biofermenting the mixture of sludge and aquatic plants to thereby obtain a valued product. The method according to the invention makes it possible to treat manure, and more particularly pig manure, efficiently and inexpensively so as to obtain an environmentally acceptable product, either a compost or litter for certain farms.

Description

- 2173 ~ 8 ~

PROCESS OF TRAll ~ .L. ~ HORSES

Dn ~ ATN ~ TECHNICAL

The present invention relates to the field of treatment or the development of animal manure. More in particular, the invention relates to a method for treating slurry to obtain a valued product such as compost, an organic, environmentally acceptable fertilizer.

BR ~ VE DESCRIPTION OF THE PREVIOUS L ~ nNlQUES

Currently, the disposal of slurry or liquid manure, more particularly the pig manure which is generally of liquid consistency at g0-95%, is done mainly by simple spreading in fields or in processing using mechanical presses or membranes filters. These different techniques generate serious economic, agricultural and environmental problems.

Economic problems Indeed, certain processes, such as the separation of solids using mechanical presses or membranes filters, require very high investments. The infrastructure and equipment costs required to the use of slurry is very high and the value residual product is very minimal. For exemple, in the field of pig manure processing, storage systems and pumping equipment, mixing, transport and spreading currently used can easily exceed $ Z00, aoo for a farm average. In such a case, the fertilizing value, once warehousing, transportation and spreading paid, achieved about $ 0.50 per pork produced.

2173 ~ 8 ~

Inconv ~ ni ~ nt ~ ~ ronomiq ~

In addition, in the majority of cases, and more particularly in cases where the spreading technique is used, it proves difficult to produce an overall plan of integrated fertilization. Indeed, in the processes of slurry treatment, you usually have to face the phosphorus buildup problem, not to mention others potential problems, such as heavy metals and others. The slurry contains very little organic matter and, at in the long run, we see soil degradation in which we observe a decrease in the buffering capacity. Of more, there is compaction of soils by the passage of very heavy tanks in the fields during spreading, which usually happens when the soils are very little dried up.

Environmental problems Apart from air pollution by the emanation of gases ammoniacal, sulfurous and others, the slurry is found often caused by rainwater in rivers neighboring or in the water table. This pollution causes enormous harm to aquatic life and degrades the water quality.
Methods for Treating Slurry Known in the Art do not effectively avoid problems mentioned above. In addition, the implementation of these processes generally requires investment very high.
There is therefore currently a real need for a process for treating slurry effectively, that is say in order to get a product environmentally acceptable and inexpensive.

~ 173Q85 DESCRIPTIaN SQuMATR ~ OF THE INVENTION

The present invention meets this need by proposing a process for treating slurry which does not require a very high investment and which allows obtaining a valued product, such as compost. More in particular, the subject of the present invention is a process for treating a slurry made up of a mixture liquid from urine and faeces from domestic animals, proceeded comprising the following steps:
a) clarification by aeration of the slurry so get floating sludge over a solution liquid;
b) purification of the liquid solution obtained at step (a) in a swamp of aquatic plants;
c) recovery of the sludge obtained in step (a) and mixture of these with part of the aquatic plants mowed in the marsh of step (b); and d) biofermentation of the mixture of sludge and plants aquatic to obtain a valued product.
Advantageously, the method according to the invention allows, from a slurry which generally has a consistency liquid ranging from g0-95% and giving off odors foul-smelling, to keep solids still good value, to turn all the other constituents into mud and aquatic plants to extract all their riches and ultimately get a good product quality and stabilized, using only processes organic produce with significant added value.
3a DESCRIPTION OF THE FIGURES

The characteristics of the present invention will be better understood in the following non-limiting reading of a preferred embodiment of the invention made in referring to the attached drawing, described below and in which:

2 1 ~ 3085 FIG. 1 represents a block diagram of a mode of preferred implementation of the method according to the invention.

DESCRIPTION OF ~ ATT.T. ~ OF AN EMBODIMENT
~ K ~ É OF L'NN ~ NllON

As shown in Figure 1, according to a mode of preferred embodiment of the present invention, a pool of clarification is fed with slurry (4) for treatment.
The slurry (4) is clarified in this basin by introducing therein air (5) or oxygen; this clarification (2) having due to bacterial and enzymatic degradation of the slurry (4) under aerobic conditions. Slurry is, of preferably treated in this basin for a period of at least two days. Sludge (6) floating above a clarified liquid solution are thus produced. Sludge (6) are collected and deposited in a mixer. The liquid clarified (8) is poured into a swamp of plants aquatic (10) to be purified. Part of the plants marsh (10) is harvested and preferably dried. These harvested plants (12) are then mixed (14) with the bacterial sludge (6) comprising solids and bacteria. This mixture of mud and plants (16) is then subjected to biofermentation stabilization (18), thus making it possible to obtain a valued product (20), usable as compost, agricultural fertilizer, or litter for certain farms.
Each of the clarification steps (2), of purification in the aquatic marsh (10) and biofermentation (18) will now be the subject of a more detailed description.

ClArifit ~ -Ation It has been observed that slurry, when brought into the gravity pits, lets out solid particles.
If the structure of the slurry is altered by pumping in 21 7 3 ~

of the storage tanks, the solid particles have tendency to end up at the bottom of the basin. This is due to the fact that faeces, as rejected by animals, contain gases which decrease the specific gravity, thus allowing flotation. The action of the turbine, used in the prior art to bring the liquid manure from the pre-pit to the storage tank, destroys the product structure and allows the escape of gases. The solid particles resulting from the process are found at tank bottom.
According to a preferred embodiment of the invention, slurry (4) is pumped from the pre-pit into tanks degradation using turbine pumps to to homogenize the product and reduce the solids finest particles possible. ~ in this basin, the slurry (4) is clarified by aeration, preferably by means membranes placed at the bottom of the basin letting out tiny air bubbles that produce oxygen necessary for the development of enzymes and bacteria present in the middle. For example, the products Flex-a-Tub manufactured by Parks and Corporation can be used to aerate the basin and thus allowing the clarification (2) of the slurry. The bacteria produce viscous sludges which are entrained on the surface by air bubbles. To these muds viscous stick the solid particles in slurry suspension, so that after a some time the liquid is almost completely cleared of all solid particles and will not contain substantially than organic and mineral salts in solution. Solids, i.e. sludge (6), are end up floating above a liquid solution (8) and are collected on the surface to be transported to Trademark 2 1 7 3 i ~ 8 5 a mixer. The liquid solution (8) then flows into a swamp of aquatic plants (10) to be purified there.
Preferably, the pH at the clarification stage should not not go lower than 6 nor go higher than 8, the ideal pH for maximum activity of varying bacteria between 7 and 8.
Preferably, the temperature at this stage is between 5 and 40 C, the ideal temperature for development of bacteria between 20 and 25 C.
To maximize ventilation throughout the mass liquid, the slurry is preferably stirred during its clarification. This mixing can be carried out thanks to a internal pumping or by other means known in the art field. In this way, the liquid is moving at the size of the pool, eliminating dead spots where can build up solids, reducing the effectiveness of separation system.
As the work of bacteria quickly eliminates gas fumes, the arrival of slurry is preferably done at the bottom of the basin using a pipe which can be designed for this purpose. Bad smells are then eliminated.

pllrificAtion ~ P 1 A. ~ 1 lltion li ~ li ~ e The marsh for aquatic plants (10) is fitted out for purifying the liquid solution (8) of all of its organic salts and minerals, leaving only pure water (11) which will evaporated by plants. Here, pure water means a water containing no polluting elements. Purification of a polluted solution in a swamp of aquatic plants is already known in the prior art. ~ in such a swamp, the soil in which the plants are installed contains usually enough clay to allow cation exchanges necessary ~ ~ Areas for purification work.
Preferably, a slight slope allows the flow of the liquid along the entire length of the marsh, and a pipeline ~ 73 ~ 5 ensures flow throughout its surface. To favor the development of a good (root) root system, the pelvis preferably has a minimum of 18 inches of depth. In order to facilitate the work of harvesting plants, the pond should not exceed 18 feet in width.
The liquid solution (8) flows from the clarification tank (2) at the marsh (10) by gravity, since in the preferred embodiment, the upper wall of the basin is more higher than the bottom of the swamp.
lo Preferably, the aquatic plants present in the marshes are chosen from the group consisting of phragmite australis, bulrush, inert bromine, phalaris, reed canarygrass, ryegrass and iris, ideal plant being the common phragmite or australis. This plant is very rustic and has the distinction of remaining active all year round. Even in winter under the snow, it does not loses only 20% of its effectiveness. To increase the quantity, and the quality of greenery produced, we can have recourse, in season, to other plant species known for their efficiency.
According to a preferred variant, the plants growing in the marsh, and more particularly the foliage of these plants, are harvested when they are the most nutritious, without harming the development of their root system. These plants harvested can then be dried and chopped, before to be mixed with the sludge (8) obtained during the clarification (2). This mixture of mud and dried plants (16) is then poured into a biofermentation bay.
For an ideal treatment, this mixture (16) is transferred when it reaches a humidity level between 55 and 60%.

Biofermentation When the mixture is introduced into the bay biofermentation, it normally has a C / N ratio of around ~ 17 ~

1/20, and it is likely to promote development bacteria. According to a preferred embodiment of the invention which accelerates the reaction, a certain amount of air (19) is injected into the mass, i.e. approximately 100 to 150 l / min of air per cubic meter of mixture. So, he there is a multiplication of thermophilic bacteria present, and their activity causes a rise in temperature up to around 175 F in less than 4 hours. For now this activity for 5 to 6 days, a stable product (odorless), easy to handle, and not at all offensive is obtained.
All of the above operations can advantageously be done under cover, building or greenhouse, allowing to overcome the disadvantages atmospheric, such as abundant rain in summer and very cold temperatures in winter, these extreme conditions can stop the production of plant matter in the swamp and thus reduce the supply of plant material which is important for obtaining a compostable mixture.
Although a preferred embodiment of the invention has been described in detail above and illustrated in the drawing annexed, the invention is not limited to this single mode of realization and several changes and modifications can be carried out by a person skilled in the art without go beyond the scope or spirit of the invention.

Claims (17)

1. A method for treating a slurry consisting of a liquid mixture of urine and faeces of domestic animals, including the following steps:
a) clarification by aeration of the slurry so get floating sludge above a liquid solution;
b) purification of the liquid solution obtained at step (a) in a swamp of aquatic plants;
c) recovery of the sludge obtained in step (a) and mixture of these with part of the plants aquatic mowns in the marsh of step (b);
and d) biofermentation of said mixture of sludge and plants aquatic to obtain a valued product. 2. The method according to claim 1, wherein the aquatic plants used in the marsh at the stage of purification (b) are chosen from the group consisting of phragmite australis, bulrush, inert bromine, phalaris, reed canarygrass, ryegrass and iris. 3. The method according to claim 2, wherein the Aquatic plants are made up of Phragmite australis. 4. The method of claim 2, comprising the step additional chopping and drying of aquatic plants before mixing with the sludge. 5. The method of claim 4, wherein said part of the aquatic plants mixed with the sludge to step (c) consists of a leaf of said plants. 6. The method according to claim 4, wherein the slurry is stirred during the clarification step (a). 7. The method of claim 6, wherein the clarification (a) takes place in an aeration tank comprising ventilation means located at the bottom of the pool. 8. The method according to claim 7, wherein the clarification (a) is carried out at a pH between 6 and 8. 9. The method according to claim 8, wherein the clarification (a) is carried out at a pH between 7 and 8. 10. The method of claim 9, wherein the clarification (a) takes place at a temperature included between 5 ° C and 40 ° C. 11. The method according to claim 10, wherein the clarification (a) takes place at a temperature included between 20 ° C and 25 ° C. 12. The method of claim 11, wherein the clarification step (a) has a duration of at least two days. 13. The method of claim 12, wherein the liquid solution is transferred from the aeration tank to stage (a) at the marsh of stage (b) by gravity. 14. The method according to claim 2, wherein the mixture of sludge and aquatic plants at one level humidity between 55 and 60% at the start of the biofermentation. 15. The method according to claim 14, in which the biofermentation stage (c), we inject between 100 and 150 l / min of air per cubic meter of said mixture of sludge and aquatic plants. 16. The method of claim 15, wherein the biofermentation stage (d) lasts from 4 to 5 days. 17. A method for treating a slurry consisting of a liquid mixture of urine and faeces of domestic animals, including the following steps:
a) clarification by aeration and mixing of the slurry to get floating sludge over a liquid solution, clarification taking place in an aeration tank comprising aeration means located at the bottom of the basin, at a pH between 6 and 8, and at a temperature between 5 ° C and 40 C, for a period of at least less two days;
b) purification of the liquid solution obtained at step (a) in a swamp of aquatic plants chosen from the group consisting of the phragmite australis, bulrush, inert bromine, phalaris, reed canarygrass, ryegrass and the iris;
c) recovery of the sludge obtained in step (a) and mixture of these with part of said chopped and dried aquatic plants; and d) biofermentation of said mixture of sludge and plants aquatic for a period of 4 to 5 days in injecting between 100 and 150 l / min of air per meter cube of said mixture to thus obtain a compost, said mixture having a humidity level between 55 and 60% at the start of the biofermentation stage.