CA2098932A1 - Activated industrial production of biological gas and compost using liquid manure anaerobic mesophilic fermentation - Google Patents

Abstract

The present invention relates to a plant for the treatment of fresh organic liquid manure having less than ten (10) days, operating in compliance with the rules of hygiene and the environment while producing energy in the form of methane gas, a secondary chemical in the form of carbon dioxide and organic fertilizer or as fuel. In the present invention in order to generate the maximum of methane gas, the anaerobic fermentation producing the biological gas is carried out by the anaerobic mesophilic bacteria operating under optimal conditions at the temperature of forty (40) degrees centigrade + 15% and this fermentation takes place. mainly in a sealed fermentation tank called primary digester-accelerator comprising above the fermentation area fixed horizontal or vertical runoff surfaces where microbial colonies proliferate. While the post-fermentation and decantation of the digested organic sludge takes place in a second sealed tank called the secondary digester. In order to comply with environmental standards, the waste water is treated in a flocculating decanter before it is discharged outside the plant or used by recirculation.

Description

2098 ~ 32 DESCRlPTlF MEMORY

The present invention relates to the production of a gas producing plant organic (biogas) and organic fertilizer (digestate) from organic manure liquids.

Approximately until 1960, liquid organic manures did not pose practically no problem because the production was low. The manure producer knew its value well as an organic fertilizer and, after fermentation, used it.
for his personal needs.

But now the artisanal stage has been replaced by production industrial which poses very serious pollution problems because the tonnage of manure - ~
product is huge. For example, there are currently in Quebec about five ~: ~
million (5,000,000) pigs producing twenty thousand (20,000) tonnes of liquid manure. ~ ~ -. .
'' Breeders usually get rid of it by spreading it for certain periods on the cultivated grounds and this very often in too great quantity without having it fermented. In this way, pathogens and parasites proliferate and end up in agricultural products or pollute the water table and rivers, which is very serious for the environment and public health.

Likewise, household waste also currently poses serious environmental problems because the tonnage produced in developed countries is enormous (around 1 ton / year per inhabitant).

Modern processes now shred garbage and sorting so as to keep only organic matter which, under liquid sludge can ferment like liquid organic manure from animals.

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So, by studying and experimenting with the different phenomena of anaerobic mesophilic fermentation, I discovered that it was possible to build profitable liquid organic manure processing plants producing energy renewable and organic energy while helping to clean up the environment and to preserve our pure water resources.

Relative to the drawings which illustrate the embodiment of the invention ~

- Figure 1 shows the block diagram of the plant. ~ `
- Figure 2 shows a plan view of the plant.
- Figure No. 3 shows an elevational view of the plant cut following the perpendicular axis of the building and the primary digester-accelerator;
- Figure No. 4 shows an elevational view of the plant cut following the axis of the building and the secondary digester.

Designed to treat dilute organic sludge produced by around 300 t / day of organic household waste or liquid manure from 200,000 pigs, or approximately 960m3 / day, the factory operates as follows:
, On arrival of the raw influent at the fermentation plant by pumping or by tankers, liquid organic manures pass through a weighing device (1) before emptying by pumping or gravity into a sealed device comprising a receiving tank with a capacity of 2000 m3 (2). This volume allows you to store and distribute the influent for a period of approximately 2 days. So a system failure would not cause any problem despite the arrival of 960 m3 / day.

From the receiving device, the influent passes into a tank (3) where after stirring and dilution it is taken up by a pumping system (4) designed to influence very loaded and sending it to the primary digestion device. The operation of this part of the installation is fully automatic and is a function of:

- 3 -digester which controls the pumping of the inlet of the influent into the tank and the automatic analyzer which, depending on the results of the anaerobic fermentation, controls the dilution and the brewing time as a function of the carbon / zote ratio (C / N) which must be able to vary between 6 and 22/1 and the percentage of organic matter dryer which must be able to vary between 6 and 35 ~ / o.

After dilution and mixing, the influent is pumped to the primary digestion which takes place in a device composed of a perfectly watertight concrete tank and insulated called primary digester-accelerator with a volume of 9000 m3 (~) which allows anaerobic fermentation lasting 5.5 to 7 days with a dilute inflow of approximately 960 m3 / day.

This tank mainly consists ~

- Of a high part before a volume of approximately 2000 m3, where by pumping (6) the effluent drips on inclined or vertical horizontal surfaces which serve as habitats and places of development for bacteria acidogenic and methanogenic mesophiles (7). These rough surfaces are designed to provide a minimum of one square meter per 100 kilograms / day of volatile solids sent to the tank.
, - Of a lower part (8! ~ Before a volume of about 7000 m3, where the effluent builds up after trickling on inclines.
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This mass in fermentation, which must have the best homogeneity possible, is set in motion and stirred by the pumps provided for filling ~ -

(4) and which automatically recirculate the effluent in fermentation thanks to to a set of electric valves, by-pass and pipes (9) which also allow effluent removal ~ from multiple locations in the digester-accelerator primary. Brewing can also be carried out by insufflation of biogas.
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r ~ 20 ~ 98932 After 5.5 to 7 days of fermentation, the effluent collected at the part center of the primary digester-accelerator is directed to a second compound device ~
a perfectly sealed and thermally insulated concrete tank, similar to the lower part of the previous one but with a volume of 3000m3, which allows an anaerobic fermentation lasting a maximum of 3 days for an effluent inlet of 810 m3 / day from of the primary digester-accelerator. This second digester is called a digester secondary (10). These 810 m3 of fermentation effluent are transferred from a digester to the other by pumps intended for very charged effluent identical to the previous ones (4).

In order to ensure good settling of sludge, the secondary digester does not no mixing by recirculation of the effluent in fermentation.

In order to maintain optimum fermentation, the temperature of the mass must be maintained between 36 and 45 degrees centigrade. For this, heating called heat exchangers with circulation of hot water are provided for exchange with the fermenting mass around 14,000,000 BTU maximum per hour (11). They would be composed of several elements that can work separately and the same charged effluent pumps ensure mixing and circulation of the effluent reheated (4).
, At certain levels, samples are taken to monitor the sludge fermentation and temperature.

The flow of hot water in the exchangers would be controlled by sensors temperature placed inside the primary digester so as to monitor changes in fermentation conditions.

This hot water intended to heat the primary digester and the building is produced by 2 boilers (12) of 10,000.00 BTU / hour, installed in the building control and operating either with methane gas produced by anaerobic fermentation, either electrically or by burning the digestate produced.

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In the event of a winter breakdown, a single boiler would be sufficient to maintain the correct temperature for several days. ~;
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The biogas produced in digesters by fermentation accumulates at the -upper part of the digesters in devices called gas bell (13) and it goes then to purifiers (14) and a large tank (15) where it is stored before compression and processing.

At the outlet of the secondary digester (16), through the overflow, the effluent still contains dissolved nitrogen and suspended particles and it is necessary to purify it completely by secondary flocculation and settling in a basin at:; -multiple compartments (17) called decanter-flocculator. ~ ~, The purified effluent is channeled to the outside of the station after chlorination, treatment with Alum and measurement of the flow rate (23). Depending on the type of factory, it will be reused or rejected outside. The sludge collected at the bottom is also directed towards the sludge tank (18). i ~

From the bottom of the secondary digester where they accumulate, the digested sludge is removed by hydro-static pressure (18) to a compound device a pumping tank (19) and piston sludge pumps (20) which direct these sludge to dewatering devices called rotary vacuum dryers. -These devices are made up of large canvas cylinders rotating in a basin filled with digested sludge (21). By creating a vacuum inside, the water filters through the canvas and flows to the raw water tank. The sludge cake is then detached from the outer surface of the canvas and a conveyor belt transports it to the storage location (22) after passing through a dehydrator.

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In addition to the vacuum pumps the rotary dryers include pumps of coagulant reagents.

Leaving the digesters, the biogas abandons its sulfurous hydrogen in a steel paring device (14.1) (approx. 1 g maximum of H2S per m3). The purifier being double, one half regenerates while the other half is in service.

The biogas then passes through a condenser (14.2) called the H20 scrubber.
where it loses most of its moisture on cooling elements. Over there the biogas is then directed to the storage device. In order to have a volume buffer, there is provision for biogas a device which can contain approximately 3 hours of production of biological gas. This device called a gasometer (15) has a useful capacity about 4,000 m3. It is a classic gasometer with metallic mobile tank and sealing by liquid ring.

From the gasometer, the biogas is transported to the building of compressors where methane is compressed before being stored outside (24) and after separation of the carbon dioxide (25) during the purification treatment. .
, Subsequently, for delivery to users, methane would be stored in pressure tanks (26) which, in total, can store 2 days of production, i.e. 6 tanks of 30 m3.

Similarly the production of carbon dioxide would be stored in 3 30 m3 tanks (27).

A room for the sale and shipment of different products (28):
would also be planned in the factory building.

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To function properly, the fermentation part of this plant, absorbing 960 m3 / day of liquid organic manure, needs 4 men, 8 hours per day and 6 days per week, that is:

1. A person in charge of the installation responsible for monitoring the order, -general maintenance and customer relations. ~ -2. A mechanic-electrician responsible for repairs, lubrication and replacement the manager if necessary. ; ~

3. Two men for the arrival of liquid manure, the warehouse, the large ones ~ ~ -cleanings and deliveries.

4. A part-time biochemist. ~;

5. In addition to this staff, it is necessary to plan 8750 hours per year - - ~ ~ ~ `s industrial surveillance.

The operation of the installation is fully automatic because all the data concerning it are rowed ~ ées to a mini-computer which is programmed for take the necessary decisions and if necessary notify the management of an incident remotely such as: gas, temperature, level, malfunction, etc. alarms In order to supply the fermentation part of the plant with electrical energy, it a three-phase transformer station of 200 KVA 25,000 / 600/347 V - 60 Hz is planned, connected by underground cable to the control building. In the case of heating electric, the transformer station will be planned for 500 kVA.

In addition, a control panel containing all the switchgear power 600 V as well as the auxiliaries, is provided to control all the equipment distance and supply the installation.

20g8932 In order for the factory to comply with hygiene regulations, provision will be made in the main building, a room containing a refectory, a cloakroom with sinks, showers, etc ...

Similarly, the main building will also contain a room serving office and a small workshop.

Treatment results (extrapolation of trials) A) If liquid organic pig manure is used, the results of daily treatment of 960 m3 / day are as follows:
1. About 18,000 m3 / day of pure organic methane gas (15.5 TEP) 2. About 9,000 m3 / day of pure carbon dioxide. -; -3. About 70 tonnes / day of dry sludge.
4. About 800 m3 / day of purified water which is discharged down the drain, or recycled.

NB: The results are slightly different depending on the source of the liquid organic manure: oxen, cows, chickens, etc.

B) For the Montreal region, if crushed household garbage is used and sorted to keep only organic matter, the results of daily treatment of 300 tonnes / day of organic matter are the following:
1. About 21,000 m3 / day of pure organic methane gas (18 TEP) 2. About 9,000 m3 / day of pure carbon dioxide. ~:
3. About 75 tonnes / day of dried sludge. ~ -4. About 800 m3 / day of purified water which is recycled.

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Claims (4)

Claims The achievements of the invention, in respect of which an exclusive right of ownership or privilege is claimed, are defined as follows: 1. A new industrial process continuously producing biological gas (biogas) and digestate from liquid organic matter using mesophilic anaerobic microbial and bacterial fermentation and having the following main characteristics:
a) a reception step in perfectly sealed devices compounds of watertight tanks for organic liquids and receiving surfaces placed in a slight depression for materials organic solids.
b) a step of grinding, dilution and homogenization in a device perfectly waterproof to obtain the following material levels organic:
- pig manure - lizier (OM = 3 to 6%) after concentration 8 to 10%? 5%
- cattle manure (OM = 3 to 6%) after concentration 8 to 10%? 5%
- chicken manure (OM = 35%) after dilution 8 to 10%? 5%
- fresh sewage sludge (OM = 2 to 5%) after concentration 8 to 10%? 5%
- septic tanks (MO = 3 to 4%) after concentration 8 to 10%? 5%
- organic matter from residues of crops (OM = 35%) after dilution 8 to 10%? 5%
- organic waste household (OM = 45%) after dilution 8 to 10%? 5%

and during this step, the body fluids are warmed before the discharge into the primary fermenter.
c) A primary fermentation step that takes place in a device sealed perfectly thermally insulated called primary digester having fixed contact and runoff surfaces installed inclined to offer with a minimum distance of 0.50 meter between them a surface rough minimum of one square meter per 100 kilograms / day of solids volatiles sent to the digester and to these contact surfaces, the acidogenic and methanogenic anaerobic mesophilic bacteria are develop depending on the nature of the organic matter for three to seven days at an average temperature of thirty-five degrees centigrade (35 ° C) ? 15 percent and that in a very well brewed atmosphere or the PH of the solution is maintained between 6.5 and 8.

d) A secondary fermentation step which takes place after pumping in a tight thermally insulated device called a digester secondary which is similar to the previous one but not stirred and without surface stationary contact to allow settling and recovery of fermented sludge and the final development of mesophilic bacteria anaerobic methanogens for two to four days at a temperature average of thirty-five degrees centigrade (35 ° C)? 15 percent and this in an environment where the pH of the solution is maintained between 7 and 8.

e) A stage of dehydration of the fermented sludge which after pumping is mechanically transformed by processes using vacuum, heat, filtering, etc. in dry organic amendment or fuel (4500 BTU / lbs).

f) A stage of storing the dry organic amendment called digestate and fuel derived from organic waste which is digestate that has undergone further drying to about 40% organic matter.

g) A stage of storing biogas produced by fermentation in a device for temporarily keeping it in its gaseous form after having purified it before its use in a cogeneration device.

h) A stage of treatment of the waste water in a device settling and flocculation so as to make it reusable without causing of fermentation poisoning and so as to comply with the standards of the ministries of the environment if it is necessary to reject it with the following maximum rates:
2. An industrial process such as that defined in claim 1 where the dilution of organic liquid from crushed and sorted household waste to keep only organic matter, human waste or animals such as pig, beef, cow, horse, poultry, etc.
is carried out so as to have a ratio of carbon to nitrogen included between 6 and 22 out of 1 (C / N = 6/1 to 22/1) depending on the products to be treated and a percentage of dry organic matter between 6 and 25%
depending on the products to be treated. 3. An industrial process as defined in claim 1 and having the treatment capacity adapted to the volume and nature of the liquid.
organic to be treated. 4. An industrial process as defined in claim 1 and suitable for body fluid that needs to be treated but operates with bacteria anaerobic thermophiles at a fermentation temperature of sixty degrees centigrade (60 ° C)? 10 percent.