CA1177181A - Industrial production of biological gases and composts through anaerobic fermentation of liquid manures - Google Patents

Abstract

The present invention relates to a plant for the treatment of fresh liquid manure having less than ten (10) working days while respecting the rules of hygiene and the environment while producing energy in the form of methane gas, a chemical product. secondary in the form of carbon dioxide and organic fertilizer. In the present invention in order to generate the maximum amount of methane gas, the anaerobic fermentation producing the biological gas is carried out by the anaerobic thermophilic bacteria operating under optimal conditions at the temperature of sixty (60) degrees centigrade? 5% and this fermentation takes place mainly in a sealed tank stirred with fermentation called the primary digester, while the post-fermentation and decantation of digested organic sludge occurs 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 being discharged outside the factory.

Description

MEMORY DESCRIPTION

The present invention relates to the production of a factory organic gas (biogas) and organic fertilizer (compost) from liquid manure.

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

But now the craft stadium has been replaced by pro-Industrial production, which poses very serious pollution problems because the tonnage of manure produced is enormous. There are currently in breeding in Quebec about four million (4,000,000) pigs which daily produce sixteen thousand (16,000) tonnes of liquid manure of.

Breeders in general get rid of it by spreading it dre during certain periods on cultivated land and this very often in too large a quantity without having fermented it. Of this way, pathogens and parasites proliferate and are found in agricultural products or pollute the water table ticks and rivers, which is very serious for the environment and public health.

So, by studying and experimenting with the different phenomena of thermophilic anaerobic fermentation, I discovered that was possible to build profitable processing plants liquid manure producing renewable energy and fertilizer ; -2-~ 3 ~;

organic while helping to clean up the environment and pre-serve our pure water resources.

Relative to the drawings which illustrate the realization of the note:
- Figure n 1 shows the block diagram of the factory.
- Figure 2 shows a plan view of the plant.
- Figure 3 shows an elevational view of the cut plant along the axis of the building and the secondary digester.

As planned to treat the liquid manure of 2OO 000 pigs, the factory operates as follows:

When the raw effluent arrives at the factory, the tankers contain liquid manure, pass over a weighing device (l) before emptying by pumping or gravity into a sealed waterproof device nant a receiving tank with a capacity of 2500 m3 (2). This volume makes it possible to store and distribute the effluent delivered by truck for a period of approximately 3 days. So a system crash would not cause a problem despite the delivery of 840 m3 / day.

From the receiving device, the effluent passes into a tank (3) where after mixing and dilution it is taken up by a pumping system (4) intended for very loaded effluent and which sends it into the device primary digestion. The operation of this part of the ins-tallation is fully automatic and is a function of:
digester which controls pumping, from the entry of the effluent into the tank and the automatic analyzer which controls the dilution and the brewing time as a function of the carbon / nitrogen ratio (C / N) which must be able to vary between 12 and 20/1 depending on the results of the fermentation anaerobic tion.

~ 1 ~ `7 ~ .81 After dilution and stirring the effluent is pumped to digestion primary which is carried out in a device composed of a tank in perfectly waterproof and insulated tank with a volume of 6,500 m3 (5) called the primary digester. This volume allows an ana fermentation robie lasting 7 days with a diluted effluent intake of approx.
ron 920 m3 / day. The mass in fermentation which must have the best their possible homogeneity is set in motion and stirred by the pumps provide for filling and which automatically ensure recirculation of the fermentation effluent thanks to a set of electric valves, ~ y-pass and piping (6) which allow collecting effluent from multiple locations in the diges-primary tor.

After 7 days of fermentation, the effluent collected at the part high of the primary digester is directed to a second device composed of a perfectly sealed and thermally insulated concrete tank area b the previous one but with a volume of 3 ~ ûO m3, which allows a Anaerobic fermentation lasting 3 days for entry of ef-920 m3 / day flow from the primary digester. This second digester is called secondary digester. These 920 m3 / day of eff-fluent in fermentation are transferred from one digester to the other by pump ~ designed for highly charged effluent identical to the previous-your.
In order to ensure good settling of the sludge, the secondary digester Daire does not involve mixing by recirculation of the effluent in fermentation.

In order to maintain optimum fermentation, the temperature of the mass should be maintained between 57 and 65 degrees centigrade. For that, r ~ heating devices called heat exchangers-r ~
hot water circulation are provided to exchange with the mass in ~ 7'71. ~

fermentation around 6.00U, 000 BTU maximum per hour (8). They ~ are composed of several elements that can work separately ~ é-and the same charged effluent pumps ensure mixing and circulation of the heated effluent (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 temperature sensors placed inside the digesters so to monitor the evolution of fermentation conditions.

This hot water intended to heat the digesters and the building is produced by Z boilers (9) of 4,000, noo BTU / hour, installed in the control building and running on methane gas produced by anaerobic fermentation.

In the event of a winter breakdown, a single boiler would be sufficient to maintain the correct temperature for several days.

Biogas produced in digesters by fermentation accumulates at the top of the digesters in a device called a bell gas (lO) and then it goes to purifying devices (11) and a large tank (12) where it is stored before it liquefies.

Through the overflow of the secondary digester (13), the effluent flows through gravity up to a device called a dancer-flocculator (14) where it will complete its purification.

From the lower part of the secondary digester where they accumulate slow, digested sludge is removed by hydro-static pressure (15) to a device composed of a pumping tank (16) and piston sludge pumps (17 ~ which direct this sludge to the dewatering devices called rotary vacuum ~ asseurs.

These devices are made up of large rotating cylinders in a basin filled with digested sludge (18). By creating a depression inside, the water filters through the canvas and flows then to the raw water tank. The dried mud cake is then detached from the outer surface of the canvas and a carpet transporter transports it to the storage location (19).

In addition to vacuum pumps, rotary dryers include coagulating reagent feed pumps and dosers.

At the outlet of the digester, the effluent still contains particles in suspension and it is necessary to completely purify it by secondary flocculation and decantation in a basin with compartments multiple elements (14) called decanter-flocculator.

The sludge collected at the bottom is also directed towards the sludge tank (16), while the purified effluent is cana-towards the outside of the station after clorination, treatment Alum and flow measurement (20).

Leaving the digester, the biogas abandons its sulfurous hydrogen 20 in a steel trimmer (11.1) (approximately 4 9. of ; H2S per m3). The purifier being double, half regenerates during while the other half is on duty.

The biogas then passes through a condenser (11,2) called a purifier.
H20 where it loses a good part of its humidity on elements refrigerants. Thereafter, the biogas is directed to the device storage in order to have a buffer volume. It is planned for the biogas a device that can contain around 8 hours of production of biological gas. This device called a gasometer (12) has a capacity useful city of about 12,000 m3. It is a classic tank gasometer metallic mobile and liquid ring sealing.

From the gasometer, the biogas is transported to the building of the pressers where methane is liquefied before being stored outside laughing (21), after separation of carbon dioxide (22).

Subsequently, for delivery to users, methane would be stored in pressure tanks (23) which, when total, can store 14 days of production or 8 tanks 2 ~ m3.

Similarly the production of carbon dioxide would be stored in 4 20 m3 tanks (24).

A room for the sale and shipment of different products (25) would also be planned in the factory building.

To function properly, this plant, absorbing 840 m3 / day of liquid manure, needs 3 men, 8 hours a day and 6 days per week, either:
l. A facility manager responsible for monitoring the order, general maintenance and relations with clients.

2. A mechanic-electrician responsible for repairs, lubrication and replacing the manager if necessary.

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3. A man to unload the lizier or liquid manure, the warehouse, heavy cleaning and deliveries.

4. In addition to this staff, it is necessary to plan 8750 hours per year of industrial surveillance.

The operation of the installation is fully automatic because all data concerning it is brought back to a mini-computer which is programmed to make the necessary decisions and 8U need remotely notify the direction of an incident such as: gas alarm, temperature, level, malfunction, etc.

In order to supply the plant with electrical energy, a substation is provided -phase transformer on pole 650 kVA 25,000 / 6ûO / 347 V - 60 Hz, connected by underground cable to the control building.

Plus 5 ~ a control panel containing all the equipment power 600 V as well as the auxiliaries, is provided to control all remote equipment and supply the installation.

In order for the factory to comply with hygiene regulations it will be provided 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.

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Treatment results (extrapolation of trials) ._ If liquid pig manure is used, the results of daily treatment of 840 m3 / day are as follows:
1. About 29,400 m3 / day of pure organic methane gas (27 TEP) 2. About 14,000 m3 / day of pure carbon dioxide.
3. About 110 tonnes / day of dry sludge.
4. About 650 m3 / day of purified water which is discharged into the sewer, the rest being recycled ~.

Claims (3)

The realizations of the invention, about which a right exclusive ownership or lien is claimed, are defined as following: 1. An industrial process producing biological gas and compost from organic liquid manure from pigs using the Thermophilic anaerobic microbial fermentation comprising:
a) A reception step in a device perfectly waterproof.
b) Optimal dilution and homogenization in a device perfectly waterproof, also allowing reheating and repression.
c) Primary fermentation in a perfectly iso-thermally brewed where thermophilic bacteria anaerobic acidogenic and methanogenic intimately mixed grow for seven (7) days at a temperature ambient of sixty degrees centigrade (60 ° C)? 5 percent;
d) Secondary fermentation and decantation in a dispo-perfectly thermally insulated sitive where bacteria methanogenic anaerobic thermophiles continue to develop lopper for three (3) days at an ambient temperature of sixty degrees centigrade (60 ° C)? 5 percent while allowing decantation and recovery of digested sludge rees;
e) Storage of the biogas in liquid form in a device also allowing it to be temporarily stored under its gaseous form to be able to purify it.

f) Treatment of the waste water in a decanting device tation-flocculation so as to make it conform to standards from the Ministry of the Environment before its rejection.
g) Dehydration by vacuum in a device which after pumping transforms the digested sludge into dry organic fertilizer (compost). 2. An industrial process such as that defined in the claim 1 where the dilution of organic liquid manure from animals such as beef or cow, horse, poultry, etc .;
human or household waste crushed and sorted so as not to serve as organic matter, is made so as to have a carbon to nitrogen ratio of between 12 and 20 out of 1 (C / N = 12/1 to 20/1). 3. An industrial process such as that defined in the claims I and II and having its processing capacity adapted to volume of liquid manure to be treated.