METHOD AND SYSTEM FOR THE PRODUCTION OF BIOFERTILISERS

• US 20090301150A1
• Filed: 06/02/2006
• Published: 12/10/2009
• Est. Priority Date: 06/02/2005
• Status: Active Grant

• Current Assignee: Institut De Recherche Et De Developpement En Agroenvironnement Inc. (IRDA)
• Original Assignee: Institut De Recherche Et De Developpement En Agroenvironnement Inc. (IRDA)
• Inventors: Dutil, Camil, Douhéret, Jocelyn, Chabot, Rock, Zegan, Dan
• Granted Patent: US 8,124,401 B2
• Time in Patent Office: Days
• US Class Current: 71/9
• CPC Class Codes: C02F 11/16 using drying or composting beds
• CPC Class Codes: C05F 17/40 Treatment of liquids or slurries
• CPC Class Codes: C05F 17/60 Heating or cooling during the treatment
• CPC Class Codes: C05F 3/00 Fertilisers from human or animal excrements, e.g. manure
• CPC Class Codes: C05F 3/06 Apparatus for the manufacture
• CPC Class Codes: C05F 7/00 Fertilisers from waste water, sewage sludge, sea slime, ooze or similar masses
• CPC Class Codes: Y02A 40/20 Fertilizers of biological origin, e.g. guano or fertilizers made from animal corpses
• CPC Class Codes: Y02P 20/129 Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
• CPC Class Codes: Y02P 20/133 Renewable energy sources, e.g. sunlight
• CPC Class Codes: Y02P 20/145 the feedstock being materials of biological origin
• CPC Class Codes: Y02W 10/30 Wastewater or sewage treatment systems using renewable energies
• CPC Class Codes: Y02W 10/37 using solar energy
• CPC Class Codes: Y02W 30/40 Bio-organic fraction processing; Production of fertilisers from the organic fraction of waste or refuse

Abstract

The invention relates to a method and a system for producing biofertilizers, from sludge that are stabilized, dried, and rich in fertilizing matters originating from high load effluent treatment method. Such solution may be integrated into an already existing treatment facility for industrial, municipal, or agronomical organic effluents (100), and is based on recovering the thermal energy created during the treatment steps of such system in bioreactors (120), air suppression units (122), biodrying units (500), drying units (600), and other units. Such recovery of energy creates a synergy that allows the increase of efficacy and yield of bioreactors (120) due to a greater stability from the temperature regulation, thus ensuring an important energy saving for the final drying step in producing biofertilizers.

Claims

1. A method for transforming high load sludge into dried biofertilizer comprising the steps of:

a. exothermic and aerobic treatment of high load effluent until reaching a sludge at least partially stabilized;

b. mixing at least partially the stabilized sludge with another sludge at least partially stabilized in order to obtain a percentage between about 25 and 50% of dried matter in the sludge mixture;

c. drying the sludge mixture using exothermic biodrying at a temperature between 50 and 75°

C., for a duration sufficient for obtaining a stabilized biofertilizer;

d. recovering the thermal energy released in at least one of steps a) and c) to direct it towards one of the drying units; and

e. drying the biofertilizer stabilized in step c) in the drying unit by applying the thermal energy recovered in step d) until obtaining a dried biofertilizer with a humidity level less than 30%.

2. The method of claim 1, characterized in that the sludge mixture includes a sludge at least partially stabilized and a stabilized biofertilizer obtained in step c) from a previous realization of the method.

3. The method of claim 1, characterized in that the sludge mixture includes a sludge at least partially stabilized and a dried biofertilizer obtained in step e) from a previous realization of the method.

4. The method of claim 1, characterized in that the realization of step c) reduces at least partially the pathogenic microorganisms population and the odors present in sludge or sludge mixture before executing step c).

5. The method of claim 1, characterized in that the thermal energy produced in step

a) is recovered in step d) and redirected towards step a) for regulating the temperature of said exothermic reaction to values ranging between 20 and 40°

C.

6. The method of claim 1, characterized in that the drying in step e) is realized at a temperature equal to or lower than 60°

C.

7. The method of claim 1, characterized in that the application of thermal energy to step e) is constant due to the continuous mode of execution of said method.

8. The method of claim 1, characterized in that the recovery of the thermal energy in step d) creates stale air, said stale air is filtrated before removal by passage through an element of the group including the high load effluent, the sludge at least partially stabilized, the sludge mixture, a dust removal unit, and a biofilter.

9. The method of claim 1, characterized in that at least one of the drying steps c) and e) uses the thermal energy from a source including the thermal energy released during step a), the thermal energy released during step c), and the thermal energy released during step e).

10. The method of claim 9, characterized in that the thermal energy comes from an auxiliary energy system, said auxiliary energy system including a system that uses solar energy, an electrical system, a gas system, a thermopump, and a system that may generate thermal energy.

11. A system for transforming a high load effluent into dried biofertilizers including:

i. a means of exothermal and aerobic treatment of a high load effluent enabling to obtain a sludge at least partially stabilized;

ii. a means for mixing sludge at least partially stabilized for obtaining a sludge mixture, said means being equipped with a dosing system for adjusting a parameter to a desired value, including the percentage of dried matters and degree of porosity of the sludge mixture;

iii. a biodrying means allowing exothermic reaction of the sludge mixture until obtaining a stabilized biofertilizer;

iv. a means of transferring thermal energy for recovering the thermal energy generated by at least one of the means of the group including the means for exothermal and aerobic treatment of a high load effluent, the means for sludge recovery, the means for sludge mixture, and the means for biodrying; and

v. a means of drying, fed in thermal energy by said means of thermal energy transfer.

12. The system of claim 11, characterized in that the biodrying means is equipped with a stirring means that allows the homogenization of the sludge mixture.

13. The system of claim 11, characterized in that the biodrying system is equipped with an aeration means that enables aerating the sludge mixture.

14. The system of claim 11, characterized in that the feeding of the drying means with thermal energy is constant due to the continuous mode of operation of said system.

15. The system of claim 11, characterized in that the means of energy transfer is a thermal exchanger or a thermopump.

16. The system of claim 11, including an auxiliary energy system that may provide an additional thermal energy through thermal energy transfer.

17. The system of claim 11, characterized in that the means of thermal energy transfer creates stale air, said means of thermal energy transfer including a means of filtration of said stale air before removing said stale air from the system.

18. The system of claim 17, characterized in that the filtration means is a system allowing the passage of the stale air through an element of the group including the high load effluent, the at least partially stabilized sludge, the sludge mixture, a dust removal unit, and a biofilter.