Patent EA-000148-B1 (EA)
Title: Fertilizer and process for production thereof
Inventor: FJELLDAL ERLING
IPC: C05F9/00
Filed: 1996-04-18
Abstract: 1. A process for producing a fertilizer from an organic waste material having a water content of no more than 90% by weight and a pH of approximately 9.0 or above which comprises introducing nitrogen dioxide or a precursor thereof into said waste material in sufficient amount to reduce the pH by at least 2.0 pH units. 2. A process for producing a fertilizer from an organic waste material, said material comprising no more than about 90% by weight water which process comprises the steps of: (a) adding an alkali to said organic waste material in sufficient amount to increase the pH by at least 2.0 pH units and (b) introducing nitrogen dioxide (NO2) or a precursor thereof into the material produced in step (a) in sufficient amount to reduce the pH by at least 2.0 pH units with the proviso that the alkali used in step (a) is not ammonia (NH3). 3. A process as claimed in Claim 2 wherein said alkali is added in sufficient amount to increase the pH to 10.0 or above and said NO2 or precursor thereof is added in sufficient amount to reduce the pH to 8.0 or below. 4. A process as claimed in Claim 2 or Claim 3 wherein the NO2, or precursor thereof is added in sufficient amount in step (b) to counteract the increase in pH caused by the alkali added in step (a) so that the pH is substantially restored to that of the starting material. 5. A process as claimed in Claim 2 or Claim 3 wherein the amount of NO2 or precursor thereof added in step (b) is in excess of that required to restore the pH of the waste to that of the starting material and the process comprises the additional step (c) of introducing ammonia (NH3) into said waste. 6. A process as claimed in Claim 1 wherein the amount of NO2 or precursor thereof added is in excess of that required to restore the pH of said waste to neutrality and the process comprises the additional step of introducing ammonia into said waste. 7. A process as claimed in Claim 1 or Claim 6 wherein after addition of said NO2 or precursor thereof or of ammonia said waste material is dried. 8. A process as claimed in any one of Claims 2 to 4 wherein the material produced in step (b) is dried. 9. A process as claimed in Claim 5 wherein the material produced in step (c) is dried. 10. A process as claimed in any one of the preceding Claims wherein said organic waste material is agricultural, industrial or household waste or sewage sludge. 11. A process as claimed in any one of the preceding Claims wherein said organic waste material comprises between 50 and 90% water by weight. 12. A process as claimed in Claim 11 wherein said organic waste material has a solids content of between 20 and 35% by weight. 13. A process as claimed in any one of the preceding Claims wherein prior to the process of fertilizer production, said organic waste material is passed through a grinder or cutter to create a slurry of uniform particle size. 14. A process as claimed in any one of the preceding Claims wherein prior to the process of fertilizer production, said organic waste material is analyzed for content of plant nutrients, metals and toxins. 15. A process as claimed in any one of Claims 2 to 5 and 7 to 14 wherein the alkali added in step (a) is selected from CaO, KOH, Ca(OH)2 and CaCO3. 16. A process as claimed in Claim 15 wherein the alkali added in step (a) is CaO. 17. A process as claimed in any one of the preceding Claims wherein said NO2 is introduced into the organic waste material in the form of a gas or a liquid. 18. A process as claimed in Claim 17 wherein said NO2 is co-injected into said organic waste material with oxygen. 19. A process as claimed in Claim 17 wherein prior to or after the introduction of said NO2 or precursor thereof oxygen is introduced into said waste material. 20. A process as claimed in any one of Claims 1 to 19 wherein said NO2 is introduced into the organic waste material as a precursor thereof, for example nitrogen tetroxide. 21. A process as claimed in any one of the preceding Claims wherein the amount of NO2 added is from about 10% to about 45% by weight of the final product. 22. A process as claimed in any one of Claims 2 to 5 and 7 to 21 wherein prior to, during or after steps (a), (b) or (c) additional nutrients are added to the organic waste material. 23. A process as claimed in Claim 1 or Claim 6 wherein additional nutrients are added to said organic waste material. 24. A process as claimed in Claim 22 or Claim 23 wherein the additional nutrients are selected from nitrogen, phosphorus, calcium, magnesium, sulfur, potassium and the salts thereof. 25. A process as claimed in any one of the preceding Claims which is a batch process carried out in a sealed vessel. 26. A process as claimed in any one of the preceding Claims which is a continuous process. 27. A process as claimed in any one of Claims 7 to 26 wherein during the drying step the water content of said organic waste material is reduced to 20% or less by weight. 28. A process as claimed in Claim 27 wherein the dried organic fertilizer is formed into particles. 29. An organic waste based fertilizer wherein the percentage by weight of nitrogen in the form of oxides of nitrogen is higher than the percentage by weight of nitrogen in the form of ammonium ion. 30. An organic waste based fertilizer as claimed in Claim 29 wherein greater than 50% of the total nitrogen content thereof is in the form of nitrates and nitrites. 31. A fertilizer as claimed in Claim 29 or Claim 30 wherein the thermotolerant coliform bacteria count per gram is less than 2500.