A METHOD FOR TREATING AN ORGANIC SUBSTANCE

Abstract: It is possible to chemically treat a biomass in the form of domestic animal manure, slurry, organically loaded effluent waste water and the like, which makes it possible to separate the fertilizing substances N, P and K and to obtain a water fraction which meets the requirements for discharge directly to a recipient. This is obtained by treating fresh biomass mechanically and/or chemically, e.g. by simple precipitation and enzymatic decomposition of the fibre content or by degasification of the manure. Phorphorus and nitrogen in the pre-treated biomass are precipitated by adding chemical reactive agents. The reactive agents are caused to react with the nitrogen compounds and the phosphorus compounds present to form new compounds which can be precipitated. Any urea content is precipitated together with nitrogen and phosphorus. Potassium is also precipitated together with nitrogen and phosphorus before separation of the biomass into the liquid fraction and the fertilizer fraction. The chemical reactive agents comprise metal ions and organic and inorganic acids.

Description: A METHOD FOR TREATING AN ORGANIC SUBSTANCE Background of the Invention. The present invention relates to a method of treating a biomass in the form of domestic animal manure, slurry, organically loaded effluent waste water and the like, or mixtures thereof, and comprising a che¬ mical treatment of the biomass. Various methods are known in which a biomass is chemically treated in connection with the separation of the biomass. The chemical treatments are ordinarily used in connection with an adjustment of the pH-value of the liquid manure, e.g. in connection with biogas manufacture. In the treatment of a biomass in the form of domestic animal manure, biologically loaded effluent waste water and the like, it has up to now been difficult to separate the biomass into components which may be utilized or which may directly be disposed of. In connection with domestic animal manure, an insufficient separation has created the need for very large storage capacities. Furthermore, transport with the spreading of the very large quantities, which main¬ ly are constituted by water, create certain problems, as the spreading is only allowed to be effected at certain times of the year. Several attempts have been made to separate the water and the nutrient salts in order to concentrate the nutrient salts into a small volume so as to make it possible to reduce the costs for storage and spreading. At the same time, the aim has been to sufficiently purify the water to allow it to be discharged directly to a recipient in order thereby to avoid the high disposal charges to the purification plant. Up to now, it has been difficult to sufficiently remove nitrogen, phosphorus and potassium from the water to allow the latter to be discharged directly to a recipient. In the treatment of domestic animal manure, it is also necessary to remove urea before allowing discharge of a water frac¬ tion. It is the object of the invention to remedy the above mentioned pro¬ blems, not exclusively in connection with domestic animal manure but generally in connection with a biomass, by providing a method which makes it possible to separate the biomass into a small fraction which may be utilized as a fertilizer and a large fraction which may direct- ly be discharged to a recipient. According to the invention this is obtained with a method which is characterized in pre-treating a fresh biomass mechnically and/or chemically, measuring NH +., PO3.-, Ct-,2and K+, precipitating the nitrogen and phosphorus content of the pretreated biomass by adding in a stoichiometric ratio of 1:1 chemical reactive agents which are caused to react with the nitrogen compounds and the phosphorus compounds present in the biomass, precipitating any urea content together with the nitrogen, phosphorus and optional potassium content of the biomass, and subsequently separating the biomass into a liquid fraction and a fertilizer fraction. Description of the Drawing. The invention will now be explained in further detail with reference to the accompanying drawings wherein Fig. 1 illustrates a flow chart for a method according to the in¬ vention, and Fig. 2 illustrates a flow chart for an alternative method according to the invention. Tank 1 is intended to receive the fresh biomass. In case of domestic animal manure, the tank 1 receives the liquid manure in a quantity corresponding to one day's production as it is desired to treat the liquid manure as fast as possible in order to limit the decomposition of urease to urea which may result in am onification. In tank 2 the fiber fraction is separated by adding a flocculation agent 14. The total fibre fraction 5 is discharged and transferred to tank 9 in which chemicals 13 are added to adjust the pH-value. Subse- quently bacteria and enzymes are added to decompose the fibres and hence to liberate/extract nitrogen, phosphorus and potassium bound in the non-transformed fibre material. Thus, in tank 9 solid material is decomposed, e.g. lignocellulose, which facilitates a subsequent remo¬ val of N, P and . N, P and K do not exist in the form of ions but are bound in the lignocellulose due to an incomplete biodegradation. The pretreated fibre fraction is transferred from tank 9 to tank 3 in which it is mixed with the liquid fraction from tank 2 (from which the fibre fraction was previously separated). By adding metal ions and adjusting the pH-value, the urea complex, ammonium and phosphate are caused to precipitate in the acid to slightly alkaline solution. The selection of the added chemicals 11 depends on how the soil and plants will react on the precipitated fertilizer type. In tank 3, two types of precipitation may be effected. Thus, an urea complex may be produced in which only urea is precipitated and (de¬ pending on the pH-value) ammonium ions may furthermore be precipitated from ammonia. Furthermore, phosphorus is precipitated. The nitrogen and phosphorus fractions as well as the urea complex are filtered off in a filter 4, and the liquid phase is transferred from tank 3 to tank 6 and the pH-value is adjusted so as to be approximately between 7.0 and 7.5. By adding metal ions and sulphate and phosphorus ions, (po¬ tassium ions) (inserted during translation, translator's remark) are precipitated as a double salt which is filtered off in a filter 7. The substances from the filters 4 and 7 may be mixed to form an organic fertilizer containing N, P and K. The liquid fraction is then trans¬ ferred to a tank 8 and will consist of water which may be discharged directly into the external environment without violating public limit values for nitrogen and phosphorus content. The water will also be purified of potassium. Thus, by means of the above method it is possible to obtain a water fraction which can be discharged directly and a fertilizer fraction which can be used as a dried fertilizer or as a dissolved fertilizer containing N, P and K. Thus, the costs of handling domestic animal manure are reduced. The environmental strain is reduced as N, P and K to a higher degree are recycled in the farming. In tests with the described proces it has proved possible to obtain 15-50 kg organic fertilizer from one m 3 domestic animal manure, de¬ pending on the precipitation chemicals used. In the water fraction, residual concentrations of N and P as low as N. . ■, = 1.5 pp and P t . ι = 3.3 ppm are obtained, which allows a direct discharge to a recipient. It is noted that the method according to the present invention may comprise another pre-treatment stage than the one shown in the process chart, as the pre-treatment prior to the transfer to tank 3 e.g. may consist of degasification or biogas formation so that the supply to tank 3 comprises degasified domestic animal manure. In the latter case, urea complex will not be precipitated in tank 3, as the urea content of the manure is decomposed during the biogas formation. It will also be possible to carry out the method according to the inven¬ tion without the chemical reaction in tank 6 in which the potassium fraction is precipitated. As potassium is not a critical factor for the discharge of effluent waste water, the liquid phase from tank 3 can be discharged directly to the recipient without removal of potas- sium. However, finansial consideration will decide whether the potas¬ sium fraction is removed from the effluent waste water before the lat¬ ter is led out into the external environment. In the following various test results and examples of the chemicals used in the various proces stages are given. Tests have been made with domestic animal manure comprising urea, am¬ monium, phosphorus and potassium. In the tests, the effect of oxalic acid, COOH *. nitric acid, HNO, and optionally phosphorus acid in con- nection with metal ions were investigated in depth with a view to pre¬ cipitating compositions containing crytalline urea. Furthermore, mag¬ nesium sulfate, MgSO., 7 H D and manganese sulfate, nSO., 4 FLO are used to precipitate the crystalline metal complexes simultaneosuly for Substances are formed which are sparingly soluble in an acid solution and these substances can thus be separated by means of the filter 4 (if a chemical reaction is also carried out to separate potassium, the separation will be carried out in the filter 7). The substances formed are non-hygroscopic, which means that they are free-flowing. An analysis of the fibre fraction prior to the bio/enzymatic reaction shows the following: NH 3 P 2°5 κ 2 o kg/m 3 kg/m 3 kg/m : Untreated biomass 4.25 1.55 5.83 Fibre fraction (5) 1.96 0.58 1.76 Biodegraded material (tank 9) 1.53 0.42 1.28 Non-transferred material 0.43 0.16 0.48 This may also be illustrated in the following diagram Total nitrogen converted into NH Analysi s of un¬ Analysis of Analysis of the treated sl urry the influx outflow from tank 9 from animal from tank 2 and 5 to tank 3 after husbandry to tank 9 prior bioreaction to bioreaction By changing the type of microorganisms, and the physical and chemical parameters in tank 8 it is possible to obtain very different yields for the decomposition of the lignocellulose based on the liberated quantities of N, P and K. As previously mentioned, N,P and K do not exist in the form of ions but are bound in the lignocellulose due to an incomplete biodegradation. It will be seen that the quantity of non-transferred materials is of almost the same size in tank 9 as in the discharge water from tank 8. A fibre fraction taken at step 5 shows a content of N < 0.1 kg/10001, P = 0 kg/10001, K < 0.25 kg/1000 1. An analysis of the mixture introduced into tank 3 from tanks 2 and 9 and the liquid fraction discharged from tank 3 shows the following results: NH, P 2°5 κ 2 o kg/m 3 kg/m 3 kg/m 3 Untreated liquid manure for tank 3 4.25 1.55 5.83 Biodecomposition in tank 9 1.53 0.42 1.28 Liquid fraction from tank 2 2.29 0.97 4.07 Non-transferred material in tank 9 0.43 0.16 0.48 After precipitation in tank 3 0.46 0.17 5.83 This may also be expressed in a diagram Analysis of un¬ Analysis of Analysis of the treated slurry the influx outflow from tank 3 from animal from tank 2 to tank 6 after husbandry and 9 to tank 3 bioreaction After the precipitation in tank 3, the liquid phase is optionally transferred to tank 6 in which an adjustment of pH is effected to pre¬ cipitate the potassium content of the liquid. An analysis of the in¬ flux and the outflow from tank 6 shows the following: κ 2 o kg/m 3 5.83 5.83 Outflow from tank 8 0.46 0.17 0.48 Thi s may al so be expressed in a diagram. Analysi s of un- Analysis of Analysis of the treated slurry the influx outflow from tank 6 from animal from tank 3 to tank 8 after husbandry to tank 6 precipitation prior to precipitation The water flowing into tank 8 corresponds to the water discharged into the external environment. As a result of the method, N,P and K are reduced by approximately 90% compared to the liquid manure charged into the process. Thus, the practical tests conducted have produced residual concentra- tions of nitrogen and phosphorus which are below the normally accepted limits for contents of effluent waste water discharged to a recipient. Thus, the water fraction in tank 8 can be led directly out into the external environment, and the N,P and K fractions can be collected in a tank 10 and used as a fertilizer. Specific examples of the chemicals used have been mentioned above, and the basic chemical reaction is based on the formation of sparingly soluble substances which can be caught in a filter. The basic chemical reactions forming part of the method according to the invention are based on a division of the nitrogen of the manure into four main cate¬ gories: 1. Organically bound high molecular N, 2. Urea, CO(NH 2 ) 2 , 3. Ammonium in ionic form NH-, 4. Ammonium NH, dissolved in water. By adjusting pH it is possible to convert ammonia into the ionic form NH . Two categories, urea and ammonium, can then be subjected to pre- cipitation. Urea can be brought on ammonium form either enzymatically or over time, e.g. in a biogas proces. The phosphorus in the slurry is divided into two main categories: 1. Fibre bound P, _2 2. oonnoohhyyddrroogenphosphate, HPO ^ as a residual product from metabolic processes Category 1 is small, and phosphorus will constitute a total of appro- xi ately 1/4 of the nitrogen content. This is a challenge to simulta¬ neous precipitation. The following gives examples of tests carried out with chemicals which are added as reactive agents. 1. Oxalic acid Hypothesis: 2(NH 2 ) 2 C0 + (C00H) 2 Precipitation test according to the hypothesis: Medium: urea corresponding to 5g N t t ■,/! dissolved in deionized wa¬ ter. Reactive agent: oxalic acid dissolved in soft water to pH 2. A residual product of N t + - in a number of from 852, 697, and 707 ppm, respectively, was obtained. Each of these tests states an average of 5-15 individual tests and was carried out at pH-values of from 5.9, 2.77 and 3.45, respectively. The residual concentrations after preci¬ pitation of oxalic acid were not satisfactory, even though the mole¬ cular size of the urea complex indicates an advantageous flocculating ability which will be of significance when using slurry as a medium. Nitric acid Hypothesis: C0(NH 2 ) 2 + HN0 3 Precipitation tets according to the hypothesis. Medium: urea corresponding to 5g N t + -./l dissolved in deionized wa¬ ter. Reactive agent: nitric acid 70%.. In these tests, a residual product of N t + -, of 736 and 604 ppm, re¬ spectively, was obtained. These results are an average of 10 indivi¬ dual tests carried out at pH-values of from 5.90 and 2.77, respective- ly. Ma nesium sulfate C0 2 + 2NH 3 N + H 4 + H^O "1 N + H 4 + HP0 "2 N + H 4 + PO "3 N + H 4 + Mg +2 + P0 4 3 - NH 4 MgP0 4 χ H 2 0 Precipitation test according to the hypothesis. Medium: ammonium corresponding to 5g N f -,/1 (5000 ppm) and P0 4 cor¬ responding to 0.45 g P +0 - a -ι/T (450 ppm) dissolved in deionized water. Concentrations and proportions of N and P correspond to manure. Reactive agents: Magnesium sulfate 0.1 mol/1 Trisodiumphosphate 0.1 mol/1 Sodiumcarbonate 0.1 mol/1 Phosphoric acid, concentrated. These tests gave the following residual products. pm The above main group of tests states an average of 5-20 individual tests at the pH 2 stated. Manganese sulfate Hypothesis: NH 3 + H 3 P0 4 N + H 4 + H^O "1 N + H 4 + Mn +2 + P0~ 3 NH 4 MnP0 4 χ H 2 0 Precipitation test according to the hypothesis. _3 Medium: ammonium corresponding to 5g N total /l (5000 ppm) and P0 4 cor¬ responding to 0.45 g P +ota -ι/l (450 ppm) dissolved in deionized water. Concentrations and proportions of N and P correspond to manure. Reactive agents: Manganese sulfate 0.1 mol/1 Trisodiumphosphate 0.1 mol/1 Sodiumcarbonate 0.1 mol/1 Phosphoric acid, concentrated. These tests gave the following results. The above main groups of tests state an average of 5-20 individual tests at the pH 2 stated. The tests conducted on precipitation of urea complexes have shown that the processes are feasible, even though the experimental yields have been lower than immediately would be expected with the pH range test¬ ed. An efficient precipitation can only take place under extreme acid conditions. The results show that the optimum of the process has not been reached even in chemically pure solutions. Extrapolation of the results indicates a more advantageous precipitation of the urea com¬ plex. Tests on simultaneous precipitation of phosphorus and ammonium with metals show high experimental yields. It has been found that the op¬ timum process conditions have to be reached within a very narrow in¬ terval. Tests with a pH-value of about 8 have shown a remarkably ef- ficient ammonium removal for manganese. Furthemore, manganese is pre¬ ferred to magnesium due to the efficiency and a lower pH-value. Examples of chemicals (11) for reactions in tank 3. pH4 ■ 10 + n °C -3, Temp.10 100 M + (H.P04 ) + NH4 NH4MP04, xi H2O xι=0,l,2,3. (NH4)yMzHt(P04)v, xi H2O y = 1,2,3,4 NH4MnPθ4, H2O z = 1,2....10 NH4MgP04, 6 H2O v =1,2....18 (NH4)4Mg(PO4)2, H2O t = 0.1.2..3 Example NH4CaPθ4, 7H2O NH4CaH3(Pθ4)2, H2O pH4. 10 Temp.10 ■ 100 °C n + (H + ,P0 ' 4 3 ) + NH4 NH4M(HPθ4)2, X2 H2O X2 = 0,l,2,3. Example NH4Mg(HPθ4)2, H2O 2MPO4.NH3, X3 H2O X3 = 0,l,2,3. 2FePθ4,NH3, 4H2O pH4-10 ,+ n Temp.10 - 100 °C M (H + ,P2θ? 4 ) + NH4 NH4JMHyP2θ7, X5 H2O X6 =0,1,2,... Ex -5 M + (H + ,P3θ ' ιo) + NH4 X8 = 0.1....1 NH4Mn2P3θιo, 6 H2O + n +2 +2 +2 +2 +2 +2 +2 +3 +2 +3 +3 +1 +2 +3 M.: Mg , Ca , Ba , Be , Co , Zn , Mn, Mn , Fe , Fe , Al , Cu , Cu , B . Si etc , Examples of chemicals (12) for reactions in tank 6. pH4-10 Temp.10 - 100 °C M n + (H + ,P04 3 ) + K + KMP04, xi H2O xι=0,l,2,3. (K)yMzHt(P04)v, xi H2O = 1,2,3,4 KMnPO4, H2O z = 1.2....10 KMgPθ4, 6 H2O v =1,2....18 (K)4Mg(P04)2, H2O t = 0,1,2.3 Example K4CaP04, 7H20 pH4. 10 Temp.10 • 100 °C ύ n + (H + ,P0 ' 4 3 ) + K KM(HP04)2, X2 H2O X2 = 0,l,2,3. Example (K)2Ca(HP04)2, H2O pH4 ■ 10 •n Temp.10 100 °c + (if P2O7 4 ) + K KMHyP2θ7,X5H2θ 6 =0,1,2,. KMnP2θ7, H2O y =0 or Example KMHP207, X7 H2θ KMnHP2θ7, H2O pH4-10 +n + -5 + Temp.10 - 100 °C M + (H ,P3θιo) +K KM2P3θlO, X8 H2θ X8 = 0,1,.. KMn2P3θιo, 6 H2O + n +2 +2 +2 +2 +2 +2 +2 +3 +2 +3 +3 +1 +2 +3 M.: Mg , Ca , Ba , Be , Co , Zn , Mn, Mn , Fe , Fe , Al . Cu , Cu , B , Si etc . Examples of chemicals (12) for reactions in tank 6 (cont.). pH4-10 Temp.10 -100 °C M " "+ (H + ,P0 ' 4 3 ) + K+ &H4 NH4KMH(P04) 2 , 2 H2O X2 = 0,1,2,3. NH4KMnH(P04)2, 3H2O Example (K)2Ca(HPθ4)2, H2O KFe(HPθ4)2 pH4-10 Temp.10 - 100 U C M + + ( H + , P2O7 4 ) + K + + &H4 NH4KMHyP2θ7, X5 H2O X6 =0,1,2,.. NH4KMnP2θ7, 3 H2O y = 0 or Example NH4KMnHP2θ7, H2O + n +2 +2 +2 +2 +2 +2 +2 +3 +2 +3 +3 +1 +2 +3 M.: Mg , Ca , Ba , Be , Co , Zn , Mn, Mn , Fe , Fe , Al , Cu , Cu , B , Si etc . Fig. 2 illustrates a plant substantially like the one shown in Fig. 1, but in which a heat exchanger is inserted at the treatment stage treat¬ ing the liquid fraction. This is associated with problems as there is a risk that a precipitate may be formed and the heat exchanger conse- quently may be blocked. This problem is solved by the present embodi¬ ment as two chemical process steps are carried out, one process step before and one process step after the heat exchanger, the first step i.a. ensuring that no precipitate is formed in the heat exchanger. Fresh manure is added to tank 1 and subsequently the fresh manure is transferred to a fibre separation step 2 in which the fibres present in the manure are separated from the fresh manure. The separated fibre amount 5 is passed to a composting plant 9 of a known type. However, the separation of fibres may optionally be omitted. The liquid frac¬ tion of the manure is passed to a pre-mixer 15 after the concentration of the following ions has been measured at point 16: ammonium ions, phosphate ions, carbonate ions and potassium ions. Depending on pri¬ marily the concentration of ammonium and carbonate, acid and (alkaline ions) (inserted during translation, translator's remark), preferably phosphate ions, H and X n ~, respectively, are added. The added acid ions, H , are preferably derived from phosphorus acid, whereas the added base ions, X n" , may be a phosphate-containing anion. This re¬ sults in that the carbonate ion present in the liquid fraction is bound to the base ion and water and forms C0 2 which is liberated in the form of gas. In order to avoid precipitation in the heat exchanger 17, it is necessary to keep the acidity sufficiently low, which means a pH-value of from 5 or less, preferably 3.5. The liquid fraction is then passed through the heat exchanger 17 in which the temperature of the fraction is adjusted to between 40 and 50 β C, preferably 45 C C. Af¬ ter the liquid fraction has passed through the heat exchanger 17, it is passed to a after-mixer 18, in which adjustment of the acidity is repeated, but at this stage the purpose of the adjustment is to form fertilizing substances which can be precipitated. Preferably, the li¬ quid fraction supplied to the after-mixer 18 has at the inlet 19 an acidity corresponding to pH = 3.5 as mentioned above. In the after- mixer various metal ions, M * and M t, and alkaline ions, B m" , are added. The metal ions are preferably Mn-ions and Mg-ions, whereas the alkaline ions preferably are CO 3 -ions. However, other ions may also be used, but the addition of the above mentioned ions will result in the highest fertilizer value of the precipitates formed. The amount of the added ions is adjusted so that the pH-value is increased to be¬ tween 7 and 9, preferably 8.2 and so that the substances which conse¬ quently may be precipitated are substances which can be used for fer¬ tilization or which are not sparingly soluble or in any other way da- maging to the environment. In the addition of acid, metal and alkaline ions in the first and second proces step, respectively, the addition is exclusively effected in a stoichiometric ratio of 1:1. The follow¬ ing test descriptions with accompanying tables and graphic depictions illustrate that the ammonium content, either in the form of NH 4 MnP0 4 or NH 4 MgP0 4 , has its lowest value at a temperature of about 45°C and at pH = 8.2. Moreover, it appears from the graphic depictions that in case zinc is used as a metal ion, pH must be in the range of between 8.5 and 9.1 in order have a minimum amount of ammonium ions. After the liquid fraction is made alkaline in the after-mixer 18 with a pH of about 8.2 measured at point 20, optionally by recirculating the fraction in the mixer, it is passed to a separator 21. In the se¬ parator, the temperature is reduced to between 10 and 12 β C and a sepa¬ ration of fertilizing substances is thus effected and the substances are precipitated. The liquid fraction which remains after the separa¬ tion is very pure and can be discharged directly as effluent waste water 22 or to another recipient 23. In the separator 21, a degasifi- cation of C0 9 is effected provided the alkaline ions supplied to the 2- after-mixer 18 are C0 3 -ions. The precipitated fertilizing substances 24 are dried in a centrifuge and the liquid extracted is passed to a recipient 23. The dried nutrients 26 are mixed in a solid-matter mixer 27 with the fibre fraction 5 which was separated in 2 and composted in 9. An air drying may optionally be effected after the mixing at point 28. The described method results in a organic fertilizer mass 29 which is enriched with the nutrients 24 which are separated from the fresh manure as part of the method according to the invention. In the following tables of results optained with a plant of the above mentioned type are tabulated. Medium: ammonium corresponding to 5g N^^/l (5000 ppm) and PO 4 cor¬ responding to 0.45 g P +Q+ ai/l (450 ppm) dissolved in deionized water. Concentrations and proportions of N and P correspond to the degasified manure which is being processed. Reactive agents: Manganese chloride 0.5 mol/1 Phosphoric acid concentrated Natrium carbonate 0.5 mol/1. Test conditions: The concentration of ammunion ions are maintained constant so as to correspond to 0.27 mol/1, equivalent amounts of phosphoric acid and manganese chloride are added, the resultant solution is heated to the temperatures stated for the test, the solution is then made alkaline by adding natrium carbonate so that pH = 8.2, which means pH is con¬ stant. Measurements are performed, i.e. a small sample of the liquid fraction is initially taken to determine the NH . Subsequently, the precipitate is filtered off at vacuum and by washing with ion-exchang¬ ed water. The precipitate is dried at 80 β C for 48 hours before the concentration of NH in the precipitate is determined by dissolving the latter in mineral acid. The precipitate has the following compo¬ sition: H 4 MnP0 4 ,H 2 0. These tests gave the following results. 21 Medium: ammonium corresponding to 5g NH 4 /1 (5000 ppm) and P0 4 corre¬ sponding to 0.45 g P-to t -i/l (450 ppm) dissolved in deionized water. Concentrations and proportions of N and P correspond to the degasified manure which is being processed. Reactive agents: Manganese chloride 0.5 mol/1 Phosphoric acid concentrated Natrium carbonate 0.5 mol/1. Test conditions: The concentration of ammunion ions are maintained constant so as to correspond to 0.27 mol/1, equivalent amounts of phosphoric acid and manganese chloride are added, the pH-value is measured (point 19) = pH,. The solution is then made alkaline with natrium carbonate. After addition of a varying amount of natrium carbonate, the pH-value is measured (point 20) = pH 2 « The test is conducted by initially taking out a small sample of the liquid fraction to determine NH 4 and subse¬ quently by separating the precipitate by filtration at vacuum and by washing with ion-exchanged water. The precipitate is dried at 80°C for 48 hours before determining the NH 4 content in NH 4 MnP0 4 ,H 2 0. These tests gave the following results. 25 30 35

Claims: C L A I M S 1. A method of treating a biomass in the form of domestic animal manu¬ re, slurry, organically loaded effluent waste water and the like, or mixtures thereof, and comprising a chemical treatment of the biomass, c h a r a c t e r i z e d in pre-treating a fresh biomass mechnically + 3- -2 + and/or chemically, measuring NH 4 , P0 4 , C0 3 and K , precipitating the nitrogen and phosphorus content of the pretreated biomass by adding in a stoichiometric ratio of 1:1 chemical reactive agents which are caused to react with the nitrogen compounds and the phosphorus com¬ pounds present in the biomass, precipitating any urea content together with the nitrogen, phosphorus and optional potassium content of the biomass, and subsequently separating the biomass into a liquid frac¬ tion and a fertilizer fraction. 2. A method according to claim 1, c h a r a c t e r i z e d in that the pre-treatment of a fresh biomass comprises the steps of precipi¬ tating a fibre fraction, separating the fibre fraction from the liquid fraction, adjusting the pH-value of the fibre fraction, decomposing the fibre fraction by adding microorganisms and/or enzymes to liberate nitrogen bound in the fibres, remixing the biologically decomposed fibre fraction with the liquid fraction, adjusting the pH-value of the biomass thus treated before adding chemicals in the form of a reactive agent in the form of metal ions. 3. A method according to claim 2, c h r a c t e r i z e d in that the chemically reactive agents furthermore comprise organic or inorga¬ nic acids to form urea complexes which are precipitated together with the nitrogen and phoshorus compounds formed. 4. A method according to any of the preceding claims, c h a r a c - t e r i z e d in that the chemical reactions are carried out at a pH- value of between 3.5 and 10 and at a temperature of between 10° and 100°. 5. A method according to claim 1, c h a r a c t e r i z e d in that the pre-treatment of the fresh biomass consists of a degasification and a subsequent mechanical filtration, an adjustment of the pH-value of the biomass and an addition of the reactive agents in the form of metal ions and an adjustment with phosphate ions. 6. A method according to claim 4, c h a a c t e r i z e d in that the pH-adjustment of the biomass is effected in two steps, by effect- ing an initial adjustment to a pH-value of from 3-5, preferably 3.5, followed by a preheating of the biomass to a temperature in the range of from 40-55 β C, and by effecting a second pH-adjustment by adjusting the pH-value to 8-9.5, preferably about 8.2, followed by the precipi¬ tation. 7. A method according to claim 5, c h a r a c t e r i z e d in that the separation into a liquid fraction ana a fertilizer fraction is effected by precipitation, and that the precipitated material is further separated by centrifuging, and subsequently that the preci- pitated material is optionally mixed with the fibre fraction which is mechanically filtered off. 8. A method according to claim 1 and 2, c h a r a c t e r i z e d in that the potassium compound content of the biomass is precipitated by adding chemically reactive agents which react with the potassium com¬ pounds present in the biomass, that the potassium fraction is separat¬ ed and mixed with the nitrogen and phoshorus-containing fertilizer fraction, and that the remaining liquid fraction is discharged direct¬ ly to a recipient. 9. A method according to any of the preceding claims, c h a r a c ¬ t e r i z e d in that the urea content of the pre-treated biomass is precipitated by adding an organic or inorganic acid, preferably oxalic acid, nitric acid or phosphorus acid in connection with metal ions, which reacts with the urea of the biomass to form urea complexes which are subsequently separated from the liquid fraction of the biomass and discharged together with the nitrogen and phoshorus-containing ferti¬ lizer fraction. 10. A method according to any of the preceding claims, c h a r a c ¬ t e r i z e d in that the nitrogen, phosphorus, potassium and option¬ ally urea complexes are precipitated simultaneously.

Inventors: VESTERAGER NIELS OLE, VESTERAGER, NIELS, OLE
Applicants: VESTERAGER NIELS OLE, VESTERAGER, NIELS, OLE
Application year: 1991
Main classification: C02F9
IPC codes: C02F1, C02F3, C02F9, C05F3