METHOD OF REDUCING HARMFUL GAS EMISSIONS FROM ORGANIC FERTILIZERS
20260000010 ยท 2026-01-01
Assignee
Inventors
Cpc classification
International classification
Abstract
The invention relates to a method of reducing emissions of harmful gases from farm manure during storage of same, the method comprising the steps of acidifying the farm manure and adding a cyanamide salt composition to the farm manure.
Claims
1. A method of reducing emission of harmful gases from farm manure during its storage, the method comprising: a) providing a farm manure, b) acidifying the farm manure to a pH value in the range from 4.5 to 6.5, and c) adding 0.01 wt. % to 1.0 wt. %, based on the total weight of the farm manure, of a cyanamide salt composition to the farm manure.
2. The method of claim 1, wherein providing the farm manure occurs before or simultaneously with acidification and addition of the cyanamide salt composition.
3. The method of claim 1, wherein the farm manure is acidified to the pH value in the range from 5.0 to 6.3 in step b).
4. The method of claim 1, wherein step b) is carried out with an acid selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, silicic acid, formic acid, acetic acid, lactic acid, oxalic acid, citric acid, fumaric acid, benzoic acid, maleic acid, and mixtures thereof.
5. The method of claim 1, wherein the cyanamide salt composition comprises; a) 25 to 95 wt. % of cyanamide salt, b) up to 15 wt. % of free carbon, charcoal or graphite, c) 1 to 40 wt. % of at least one compound comprising carbonates, d) less than 20 wt. % of oxides and hydroxides, e) up to 15 wt. % of water, wherein the percentages by weight in each case is based on the total weight of the cyanamide salt composition.
6. The method of claim 1, wherein a total amount of cyanamide salt added to the farm manure is in the range from 0.5 to 10 kg per 1 m.sup.3 based on the total amount of farm manure.
7. The method of claim 1, wherein the farm manure is liquid manure, dung slurry, or biogas fermentation residues.
8. The method of claim 1, wherein the harmful gas is selected from the group consisting of ammonia, carbon dioxide, nitrous oxide, methane and hydrogen sulfide.
9. The method of claim 1, wherein the cyanamide salt composition reduces the emission of harmful gas comprising hydrogen sulfide, and wherein the farm manure is acidified with sulfuric acid.
10. The method of claim 5, wherein the cyanamide salt is calcium cyanamide.
11. The method of claim 5, wherein the carbonates comprise magnesium carbonate, magnesium hydrogen carbonate, calcium carbonate, calcium hydrogen carbonate, or mixtures thereof.
12. The method of claim 5, wherein the oxides and hydroxides are selected from the group consisting of magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, and mixtures thereof.
13. The method of claim 2, wherein acidification can take place before, after, or simultaneously with addition of the cyanamide salt composition.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0101]
[0102]
[0103]
[0104]
[0105]
[0106]
EXAMPLES
[0107] Two test series were carried out with cattle liquid manure to record gas emissions during the storage of farm manures. Test variants with different acids, with and without CaCN.sub.2 treatment were investigated.
1. Material and Methods
1.1 Cattle Liquid Manure:
[0108] Fresh cattle liquid manure (farm manure) was obtained from a dairy farm in Bavaria. The cattle liquid manure was neither diluted with rinsing/cleaning water or the like, nor was it contaminated with litter. The cattle liquid manure was taken from the antechamber of the drainage channel in the direction of the liquid manure pit.
[0109] The analysis of the untreated cattle liquid manure for the two test series yielded the following values:
TABLE-US-00001 TABLE 1 Characteristics of the cattle liquid manures used. Parameters Test series 1 Test series 2 Total nitrogen 0.45 wt. % 0.41 wt. % Ammonium nitrogen 0.20 wt. % 0.15 wt. % Dry matter content 8.37 wt. % 9.38 wt. % pH value 7.49 6.89
1.2 Acidification of Cattle Liquid Manure:
[0110] To acidify the cattle liquid manure, 80 or 95% sulfuric acid (H.sub.2SO.sub.4), 32% hydrochloric acid (HCl), 100% acetic acid (HOAc), 50% citric acid (CA) or 90% lactic acid (LA; racemate of D and L-lactic acid) was used. The cattle liquid manure was mixed with the respective acid while stirring and adjusted to the desired pH value (pH 6.0 or pH 5.5). The pH values were measured using a SevenGo Duo pH/Cond meter SG23 from Mettler Toledo.
1.3 Composition of the CaCN.SUB.2 .Formulations (F1 & F2):
[0111] Two compositions comprising calcium cyanamide (CaCN.sub.2) were used to reduce harmful gas emissions during the storage of farm manures. The CaCN.sub.2 formulations (F1 & F2) used in the examples are composed as follows:
TABLE-US-00002 TABLE 2 Composition of the CaCN.sub.2 formulations F1 and F2. Component F1 F2 Calcium cyanamide 45.9 wt. % 43.6 wt. % Calcium hydroxide 16.3 wt. % 16.7 wt. % Calcium carbonate 9.50 wt. % 9.84 wt. % Calcium nitrate 0.97 wt. % 0.62 wt. % Free carbon 9.90 wt. % 11.4 wt. % Magnesium carbonate 7.60 wt. % 7.92 wt. % Water 9.83 wt. % 9.92 wt. %
[0112] The CaCN.sub.2-containing composition F1 has a total nitrogen content of 18.5% and a cyanamide nitrogen content of 16.1%. The CaCN.sub.2-containing composition F2 has a total nitrogen content of 18.3% and a cyanamide nitrogen content of 15.3%.
1.4 General Test Procedure:
[0113] In a 6-litre wide-necked polyethylene (PE) container with a tight-fitting lid, a defined amount of the cattle liquid manure (farm manure) according to 1.1 is added either untreated or adjusted to a pH value of 6.0 or 5.5 with one of the acids listed. Then, in some examples, a defined amount of the composition F1 or F2 and thus of CaCN.sub.2 is added and stirred in. More detailed information on the application rates of the farm manure and the additives of the different examples and comparative examples are shown in Table 3. Once all substances have been added and stirred in, the 6-liter wide-necked container is tightly closed. To collect the emitting gases during anaerobic storage, a gas-tight opening is made in the lid of the wide-neck container, to which a gas storage bag (nominal volume 5.6 liters) is connected so that no atmospheric oxygen can enter the wide-neck container. The respective mixture is stored at a temperature of 231 C. for a defined period of time. The filled gas storage bag is changed at regular intervals, the collected gas volume is determined volumetrically and the gas composition is analyzed using a biogas measuring device (Optima 7 from MRU Messgerthe fr Rauchgase und Umweltschutz GmbH) and a photoacoustic infrared spectrometer (Innova 1512 from Luma Sense Technologies).
TABLE-US-00003 TABLE 3 Test series on gas release during anaerobic storage of cattle liquid manure. Cattle liquid Example manure [kg] Acid [g] F1/F2 [g] Test series 1 Control (V1) 3.05 H.sub.2SO.sub.4 pH 6.0 + 0.21% F1 (B1) 3.02 24.5 6.33 H.sub.2SO.sub.4 pH 5.5 + 0.21% F1 (B2) 3.00 31.2 6.31 H.sub.2SO.sub.4 pH 6.0 (V2) 3.01 24.4 H.sub.2SO.sub.4 pH 5.5 (V3) 3.00 31.2 F1 0.21% (V4) 3.05 6.34 F1 0.29% (V5) 3.04 8.86 Test series 2 Control (V6) 3.00 H.sub.2SO.sub.4 pH 5.5 + 0.22% F2 (B3) 3.00 16.3 6.55 H.sub.2SO.sub.4 pH 5.5 + 0.13% F2 (B4) 3.00 16.4 3.93 HCl pH 5.5 + 0.22% F2 (B5) 3.00 35.8 6.55 HOAc pH 5.5 + 0.22% F2 (B6) 3.00 22.6 6.55 CA pH 5.5 + 0.22% F2 (B7) 3.00 41.5 6.55 LA pH 5.5 + 0.22% F2 (B8) 3.00 40.4 6.55 H.sub.2SO.sub.4 pH 5.5 (V7) 3.00 17.6 F2 0.22% (V8) 3.00 6.55 F2 0.13% (V9) 3.00 3.94
2. Determination of Gas Emissions
2.1 Test Series 1
2.1.1 Comparative Example V1 (Control):
[0114] As a reference for the emitted gas quantities during the anaerobic storage of treated farm manure, 3.05 kg of untreated cattle liquid manure without additives was examined (control experiment V1 according to Table 3). The gas storage bags were changed and analyzed after 14, 67, 78, 85, 95, 108, 115, 136, 156, 179, 218, 248, 267, 295, 357 and 400 days. The total gas volume emitted (V.sub.ges) and the specific volumes of methane (CH.sub.4), carbon dioxide (CO.sub.2) and hydrogen sulfide (H.sub.2S) are listed cumulatively in Table 4. For better comparability, the determined gas volumes are standardized to 1.00 kg of cattle liquid manure. The development of the respective gases over time is shown in
TABLE-US-00004 TABLE 4 Cumulative gas emissions based on 1.00 kg of cattle liquid manure in liters or milliliters. Storage time Comparative example V1 [Days] CH.sub.4 [L] CO.sub.2 [L] H.sub.2S [mL] V.sub.ges [L] 14 0.14 0.52 0.83 1.54 67 0.39 0.96 1.97 3.20 78 1.23 1.33 3.57 4.92 85 1.56 1.45 3.60 5.63 95 2.38 1.81 3.61 7.24 108 3.08 2.25 3.61 8.78 115 3.92 2.69 3.61 10.3 136 4.38 2.94 3.61 11.6 156 4.91 3.26 3.61 13.0 179 4.96 3.30 3.61 13.4 218 5.19 3.46 3.61 14.4 248 5.20 3.47 3.61 14.7 267 5.22 3.49 3.61 14.8 295 5.23 3.50 3.61 15.0 357 5.23 3.51 3.61 15.3 400 5.24 3.51 3.61 15.5
2.1.2 Combination of Acidification and CaCN.SUB.2 .Treatment of Cattle Liquid Manure (B1 and B2):
[0115] According to Example B1 (Table 3), 3.02 kg of cattle liquid manure was adjusted to a pH value of 6.0 with 24.5 g of 80% H.sub.2SO.sub.4. Subsequently, 6.33 g of CaCN.sub.2 formulation F1 was added and stirred in. According to Example B2 (Table 3), 3.00 kg of cattle liquid manure was adjusted to a pH of 5.5 with 31.2 g of 80% H.sub.2SO.sub.4. Subsequently, 6.31 g of CaCN.sub.2 formulation F1 was added and stirred in. The gas storage bags were changed and analyzed for both examples after 14, 67, 85, 108, 136, 156, 179, 218, 248, 267, 295, 357 and 400 days. The total gas volumes emitted (V.sub.ges) and the specific volumes of methane (CH.sub.4), carbon dioxide (CO.sub.2) and hydrogen sulfide (H.sub.2S) are listed cumulatively in Table 5. For better comparability, the determined gas volumes are standardized to 1.00 kg of cattle liquid manure. The development of the respective gases over time is shown in
TABLE-US-00005 TABLE 5 Cumulative gas emissions based on 1.00 kg of cattle liquid manure in liters or milliliters. Example B1 Example B2 Storage (H.sub.2SO.sub.4 pH 6.0 + 0.21% F1) (H.sub.2SO.sub.4 pH 5.5 + 0.21% F1) duration CH.sub.4 CO.sub.2 H.sub.2S V.sub.ges CH.sub.4 CO.sub.2 H.sub.2S V.sub.ges [Days] [L] [L] [mL] [L] [L] [L] [mL] [L] 14 0.00 0.01 0.00 0.10 0.00 0.00 0.00 0.20 67 0.00 0.04 0.00 0.53 0.00 0.01 0.00 0.28 85 0.00 0.05 0.00 0.73 0.00 0.02 0.00 0.38 108 0.00 0.06 0.01 0.89 0.00 0.02 0.07 0.42 136 0.00 0.07 0.14 0.96 0.00 0.03 0.18 0.55 156 0.00 0.07 0.25 1.13 0.00 0.03 0.24 0.57 179 0.00 0.08 0.35 1.28 0.00 0.04 0.32 0.57 218 0.00 0.08 0.39 1.28 0.00 0.04 0.38 0.71 248 0.00 0.08 0.41 1.34 0.00 0.04 0.40 0.71 267 0.00 0.08 0.44 1.41 0.00 0.04 0.42 0.81 295 0.01 0.08 0.53 1.57 0.00 0.04 0.42 0.82 357 0.09 0.11 2.18 2.04 0.03 0.05 0.47 1.21 400 0.32 0.18 4.90 2.77 0.15 0.07 1.04 1.69
Discussion of the Results:
[0116] Total emissions: After 400 days of anaerobic storage, 15.5 L of total gas were released based on 1.00 kg of cattle liquid manure in the reference experiment (V1). Acidification with 80% H.sub.2SO.sub.4 to pH 6.0 and subsequent addition of CaCN.sub.2 (Example 1) can reduce emissions by 82.1% to 2.77 L. An even more effective reduction was achieved by acidification with 80% H.sub.2SO.sub.4 to pH 5.5 and subsequent addition of CaCN.sub.2 (Example 2). Compared to the reference experiment (V1), the total emissions were reduced by 89.1% to 1.69 L.
[0117] CH.sub.4 emissions: After 400 days of anaerobic storage, 5.24 L of CH.sub.4 were released based on 1.00 kg of cattle liquid manure in the reference experiment (V1). Acidification to pH 6.0 and subsequent addition of CaCN.sub.2 (Example 1) can reduce emissions by 93.9% to 0.32 L. An even more effective reduction was achieved by acidification to pH 5.5 and subsequent addition of CaCN.sub.2 (Example 2). Compared to the reference experiment (V1), CH.sub.4 emissions were reduced by 97.1% to 0.15 L.
[0118] CO.sub.2 emissions: After 400 days of anaerobic storage, 3.51 L of CO.sub.2 were released based on 1.00 kg of cattle liquid manure in the reference experiment (V1). Acidification to pH 6.0 and subsequent addition of CaCN.sub.2 (Example 1) can reduce emissions by 94.9% to 0.18 L. An even more effective reduction was achieved by acidification to pH 5.5 and subsequent addition of CaCN.sub.2 (Example 2). Compared to the reference experiment (V1), CO.sub.2 emissions were reduced by 98.0% to 0.07 L.
[0119] H.sub.2S emissions: After 400 days of anaerobic storage, 3.61 mL of H.sub.2S was released based on 1.00 kg of cattle liquid manure in the reference experiment (V1). Acidification to pH 6.0 and subsequent addition of CaCN.sub.2 (Example 1) increased the emissions by 35.7% to 4.90 mL. In contrast, an effective reduction was achieved by acidification to pH 5.5 and subsequent addition of CaCN.sub.2. Compared to the reference experiment, the H.sub.2S emissions were reduced by 71.2% to 1.04 mL.
[0120] The combination of liquid manure acidification with H.sub.2SO.sub.4 and subsequent CaCN.sub.2 treatment is therefore a very effective measure for reducing harmful gas emissions, in particular methane and carbon dioxide, when storing farm manure such as cattle liquid manure. Compared to the control experiment (V1) with untreated cattle liquid manure, almost no harmful gas emissions were detected over a period of 400 days. A lower pH value of 5.5 at the beginning of storage results in a 39.0% reduction in total emissions compared to total emissions at pH 6.0. The reduction in harmful CH.sub.4, CO.sub.2 and H.sub.2S emissions by 53.1%, 61.1% and 78.8% respectively is even higher.
[0121] An increased potential can only be observed with regard to the formation and release of H.sub.2S, which is due to acidification with H.sub.2SO.sub.4. This introduces additional sulphate (SO.sub.4.sup.2) for desulphurization (microbial degradation of SO.sub.4.sup.2 by sulphate-reducing bacteria/archaea). The influence of the pH value or the increased sulphate concentration can be further illustrated by comparing the two options of the combination of liquid manure acidification and subsequent CaCN.sub.2 treatment. Despite a slightly increased sulphate input in Example 2, the combination of a low pH value and CaCN.sub.2 treatment can also significantly reduce H.sub.2S emissions. This is also shown by comparative examples V2 and V3.
2.1.3 Acidification of Cattle Liquid Manure with H.sub.2SO.sub.4 (Comparative Examples V2 and V3):
[0122] 3.01 kg of cattle liquid manure with 24.4 g of 80% H.sub.2SO.sub.4 was adjusted to a pH value of 6.0 (comparative example V2). In comparative example 3, 3.00 kg of cattle liquid manure with 31.2 g of 80% H.sub.2SO.sub.4 was adjusted to a pH value of 5.5. The gas storage bags were changed and analyzed in both comparative examples after 14, 67, 85, 95, 108, 136, 156, 179, 218, 248, 267, 295, 323, 357 and 400 days. The total gas volumes emitted (V.sub.ges) and the specific volumes of methane (CH.sub.4), carbon dioxide (CO.sub.2) and hydrogen sulfide (H.sub.2S) are listed cumulatively in Table 6. For better comparability, the determined gas volumes are standardized to 1.00 kg of cattle liquid manure. The development of the respective gases over time is shown in
TABLE-US-00006 TABLE 6 Cumulative gas emissions V2 and V3 (based on 1.00 kg cattle liquid manure). Comparative example V2 Comparative example V3 Storage (H.sub.2SO.sub.4 pH 6.0) (H.sub.2SO.sub.4 pH 5.5) duration CH.sub.4 CO.sub.2 H.sub.2S V.sub.ges CH.sub.4 CO.sub.2 H.sub.2S V.sub.ges [Days] [L] [L] [mL] [L] [L] [L] [mL] [L] 14 0.01 0.15 0.23 0.73 0.00 0.04 0.06 0.43 67 0.07 0.33 2.49 1.68 0.03 0.15 0.40 0.97 85 0.59 0.83 10.4 3.40 0.13 0.28 2.04 1.58 95 1.24 1.28 16.8 4.83 0.53 0.62 9.97 2.83 108 1.50 1.46 17.5 5.62 1.17 0.99 17.9 4.16 136 1.56 1.49 17.6 5.99 1.41 1.09 18.5 4.79 156 1.63 1.53 17.8 6.42 1.43 1.10 18.5 4.84 179 1.83 1.62 20.4 7.21 1.45 1.11 18.6 4.88 218 2.19 1.76 28.3 8.08 1.78 1.28 21.6 5.96 248 2.41 1.83 33.6 8.64 2.52 1.60 29.5 7.39 267 2.56 1.86 36.1 8.87 2.85 1.68 32.1 8.02 295 2.76 1.91 38.9 9.29 3.48 1.81 36.2 9.02 323 2.89 1.94 40.6 9.62 357 3.01 1.96 42.0 9.85 3.72 1.84 37.1 9.63 400 3.17 1.99 43.4 10.3 4.39 2.05 41.3 10.8
Discussion of the Results:
[0123] Total emissions: After 400 days of anaerobic storage, 10.3 L of total gas were released based on 1.00 kg of cattle liquid manure in comparative example 2. The additional addition of CaCN.sub.2 (Example 1) can therefore reduce emissions by 73.1% to 2.77 L compared to V2. An even more effective reduction was achieved compared to comparative example 3. Compared to V3, the combination of acidification and subsequent CaCN.sub.2 treatment (Example 2) reduced total emissions from 10.8 L to 1.69 L, i.e. by 84.4%. If no CaCN.sub.2 treatment is carried out, this leads to an increase in total emissions of 272% (acidified cattle liquid manure in V2 compared to Example 1) or 539% (V3 compared to B2). Compared to the reference experiment (V1) with a cumulative total gas volume of 15.5 L based on 1.00 kg of cattle liquid manure, emissions were only reduced by 33.5% (V2) and 30.3% (V3) by acidifying the liquid manure alone.
[0124] CH.sub.4 emissions: After 400 days of anaerobic storage, 3.17 L of CH.sub.4 were released based on 1.00 kg of cattle liquid manure in comparative experiment V2. By adding CaCN.sub.2 (Example 1), emissions can be reduced to 0.32 L and thus by 89.9%. If Example 2 is compared with V3, the combination of acidification and subsequent CaCN.sub.2 treatment (B1) reduces CH.sub.4 emissions from 4.39 L to 0.15 L, i.e. by 96.6%. A lack of CaCN.sub.2 treatment, as examined in V2 and V3, resulted in an increase in CH.sub.4 emissions of 891% (compared to Example 1) and 2827% (compared to Example 2). Compared to the reference experiment (V1) with a cumulative CH.sub.4 volume of 5.24 L based on 1.00 kg of cattle liquid manure, CH.sub.4 emissions were only reduced by 39.5% (V2) and 16.2% (V3) by acidifying the liquid manure alone.
[0125] CO.sub.2 emissions: After 400 days of anaerobic storage, 1.99 L of CO.sub.2 were released based on 1.00 kg of cattle liquid manure in comparative example V2. In contrast, the addition of CaCN.sub.2 (Example 1) can reduce emissions to 0.18 L and thus by 91.0%. A comparison of Example 2 with V3 shows that the CO.sub.2 emissions were reduced from 2.05 L to 0.07 L and thus by 96.6% through the combination of acidification and subsequent CaCN.sub.2 treatment. Consequently, dispensing with CaCN.sub.2 treatment resulted in an increase in CO.sub.2 emissions of 1006% (compared to B1) and 2829% (compared to B2). Compared to the reference experiment (V1) with a cumulative CO.sub.2 volume of 3.51 L based on 1.00 kg of cattle liquid manure, CO.sub.2 emissions were only reduced by 43.3% (V2) and 41.6% (V3) by acidifying the liquid manure alone.
[0126] H.sub.2S emissions: After 400 days of anaerobic storage, 43.4 mL of H.sub.2S were released based on 1.00 kg of cattle liquid manure in comparative example 2. The combination of acidification and addition of CaCN.sub.2 (Example 1) reduces the emissions to 4.90 mL and thus by 88.7%. The comparison of example V3 with Example 2 shows that a reduction in H.sub.2S emissions was achieved by the combination of acidification to pH 5.5 and subsequent CaCN.sub.2 treatment from 41.3 mL to 1.04 mL and thus by 97.5%, i.e. it was even more effective than with pH 6.0. Omitting CaCN.sub.2 treatment caused an increase in H.sub.2S emissions of 786% (compared to B1) and 3871% (compared to B2). Compared to the reference experiment (V1) with a cumulative H.sub.2S volume of 3.61 mL based on 1.00 kg of cattle liquid manure, the H.sub.2S emissions were drastically increased by 1102% (V2) and 1044% (V3) by acidifying the liquid manure alone.
[0127] Acidifying the cattle liquid manure alone can already reduce the emission of certain harmful gases, such as methane and CO.sub.2. However, the use of sulfuric acid increases the emission of toxic H.sub.2S due to the sulphate input. With the combined application of acidification and CaCN.sub.2 addition over a period of 400 days, the emission of harmful gases from the farm manure, including hydrogen sulfide, can be significantly reduced compared to acidification alone.
[0128] The single application of H.sub.2SO.sub.4 resulted in more than eleven times the amount of H.sub.2S being emitted during anaerobic liquid manure storage than in the control experiment (V1). Consequently, the single acidification of the liquid manure with H.sub.2SO.sub.4 inhibits the general gas emission but seems to support desulfurization and thus the H.sub.2S emission in particular. Additional treatment of cattle liquid manure with CaCN.sub.2 very effectively compensates for this effect and leads to significantly reduced H.sub.2S emissions.
2.1.4 Treatment of Cattle Liquid Manure with CaCN.sub.2 (Comparative Examples V4 and V5):
[0129] In comparative example V4, 3.05 kg of cattle liquid manure was mixed with 6.34 g of CaCN.sub.2 formulation F1 and stirred in. In comparative example V5, 3.04 kg of cattle liquid manure was mixed with 8.86 g of CaCN.sub.2 formulation F1 and stirred in. The gas storage bags were changed and analyzed in the comparative examples after 14, 67, 85, 108, 136, 156, 179, 200, 218, 234, 248, 267, 295, 323, 357 and 400 days. The total gas volumes emitted (V.sub.ges) and the specific volumes of methane (CH.sub.4), carbon dioxide (CO.sub.2) and hydrogen sulfide (H.sub.2S) are listed cumulatively in Table 7. For better comparability, the determined gas volumes are standardized to 1.00 kg of cattle liquid manure. The development of the respective gases over time is shown in
TABLE-US-00007 TABLE 7 Cumulative gas emissions in V4 and V5 (based on 1.00 kg cattle liquid manure) Comparative example V4 Comparative example V5 Storage (CaCN.sub.2 0.21%) (CaCN.sub.2 0.29%) duration CH.sub.4 CO.sub.2 H.sub.2S V.sub.ges CH.sub.4 CO.sub.2 H.sub.2S V.sub.ges [Days] [L] [L] [mL] [L] [L] [L] [mL] [L] 14 0.00 0.04 0.00 0.36 0.00 0.01 0.00 0.15 67 0.04 0.32 0.01 1.64 0.02 0.23 0.00 1.17 85 0.04 0.33 0.01 1.71 0.03 0.25 0.00 1.36 108 0.05 0.34 0.01 1.85 0.03 0.26 0.00 1.43 136 0.08 0.36 0.01 2.21 0.03 0.26 0.00 1.59 156 0.32 0.51 0.01 3.26 0.03 0.27 0.00 1.72 179 1.02 0.76 0.01 4.94 0.04 0.28 0.00 2.02 200 1.77 1.05 0.01 6.64 218 2.39 1.32 0.01 8.08 0.14 0.33 0.00 2.61 234 3.16 1.71 0.01 9.79 248 3.88 2.10 0.01 11.3 0.47 0.47 0.00 3.73 267 4.36 2.29 0.01 12.5 0.91 0.66 0.00 4.78 295 4.63 2.39 0.01 13.4 1.62 1.01 0.00 6.44 323 4.73 2.43 0.01 14.1 2.31 1.31 0.00 7.95 357 4.76 2.45 0.01 14.4 2.92 1.52 0.00 9.26 400 4.76 2.46 0.01 14.6 3.38 1.71 0.01 10.6
Discussion of the Results:
[0130] Total emissions: After 400 days of anaerobic storage, 14.6 L of total gas were released based on 1.00 kg of cattle liquid manure in comparative example V4. According to Examples 1 and 2, the additional CaCN.sub.2 treatment reduced emissions by 80.7% to 2.77 L and 88.4% to 1.69 L compared to V4. A comparison of Examples 1 and 2 with V5 shows a reduction in total emissions through the combination of acidification and subsequent CaCN.sub.2 treatment of 10.6 L to 2.77 L and thus by 73.9% and to 1.69 L and thus by 84.1%. If prior liquid manure acidification with H.sub.2SO.sub.4 is omitted, the total emissions increase by 427-764% (comparison of B1 and B2 with V4) or by 283-527% (comparison of B1 and B2 with V5). Compared to the reference experiment (V1) with a cumulative total gas volume of 15.5 L based on 1.00 kg of cattle liquid manure, the emissions were reduced by 5.81% (V4) and 31.6% (V5) by CaCN.sub.2 treatment alone.
[0131] CH.sub.4 emissions: After 400 days of anaerobic storage, 4.76 L of CH.sub.4 were released based on 1.00 kg of cattle liquid manure in comparative experiment V4. Additional acidification reduced the emissions to 0.32 L and thus by 93.3% (Example 1) and to 0.15 L and thus by 96.8% (Example 2). A similar reduction results from the comparison of Examples 1 and 2 with example V5. The CH.sub.4 emission from the combination of acidification and subsequent CaCN.sub.2 treatment is reduced from 3.38 L to 0.32 L and thus by 90.5% (Example 1) and to 0.15 L and thus by 95.6% (Example 2). By omitting prior liquid manure acidification with H.sub.2SO.sub.4 as in Examples 1 and 2, CH.sub.4 emissions increase by 1388-3073% and 956-2153% respectively. Compared to the reference experiment (V1) with a cumulative CH.sub.4 volume of 5.24 L based on 1.00 kg of cattle liquid manure, the CaCN.sub.2 treatment alone reduces CH.sub.4 emissions by 9.16% (V4) and 35.5% (V5).
[0132] CO.sub.2 emissions: After 400 days of anaerobic storage, 2.46 L of CO.sub.2 were released based on 1.00 kg of cattle liquid manure in comparative experiment V4. Additional acidification reduced the CO.sub.2 emissions to 0.18 L and thus by 92.7% (Example 1) and to 0.07 L and thus by 97.2% (Example 2). A slightly smaller reduction results from the comparison of Examples 1 and 2 with V5. The CO.sub.2 emissions in B1 and B2 fall from 1.71 L to 0.18 L and thus by 89.5% and to 0.07 L and thus by 95.9% respectively compared to V5. The omission of prior liquid manure acidification with H.sub.2SO.sub.4 causes an increase in CO.sub.2 emissions compared to B1 and B2 of 1267-3414% (V4) and 850-2343% (V5). Compared to the reference experiment (V1) with a cumulative CO.sub.2 volume of 3.51 L based on 1.00 kg of cattle liquid manure, CO.sub.2 emissions are reduced by 29.9% (V4) and 51.3% (V5) by CaCN.sub.2 treatment alone.
[0133] H.sub.2S emissions: After 400 days of anaerobic storage, 0.01 mL of H.sub.2S was released based on 1.00 kg of cattle liquid manure in each of the comparative experiments V4 and V5. In Examples 1 and 2, the additional acidification increased the emissions to 4.90 mL and 1.04 mL respectively. The omission of prior liquid manure acidification with H.sub.2SO.sub.4 results in a reduction in H.sub.2S emissions of 99.0-99.8% (V4/V5 compared to B1 and B2). Compared to the reference experiment (V1) with a cumulative H.sub.2S volume of 3.61 mL based on 1.00 kg of cattle liquid manure, the H.sub.2S emissions were reduced by 99.7% (V4 and V5) by CaCN.sub.2 treatment alone.
[0134] Comparative experiments V4 and V5 also show that the treatment of an acidified farm manure with calcium cyanamide can further reduce harmful gas emissions compared to treatment with CaCN.sub.2 alone. However, the effect of desulphurization is not achieved when CaCN.sub.2 is added alone. Overall, however, the advantages of the synergetic effects of the combined method clearly outweigh the disadvantages, in particular as a stronger H.sub.2S development only sets in relatively late, after more than 300 days, when the cattle liquid manure is stored anaerobically.
2.2 Test Series 2
2.2.1 Comparison Example V6 (Control):
[0135] As a reference for the emitted gas quantities during the anaerobic storage of treated farm manure, 3.00 kg of untreated cattle liquid manure without additives was examined (control experiment V6 according to Table 3). The gas storage bags were changed and analyzed after 7, 33, 69, 85, 96, 104, 112, 117, 124, 133, 139, 147, 156 and 167 days. The total volume of gas emitted (V.sub.ges) and the specific volumes of methane (CH.sub.4), carbon dioxide (CO.sub.2), hydrogen sulfide (H.sub.2S), ammonia (NH.sub.3) and nitrous oxide (N.sub.2O) are listed cumulatively in Table 8. For better comparability, the gas quantities determined are standardized to 1.00 kg of cattle liquid manure. The development of the respective gases over time is shown in
TABLE-US-00008 TABLE 8 Cumulative gas emissions based on 1.00 kg of cattle liquid manure in liters or milliliters. Storage Comparative example V6 (control) time CH.sub.4 CO.sub.2 H.sub.2S NH.sub.3 N.sub.2O V.sub.ges [Days] [L] [L] [mL] [mL] [mL] [L] 7 0.17 0.80 1.25 0.05 0.21 1.85 33 0.32 1.46 1.57 0.08 0.42 3.01 69 0.76 2.04 7.54 0.11 0.60 4.78 85 1.77 2.53 8.62 0.14 0.74 6.58 96 2.81 3.08 8.80 0.18 0.90 8.38 104 3.87 3.61 8.83 0.21 1.05 10.1 112 4.98 4.15 8.84 0.26 1.21 12.0 117 6.11 4.65 8.85 0.31 1.35 13.8 124 7.33 5.14 8.87 0.34 1.48 15.6 133 8.45 5.67 8.87 0.39 1.63 17.4 139 9.40 6.32 8.88 0.42 1.82 19.2 147 10.2 6.85 8.88 0.45 1.98 20.6 156 10.7 7.19 8.88 0.47 2.09 21.6 167 11.3 7.56 8.88 0.49 2.21 22.8
2.2.2 Combination of Acidification and CaCN.SUB.2 .Treatment of Cattle Liquid Manure (B3-B8):
[0136] According to example B3 (Table 3), 3.00 kg of cattle liquid manure was adjusted to a pH of 5.5 with 16.3 g of 95% H.sub.2SO.sub.4. Subsequently, 6.55 g of CaCN.sub.2 formulation F2 was added and stirred in. According to example B4 (Table 3), 3.00 kg of cattle liquid manure was adjusted to a pH of 5.5 with 16.4 g of 95% H.sub.2SO.sub.4. Subsequently, 3.93 g CaCN.sub.2 formulation F2 was added and stirred in. Furthermore, 3.00 kg of cattle liquid manure was adjusted to a pH value of 5.5 with 35.8 g of 32% hydrochloric acid (HCl, example B5), 22.6 g of 100% acetic acid (HOAc, example B6), 41.5 g of 50% citric acid (CA, example B7) and 40.4 g of 90% lactic acid (LA, example B8) and then 6.55 g of CaCN.sub.2 formulation F2 was added and stirred in. The gas storage bags were changed and analyzed for all examples after 7, 33, 69, 85, 96, 104, 112, 117, 124, 133, 139, 147, 156 and 167 days. The total gas volumes emitted (V.sub.ges) and the specific volumes of methane (CH.sub.4), carbon dioxide (CO.sub.2), hydrogen sulfide (H.sub.2S), ammonia (NH.sub.3) and nitrous oxide (N.sub.2O) are listed cumulatively in Tables 9-11. For better comparability, the gas quantities determined are standardized to 1.00 kg of cattle liquid manure. The development of the respective gases over time is shown in
TABLE-US-00009 TABLE 9 Cumulative gas emissions based on 1.00 kg of cattle liquid manure in liters or milliliters. Example B3 Example B4 Storage (H.sub.2SO.sub.4 pH 5.5 + 0.22% F2) (H.sub.2SO.sub.4 pH 5.5 + 0.13% F2) duration CH.sub.4 CO.sub.2 H.sub.2S NH.sub.3 N.sub.2O V.sub.ges CH.sub.4 CO.sub.2 H.sub.2S NH.sub.3 N.sub.2O V.sub.ges [Days] [L] [L] [mL] [mL] [mL] [L] [L] [L] [mL] [mL] [mL] [L] 7 0.00 0.05 0.00 0.00 0.01 0.40 0.00 0.06 0.00 0.00 0.02 0.60 33 0.00 0.09 0.01 0.00 0.02 0.75 0.00 0.13 0.02 0.01 0.03 0.90 69 0.00 0.12 0.01 0.01 0.03 1.08 0.00 0.15 0.03 0.01 0.04 0.97 85 0.00 0.13 0.01 0.01 0.03 1.10 0.00 0.16 0.09 0.01 0.04 1.23 96 0.00 0.14 0.01 0.01 0.03 1.13 0.00 0.18 0.22 0.01 0.04 1.30 104 0.00 0.14 0.01 0.01 0.03 1.20 0.00 0.19 0.38 0.01 0.05 1.47 112 0.00 0.15 0.02 0.01 0.04 1.20 0.00 0.21 0.62 0.02 0.05 1.63 117 0.00 0.16 0.03 0.01 0.04 1.24 0.00 0.22 0.85 0.02 0.05 1.70 124 0.00 0.16 0.06 0.01 0.04 1.25 0.00 0.23 1.05 0.02 0.05 1.75 133 0.00 0.17 0.14 0.01 0.04 1.37 0.00 0.24 1.27 0.02 0.05 1.82 139 0.00 0.17 0.22 0.01 0.04 1.37 0.01 0.25 1.45 0.02 0.06 1.98 147 0.00 0.18 0.27 0.01 0.04 1.51 0.01 0.25 1.55 0.02 0.06 1.99 156 0.00 0.18 0.37 0.01 0.04 1.57 0.01 0.26 1.84 0.02 0.06 2.12 167 0.00 0.18 0.49 0.02 0.04 1.74 0.02 0.28 2.56 0.03 0.06 2.25
TABLE-US-00010 TABLE 10 Cumulative gas emissions based on 1.00 kg of cattle liquid manure in liters or milliliters. Example B5 Example B6 Storage (HCl pH 5.5 + 0.22% F2) (HOAc pH 5.5 + 0.22% F2) duration CH.sub.4 CO.sub.2 H.sub.2S NH.sub.3 N.sub.2O V.sub.ges CH.sub.4 CO.sub.2 H.sub.2S NH.sub.3 N.sub.2O V.sub.ges [Days] [L] [L] [mL] [mL] [mL] [L] [L] [L] [mL] [mL] [mL] [L] 7 0.00 0.03 0.00 0.00 0.01 0.27 0.00 0.04 0.00 0.00 0.01 0.53 33 0.00 0.08 0.01 0.00 0.02 0.62 0.00 0.12 0.01 0.01 0.04 0.97 69 0.00 0.09 0.01 0.01 0.02 0.82 0.00 0.14 0.01 0.01 0.04 1.17 85 0.00 0.10 0.01 0.01 0.02 0.88 0.00 0.16 0.01 0.01 0.04 1.23 96 0.00 0.10 0.01 0.01 0.02 1.02 0.00 0.16 0.01 0.01 0.04 1.25 104 0.00 0.10 0.01 0.01 0.02 1.02 0.00 0.16 0.01 0.01 0.04 1.38 112 0.00 0.11 0.01 0.01 0.02 1.02 0.00 0.17 0.01 0.01 0.04 1.52 117 0.00 0.11 0.01 0.01 0.02 1.14 0.00 0.17 0.02 0.01 0.04 1.55 124 0.00 0.11 0.01 0.01 0.02 1.21 0.00 0.18 0.02 0.01 0.04 1.55 133 0.00 0.12 0.01 0.01 0.02 1.34 0.00 0.18 0.02 0.01 0.04 1.56 139 0.00 0.12 0.01 0.01 0.02 1.34 0.00 0.19 0.02 0.01 0.04 1.69 147 0.00 0.12 0.01 0.01 0.02 1.41 0.00 0.19 0.02 0.02 0.04 1.69 156 0.00 0.12 0.01 0.01 0.02 1.41 0.00 0.19 0.02 0.02 0.04 1.86 167 0.00 0.13 0.01 0.02 0.02 1.45 0.00 0.20 0.02 0.02 0.05 1.93
TABLE-US-00011 TABLE 11 Cumulative gas emissions based on 1.00 kg of cattle liquid manure in liters or milliliters. Example B7 Example B8 Storage (CA pH 5.5 + 0.22% F2) (LA pH 5.5 + 0.22% F2) duration CH.sub.4 CO.sub.2 H.sub.2S NH.sub.3 N.sub.2O V.sub.ges CH.sub.4 CO.sub.2 H.sub.2S NH.sub.3 N.sub.2O V.sub.ges [Days] [L] [L] [mL] [mL] [mL] [L] [L] [L] [mL] [mL] [mL] [L] 7 0.00 0.36 0.00 0.02 0.13 0.97 0.00 0.06 0.00 0.00 0.02 0.53 33 0.00 0.45 0.01 0.03 0.15 1.35 0.00 0.69 0.00 0.05 0.22 1.78 69 0.01 0.54 0.01 0.04 0.17 1.68 0.00 0.71 0.00 0.05 0.22 1.98 85 0.01 0.57 0.01 0.04 0.18 1.95 0.00 0.72 0.00 0.05 0.22 2.05 96 0.02 0.59 0.01 0.04 0.18 2.08 0.00 0.73 0.00 0.05 0.22 2.07 104 0.02 0.60 0.02 0.04 0.18 2.15 0.00 0.73 0.01 0.05 0.22 2.13 112 0.02 0.61 0.02 0.05 0.19 2.25 0.00 0.74 0.01 0.05 0.23 2.14 117 0.02 0.62 0.02 0.05 0.19 2.42 0.00 0.74 0.01 0.05 0.23 2.15 124 0.03 0.63 0.02 0.05 0.19 2.62 0.00 0.75 0.01 0.05 0.23 2.16 133 0.03 0.65 0.02 0.05 0.19 2.78 0.00 0.75 0.01 0.05 0.23 2.22 139 0.03 0.66 0.02 0.05 0.19 2.88 0.00 0.76 0.01 0.05 0.23 2.23 147 0.04 0.67 0.03 0.05 0.20 2.92 0.00 0.76 0.01 0.05 0.23 2.36 156 0.04 0.68 0.03 0.06 0.20 2.95 0.00 0.76 0.01 0.05 0.23 2.43 167 0.05 0.70 0.03 0.06 0.20 2.95 0.00 0.76 0.01 0.06 0.23 2.63
Discussion of the Results:
Total Emissions, CH.sub.4, CO.sub.2 and H.sub.2S Emissions:
[0137] After 167 days of anaerobic storage, 22.8 L of total gas, 11.3 L of CH.sub.4, 7.56 L of CO.sub.2 and 8.88 mL of H.sub.2S were released based on 1.00 kg of cattle liquid manure in the reference experiment V6. Acidification with various acids to pH 5.5 and subsequent addition of CaCN.sub.2 (examples 3-8) can very significantly reduce emissions. Accordingly, the total emissions could be reduced by 87.1-93.7%, the CH.sub.4 emissions by 99.5-100%, the CO.sub.2 emissions by 89.9-98.3% and the H.sub.2S emissions by 71.2-99.9%. The acid used for acidification only plays a subordinate role in the emission reduction effect. However, the use of sulfuric acid (examples 3 and 4) increases H.sub.2S emission due to the additional sulphate input. The influence of the dosing quantity of CaCN.sub.2 (formulation F2) can be seen in examples 3 and 4. The H.sub.2S emissions of 8.88 mL (reference experiment V6) are reduced in example 4 to 2.56 mL (71.2%) and 0.49 mL (94.4%) in example 3.
Nh.SUB.3 .Emissions:
[0138] After 167 days of anaerobic storage, 0.49 mL of NH.sub.3 was released based on 1.00 kg of cattle liquid manure in the reference experiment (V6). Acidification with various acids to pH 5.5 and subsequent addition of CaCN.sub.2 (examples 3-8) can reduce emissions by 88.4-96.8%.
N.SUB.2.O Emissions:
[0139] After 167 days of anaerobic storage, 2.21 mL of N.sub.2O was released based on 1.00 kg of cattle liquid manure in the reference experiment (V6). Acidification with various acids to pH 5.5 and subsequent addition of CaCN.sub.2 (examples 3-8) can reduce emissions by 89.7-99.0%.
[0140] The test series shows that the combination of liquid manure acidification and subsequent CaCN.sub.2 treatment is a very effective measure for reducing harmful gas emissions when storing farm manures, such as cattle liquid manure. The type of acid used for acidification is less decisive for the reduction of (harmful gas) emissions than the set pH value. In addition, the dosing quantity of CaCN.sub.2 can be reduced in combination with an acid without compromising the reduction in gas emissions compared to treatment with CaCN.sub.2 alone.
2.2.3 Acidification of Cattle Liquid Manure with H.sub.2SO.sub.4 (Comparative Example V7):
[0141] 3.00 kg of cattle liquid manure with 17.6 g of 95% H.sub.2SO.sub.4 was adjusted to a pH value of 5.5 (comparative example V7). The gas storage bags were changed and analyzed after 7, 33, 69, 85, 96, 104, 112, 117, 124, 133, 139, 147, 156 and 167 days in the comparative example. The total gas volumes emitted (V.sub.ges) and the specific volumes of methane (CH.sub.4), carbon dioxide (CO.sub.2), hydrogen sulfide (H.sub.2S), ammonia (NH.sub.3) and nitrous oxide (N.sub.2O) are listed cumulatively in Table 12. For better comparability, the gas quantities determined are standardized to 1.00 kg of cattle liquid manure. The development of the respective gases over time is shown in
TABLE-US-00012 TABLE 12 Cumulative gas emissions V7 (based on 1.00 kg of cattle liquid manure) in liters or milliliters. Comparative example V7 (H.sub.2SO.sub.4 pH 5.5) Storage time CH.sub.4 CO.sub.2 H.sub.2S NH.sub.3 N.sub.2O V.sub.ges [Days] [L] [L] [mL] [mL] [mL] [L] 7 0.00 0.07 0.07 0.01 0.02 0.53 33 0.03 0.34 0.51 0.02 0.10 1.27 69 0.17 0.59 3.16 0.03 0.17 2.13 85 0.42 0.83 12.1 0.04 0.24 3.12 96 0.73 1.08 22.2 0.06 0.31 3.98 104 1.23 1.42 32.2 0.07 0.40 5.02 112 1.62 1.66 41.4 0.09 0.47 5.85 117 1.75 1.73 44.1 0.09 0.49 6.25 124 1.88 1.80 46.9 0.09 0.51 6.62 133 1.99 1.87 49.5 0.09 0.52 6.92 139 2.03 1.89 50.3 0.10 0.53 7.08 147 2.05 1.90 50.7 0.10 0.53 7.12 156 2.07 1.91 51.0 0.10 0.53 7.18 167 2.09 1.92 51.3 0.10 0.54 7.19
Discussion of the Results:
Total Emissions, CH.sub.4, CO.sub.2 and H.sub.2S Emissions:
[0142] After 167 days of anaerobic storage, 7.19 L of total gas, 2.09 L of CH.sub.4, 1.92 L of CO.sub.2 and 51.3 mL of H.sub.2S were released based on 1.00 kg of cattle liquid manure in comparative example V7. By adding CaCN.sub.2 (examples 3-8), a reduction in emissions can be achieved compared to V7. The total emissions could be reduced by 59.0-79.8%, the CH.sub.4 emissions by 97.6-100%, the CO.sub.2 emissions by 60.4-93.2% and the H.sub.2S emissions by 95.0-100%. If no CaCN.sub.2 treatment was carried out, this led to a significant increase in total emissions, including CH.sub.4, CO.sub.2 and H.sub.2S emissions (acidified cattle liquid manure in V7 compared to examples 3-8). Compared to the reference experiment (V6) with cumulative volumes of total gas (22.8 L), CH.sub.4 (11.3 L), CO.sub.2 (7.56 L) and H.sub.2S (8.88 mL) based on 1.00 kg of cattle liquid manure, the emissions were reduced by 68.5% (V.sub.ges), 81.4% (CH.sub.4) and 74.6% (CO.sub.2) by the acidification of the liquid manure with sulfuric acid alone and the H.sub.2S emission increased drastically by 477.4%.
NH.SUB.3 .Emissions:
[0143] After 167 days of anaerobic storage, 0.10 mL of NH.sub.3 was released based on 1.00 kg of cattle liquid manure in comparative example V7. By adding CaCN.sub.2 (examples 3-8), emissions can be reduced to 0.02-0.06 mL and thus by 40.0-80.0%.
N.SUB.2.O Emissions:
[0144] After 167 days of anaerobic storage, 0.54 mL of N.sub.2O was released based on 1.00 kg of cattle liquid manure in comparative example V7. The combination of acidification and addition of CaCN.sub.2 (examples 3-8) reduces the emissions to 0.02-0.23 mL and thus by 57.4-96.3%.
[0145] The findings of the second test series confirm or extend the results from the first test series. For example, the emissions of harmful gases from farm manures can be significantly reduced by a combined application of acidification and CaCN.sub.2 addition compared to acidification alone. In particular when using sulfuric acid, the sometimes considerable H.sub.2S emissions can be compensated for by a low CaCN.sub.2 dosage.
2.2.4 Treatment of Cattle Liquid Manure with CaCN.sub.2 (Comparative Examples V8 and V9):
[0146] In comparative test V8, 3.00 kg of cattle liquid manure was mixed with 6.55 g of CaCN.sub.2 formulation F2. In comparative test V9, 3.00 kg of cattle liquid manure was mixed with 3.94 g of CaCN.sub.2 formulation F2. The gas storage bags were changed and analyzed in both comparative examples after 7, 33, 69, 85, 96, 104, 112, 117, 124, 133, 139, 147, 156 and 167 days. The total gas volumes emitted (V.sub.ges) and the specific volumes of methane (CH.sub.4), carbon dioxide (CO.sub.2), hydrogen sulfide (H.sub.2S), ammonia (NH.sub.3) and nitrous oxide (N.sub.2O) are listed cumulatively in Table 13. For better comparability, the gas quantities determined are standardized to 1.00 kg of cattle liquid manure. The development of the respective gases over time is shown in
TABLE-US-00013 TABLE 13 Cumulative gas emissions in V8 and V9 (based on 1.00 kg of cattle liquid manure) in liters and milliliters. Comparative example V8 Comparative example V9 Storage (CaCN.sub.2 0.22%) (CaCN.sub.2 0.13%) duration CH.sub.4 CO.sub.2 H.sub.2S NH.sub.3 N.sub.2O V.sub.ges CH.sub.4 CO.sub.2 H.sub.2S NH.sub.3 N.sub.2O V.sub.ges [Days] [L] [L] [mL] [mL] [mL] [L] [L] [L] [mL] [mL] [mL] [L] 7 0.00 0.08 0.00 0.01 0.02 0.57 0.00 0.14 0.03 0.01 0.04 0.75 33 0.02 0.37 0.01 0.03 0.12 1.43 0.08 0.74 0.34 0.06 0.22 2.03 69 0.05 0.52 0.02 0.04 0.17 2.10 0.11 0.86 0.52 0.07 0.25 2.50 85 0.06 0.55 0.02 0.04 0.18 2.30 0.12 0.89 0.54 0.07 0.26 2.73 96 0.06 0.57 0.02 0.04 0.18 2.43 0.19 1.01 0.58 0.07 0.29 3.26 104 0.07 0.58 0.02 0.04 0.19 2.45 0.35 1.16 0.59 0.08 0.34 3.94 112 0.08 0.60 0.03 0.05 0.19 2.52 0.66 1.37 0.59 0.09 0.40 4.68 117 0.10 0.62 0.03 0.05 0.20 2.58 0.91 1.52 0.60 0.10 0.44 5.24 124 0.12 0.64 0.03 0.05 0.20 2.72 1.22 1.68 0.60 0.11 0.49 5.87 133 0.18 0.70 0.03 0.05 0.22 3.18 1.56 1.85 0.60 0.12 0.54 6.71 139 0.26 0.77 0.03 0.06 0.24 3.55 1.78 1.97 0.60 0.12 0.57 7.17 147 0.48 0.92 0.03 0.07 0.29 4.25 2.08 2.13 0.60 0.13 0.62 7.81 156 0.83 1.11 0.03 0.08 0.35 5.21 2.49 2.34 0.60 0.15 0.68 8.67 167 1.09 1.24 0.03 0.09 0.40 5.88 3.14 2.66 0.60 0.16 0.77 9.87
Discussion of the Results:
Total Emissions, CH.sub.4, CO.sub.2 and H.sub.2S Emissions:
[0147] After 167 days of anaerobic storage, 5.88 L of total gas, 1.09 L of CH.sub.4, 1.24 L of CO.sub.2 and 0.03 mL of H.sub.2S were released based on 1.00 kg of cattle liquid manure in comparative example V8. Compared to V8, a significant reduction in total emissions (49.8-75.3%), CH.sub.4 emissions (95.4-100%) and CO.sub.2 emissions (38.7-89.5%) were achieved in examples 3 and 5-8. The comparison of V9 and example 4 shows a similar picture, with total emissions being reduced from 9.87 L to 2.25 L (77.2%), CH.sub.4 emissions from 3.14 L to 0.02 L (99.4%) and CO.sub.2 emissions from 2.66 L to 0.28 L (95.1%). If the previous liquid manure acidification is omitted, there is an increase in total emissions, CH.sub.4, CO.sub.2 (comparison of B3-8 with V8 and V9) and H.sub.2S emissions (comparison of B5-8 with V8 and V9). However, due to the absence of sulphate input from sulfuric acid, there is a reduction in H.sub.2S emissions if the acid is omitted (comparison of B3 and B4 with V8 and V9).
NH.SUB.3 .Emissions:
[0148] After 167 days of anaerobic storage, 0.09 mL of NH.sub.3 was released based on 1.00 kg of cattle liquid manure in comparative example V8. By adding CaCN.sub.2 (examples 3 and 5-8), a reduction in emissions to 0.02-0.06 mL and thus by 33.3-77.8% can be achieved. A comparison of V9 with B4 shows a reduction in NH.sub.3 emissions from 0.16 mL to 0.03 mL, i.e. by 81.3%.
N.SUB.2.O Emissions:
[0149] After 167 days of anaerobic storage, 0.40 mL of N.sub.2O was released based on 1.00 kg of cattle liquid manure in comparative example V8. The combination of acidification and addition of CaCN.sub.2 (examples 3 and 5-8) reduces the emissions to 0.02-0.23 mL and thus by 42.5-95.0%. The comparison of V9 with B4 reveals a reduction in NH.sub.3 emissions from 0.77 mL to 0.06 mL and thus by 92.2%.
[0150] The results of the second test series show that, in addition to the formation and release of the harmful gases CH.sub.4, CO.sub.2 and H.sub.2S, NH.sub.3 and N.sub.2O emissions can also be further reduced by treating an acidified farm manure with calcium cyanamide compared to treatment with CaCN.sub.2 alone. The lower concentrated CaCN.sub.2 treatment (V9/B4) shows similarly good results as the higher dosed option (V8/B3). The combination of liquid manure acidification and CaCN.sub.2 treatment shows a very good effect in terms of gas release even when the CaCN.sub.2 dosage is reduced (B4) and even outperforms the higher concentrated CaCN.sub.2 treatment alone (V8).
2.2.5 Long-Term Measurements within Test Series 2
[0151] Test series 2 was continued over a longer period of time until it was completed after 335 days. As an example, the total gas volumes (V.sub.ges) and the specific volumes of methane (CH.sub.4), carbon dioxide (CO.sub.2), hydrogen sulfide (H.sub.2S), ammonia (NH.sub.3) and nitrous oxide (N.sub.2O) emitted on two further measurement days, after 268 and 335 days of storage respectively, are listed cumulatively in Table 14.
TABLE-US-00014 TABLE 14 Cumulative gas emissions of test series 2 (V6-V9 and B3-B8; based on 1.00 kg cattle liquid manure) after 268 and 335 days of storage. CH.sub.4 CO.sub.2 H.sub.2S NH.sub.3 N.sub.2O V.sub.ges Experiment [L] [L] [mL] [mL] [mL] [L] Storage period 268 days Comparative example V6 (control) 13.5 9.19 8.88 0.57 2.76 28.4 Comparative example V7 (H.sub.2SO.sub.4 pH 5.5) 2.91 2.23 56.9 0.11 0.62 9.19 Comparative example V8 4.71 3.07 0.03 0.19 0.97 14.0 (CaCN.sub.2 0.22%) Comparative example V9 9.10 5.40 0.60 0.33 1.55 20.4 (CaCN.sub.2 0.13%) Example B3 0.01 0.23 1.77 0.02 0.05 2.41 (H.sub.2SO.sub.4 pH 5.5 + 0.22% F2) Example B4 0.65 0.73 11.4 0.06 0.18 4.19 (H.sub.2SO.sub.4 pH 5.5 + 0.13% F2) Example B5 0.00 0.15 0.01 0.02 0.03 1.95 (HCl pH 5.5 + 0.22% F2) Example B6 0.00 0.23 0.02 0.02 0.05 2.27 (HOAc pH 5.5 + 0.22% F2) Example B7 0.24 0.89 0.03 0.07 0.25 4.50 (CA pH 5.5 + 0.22% F2) Example B8 0.01 0.80 0.01 0.06 0.23 3.00 (LA pH 5.5 + 0.22% F2) Storage period 335 days Comparative example V6 (control) 13.7 9.36 8.88 0.58 2.82 29.5 Comparative example V7 (H.sub.2SO.sub.4 pH 5.5) 5.30 3.07 76.5 0.16 0.83 12.9 Comparative example V8 6.39 4.00 0.03 0.24 1.27 18.0 (CaCN.sub.2 0.22%) Comparative example V9 9.85 5.89 0.60 0.35 1.71 22.5 (CaCN.sub.2 0.13%) Example B3 0.23 0.39 5.45 0.03 0.09 3.84 (H.sub.2SO.sub.4 pH 5.5 + 0.22% F2) Example B4 0.83 0.81 15.2 0.06 0.19 4.59 (H.sub.2SO.sub.4 pH 5.5 + 0.13% F2) Example B5 0.01 0.16 0.01 0.02 0.03 2.35 (HCl pH 5.5 + 0.22% F2) Example B6 0.00 0.23 0.02 0.03 0.05 2.37 (HOAc pH 5.5 + 0.22% F2) Example B7 2.24 1.93 0.04 0.13 0.52 8.87 (CA pH 5.5 + 0.22% F2) Example B8 0.01 0.81 0.01 0.07 0.23 3.07 (LA pH 5.5 + 0.22% F2)
[0152] The long-term measurements show that gas emissions from liquid manure can be greatly reduced in the long term through treatment with calcium cyanamide in combination with acidification of the liquid manure. The long-term measurements also impressively demonstrate the synergistic effect of the two measures.
SUMMARY OF THE RESULTS
[0153] As the examples show, the combination of acidifying farm manure and subsequent CaCN.sub.2 treatment is a very effective measure for reducing harmful gas emissions during the storage of farm manure.
[0154] The treatment of farm manures with CaCN.sub.2 alone is already a good measure for reducing harmful gas emissions. Acidification of the farm manure can also reduce gas emissions. However, while the acidification of farm manure is a process that must be applied several times to effectively reduce harmful gas emissions, in combination with CaCN.sub.2 treatment, a single acidification at the beginning of storage is usually sufficient for a long-term reduction in emissions.
[0155] Furthermore, a strong synergy effect can be observed in the reduction of gas emissions, in particular in the reduction of harmful ammonia, carbon dioxide, nitrous oxide, methane and hydrogen sulfide releases, when acidification of the farm manure is combined with CaCN.sub.2 treatment. For example, methane emissions after more than 5 months (156 or 167 days) are reduced by 66.8-81.4% (V2, V3 and V7) by acidification alone and by 72.1-99.4% (V4, V5, V8 and V9) by CaCN.sub.2 treatment alone. If both measures are combined, the reduction is 99.5-100% (B1-B8), i.e. higher than would be expected from the individual measures. Acidification alone also leads to a reduction in CO.sub.2 emissions of 53.1-74.6% (V2, V3 and V7). Pure CaCN.sub.2 treatment leads to a reduction of 64.8-91.7% (V4, V5, V8 and V9). If both measures are combined, the reduction is 89.9-99.1% (B1-B8), i.e. better than would be expected from the individual measures. The picture is similar for NH.sub.3 and N.sub.2O emissions. While acidification alone only reduces NH.sub.3 and N.sub.2O releases by 79.7% and 75.7% respectively (V7), the combined process results in reductions of 88.4-96.8% and 89.7-99.0% respectively (B1-B8). In contrast, the use of CaCN.sub.2 alone reduces ammonia and nitrous oxide emissions by 67.4-82.0% and 65.1-82.0% respectively (V8 and V9).
[0156] With longer storage times, the synergy effect is even more significant compared to the individual applications. For example, a combination of liquid manure acidification and CaCN.sub.2 treatment after 400 days of storage (B1 and B2) still results in a reduction in CH.sub.4 emissions of 93.9-97.1% and CO.sub.2 emissions of 94.9-98.0%. In contrast, when only one of the two measures was applied, CH.sub.4 and CO.sub.2 emissions were only reduced by 16.2-39.5% and 41.6-43.3% respectively with liquid manure acidification alone (V2 and V3) and by 9.2-35.5% and 29.9-51.3% respectively with CaCN.sub.2 treatment alone (V4 and V5). In general, only negligible emissions were detected after initial adjustment of the pH value of the tested cattle liquid manure to 6.0 or 5.5 and subsequent CaCN.sub.2 treatment during anaerobic storage over a period of 400 days.
[0157] In addition, the method according to the invention also shows an excellent effect over a long period of time when setting higher pH values (6.0 vs. 5.5) and at a lower CaCN.sub.2 dosage (0.13% vs. 0.22%). As a result, both the required amount of acid and the dosage of cyanamide salt can be reduced while maintaining an effective reduction in (harmful gas) emissions during the storage of farm manures.
[0158] The type of acid used for acidification is hardly relevant for the synergistic effect of the method described herein. However, in addition to ecological (in particular higher H.sub.2S and N.sub.2O emissions due to sulfuric and nitric acid) and economic (price, availability and logistics) factors, safety aspects (sources of danger for humans and animals and material resistance/corrosion) also influence the selection.