CS225905B1 - The method of biological reclamation of fly ash - Google Patents

Abstract

A method of biological reclamation of fly ash with a pH of 4 to 10, characterized in that the fly ash layer is saturated with pig or cattle or poultry manure, optionally also with feces with a nitrogen content of 0.01 to 1.5%; phosphorus of 0.005 to 0.8%; potassium of 0.01 to 1.2% and dry matter of 0.5 to 18% by weight in a dose of 20 to 4,000 tons per 1 ha, optionally supplemented with mineral nutrients by industrial fertilizers with a nitrogen content in the range of 0.1 to 1.5%; phosphorus from 20 to 500 mg and potassium from 50 to 1,000 mg per 1 kg of ash, or in acid ash with a pH of up to 5, the pH is adjusted with lime above 5 in a dose of 5 to 2 t CaO per 1 ha and either directly in the resulting substrate or after it is transported through the soil in a layer preferably from 5 to 30 cm high, or up to 50 cm, crops are immediately grown.

Description

The invention solves a method of biological reclamation of fly ash deposits (of power plants, heating plants and other industrial enterprises) by fertilizing with pig, cattle or poultry manure, which is a source of nutrients, water and biological revitalization of fly ash.

The current method of biological reclamation of fly ash layers consists in covering them with fertile topsoil, usually at a height of 50 cm, which acts as a seed material. Fertilization is provided mainly by industrial fertilizers, so that the revitalization of fly ash is lengthy and therefore pioneer plants must be grown here at the beginning of the reclamation, only later it is possible to include cultural plants in the reclamation sowing process. The method of biological reclamation according to the invention eliminates the shortcomings of the methods used so far in this way»

Manure (feces or sludge) with a total N content of 0.005 to 1.5%, P 0.005 to 0.8% and K 0.01 to 1.2% of dry matter from 0.5 to 18% by weight is applied over the surface of the ash dump by conventional agricultural mechanization or a slurry pipeline, or by an irrigation system, at a rate of 20 to 4,000 t.ha ^- l. This creates a substrate with an N content ranging from 0.05 to 1.5%, P from 20 to 500 mg per 1 kg and K from 50 to 1000 mg per 1 kg of ash. If manure with a lower nutrient content is used, the dose is moved to the upper limit, or it is fertilized with conventional industrial fertilizers. If it is acid fly ash (4-5 pH), lime is also added, at a dose of 0.5 - 2.0 t CaO per 1 ha to an acceptable pH of at least 5 or more, depending on the requirements of the prevailing type of subsequently grown crops. A high dose of slurry is also used in the case of a particularly large surplus of slurry, when no other way of using it is possible and when leakage through the soil or overfilling of storage tanks could lead to pollution of the surrounding environment, especially with nitrates.

Preferably, according to the invention, sewage sludge is added simultaneously with manure or separately to the substrate in a dose of 50 to 6,000 t per 1 ha with an N content of 0.005 to 1%, P from 0.002 to 0.5%, K from 0.005 to 1% by weight, with a Zn content of up to 10,000 ppm, Cu up to 3,000 ppm, Ni up to 500 ppm, Cr up to 1,000 ppm, Pb up to 1,000 ppm, Cd up to 25 ppm, Hg up to 25 ppm, Mo up to 2,000 ppm and either directly in the resulting substrate or after covering it with soil to a depth of 50 cm, crops are immediately grown.

A significant benefit of the invention compared to the prior art is that in the case of a particularly large surplus of slurry due to ecological balance, when no other way of using it is possible and when there could be leakage through the soil or overfilling of storage tanks, pollution of the surrounding environment, especially with nitrates. The high filtration capacity of fly ash allows the use of orders of magnitude higher doses of slurry (e.g. 2000 t per 1 ha) compared to doses in the field (e.g. 200 t per 1 ha), without leakage of slurry and thus pollution of the surroundings.

The next step depends on the purpose of fertilizing the storage area: 1/ to reduce dust, it is not necessary to apply the slurry by dragging it, but it is advisable to leave the crust created by surface slurry application intact, as it already largely protects the storage area surface against dust. Sowing follows immediately after fertilization, and aerial sowing is organizationally advantageous (fast). The basic component of a simple seed mixture is fast-growing crops, e.g. mustard, rapeseed (preferably Akela) or with an admixture of clover grass seed if it is necessary to create a longer-term vegetation cover (1 year or more). Any common seed can be used in the mixture, but cheap seeds are preferred. From grasses, it is advisable to use reed fescue or another crop that can withstand possible waterlogging, which can occur during storage operation when the water level needs to be raised, so that it floods the sandy beach with vegetation.

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During short-term shutdown of the landfill (up to 1/2 year) and its treatment against dust, the harvested crops are not expected to be harvested. Only in the case of longer-term shutdown of the landfill (from 1 1/2 to 2 years) can the vegetation be used for harvesting, depending on local conditions. After the landfill is put back into operation, the vegetation is usually flooded with a new layer of fly ash.

2/ For the final reclamation of a permanently decommissioned landfill, slurry can also be applied directly to the surface layer of fly ash, or after it has been covered with a layer of soil. In view of the general lack of soil and the limited transport capacity, including the lack of fuel, it is expedient to limit the application of soil, which can only be achieved by using slurry.

a/ direct fertilization of the ash deposit with slurry is used in the case of a complete lack of any soil to cover it. If this lack is permanent, a permanent clover-grass growth is immediately established there and the deposit surface will not be plowed or otherwise disturbed. The case of this method of reclamation is unique, but easy to implement. The deposit is perfectly protected against dust and from the second to third year after its establishment, the growth is used for harvesting. In the first years (from 3 to 4 years) the growth is fertilized annually, preferably in spring, with increased doses of slurry) from 100 to 1000 tons per hectare), or manure fertilization is combined with industrial fertilizers, but in such a way that at least 20% of the total must be supplied in the form of slurry. In the following years, the growth is fertilized according to standard principles. Clover or alfalfa is planted directly in the ash also in the case of a temporary shortage of topsoil, which will be added to the ash additionally. b/Fertilization with manure while simultaneously covering the ash with soil is carried out either before or after layering with soil, or twice (before and after covering), depending on organizational possibilities. When using the manure according to the invention, in addition to topsoil, lower-quality soil (from excavations, if it is free of stones, mine dumps, etc.) is effectively used, which further saves topsoil (especially in this case, manure is fertilized twice - before and after covering the storage with soil). Soils from mine dumps are particularly advantageous, which usually have suitable agrochemical properties but are heavy, clayey with a content of up to 95% clay particles. This otherwise unsuitable grain size composition is not a problem in combination with fly ash; on the contrary, both materials complement each other well after mixing, because fly ash is composed mainly of dust particles (approx. 50-60% of particles in the category from 0.01 to 0.05 mm in diameter), so that a medium-heavy soil is created. The soil layer is selected from 5 to 30 cm, but slurry is also effectively used when the soil is covered up to 50 cm (faster biological recovery than when using mineral nutrients). However, this high soil layer is almost a luxury from an economic point of view when using slurry at the same time. When using a lower layer, the soil is plowed down to the fly ash, which brings the fly ash into the profile of the future topsoil. The lower the soil layer, the more fly ash is in the topsoil and the higher the slurry dose is selected for subsequent fertilization of the thus plowed surface of the landfill.

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With a low soil layer, it is advisable to use heavy clay soil. After fertilization, the plowed area is prepared for sowing the first crop: either a green manure crop is selected (preferably mustard or a winter mixture depending on the time of year when reclamation begins), or a cereal, preferably rye, with subsequent straw plowing. Other crops are included in the crop rotation according to the usual principles of agricultural practice, but preferably those that require high fertilization intensity, including frequent inclusion of catch crops.

Examples of implementation:

Example 1

Results of a model experiment with fertilizing fly ash with pig and cattle manure with P, K fertilization. Fertilization with manure immediately increases the content of basic nutrients in fly ash, while significantly increasing yields. After the addition of mineral nutrients, the content of P, K increased further, which was reflected in a further increase in the yields of the aboveground mass of corn, especially after fertilization with pig manure. Adding K to cattle manure is not necessary in this case, since the K content increased to the luxury content, but it did not have a positive effect on increased yield formation. Yiz tab. 1

Example 2

Enrichment of fly ash with essential nutrients by systematic manure fertilization. Annual manure fertilization in a model experiment /for 4 kg of fly ash always 5 g of pure N contained in manure - according to a previously performed analysis, significantly increased the content of essential nutrients in fly ash in 3 years while simultaneously producing high corn yields, see Table 2.

Example 3

Fertilization with manure to reduce dustiness of the compound (during temporary interruption of compound operation). Fertilization with manure immediately increases the NPK content in fly ash even when using relatively low doses (150-200 t.ha ^- ^·) and thus creates favorable conditions for mustard vegetation (+ rapeseed Acacia + reed fescue). The quickly established vegetation reliably protects the compound surface against dustiness. -tab.3.

Example 4

Direct fertilization of the compost with fly ^ash slurry. The slurry has also proven itself directly in the compost field, where repeated annual fertilization of the compost surface increases the supply of main nutrients and thus creates conditions for successful vegetation of crops and relatively high yield production from the beginning of biological reclamation - Table 4.

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Table 1 Fly ash fertilized with slurry with addition of mineral nutrients - P, K.

fertilization options agrochemical oharakt. yields in g of 1 corn and containers per 4kg of ash delivered g mg.kg' 1 % green dry No. description N P To pH — N matter matter in the slurry mineral P To 1 unfertilized horse - - - 4.7 22 238 0.16 109.3 13.7 2 pig manure 5.0 - - 5.0 53 404 0.29 338.6 41.8 3 _ w _ 5.0 2.19 - 5.1 100 195 0.22 586.6 82.3 4 “ - 5.0 2.19 4.18 5.3 136 700 0.24 582.0 84.3 5 to go to Scotland 5.0 2.19 - 6.3 166 1036 0.27 485.3 62.7 6 «. ^w — 5.0 2.19 4.18 5.9 152 2070 0.23 367.3 43.3 used slurry pH P i K -pig - - - 6.9 0.027 0.079 0.165 - - -sketch - - - 7.0 0.035 0.172 0.213 - -

Table 2

ash pH mg. kg· ¹ % N total average yield of solid matter in g from 1 container P To before starting the experiment 4.6 28 82 0.15 4.0 after three years of fertilizing with pig manure 5.1 92 283 0.32 74.7 cattle 5.7 59 899 0.29 71.7 poultry 6.1 106 242 0.28 70.8

Table 3

ash to jda·. t.ha ¹ pH % N.total mg. P •kg ¹ K number of plants 2 per 1 m green mass yield in t.ha ^-1 before fertilization - after fertilization with manure 5.2 0.04 10 49 “· - pigs 200 6.0 0.13 37 290 384 10.4 -cattle 150 6.0 0.09 24 724 ⁵⁶⁹ 87.9

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Example 5

Reducing the soil layer to carry the surface is complicated by the final reclamation and the use of mine tailings instead of topsoil.

The addition of fly ash to heavy soil has generally known beneficial effects in terms of improving their mechanical composition and thus making cultivation easier. A dose of 800 t of fly ash per 1 ha does not worsen the agrochemical characteristics of these soils, on the contrary, it improves them, increasing in the 1st year after the introduction of fly ash (Table 5). Fertilizing the soils treated in this way with manure thus directly improves plant nutrition, which was reflected in the increased yield in these experimental variants (Table 6). If there is not enough topsoil, it can be replaced with mine dumps, a mixture of 1 part fly ash and 3 parts dump soils after fertilization with manure creates practically the same conditions for yield formation as soil from fertilized cultivated topsoil (Table 6). The manure ensures the biological revitalization of mine dumps and fly ash and thus replaces topsoil in the function of inoculating (reviving) substances.

When transporting 20 cm of topsoil with ash and plowing to a depth of 25 cm, a layer of 5 cm of ash is introduced into the topsoil profile. 2a Assuming a weight of 4,000 tons of topsoil (to a depth of 20 cm) per 1 ha, a layer of 5 cm of ash weighs approximately 500 tons (roughly half the weight of the soil), which is a lower dose than that used in the aforementioned experiment (800 tons/ ^ha ) and where ash had a positive effect. The lower layer of ash does not adversely affect plant growth and yield, as plants do well in ash alone without soil, as is evident from example 4, and therefore reducing the soil layer for transporting the ash is fully feasible and highly effective.

Table 4 Results of field experiments on fly ash compost in Prunéřov.

agrochemical characteristics slurry doses basic material pH P % Κ N total average doses for 1 year in kg M.ha" ¹ from to pig manure 6.7 0.10 0.20 0.51 500 - 1222. cattle manure 7,° 0.08 0.17 0.31 318 - 856 poultry manure 6.7 0.20 0.28 0.71 598 - 1397 ash before green trial 5.8 mg.kg ^-1 % yields in OJ.ha ^-1 average 21 111 0.18 in 1 year after 3 years of vegetation hun - arable land 5.3 25 97 0.16 0.9 unfertilized -clover grass 5.4 24 99 0.15 5.2 control -alfalfa 5.4 17 116 0.16 4.3 -r w $7 yearly hon-arable land 5.4 45 190 0.20 33.1 5.7 55 151 0.20 39.4 to (average Kj. -alfalfa S P.S.D) 5.6 57 179 0.20 38.4

225,905 cultivated crops arable landowner mustard, sunflower with corn, oats for grain clover» mustard, winter mixture+ undersowing clover» alfalfa» mustard, oz. mixture+ undersowing alfalfa

Kj.P - pigs Kj.S - cattle Kj.D - poultry

Table 5. Agrochemical characteristics of materials used before establishing the model experiment substrate description mg.kg^ %

pH P To Mg ' N humus control ornioe 7.5 48 212 205 0.18 3.08 topsoil + fly ash 1st year after incorporation/800 t.ha ^-1 / 7.2 them 302 223 0.19 4.28 control ornioe 7.3 17 219 . 162 0.24 3.43 top soil+ash 10th year of incorporation after 7.4 30 190 185 0.19 3.71 mixture of 3 parts fly ash and 1 part mine dumps 1 5.9 22 120 262 0.15 11.6 ⁺ mixture of 3 parts fly ash and coal, mine tailings 3 children- 6.2 21 200 514 0.10 5.20

⁺ the ash value determined from the ash does not correspond to the humus determined in the soil, it concerns all carbonaceous components contained in the ash.

Table 6. Yields of dry matter of corn in g from 1 container

substrate description unfertilized control + pig manure 5g nitrogen /4 kg year 2nd year average 1st year 2nd year average control ornioe 46.6 18.6 33.6 125.0 63.6 94.3 ornioe + ash 1st year after incorporation 79.9 17.2 48.5 164.9 141.0 152.9 control topsoil 44.3 19.0 31.6 106.9 85.3 97.1 topsoil + ash 10th year after incorporation, 49.9 20.8 35.3 99.9 103.6 101.7 mixture of 3 parts fly ash and 1 part mine tailings 17.3 5.6 11.4 50.6 82.9 '66.7 mixture of 1 part fly ash and 3 parts mine dumps 20.0 5.6 12.8 95.6 97.9 96.7

Using manure (feces or sludge) has these advantages »

a) significant acceleration of reclamation processes with the current possibility of immediate cultivation of crops on the reclaimed fly ash composition, immediately from the start of reclamation

b) saving on the surface of the compound and thus significant savings in financial and fuel costs

-transportation capacities

-industrial fertilizers, which can be almost completely replaced by manure

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c) more efficient use of manure /an important organic fertilizer/, which, due to frequent excess, cannot always be used in its entirety for the effective fertilization of agricultural lands and is thus a source of environmental pollution (overfertilization of fields, contamination of water with nitrates, etc.).

d) reduction of secondary dustiness of fly ash compounds, which will be at least 2 times cheaper than the hydroseeding used so far.

a) significant improvement of the environment in the vicinity of ash dumps and livestock production facilities.

Claims (2)

SUBJECT OF THE INVENTION Method for biological reclamation of fly ash composition of pH 4 to 10 by organic fertilizer fertilization, characterized in that the fly ash layer is sieved by slurry of pigs and / or cattle and / or poultry, possibly also sewage sludge and / or faeces, nitrogen content from 0.005 de 1.5%, f phosphorus from 0.005 to 0.8%, potassium from 0.01 to 1.2% dry matter from 0.5 to 18% by weight in a dose from 20 to 4,000 t / ha, optionally supplemented with mineral nutrients by fertilizers with nitrogen content 0.1 to 1.5%, phosphorus from 20 to 500 mg and potassium from 50 to 1000 mg per kg of fly ash, with 0.5 to 2 t of CaO added per ha if the pH of the fly ash is less than 5, whereupon the crops are immediately cultivated either directly in the formed substrate or after being passed through the soil in a layer of 5 to 50 cm, preferably up to 30 cm. Method according to claim 1, characterized in that sewage sludge is added to the substrate, either together with slurry and / or faeces or separately, at a rate of from 50 to 6 000 t per ha with a nitrogen content of from 0.005 to 1% of phosphorus. from 0.002 to 0.5%, potassium from 0.005 to 1% by weight. and with zinc content up to 10 ppm, copper up to 3,000 ppm, nickel up to 500 ppm, chromium up to 10 ppm, lead up to 10 ppm, cadmium up to 25 ppm, mercury up to 25 ppm, cobalt up to 50 ppm and molybdenum up to 2,000 ppm and either directly in the formed substrate or after its placement with soil up to 50 cm are immediately cultivated crops.