1-hour sludge drying agent and its application in sludge drying and nutrient soil

Abstract

The present invention belongs to the field of environmental technology, and relates to a kind of 1 hour grade sludge drying agent and its application in sludge drying and nutrient soil.By weight percentage, the drying agent includes calcium oxide 50 60%, sodium hydroxide 5 10%, aluminum powder 5 10%;The drying agent is applied in sludge drying:Dry biomass is added to the sludge with a moisture content of 70 80wt% and stirred evenly, then a drying agent is added and stirred evenly, then allowed to stand for 1h, so that the moisture content of the sludge is reduced to less than 33wt%, heavy metal passivation 97 99%, harmful bacteria are killed 100%, and dry sludge is obtained;The application of the drying agent in nutrient soil:The dry sludge obtained by drying the drying agent is prepared into nutrient soil particles with slow-release function together with urea by mechanical granulation.The present invention significantly improves the efficiency of sludge treatment, reduces processing time and cost, and realizes resource utilization of sludge.

Description

Technical Field

[0001] The invention belongs to the field of environmental technology and relates to a 1-hour sludge drying agent and application thereof in sludge drying and nutrient soil. Background Art

[0002] Currently, the mainstream method for treating sludge both domestically and internationally is mechanical extrusion followed by incineration or landfill. However, due to the complex structural characteristics of sludge, it is difficult to reduce its moisture content to below 60wt% through mechanical dehydration. This not only increases energy consumption during subsequent treatment but also causes environmental pollution. To address this issue, researchers have attempted to add conditioning agents (such as calcium oxide, biomass powder, and slag) to the sludge to enhance its dehydration properties. However, these technologies still require the use of a filter press for dehydration, which not only increases operational complexity but also generally requires a prolonged dehydration process.

[0003] In order to solve the above problems, some new sludge dewatering technologies have been proposed, aiming to improve the sludge treatment efficiency. For example, patent application CN112159073A discloses an inorganic mineral composite dehydrating agent prepared from cement, aluminate cement, alkaline earth metal oxides, artificial volcanic ash, gypsum and limestone, but it still needs to be dried or squeezed for dehydration, which takes a long time. Patent application CN113860701A discloses a sludge dehydrating agent. Although it has self-heating properties and can reach a temperature of 40-50°C after 3-4 hours, its dehydration efficiency is still low, resulting in a long overall drying process. Patent application CN113860700A discloses a method of mixing biomass ash and sludge in combination with sun drying, but the drying time still takes one week, and the efficiency is relatively low.

[0004] In summary, although there are a variety of sludge dewatering methods in the prior art, they generally have the problem of being time-consuming. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems existing in the prior art and provide a 1-hour sludge drying agent and its application in sludge drying and nutrient soil.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A one-hour sludge drying agent comprises, by weight percentage, 50-60% calcium oxide, 5-10% sodium hydroxide, and 5-10% aluminum powder.

[0008] The one-hour sludge drying agent of the present invention can achieve 1-hour drying of sludge without heating. The main reasons are: ① calcium oxide plays a skeleton and preheating role in the sludge; ② sodium hydroxide and aluminum powder generate a huge amount of heat, causing the sludge temperature to rise to 100°C in 1 minute; ③ oxygen in the air, sodium hydroxide and aluminum powder combine to generate free radicals, which can decompose sludge particles, destroy the sludge water-locking structure, make the sludge hydrophobic, and convert bound water into easily removable free water. The free water quickly heats up to 100°C, turns into water vapor, and quickly escapes in the channel formed by the calcium oxide, so that the moisture content of the sludge drops to below 33wt% after 1 hour.

[0009] As the preferred technical solution:

[0010] The one-hour sludge drying agent as described above further comprises, by weight percentage, 5-10% zero-valent nano-iron, 5-10% heat-insulating agent (diatomaceous earth, kaolin or other natural clay), and 5-10% porous biochar; wherein the functions of the zero-valent nano-iron include: reducing the valence of heavy metals, adsorbing heavy metals, increasing the iron content of sludge, and thereby improving the nutrients of the nutrient soil prepared from the sludge; the functions of the heat-insulating agent include: acting as a skeleton, diluting water, hindering heat loss, and adsorbing heavy metals; the functions of the porous biochar include: acting as a skeleton, adsorbing heavy metals, and improving the nutrients of the nutrient soil prepared from the sludge.

[0011] As described above, the one-hour sludge drying agent has an average particle size of porous biochar of 100-200 mesh. Controlling the particle size of porous biochar is beneficial to reducing the degree of shrinkage during soil drying, improving soil structure, and increasing soil water retention capacity.

[0012] The preparation steps of the porous biochar as a 1-hour sludge drying agent are as follows:

[0013] (a) Washing straw (rice, corn) 3-5 times, drying at 105-125°C for 10-12 hours, and crushing to obtain straw powder;

[0014] (b) mixing straw powder and potassium hydroxide powder uniformly, with the mass of potassium hydroxide being 5-10% of the mass of the straw powder, and carbonizing the mixture in a muffle furnace at 900-1000° C. for 10-12 hours under a nitrogen atmosphere;

[0015] (c) Cooling the carbonized product, mixing the carbonized product with a 1-2 mol / L aqueous hydrochloric acid solution, stirring for 10-15 hours, filtering, washing with water until neutral, drying at 105-125° C. for 12-15 hours, grinding and sieving to obtain porous biochar.

[0016] As described above, the one-hour sludge drying agent has an average particle size of 30-70 nm for zero-valent nano-iron. The present invention sets the particle size of zero-valent nano-iron to 30-70 nm based on its high efficiency and wide applicability in environmental remediation and pollution control. This particle size range can maximize its reaction activity, maintain good dispersibility, and expand its application field, thereby playing a greater role in practical applications.

[0017] The preparation process of the one-hour sludge drying agent, zero-valent nano-iron, as described above, is as follows: ferrous sulfate heptahydrate and sodium borohydride at a molar ratio of 2:1-1.2 are added to deionized water, and nitrogen is continuously introduced. After stirring for 5-8 hours, the product is recovered with a magnet, rinsed with deionized water 3-5 times, vacuum-dried, and ground to obtain zero-valent nano-iron.

[0018] The present invention also provides a sludge drying method, which comprises adding dry biomass (mushroom residue, sawdust, furfural residue, etc.) to sludge with a moisture content of 70-80wt% (obtained by plate and frame filter pressing) and stirring evenly, then adding a drying agent and stirring evenly, and then standing for 1 hour, so that the moisture content of the sludge is reduced to below 33wt%, heavy metals are passivated by 97-99%, and harmful bacteria are killed by 100%, thereby obtaining dry sludge, wherein the drying agent is a 1-hour sludge drying agent as described in any of the above items.

[0019] As the preferred technical solution:

[0020] In the sludge drying method as described above, the mass of the dry biomass is 10-20% of the mass of the sludge, and the mass of the drying agent is 10-30% of the mass of the sludge.

[0021] The present invention also provides a dry sludge, which is prepared by using any of the above sludge drying methods.

[0022] The present invention also provides an application of the dry sludge as described above, wherein urea is added to the dry sludge and mechanical granulation is performed to obtain nutrient soil particles with a slow-release function, wherein the mass of urea is 60-70% of the mass of the dry sludge.

[0023] Beneficial effects:

[0024] (1) The present invention significantly improves the efficiency of sludge treatment, reduces treatment time and cost, and can quickly dry sludge to a moisture content below 33 wt% within 1 hour.

[0025] (2) The present invention utilizes the heat generated by the internal reaction of the desiccant to achieve sludge temperature increase and water evaporation, reducing energy consumption and carbon emissions, and conforming to the concept of green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1is the sludge in Example 1 ( Figure 1 a) and dry sludge ( Figure 1 Actual picture of b);

[0027] Figure 2 is the temperature rise curve of the sludge during the drying process in Example 1;

[0028] Figure 3 The change in the number of Escherichia coli in the sludge in Example 1 before and after drying;

[0029] Figure 4 It is the 1-20 day urea release rate of the nutrient soil particles with slow-release function in Example 1. DETAILED DESCRIPTION

[0030] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0031] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0032] Heavy metal passivation rate: Determined in accordance with the "Determination of the total amount of 19 metal elements in soil and sediments by inductively coupled plasma mass spectrometry" (HJ 1315-2023).

[0033] Killing rate of harmful bacteria: Determined in accordance with the "Standard Test Method for Urban Sludge" (CJ / T 221-2023) and the "Agricultural Sludge Pollutant Control Standard" (GB 4284-2018).

[0034] Urea release rate: Spread 40g of washed quartz sand (particle size 2.5-5mm) evenly on a culture dish, take 10g of nutrient soil particles with slow-release function and place them in the culture dish. Spray 5ml of water regularly every day. For 20 consecutive days, take out 2g of quartz sand from the culture dish every day and mix it with 5ml of deionized water. Analyze the urea content in the mixture by ultraviolet spectrophotometer.

[0035] Example 1

[0036] A method for preparing nutrient soil particles with a slow-release function, comprising the following steps:

[0037] (1) Preparation of raw materials;

[0038] Straw: rice straw;

[0039] Potassium hydroxide;

[0040] Hydrochloric acid aqueous solution: concentration is 1 mol / L;

[0041] Ferrous sulfate heptahydrate;

[0042] Sodium borohydride;

[0043] Deionized water;

[0044] calcium oxide;

[0045] Sodium hydroxide;

[0046] Aluminum powder;

[0047] Insulation agent: diatomaceous earth;

[0048] Sludge: moisture content is 70wt%, as shown in the figure Figure 1 As shown in a;

[0049] Dry biomass: dried mushroom residue;

[0050] urea;

[0051] (2) Preparation of porous biochar and zero-valent nano-iron respectively;

[0052] The preparation steps of porous biochar are as follows:

[0053] (a) The straw was washed five times, dried at 105°C for 10 h, and pulverized to obtain straw powder;

[0054] (b) Straw powder and potassium hydroxide were uniformly mixed in a mass ratio of 10:1, and carbonized at 900°C for 10 h under a nitrogen atmosphere to obtain a carbonized product;

[0055] (c) cooling the carbonized product, mixing the carbonized product with a hydrochloric acid aqueous solution at a mass ratio of 1:10, stirring for 11 h, filtering, washing with water until neutral, drying at 105°C for 12 h, grinding and sieving to obtain porous biochar with an average particle size of 100 mesh;

[0056] The preparation steps of zero-valent nano-iron are as follows: ferrous sulfate heptahydrate and sodium borohydride at a molar ratio of 2:1 are added to deionized water, and nitrogen is continuously introduced. After stirring for 5 hours, the product is recovered with a magnet, rinsed with deionized water three times, vacuum-dried, and ground to obtain zero-valent nano-iron with an average particle size of 30 nm.

[0057] (3) Preparation of 1-hour sludge drying agent;

[0058] By weight percentage, the 1-hour sludge drying agent is composed of 60% calcium oxide, 10% sodium hydroxide, 10% aluminum powder, 5% zero-valent nano-iron, 5% heat preservation agent and 10% porous biochar;

[0059] (4) Preparation of dry sludge;

[0060] Add dry biomass to the sludge and stir evenly, then add a 1-hour sludge drying agent and stir evenly, and then let it stand for 1 hour to reduce the moisture content of the sludge to 33wt%, deactivate 99% of heavy metals, kill 100% of harmful bacteria, and obtain dry sludge; wherein the mass of the dry biomass is 10% of the mass of the sludge, and the mass of the 1-hour sludge drying agent is 10% of the mass of the sludge;

[0061] The actual picture of dry sludge is as follows Figure 1 As shown in b, the temperature rise curve of sludge during the drying process is as follows Figure 2 As shown in the figure, the changes in the number of E. coli in the sludge before and after drying are as follows: Figure 3 As shown;

[0062] (5) Preparation of nutrient soil particles with slow-release function;

[0063] Urea is added to dry sludge and mechanical granulation is performed to obtain nutrient soil particles with a slow-release function; wherein the mass of urea is 60% of the mass of the dry sludge.

[0064] The urea release rate of the finally obtained nutrient soil particles with slow-release function in 1 to 20 days is as follows: Figure 4 shown.

[0065] Example 2

[0066] A method for preparing nutrient soil particles with a slow-release function, comprising the following steps:

[0067] (1) Preparation of raw materials;

[0068] Straw: rice straw;

[0069] Potassium hydroxide;

[0070] Hydrochloric acid aqueous solution: concentration is 1.5 mol / L;

[0071] Ferrous sulfate heptahydrate;

[0072] Sodium borohydride;

[0073] Deionized water;

[0074] calcium oxide;

[0075] Sodium hydroxide;

[0076] Aluminum powder;

[0077] Insulation agent: kaolin;

[0078] Sludge: moisture content is 75wt%;

[0079] Dry biomass: dry sawdust;

[0080] urea;

[0081] (2) Preparation of porous biochar and zero-valent nano-iron respectively;

[0082] The preparation steps of porous biochar are as follows:

[0083] (a) The straw was washed three times, dried at 110°C for 11 h, and pulverized to obtain straw powder;

[0084] (b) Straw powder and potassium hydroxide were uniformly mixed in a mass ratio of 15:1, and carbonized at 950°C for 11 h under a nitrogen atmosphere to obtain a carbonized product;

[0085] (c) cooling the carbonized product, mixing the carbonized product with a hydrochloric acid aqueous solution at a mass ratio of 1:10, stirring for 12 h, filtering, washing with water until neutral, drying at 110° C. for 13 h, grinding and sieving to obtain porous biochar with an average particle size of 120 mesh;

[0086] The preparation steps for zero-valent nano-iron are as follows: ferrous sulfate heptahydrate and sodium borohydride at a molar ratio of 2:1.15 are added to deionized water, and nitrogen is continuously introduced. After stirring for 6 hours, the product is recovered with a magnet, rinsed with deionized water four times, vacuum-dried, and ground to obtain zero-valent nano-iron with an average particle size of 50 nm.

[0087] (3) Preparation of 1-hour sludge drying agent;

[0088] By weight percentage, the 1-hour sludge drying agent is composed of 55% calcium oxide, 5% sodium hydroxide, 10% aluminum powder, 10% zero-valent nano-iron, 10% heat preservation agent and 10% porous biochar;

[0089] (4) Preparation of dry sludge;

[0090] Add dry biomass to the sludge and stir evenly, then add a 1-hour sludge drying agent and stir evenly, and then let it stand for 1 hour to reduce the moisture content of the sludge to 29wt%, deactivate 98% of heavy metals, kill 100% of harmful bacteria, and obtain dry sludge; wherein the mass of the dry biomass is 15% of the mass of the sludge, and the mass of the 1-hour sludge drying agent is 15% of the mass of the sludge;

[0091] (5) Preparation of nutrient soil particles with slow-release function;

[0092] Urea is added to the dry sludge and mechanical granulation is performed to obtain nutrient soil particles with a slow-release function; wherein the mass of urea is 65% of the mass of the dry sludge.

[0093] The urea release rate of the finally prepared nutrient soil particles with slow-release function was 92% over 20 days.

[0094] Example 3

[0095] A method for preparing nutrient soil particles with a slow-release function is basically the same as Example 2, except that: in step (3), the weight percentage of sodium hydroxide is 10%, and the weight percentage of zero-valent nano-iron is 5%; in step (4), after standing for 1 hour, the moisture content of the sludge is reduced to 30wt%, the heavy metal is passivated by 99%, and the harmful bacteria are killed by 100%.

[0096] The urea release rate of the finally obtained nutrient soil particles with slow-release function from 1 to 20 days is shown in Table 1:

[0097] Table 1

[0098] Time (days) Urea release rate (%) Time (days) Urea release rate (%) 1 20 11 65 2 26 12 68 3 32 13 73 4 35 14 78 5 43 15 82 6 46 16 85 7 51 17 86 8 54 18 85 9 57 19 87 10 64 20 89

[0099] Example 4

[0100] A method for preparing nutrient soil particles with a slow-release function is basically the same as Example 2, except that: the zero-valent nano-iron and porous biochar in step (3) are replaced with an equal mass of a heat preservation agent (the same as Example 3); after standing for 1 hour in step (4), the moisture content of the sludge is reduced to 30wt%, the heavy metal is passivated by 98%, and the harmful bacteria are killed by 100%.

[0101] The urea release rate of the finally prepared nutrient soil particles with slow-release function was 89% over 20 days.

[0102] Example 5

[0103] A method for preparing nutrient soil particles with a slow-release function, comprising the following steps:

[0104] (1) Preparation of raw materials;

[0105] Straw: corn stalks;

[0106] Potassium hydroxide;

[0107] Hydrochloric acid aqueous solution: concentration is 2 mol / L;

[0108] Ferrous sulfate heptahydrate;

[0109] Sodium borohydride;

[0110] Deionized water;

[0111] calcium oxide;

[0112] Sodium hydroxide;

[0113] Aluminum powder;

[0114] Insulation agent: kaolin;

[0115] Sludge: moisture content is 80wt%;

[0116] Dry biomass: dry furfural residue;

[0117] urea;

[0118] (2) Preparation of porous biochar and zero-valent nano-iron respectively;

[0119] The preparation steps of porous biochar are as follows:

[0120] (a) The straw was washed five times, dried at 125°C for 12 h, and pulverized to obtain straw powder;

[0121] (b) Straw powder and potassium hydroxide were uniformly mixed in a mass ratio of 20:1, and carbonized at 1000°C for 12 h under a nitrogen atmosphere to obtain a carbonized product;

[0122] (c) cooling the carbonized product, mixing the carbonized product with a hydrochloric acid aqueous solution at a mass ratio of 1:10, stirring for 13 h, filtering, washing with water until neutral, drying at 125° C. for 14 h, grinding and sieving to obtain porous biochar with an average particle size of 170 mesh;

[0123] The preparation steps for zero-valent nano-iron are as follows: ferrous sulfate heptahydrate and sodium borohydride at a molar ratio of 2:1.2 are added to deionized water, and nitrogen is continuously introduced. After stirring for 7 hours, the product is recovered with a magnet, rinsed with deionized water five times, vacuum-dried, and ground to obtain zero-valent nano-iron with an average particle size of 60 nm.

[0124] (3) Preparation of 1-hour sludge drying agent;

[0125] By weight percentage, the 1-hour sludge drying agent is composed of 50% calcium oxide, 10% sodium hydroxide, 10% aluminum powder, 10% zero-valent nano-iron, 10% heat preservation agent and 10% porous biochar;

[0126] (4) Preparation of dry sludge;

[0127] Add dry biomass to the sludge and stir evenly, then add a 1-hour sludge drying agent and stir evenly, and then let it stand for 1 hour to reduce the moisture content of the sludge to 25wt%, deactivate 97% of heavy metals, kill 100% of harmful bacteria, and obtain dry sludge; wherein the mass of the dry biomass is 20% of the mass of the sludge, and the mass of the 1-hour sludge drying agent is 20% of the mass of the sludge;

[0128] (5) Preparation of nutrient soil particles with slow-release function;

[0129] Urea is added to dry sludge and mechanical granulation is performed to obtain nutrient soil particles with a slow-release function; wherein the mass of urea is 70% of the mass of the dry sludge.

[0130] The urea release rate of the finally prepared nutrient soil particles with slow-release function was 94% over 20 days.

[0131] Example 6

[0132] A method for preparing nutrient soil particles with a slow-release function, comprising the following steps:

[0133] (1) Preparation of raw materials;

[0134] Straw: corn stalks;

[0135] Potassium hydroxide;

[0136] Hydrochloric acid aqueous solution: concentration is 2 mol / L;

[0137] Ferrous sulfate heptahydrate;

[0138] Sodium borohydride;

[0139] Deionized water;

[0140] calcium oxide;

[0141] Sodium hydroxide;

[0142] Aluminum powder;

[0143] Insulation agent: diatomaceous earth;

[0144] Sludge: moisture content is 70wt%;

[0145] Dry biomass: dried mushroom residue;

[0146] urea;

[0147] (2) Preparation of porous biochar and zero-valent nano-iron respectively;

[0148] The preparation steps of porous biochar are as follows:

[0149] (a) The straw was washed four times, dried at 105°C for 10 h, and pulverized to obtain straw powder;

[0150] (b) Straw powder and potassium hydroxide were uniformly mixed in a mass ratio of 20:1, and carbonized at 900°C for 10 h under a nitrogen atmosphere to obtain a carbonized product;

[0151] (c) cooling the carbonized product, mixing the carbonized product with a hydrochloric acid aqueous solution at a mass ratio of 1:10, stirring for 15 h, filtering, washing with water until neutral, drying at 120° C. for 15 h, grinding and sieving to obtain porous biochar with an average particle size of 200 mesh;

[0152] The preparation steps for zero-valent nano-iron are as follows: ferrous sulfate heptahydrate and sodium borohydride at a molar ratio of 2:1.2 are added to deionized water, and nitrogen is continuously introduced. After stirring for 8 hours, the product is recovered with a magnet, rinsed three times with deionized water, vacuum-dried, and ground to obtain zero-valent nano-iron with an average particle size of 70 nm.

[0153] (3) Preparation of 1-hour sludge drying agent;

[0154] By weight percentage, the 1-hour sludge drying agent is composed of 60% calcium oxide, 10% sodium hydroxide, 5% aluminum powder, 10% zero-valent nano-iron, 10% insulation agent and 5% porous biochar;

[0155] (4) Preparation of dry sludge;

[0156] Add dry biomass to the sludge and stir evenly, then add a 1-hour sludge drying agent and stir evenly, and then let it stand for 1 hour to reduce the moisture content of the sludge to 30wt%, deactivate 98% of heavy metals, kill 100% of harmful bacteria, and obtain dry sludge. The mass of the dry biomass is 20% of the mass of the sludge, and the mass of the 1-hour sludge drying agent is 30% of the mass of the sludge.

[0157] (5) Preparation of nutrient soil particles with slow-release function;

[0158] Urea is added to dry sludge and mechanical granulation is performed to obtain nutrient soil particles with a slow-release function; wherein the mass of urea is 70% of the mass of the dry sludge.

[0159] The urea release rate of the finally prepared nutrient soil particles with slow-release function was 96% over 20 days.

Claims

1. A 1-hour sludge drying agent, characterized in that: Calculated by weight, it consists of 50-60% calcium oxide, 5-10% sodium hydroxide, 5-10% aluminum powder, 5-10% zero-valent nano-iron, 5-10% heat preservation agent, and 5-10% porous biochar.

2. A 1-hour grade sludge drying agent according to claim 1, characterized in that, The average particle size of the porous biochar is 100-200 mesh.

3. A 1-hour grade sludge drying agent according to claim 2, characterized in that, The preparation steps of porous biochar are as follows: (a) washing the straw, drying it, and crushing it to obtain straw powder; (b) mixing the straw powder and potassium hydroxide uniformly, wherein the mass of the potassium hydroxide is 5-10% of the mass of the straw powder, and carbonizing the mixture at 900-1000° C. for 10-12 hours under a nitrogen atmosphere; (c) Cooling the carbonized product, mixing the carbonized product with a 1-2 mol / L hydrochloric acid aqueous solution, stirring, filtering, washing with water until neutral, drying, grinding and sieving to obtain porous biochar.

4. A 1-hour grade sludge drying agent according to claim 1, characterized in that, The average particle size of zero-valent nano-iron is 30-70nm.

5. A 1-hour grade sludge drying agent according to claim 4, characterized in that, The preparation process of zero-valent nano-iron is as follows: ferrous sulfate heptahydrate and sodium borohydride at a molar ratio of 2:1-1.2 are added to deionized water, and nitrogen is continuously introduced. After stirring for 5-8 hours, the product is recovered with a magnet, rinsed with deionized water, vacuum-dried, and ground to obtain zero-valent nano-iron.

6. A sludge drying method, characterized in that: Add dry biomass to sludge with a moisture content of 70-80wt% and stir evenly, then add a drying agent and stir evenly, and then let it stand for 1 hour to reduce the moisture content of the sludge to below 33wt%, passivate 97-99% of heavy metals, kill 100% of harmful bacteria, and obtain dry sludge, wherein the drying agent is a 1-hour sludge drying agent according to any one of claims 1 to 5, and the mass of the drying agent is 10-30% of the mass of the sludge.

7. A sludge drying method according to claim 6, characterized in that: The mass of dry biomass is 10-20% of the mass of sludge.

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