KR101024447B1 - Production of refuse derived fuel with biomass using microbial materials - Google Patents

Abstract

PURPOSE: A solid fuel producing method with organic waste using a microbial agent is provided to prevent the environment contamination by removing the moisture from the waste using heat generated from the metabolism of microorganisms. CONSTITUTION: A solid fuel producing method with organic waste using a microbial agent comprises the following steps: mixing dewatering sludge, food waste, combustible industrial waste including woodchip and sawdust, and the microbial agent(100); decomposing the organic waste by inserting the mixed sludge complex into a fermentation-dryer using the metabolism of microorganisms, and drying(210,220); mixing the dried sludge complex with the food waste(300); inserting the mixture into an aging-dryer heated by a boiler using solid fuel formed by the organic waste(400); crushing the aged mixture, after separating wood chips(500); and molding the crushed mixture into the solid fuel(600).

Description

Production of Refuse Derived Fuel with Biomass Using Microbial Materials}

The present invention relates to a method for producing solid fuel using sewage sludge and food waste, and more particularly, to reduce and reduce the mixture of sewage sludge and food waste by removing organic matter and water by exothermic reaction of microorganisms. The present invention relates to a method for producing a solid fuel having a high calorific value by further adding food waste to the prepared mixture and drying it again.

Sewage sludge is a sediment that is separated from the liquid generated from sewage and wastewater treatment, and sludge produced by the continuous increase of domestic sewage and wastewater treatment plant construction along with industrial development has generated 7,631㎥ / day in 347 treatment plants in 2007. In 2011, 460 treatment plants increased by 10,259㎥ / day.

Food waste is the food waste that is thrown away at home or in restaurants, and the quality of life and food waste accounted for about 30%. Domestic food waste generation continues to increase, increasing 3% annually from 14,500㎥ / day in 2007 to 17,100㎥ / day in 2012. As a result, the economic value of 18 trillion won per year is lost.

Sewage sludge causes shortening of the landfill, odor generation, leachate generation and concentration by landfill due to high water content around 75 ~ 80%, causing soil and groundwater contamination around landfill, and cost and management cost of leachate treatment facility. Excessive amount is a cause of raising processing cost. This high water content lowers the calorific value during incineration, increasing the amount of auxiliary fuel used, and generating air pollutants such as chlorine compounds and dioxins due to the lowering of the incineration temperature.

Food waste is an organic matter with a water content of 80-90%, and can be used as a substrate for feed, compost, and biogas production. Feeding can use food waste as livestock feed. However, the supply and demand is uncertain, it may cause direct and indirect damage to the livestock due to the possibility of the disease of the livestock and the incorporation of foreign substances, there is a problem that the consumer is particularly limited.

In addition, domestic waste wood production amounted to 5,115 thousand tons / year, with 48% of forest by-products, 36% of industrial waste wood including construction waste wood, and 16% of domestic waste wood. The waste wood is treated in a landfill 50%, incineration 14%, recycling 36%.

Meanwhile, in accordance with the Enforcement Regulations of the Waste Management Act, direct landfilling of sludge has been banned since July 2003. Since January 2005, direct dumping of food waste has been banned. Under the London Convention, dumping of sea dumping is expected to be banned in 2011. However, there is an urgent need for countermeasures for disposal of organic waste since there is no treatment method that can cope with ocean dumping.

Recently, Korea has greatly increased its investment in green growth projects aimed at reducing energy dependence abroad and green environment. In particular, as one of the ways to make the best use of existing resources, the government will invest 6 trillion won in 2012 and 29 trillion won in 2020 in the project to convert organic waste into renewable energy.

As the organic waste sludge, food waste, and combustible industrial waste were reassessed as resources, the recycling of organic waste began to take off. In addition, as of 2007, the treatment of organic wastes was 2% landfill, 11% incineration, 68.5% ocean discharge, and 13.5% recycling. However, with the ban on marine dumping from 2011, recycling or resourceization (cover material, carbonization, cement raw materials, green soil, composting, fuelization, earthworm litter) is expected to rise to 70%.

Sewage sludge contains about 80% water, but more than 50% of the remaining water is composed of organic matter, so the calorific value of drying is more than 3,000kcal / kg. Therefore, it is known that by drying the sewage sludge and developing it as a solid fuel, it is possible to minimize the environmental pollution caused by the treatment of the sewage sludge and to create a high economic value.

Conventional technologies for recycling organic wastes as solid fuels include the domestic sewage / wastewater sludge treatment apparatus of Korea Patent No. 700110 and a method for producing solid fuel using sludge, and sewage and wastewater sludge of Patent No. 847247. Disclosed is a solid fuel manufacturing apparatus using a method for producing a solid raw material, and organic sludge of Korean Patent No. 693957.

For example, Korean Patent Publication No. 10-2007-76557 "Manufacturing method of solid fuel using sewage sludge and food waste and combustible waste" is the process of drying and crushing sewage sludge with water content of 10-20% or less Mixing 70% waste (weight ratio) with 10% loess, 10% lignite, 10% coke, and grinding combustible waste to a particle size of 30 to 50 mm; Mixing dry sewage sludge, food waste mixed with additives, and comminuted combustible waste in a proportion of sewage sludge 30% (weight ratio): food waste 30% (weight ratio) and combustible waste 40% (weight ratio); Drying the mixed mixture so that the moisture content is 10% or less in a hot air dryer; Extruding and molding to a predetermined size by adding a supporting material to the mixture formed by mixing and drying; Is done.

According to these conventional methods, in order to manufacture sewage sludge as a solid fuel, sewage sludge or food waste is dried within a water content of 10%, mixed with caloric aids such as coke, anthracite, wood, and oil, and then molded into a specific shape to be solid. Fuel is made In addition, the conventional solid fuelization technology is a method of drying the sludge using an external heat source, and then mixing the caloric aid or molding aid to compress the molding at high pressure. Therefore, the conventional method consumes a lot of energy to dry the sewage sludge primarily, and thus a solid fuel is manufactured, thereby obviating the purpose of recycling the sludge as renewable energy. In addition, the conventional method is prepared by mixing coke, anthracite coal, oil as auxiliary fuel to fuel and energy sludge, and molding aids such as clay or sand to improve moldability.

For example, Korean Patent Publication No. 94-14200 discloses a method and apparatus for extracting water from sludge using heated oil that dehydrates sludge and then splashes it in oil for use as fuel. 860356 discloses a method for producing solid fuel prepared by press molding coke powder, charcoal powder, sawdust and paper waste. Korean Patent Publication No. 94-204040 discloses calcium carbonate in wastes such as wood and waste paper sludge. A method of making charcoal using various combustible wastes prepared by mixing with zeolite and a binder and then pressurizing with a compression molding machine is disclosed. In addition, Republic of Korea Patent Publication No. 99-74336, Republic of Korea Patent No. 10-0319803, Republic of Korea Patent No. 10-0419189 discloses a method for fueling the waste by adding coal powder or petroleum coke to the sewage sludge. However, these conventional techniques are not only very difficult to meet the optimum conditions of combustion because the materials of very different physical properties are mixed with each other, there is a lot of pollution emissions such as incomplete combustion, and the non-combustible molding aids for improving the bonding to prevent breakage during carbonization It is added to the excessive amount is very difficult to use as a self-combustible fuel and there was a problem of odor generated by incomplete combustion. As described above, the prior art is to mix the amount of additives than the sludge solid content, and to mix, and to be a fuel using sludge as an additive rather than a solid fuel mainly composed of sludge.

As seen above, the water content of the sewage sludge is about 80% or more, and the food water content of the food waste is also 85% or more, so the part to be focused on the treatment of organic waste is water removal method. However, the conventional method of manufacturing solid fuel using organic wastes requires the high cost of treatment because it dries moisture using external energy such as electricity and oil, and it does not dry sufficiently to the inside of organic wastes during the drying process of organic wastes. Low recyclability due to odor when burning solid fuel. In addition, the increase in expenses due to high oil prices and the use of fossil fuels are one of the low-carbon green growth projects to solve the problems of global warming and climate change. Conventional methods used up to now cannot efficiently treat organic wastes.

Therefore, there is a need for a new type of solid fuel production method that minimizes energy consumed when drying sewage sludge or food waste organic waste and minimizes the use of auxiliary fuels such as coke, anthracite and oil.

The present invention has been made to solve the problems of the prior art, the main object of the present invention is to use the exothermic reaction of microorganisms without using external energy such as electricity and oil when drying the organic waste to produce a solid fuel It is to provide a solid fuel manufacturing method of organic waste using a microbial material that can minimize the use of energy by drying the organic waste.

Another object of the present invention, in order to increase the calorific value of the solid fuel, instead of adding a caloric aid such as anthracite coal, coke, oil, food waste is added to the dry sludge mixture and then dried again to produce a solid fuel calorific value and incomplete It is to provide a method for producing a solid fuel of organic waste using a microbial material that can prevent secondary pollution due to combustion.

In addition, the present invention is produced by the solid fuel only with sewage sludge, food waste and combustible industrial waste, minimizing the environmental pollution of the treatment of organic waste, as well as reducing the treatment cost of these sewage sludge, food waste and combustible industrial waste and waste resources It aims to contribute to the development of recycling and renewable energy.

In order to achieve the above object of the present invention, the solid fuel production method of the organic waste using the microbial agent according to the present invention,

Combustible industrial waste such as wood chips or sawdust is mixed with dehydrated sludge and food waste so that the total water content is 50 ~ 60% and the total C / N ratio is 30 ~ 50, and new sludge or returned microorganism is added to this sludge mixture. A primary mixing step of mixing;

The sludge mixture mixed in the first mixing process is introduced into a fermentation dryer to decompose organic substances mixed in the sludge by metabolic action of microorganisms, and to dry the sludge mixture to 40% or less by exothermic reaction of microorganisms. Fermentation drying process;

A secondary mixing step of mixing food waste by administering the mixture dried in the fermentation drying step;

In the secondary mixing process, the food waste is added to the aging dryer to dry the mixture so that the water content of the sludge mixture is less than 10%, the aging dryer is heated by the heat of the boiler using a solid fuel made of organic waste Aging drying process;

A pulverizing step of pulverizing the aging mixture generated through the aging drying process in a separator after separating wood chips from the separator;

It characterized in that it comprises a molding step of extruding the mixture pulverized in the crushing process to form a solid fuel of a predetermined size.

The fermentation drying step further includes a secondary fermentation drying step of further injecting food waste into the first dried sludge mixture to sustain the exothermic reaction of the microorganisms.

Food waste injected into the secondary fermentation drying process is characterized in that the solubilized food waste of 90% or more moisture content through acid fermentation.

The amount of food waste injected into the secondary fermentation drying process is characterized in that the injection of 10 to 20% by volume of the sludge mixture.

Food waste injected into the secondary mixing process is characterized in that the food waste containing a lot of fat components.

The amount of food waste injected into the secondary mixing process is characterized in that the injection of 80 to 100% by volume of the dry mixture.

The sludge conveying step of returning 10 to 20% by volume of the sludge mixture treated in the fermentation drying step to the primary mixer to recycle.

The method may further include a wood chip conveying step of conveying and recycling the wood chips separated in the separator installed at the front end of the crushing process to the primary mixer.

According to the present invention, by recycling the sewage sludge with food waste and combustible industrial waste as a solid fuel, it is possible to solve various problems such as environmental pollution and treatment cost due to sewage sludge and food waste, as well as their effective treatment. In addition to lowering the cost of treatment, a number of significant economic benefits can be expected, such as pollution prevention and resource recycling.

In addition, according to the solid fuel manufacturing method of the organic waste using the microbial agent according to the present invention, since the microorganisms continuously remove moisture by using heat generated when the microorganism metabolizes using the organic material of the organic waste to the organic waste. It is possible to supply solid fuel generated by low cost, as well as to actively prevent the pollution of the environment by organic waste.

The present invention also reduces the production cost of solid fuel as well as making solid fuel using only sewage sludge, food waste and organic waste such as wood chips or sawdust without using inorganic caloric aids such as anthracite, coke, oil, etc. There is an effect that can prevent the generation of pollutants during combustion of the fuel.

1 is a flow chart showing a solid fuel manufacturing method using sewage sludge according to the prior art,
Figure 2 is a process flow diagram showing a solid fuel production method of an organic waste according to the present invention,
3 is a schematic configuration diagram of a solid fuel production apparatus for implementing a solid fuel manufacturing method of the present invention,
4 is a schematic diagram showing an example of a fermentation dryer according to the present invention;
5 and 6 are graphs showing the change in moisture and weight over time.

Hereinafter, with reference to the accompanying drawings will be described in detail a solid fuel production method of an organic waste using a microbial agent according to the present invention.

First, Figure 2 is a flow chart showing a solid fuel production method of an organic waste using a microbial material according to the present invention. As shown, the solid fuel production method of the organic waste using the microbial material of the present invention,

Primary mixing process 100 for mixing combustible industrial wastes such as dewatered sludge, food waste and wood chips or sawdust; A fermentation drying process 200 for removing organic matter and water contained in the sludge mixture using microorganisms; A secondary mixing step (300) of mixing food waste by administering to the dried mixture to increase the calorific value of the solid fuel; A maturation drying step (400) of re-drying the mixture to which food waste is added again by heat of a boiler using solid fuel of organic waste; A pulverization process 500 for pulverizing the dried mixture in a powder state; And a molding process 600 for shaping the pulverized mixture into solid fuel.

In this way, the present invention is the combustible industrial waste (4) of the dehydrated sludge (3) generated in the sewage terminal treatment plant, the waste wood used as a moisture control agent and an organic material supply source in the food waste (5) discharged from each home. After mixing the microbial material or the returned microbial material to the mixture into the fermentation dryer (10) by using the metabolic action of the microorganism and the exothermic reaction of the microorganism to remove and reduce the organic matter and water contained in the sludge mixture, and then reduced The food waste is further mixed with the mixture as a caloric aid, dried again, and then pulverized and molded to prepare a solid fuel composed of organic waste.

That is, one aspect of the present invention, by mixing the dehydration sludge, food waste and combustible industrial waste dehydrated sewage sludge to maintain an appropriate moisture content and C / N ratio of the microorganisms without using an external heat source such as electricity or oil Organic waste is dried using only exothermic reaction (60 ~ 70 ℃). And another aspect of the present invention is to increase the drying efficiency by injecting food waste, in particular solubilized food waste as organic matter and water supply means to maintain the proper moisture content and C / N ratio to maintain a high temperature step for a certain time . In addition, another aspect of the present invention is to prepare a solid fuel having a high calorific value by adding food waste, particularly fatty food waste as a caloric aid to the dried mixture and aged. Another aspect of the present invention is to reduce the operating cost of the entire apparatus by drying the mixture of the fatty food waste mixed with the heat of the boiler using the solid fuel of the organic waste.

Hereinafter will be described in more detail with respect to a method for producing a solid fuel using a reduced and reduced mixture of organic waste using the microbial agent according to the present invention.

First of all, the components of organic materials used for the reduction of decomposition and stabilization of organic matter through a series of exothermic reactions while aerobic microorganisms metabolize organic matter from organic wastes are C, H, O, N, S, and P. Such organics are classified into carbohydrates, hemicelluloses, lignin, lipids, lignocelluloses and proteins. Reduction is the most important factor in decomposing organic waste such as sewage sludge and food waste using microorganisms. The main factors in the weight reduction process are the C / N ratio, temperature, moisture content, and air volume.

<C / N ratio>

Degradation of organic matter by microorganisms requires several chemicals, the most important of which is the C / N ratio. The ratio of carbon to nitrogen is a determinant of the quality of organic decomposition and is directly involved in the synthesis of microorganisms. In the decomposition of organic matter by microorganisms, carbon is provided as an energy source for microorganisms, some are synthesized into their cells, and nitrogen is mainly used for protein synthesis necessary for microbial growth. In general, the appropriate C / N ratio of weight reduction by microorganisms is known to be 20 ~ 35. If the C / N ratio is higher than 35, nitrogen deficiency starts to occur, and microbial growth is suppressed and composting is not progressed or delayed. At the same time, organic acids produced by carbon excess lower the pH of the compost and inhibit the growth and activity of microorganisms. On the contrary, when the C / N ratio is too low, nitrogen is converted into ammonia, which increases the pH, and the carbon source is a limiting factor, which leads to a delay in weight reduction and an exothermic temperature.

<Temperature>

The temperature rise in the reduction process occurs during the oxidation of organic matter by microorganisms. The high temperature exothermic reaction indicates that the decomposition of organic matter is progressing under aerobic conditions. The degree of heat generation depends on the amount of organic waste, the air injection rate, and the C / N ratio. In general, the fermentation temperature of organic waste is suitable 46 ~ 70 ℃. The high temperature of 60 ~ 70 ℃ is essential for the rapid removal of water as well as killing pathogens and weed crops.

Oxygen

Decrease is a process of decomposing organic matter by microorganisms in aerobic state, so the microorganisms should be sufficiently supplied for aerobic metabolism. Air also serves to regulate the temperature and remove moisture, CO ₂ and other gases. However, if the air is not supplied sufficiently, it becomes anaerobic and an unpleasant odor is generated.

<Moisture>

The initial moisture content suitable for weight reduction ranges from 55 to 65%. When the water content is less than 40%, the microorganism's activity is inhibited and the decomposition is delayed.In the above 65%, the oxygen supply in the sludge is not smooth, and the activity of the microorganism is suppressed, so that the weight reduction period is long, and the sludge becomes anaerobic. Done. Sewage sludge and food waste are 80 ~ 90% of moisture, so it is essential to add moisture regulators (sawdust, wood chips, rice husks, etc.) to maintain the proper moisture content of 60%. Sawdust or chaff are commonly used as moisture control agents. For example, sawdust has a high C / N ratio, large particles, high water adsorption, easy handling, and good odor adsorption.

Accordingly, the present invention mixes food waste and combustible industrial waste such as wood chips and sawdust in dewatered sludge to adjust the environment suitable for weight reduction. The general C / N ratio of food waste is about 20 ~ 30, and the C / N ratio of sawdust is about 40 ~ 50. Therefore, by adding appropriate amount of food waste and combustible industrial waste to dehydration sludge, C / N ratio suitable for weight reduction You can get it.

Composition ratio of dewatered sludge Furtherance moisture TS (Total Solid) VS (Volatile Solid) FS (Fixed Solid) ratio(%) 78 22 59 41 Weight (100 Kg) 78 22 13 9

As shown in Table 1, the organic matter content of the dewatered sludge contained only 13% of the total. This is less than the organics needed to remove moisture by the exothermic reaction of microorganisms. In other words, the sewage sludge generally has a C / N ratio of 8 to 15. On the other hand, the required C / N ratio for composting organic waste is about 20-30. Therefore, more organic matter is needed to remove moisture by using heat (60-70 ° C.) generated while microorganisms decompose organic matter. Therefore, in the primary mixing process 100 of the present invention, the dehydration sludge is mixed at a ratio of 70 to 80%, food waste 10 to 20%, wood chips and sawdust 10 to 30% (volume ratio). For example, if the mixing ratio of the food waste is less than 10%, the organic matter is insufficient and the temperature is difficult to maintain, so the reduction does not proceed. In addition, the initial moisture is adjusted to 50-60% by mixing dehydrated sludge with water content of 70-80%, food waste with water content of 80-90%, and sawdust or wood chips as moisture control agents.

Sewage sludge is dehydrated sludge dehydrated through anaerobic digestion of sewage treatment plant through dehydrator and has 70 ~ 80% water content. If the water content exceeds 90%, such as sludge from water and sewage and wastewater, dehydration may be performed in dewatering devices such as belt presses, filter presses, screw decanters, and centrifuges. As such, the present invention uses a sludge cake from which the filtrate is removed after dehydration to produce a solid fuel. Non-combustible materials such as metals in the dewatered sludge are selected through processes such as inertial screening and mechanical screening. For example, the collected dewatered sludge is stored in a hopper, and foreign matter in the sludge conveyed from the hopper is removed by a sorter. And the sludge conveyed from the sorter is conveyed to the primary mixer 10.

The food waste is food waste generated in each home and restaurant, and the metals mixed in the food waste are selected and sorted through the process of inertia screening and machine screening, and the selected food waste is shredded to a certain size by a crusher. For example, the collected food waste is stored in a hopper, foreign matter in the food waste transported from the hopper is removed by a sorter, and the food waste transported from the sorter is shredded to a certain size by a crusher. And the food waste conveyed from the crusher is conveyed to the primary mixer (10).

The combustible industrial waste is wood waste wood, the collected wood waste wood is separated through the sorting process, such as mixed soil and other materials, and only the wood waste wood is put into the grinder and the size of wood chips with a particle size of 30 ~ 50mm and 0.5 ~ 3mm Smash into size sawdust. And combustible industrial waste in the form of wood chips or sawdust conveyed from the shredder is transferred to the primary mixer (10).

The microorganism agent or microorganism is a high temperature active aerobic fermentation bacteria as MS soil microorganisms, and the main species are Bacillus licheniformis, Bacillus amyloliquefaciens, Bacillus subtilis and the like. The fermentation temperature conditions of this microorganism are operated at high temperature between 60 ℃ ~ 70 ℃, all pathogens, pest eggs, weed seeds, etc. are all killed, the fermented powder has a sweet smell and is harmless to animals and plants. The microbial agent is added to the mixing tank and mixed evenly.

And the sludge mixture sufficiently mixed in the primary mixer 10 is introduced into the fermentation dryer (20). The fermentation dryer 20 is capable of controlling the major fermentation factors such as air supply, moisture content, fermentation temperature and flipping to create an optimal environment of aerobic microorganisms. The water content of the sludge mixture in the fermentation dryer 20 should be adjusted to an appropriate level (50 ~ 60%). If the water content is low or high, fermentation will not proceed or the fermentation period will be long.

As shown in Figure 4, the fermentation dryer 20 according to the present invention is composed of a cylindrical fermentation tank 21 is provided with a screw blade 22 for stirring and transporting the sludge mixture therein. One side of the fermentation tank 21 is provided with a first inlet 23 for injecting the sludge mixture, the other side of the fermentation tank 21 is provided with an outlet 24 for discharging the dried mixture. An air inlet 25 for injecting air into the fermentation tank 21 is provided at the outlet 24 of the fermentation tank 21, and an air inlet 25 is provided at an outer circumferential surface of the fermentation tank 21. A preheating passage 26 for preheating the supplied air is provided. This preheating passage 26 is open toward the inlet 23 of the fermentation tank 21. In addition, the middle portion of the fermentation tank 21 is further provided with a second inlet port 27 for inputting solubilized food waste. And one side of the fermentation tank 21 is provided with an exhaust passage 28 for discharging water vapor generated in the fermentation tank 21.

The sludge mixture sufficiently mixed in the primary mixer 10 is introduced into the fermentation tank 21 through the first inlet 23 of the fermentation dryer 20 by dividing the amount to be treated every day at regular time intervals. And the introduced sludge mixture is turned over while moving slowly along the rotating screw blades 22. Sludge mixtures begin to be degraded by microorganisms under the right environmental conditions. Bacteria can be classified into low temperature bacteria that survive below 20 ° C, mesophilic bacteria that survive 25 to 40 ° C, and high temperature bacteria that survive above 45 ° C.

In terms of temperature reduction, the initial stage of sludge temperature rises, the high temperature stage in which cellulose or pectin in organic waste are mainly degraded, the temperature decreases, the rate of decomposition slows down, Can be divided into aging stage to settle. In the initial stage, the water content and C / N ratio of the sludge mixture are adjusted to an appropriate level, so the mesophilic bacteria and bacteria decompose substances susceptible to decomposition of sugars, amino acids, fatty acids, etc., and the sludge temperature gradually increases. Subsequently, heat is generated by the decomposition of waste by mesophilic microorganisms in the early stages, and when heat accumulates in the sludge, the temperature rises to 60 ~ 80 ℃, and at the same time, the activities of mesophilic microorganisms are stopped, and Enter the high temperature stage. High-temperature microorganisms decompose large molecular weight materials such as cellulose. At this stage, the most important thing for microbial activity is oxygen consumption, so oxygen supply is essential and moisture in the sludge mixture is removed by high temperature.

On the other hand, as the aerobic biodegradation of organic matter proceeds through the high temperature step, the C / N ratio and moisture gradually decrease. In general, the initial C / N ratio is 15 to 25. When the C / N ratio falls below 10, the temperature begins to drop. In addition, the water is drastically reduced in proportion to the air injection amount, and the water content of the sludge mixture drops to less than 30-40%. This is because the substrate was depleted by microbial decomposition and the water was evaporated by the air injection. This is because much of the organics turn into stable substances (Humus) that are no longer easily degraded. Humus has a high lignin content and low nutrients, so no further decomposition of organic matter occurs and the temperature of the sludge mixture gradually decreases.

However, when the high temperature step is switched to the aging step, the temperature of the fermentation dryer 20 falls below 40 ° C. so that drying no longer occurs. Accordingly, the present invention injects the sludge mixture at regular time intervals so that the temperature inside the fermentation dryer 20 does not fall, and adds food waste through the second inlet 27 formed in the middle portion of the fermentation dryer 20. Feed the mixture with moisture and organics.

Therefore, in the fermentation drying step 200 according to the present invention, the sludge mixture is mixed with dehydrated sludge, food waste and combustible industrial waste into the fermentation dryer, and then the temperature of the sludge mixture is decomposed by mesophilic microorganisms and high temperature microorganisms. The mixture is removed from the first fermentation drying step 210 and the first fermentation drying step 210 to remove the organic matter and water contained in the sludge mixture while raising from 20 ℃ to 70 ℃, the C / N ratio is lower The second fermentation drying step 220 to remove the residual moisture by supplying additional water and organic matter to activate the decomposition of the thermophilic microorganism to maintain the temperature of the sludge mixture at 60 ~ 70 ℃ for a certain time. At this time, in the secondary fermentation drying step 220, solubilized food waste is input to supply water and organic matter to the sludge mixture. Soluble food waste is to improve the treatment efficiency of organic matter by decomposing the organic matter to keep it in a state that is easy for microorganisms to digest. In other words, the metabolism of microorganisms, that is, organic matter such as proteins, carbohydrates and fats of large particles among the organic materials that are fed during the digestion of microorganisms is converted into small sized particles. For example, food waste is fermented in an acid fermentation tank 80 for about 2 to 6 days. Therefore, when the solubilized food waste is added to the sludge mixture, it is possible to supply sufficient organic matter and water necessary for the activity of the thermophilic microorganisms.

As such, since the fermentation dryer 20 according to the present invention maintains a high temperature (60 ~ 70 ℃) for a predetermined time, and injects the dried air toward the inlet 23 from the outlet 24 side of the fermentation dryer 20 Water vapor generated in the sludge mixture is discharged to the outside through an exhaust passage 28 installed at the inlet 23 side of the fermentation dryer 20. And the dried sludge mixture is transferred to the secondary mixer 30, the secondary mixing process 300 is performed.

 In the secondary mixing step 300, food waste is further added to the mixture dried in the fermentation drying step 200 and mixed. Here, food waste is used as a caloric aid, preferably food waste is fatty food waste such as waste cooking oil, butter, animal fats and the like. The food waste is added 10-30% of the dried sludge mixture. Solid fuels formed by sewage sludge, food waste, and waste wood industrial waste show high calorific value of 4,500 kcal / kg. When 10 ~ 30% of fatty food waste is added at the end of the fermentation process, 6,000 kcal / kg The solid fuel exhibiting a high calorific value can be produced. And the sludge mixture is evenly mixed with food waste is transferred to the aging dryer 40, the aging drying process 400 is performed.

The aging drying process 400 is to dry again the mixture to which the food waste is added so that the water content is 10 ~ 20% or less. At this time, the aging dryer 40 is heated using the heat of the boiler made of the solid fuel 2 produced according to the present invention. And the aged dried mixture is separated from the wood chip in a separator (not shown), and then transferred to the grinder 50, the grinding process 500 is performed. The separated wood chips may be returned to the first mixing tank 10 and recycled. The pulverization step 500 is pulverized the mixture made of aging drying in a powder state.

The mixture pulverized in the crushing process 500 may be used as a compost, green soil, cement raw material, cover material, or molded into a solid fuel to produce a solid fuel. In order to use the ground mixture as compost, green soil, cement raw material, and cover material, the powdered mixture is packed and shipped. In order to prepare the pulverized mixture as a solid fuel, a molding process 600 for extruding the pulverized mixture is further performed.

In the conventional solid fueling technology, a large amount of inorganic co-heating agent such as coke and anthracite is used, so that the sludge mixture is extruded by applying a pressure of about 250 to 1000 kgf / cm 2 in a high pressure compression molding machine. Therefore, it takes about 100 to 130 horsepower to produce a solid fuel of 1 ton / hr. However, according to the solid fuelization method of the present invention, since the sludge mixture dried to 10% or less includes a large amount of food waste, only about 20 to 40 horsepower is required. That is, according to the present invention can save the energy required during molding. In addition, the conventional technology is extremely high pressure in the molding process, so that the solid fuel is densified, so the porosity is very low, less than 5%, but the present invention is extruded at a low pressure to prevent densification.

The mixture dried through the molding process 600 is molded into a pellet shape having a diameter of about 10 to 30 mm and a length of about 10 to 100 mm. Besides the pellet shape, it can be molded into various shapes such as spherical shape, oval shape and diamond shape depending on the shape of the molding frame. In addition, in the present invention, since the food waste having viscosity is included in the mixture when the mixture is molded, there is no need to mix a separate molding agent or a caking agent.

The solid fuel 2 molded in the molding step 600 is dried as it is. In the drying step 700 is made of a solid raw material having a water content of 1 to 10%. And part of the finally dried solid fuel (2) is supplied to the boiler 70 to make the heat required in the aging drying process 400 is used and the rest is shipped through the packaging process (800).

As described above, in the method for producing solid fuel of organic waste using the microorganism according to the present invention, the water content is 40% in the fermentation dryer 10 by primary fermentation for about 5-6 days and secondary fermentation for 2-4 days. The sludge dried in and out was dried in the aging dryer 40 at a moisture content of 10% or less in the aging dryer 40 for 1 to 2 days by the boiler heat by the pre-regenerated solid fuel 2, and then the mixture thus produced was pulverized in the pulverizer 50. It is characterized by grinding to solid fuel.

Hereinafter, an experimental example of a method of manufacturing solid fuel of an organic waste using a microbial agent according to the present invention will be described.

Comparative Experiment 1

153kg of sewage sludge was mixed with wood chips and 162.44kg of microbial agent to 315.44kg, and then the change of temperature and removal amount were observed. As shown in the graph of FIG. 5, the temperature was increased to 42 ° C. at maximum on day 3 and gradually decreased. By weighing, the sludge was gradually removed by the microbial agent over time. As a result of the experiment, after about 14 days, the removal rate of sludge was 73% (111.7kg removal rate), and more than 90% after 90 days. According to the above comparative experiments, it was found that the weight loss can not be efficiently performed. In addition, in the present experiment, 20 kg of organic matter contained in the sludge was removed by the microorganisms 2 to 4 days, and it was found that the exothermic reaction that could remove the water no longer reacted.

Experimental Example 1

Through comparative experiments, it was found that in order to efficiently remove sludge using microbial agents, it is necessary to supply organic materials through other mediators in addition to the organic concentration of sludge. Among the factors necessary for the composting reaction, an appropriate C / N ratio needs 20 to 40. The organic waste of food waste, which is one of the organic wastes, was supplied with 10% of the total amount of food waste every other day, and the amount of change was observed. Therefore, 138kg of wood sludge was mixed with wood chips and 224kg of microbial material to make 360kg, and the change of temperature and removal amount were observed. The results are shown in the graph of FIG.

As shown in Figure 6, the sludge was gradually removed by the microbial agent with time, it was observed that the first input sludge amount of 136kg was removed by 93% or more, about 10kg remaining (removed sludge 136kg → 126kg) on day 11 . The temperature also increased only by 42 ° C in the comparative experiments, but in Experimental Example 1, the temperature increased to around 60 ° C due to the exothermic reaction of the microorganisms, and the heat of the sludge evaporated by this heat, indicating a high reduction ratio.

Moisture Change Rate of Sludge Mixture Day [d] One 3 4 6 8 9 10 11 Water content [%] 78.23 64.75 59.48 48.92 45.87 43.47 35.21 31.61

As the organic material of the sludge was removed by the microbial agent, the moisture contained in the sludge was also changed. On day 6 it began to fall below 50% and on day 10 it dropped below 40% to day 31.61%. It can be seen that the water of the sludge evaporated by the heat generated by the exothermic reaction of the microorganisms, indicating the removal of the sludge. In order to treat sludge by exothermic reactions of living organisms, the organic concentration of sludge alone is insufficient, so it has been found that supplementation of other organic matter such as food waste is necessary.

Comparative Experiment 2

The possibility of high calorie solid fuel using sludge remaining after treatment by microbial agent was tested. After 20 days of treatment with the microbial agent, the remaining sludge was recovered and naturally dried for 2 days, and then a certain amount of the sample was requested to measure the calorific value of the sludge by the Korea Testing & Research Institute. As a result, a low calorific value of 8,940 J / g (2,136 kcal / kg) was shown. In general, the total calorific value is about 3,000kcal / kg when the sewage sludge is completely dried. This shows that the organic matter contained in the dewatered sludge is sufficiently decomposed by the microbial agent used in the present invention, so that there is less carbon component remaining. Experimental results show that the remaining sludge humus after treatment by microbial agents increases the possibility of high quality compost without high organic matter concentration.

Experimental Example 2

In Experimental Example 1, after treatment for 20 days by the microbial agent, the remaining sludge was recovered and naturally dried for two days, and then a certain amount of the sample was requested to measure the calorific value of the sludge by the Korea Chemical Convergence Testing Laboratory. As a result, the low calorific value 16,800 J / g (4,014 kcal / kg) showed a calorific value. Through the above results, the possibility of fueling the humus generated by treating the sewage sludge by adding food waste during the sludge treatment process was increased.

The fuelization (or solid fuel) using the sludge humus produced in Comparative Experiment 2 and Experimental Example 1 can be used as fuel in coal, etc., but in order to obtain higher calorific value, the food waste is removed 1-2 days before the final treatment of sludge. Residual sludge can be obtained by adding more than 80 to 100% by volume of carbon, and by adding food waste containing a large amount of fat, calorific value of 5,000kcal / kg or more can be obtained.

In the above description of the technical spirit of the present invention with reference to the preferred embodiment of the present invention in detail, but the examples shown in the embodiment and the drawings are intended to help the understanding of the invention as such is not limited to the scope of the present invention As those skilled in the art will be able to make various embodiments using these embodiments, such modifications fall within the scope of the present invention as long as they are included in the following claims.

1: solid fuel manufacturing apparatus 2: solid fuel
3: dewatered sludge 4: flammable industrial waste
5: Food waste 7: Acid fermentation tank
10: primary mixer 20: fermentation dryer
21: fermentation tank 22: screw wing
23: first inlet 24: outlet
25: air inlet 26: preheating passage
27: second inlet 28: exhaust passage
30: Secondary mixer 40: Aging dryer
50: grinder 60: extrusion machine
70: boiler 100: first mixing process
200: fermentation drying process 210: first fermentation drying step
220: secondary fermentation drying step 300: secondary mixing step
400: aging drying process 500: grinding process
600: molding process 700: drying process
800: packaging process

Claims (8)

Primary mix, mixed with dehydrated sludge and combustible industrial wastes such as wood chips or sawdust, with a total water content of 50 to 60% and a total C / N ratio of 30 to 50. Process;
The sludge mixture mixed in the first mixing process is introduced into a fermentation dryer to decompose organic substances mixed in the sludge by metabolic action of microorganisms, and to dry the sludge mixture to 40% or less by exothermic reaction of microorganisms. Fermentation drying process;
A secondary mixing step of mixing food waste by administering the mixture dried in the fermentation drying step;
In the secondary mixing process, the food waste is added to the aging dryer to dry the mixture so that the water content of the sludge mixture is less than 10%, the aging dryer is heated by the heat of the boiler using a solid fuel made of organic waste Aging drying process;
A pulverizing step of pulverizing the aging mixture generated through the aging drying process in a separator after separating wood chips from the separator;
And a molding step of extruding the mixture ground in the grinding step to form a solid fuel having a predetermined size. The method of claim 1,
The fermentation drying process is a method of producing a solid fuel of organic waste using a microbial material, characterized in that it further comprises a secondary fermentation drying process for continuing the exothermic reaction of the microorganism by further injecting food waste into the first dried sludge mixture . The method of claim 2,
Food waste injected into the secondary fermentation drying process is a solid fuel production method of organic waste using a microbial material, characterized in that the solubilized food waste of 90% or more moisture through acid fermentation. The method of claim 1,
Food waste is injected into the secondary mixing process, the solid waste of the organic waste using the microbial material, characterized in that the food waste containing a lot of fat components. The method of claim 1,
Food waste is mixed with the dewatered sludge and combustible industrial waste, solid fuel manufacturing method of organic waste using a microbial material, characterized in that 10 to 20% by volume of the mixture mixture. The method of claim 3, wherein
Food waste is added to the dried sludge mixture, solid fuel production method of organic waste using a microbial material, characterized in that 10 to 20% by volume of the dried sludge mixture. The method of claim 4, wherein
Food waste is added to the dried mixture, solid fuel manufacturing method of organic waste using a microbial material, characterized in that to add 80 to 100% by volume of the dried mixture. The method of claim 1,
Solid fuel manufacturing method of the organic waste using the microbial material, characterized in that it further comprises a sludge conveying step of recycling 10 to 20% by volume of the sludge mixture treated in the fermentation drying process to the first mixing process instead of a new microbial material. .

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