JP2020022944A - Sludge dehydration promoter and sludge dehydration method - Google Patents

Abstract

To provide a low-cost and efficient dehydration technique for a sludge having high water content.SOLUTION: The dehydration method disclosed in this description includes a first step and a second step. In the first step, a sludge having high water content is blended and agitated with a dehydration promoter containing a coffee residue as a main constituent at a weight ratio of 1/3 or under to reduce the water content to 25% or under. In the second step, a new sludge is blended and agitated with a blend dehydration product obtained in the first step at a weight ratio of 1/3 or under to reduce the water content to 25% or under. After the second step, another new sludge is blended and agitated with a part or all of the blend dehydration product obtained in the previous step at a weight ratio of 1/3 or under to reduce the water content to 25% or under.SELECTED DRAWING: Figure 1

Description

  The technology disclosed in this specification is a drying promoting material for high water sludge and a sludge drying method.

  Patent Literatures 1 and 2 disclose techniques for generating solid fuel using sludge having a high water content and odor. Patent Literature 1 discloses a method in which coffee scum and organic precipitated sludge are added to activated sludge having a high water content and dried to eliminate odor. In Patent Literature 1, coffee slag having a water content of 50 to 80% is mixed and stirred at a weight ratio of 0.5 to 2 times the activated sludge. The organic sediment sludge generated when coagulating and sedimenting the emulsion or latex-containing wastewater is used. This organic sludge effectively promotes drying of the activated sludge.

  The solid fuel manufacturing method disclosed in Patent Document 2 is as follows. A granular dry product is added to a blend of a high water content organic sludge and food waste, stirred, and dried to obtain a solid fuel. The granular dried product to be added is obtained by mixing high water content organic sludge and food waste with the same composition in advance, and then drying to form particles having a water content of 20% or less and a particle size of 5 mm or less. Food wastes include coffee grounds, bran, rice bran, dried okara, and the like. When coffee slag is used as food waste, the mixing ratio of high water content organic sludge and food waste is as follows: high water content organic sludge: food waste (water content 60%) = 1: 0.4 to 1.0 (weight). Ratio) is preferred. In the case of dried coffee residue, it is said that a high water-containing organic sludge: food waste (dry) = 1: 0.2 to 0.5 (weight ratio) is preferable.

  Patent Literature 2 proposes returning a part of the obtained dried granules to the next drying step of a mixture (a mixture of high water content organic sludge and food waste). The ratio of the blend to the dry granules to be returned is such that blend: granular dry matter = 1: 0.1 to 1.5 (weight ratio). Patent Document 2 also states that it is preferable to add organic sedimentation sludge generated when the emulsion or latex-containing wastewater is subjected to coagulation sedimentation treatment.

JP 2012-124204 A JP 2014-185307 A

  The inventors of Patent Literatures 1 and 2 have further conducted tests and researches and made efforts to improve the technology for treating sludge more easily. In Patent Literature 1, food waste (coffee residue) and organic sediment sludge function as a drying accelerating material that speeds up drying of sludge. In Patent Literature 2, a granular dry product (a product obtained by mixing and drying a highly water-containing organic sludge and food waste (coffee slag)) functions as a drying accelerating material that speeds up drying of the sludge. In Patent Documents 1 and 2, coffee scum (water-containing) is mixed at about twice the weight ratio with respect to sludge. In the case of dry coffee grounds, it is mixed with sludge at a weight ratio of about 0.5 (Patent Document 2).

  The inventors of the present application have found that sludge drying more than expected can be realized by using more coffee slag as a drying accelerator for sludge.

  The sludge that is the subject of the present invention is organic sludge and livestock manure. Together, these two emissions are huge, accounting for about 50% of all industrial waste (120 million tons of organic sludge / 100 million tons of livestock manure / year). If the current average processing cost is about 10 yen (processing cost and transportation cost), it has a scale of about 2 trillion yen as a processing business. The inventors have been conducting studies on the market based on the prior invention (the inventions of Patent Documents 1 and 2) to reduce the volume of various organic sludges and livestock excreta and to increase the added value of the effluent. Was. As a result, the following became clear. The number of establishments that emit organic sludge is enormous. Moreover, the amount of sludge discharge per day ranges from about 5 kg / day to 100 ton / day. It is roughly classified into three according to the scale. In other words, they are classified into small-scale facilities (1 ton or less), medium-scale facilities (1 to 10 ton), and large-scale facilities (10 ton or more) according to the daily emissions. Among them, small-scale facilities account for more than 95% of the total. These small-scale facilities cannot invest in sludge treatment due to investment effects. Therefore, processing is performed at a very high processing cost and transportation cost (20 to 35 yen / kg).

  Why is this happening? That is because the sludge treatment technology up to now has been applied only to medium-sized and large-scale facilities and involves huge capital investment. As an example, in the case of a sewage treatment plant, drying and carbonizing large sewage sludge mainly using a carbonization treatment system at 10 or more locations nationwide (all large facilities with daily sewage sludge generation of 50 t / day or more). A system has been introduced to convert sewage sludge into solid fuel. The Japanese Industrial Standards (JIS) for solid fuels in sewage sludge have been enacted, and it is expected that capital investment will continue to progress mainly in large-scale sewage sludge discharge facilities (50 t / day or more). However, the equipment costs are on the order of several billion to eight billion yen.

  On the other hand, 95% of the facilities that discharge organic sludge are small-scale discharge facilities with daily sludge discharge of 1 t / day or less. For example, in the case of chemical facilities, for example, facilities that manufacture emulsion / latex adhesives and paints (both water-based), and automobiles, electrical, chemical, and chemicals that use these water-based adhesives and paints. After using adhesives and paints, a large amount of washing water is generated from various offices such as wood after washing. By treating the wastewater, there are a large number of establishments nationwide from several tens of kilograms of wastewater treatment sludge generated per day to 1 t / day.

  However, as for the sludge discharged from these facilities, no means including the treatment method has been developed. Because it is impossible to invest a large amount in these facilities, and if you make a capital investment, it costs the waste disposal company as industrial waste (it costs about 25 to 40 yen / kg for disposal and transportation costs). It was common to think that it was better to send out and process. However, in recent years, the processing side has become inevitable to increase the processing cost in the future due to various problems such as excessive compost and the limit of use of cement. For this reason, if the sludge discharge business cannot be treated stably in the future, there is a situation where the survival of the company may be affected.

  Under these circumstances, the inventor of the present application attempted to change the idea. Applying the technology we have developed up to now, if there is a method that can process with a low investment and can reduce the processing cost with analog equipment for not only large facilities but also small facilities, it is a breakthrough I decided that it would be a scheme. For that reason, inexpensive analog equipment for small-scale facilities was a very important point in completing the invention. We have tried various batch type stirring devices (equipment) on the market. The following six points are selection criteria. (1) Inexpensive. (2) The facility functions as a container for the input. (3) Simple equipment that can be used with ON-OFF operations. (4) The drying of the granular material is promoted by stirring, and it is not a kneading method. (5) The equipment must be as powdered as possible. (6) It should be able to quickly disperse and mix by adding a mud to the granular dried product. As a result of the examination, assuming that these six criteria are satisfied, the one corresponding to the smallest facility is a horizontal trough with stirring blades (for example, a mortar mixer). , A ribbon mixer (having ribbon-shaped blades) was selected as the most suitable stirring equipment that satisfies the above six criteria. By using these facilities as agitation dryers, it is possible to provide a system that can be applied to small-scale facilities (sludge daily amount of 1 t / day or less), and a scheme that can be applied to small to large-scale facilities in general. Can be provided.

  The inventors have developed a technique for efficiently drying high-water content sludge using coagulated sediment sludge generated when coagulation-sedimentation treatment of emulsion or latex-containing wastewater and coffee grounds to obtain a solid fuel ( Patent Documents 1 and 2). The target sludge is sewage sludge, livestock manure sludge, food sludge and coagulated sludge discharged from various factories, grease trap sludge generated in eating and drinking related kitchens, paper sludge, etc. Occurs in large quantities. These sludges are very difficult to handle because they have a very high water content (70% or more) and have an odor. Until now, such sludge has been requested to be picked up by a specialized trader, which required a considerable cost for treatment. Investigating the needs of the market, it was found that increasing the value as a solid fuel is also effective, but a technology that reduces sludge quickly and at low cost is desired.

  The inventors examined whether drying could be accelerated without using coagulated sediment sludge. Sludge is discharged every day. Rather than storing odorous sludge and treating it in large quantities at one time, it is better to dry sludge generated on that day even in a small amount to reduce the volume and make it odorless. In addition, in business establishments where sludge is generated, an almost constant amount of sludge is continuously generated every day. Store these in the establishment until they are collected by a processor. It is not good for the environment and sanitation to accumulate strong odorous mud in the office. The inventors can set up the above-mentioned stirring dryer (mortar mixer or ribbon mixer) for sludge generated every day, and simply throw the generated sludge into the sludge and automatically perform the sludge treatment by natural drying. The system was assumed. An attempt was made to develop a drying accelerator that could be used in such a manner.

  When examining a drying accelerating material, it is usual to focus on how a small amount of the drying accelerating material can dry the object (sludge). On the other hand, the amount of coffee beverages sold in the market is enormous, and coffee slag is discharged in large quantities. Along with this, a large amount of coffee slag is discharged as industrial waste at various places throughout the country. In addition, no other effective recycling process has been established for coffee grounds. Some say that deodorant function and use of fuel, but in reality most coffee slag is discharged as waste (minus raw material) to the disposal company and is treated with compost etc. Is reality. In addition, some problems have been pointed out regarding the use as compost, and at present, drainage drinking water manufacturers do not have effective recycling formulas. Thus, the inventors reversed the idea and tried to dry a small amount of sludge using a large amount of coffee slag relative to the amount of sludge, which was presumed to be inefficient.

  The present inventors can mix and agitate a highly water-containing sludge having a weight ratio of 1/3 or less with respect to a drying accelerating material mainly composed of coffee slag, and can dry the mixture in a short time. It has been found that it can be reused as a drying accelerator. If it is 1/3 or more, the water content immediately after mixing increases, and long-term stirring is required to reduce the water content of the mixture to 25% or less. As a result, the electric energy consumption required for stirring is greatly increased, and the processing cost is increased. When the sludge is 1/3 or less, the usual stirring time is 8 hours, and when the sludge is 1/3 or more, the stirring time is 12 hours or more. Although it is naturally expected that drying is promoted as the ratio of sludge to coffee slag is reduced, the idea of using a drying promoting material three times or more for sludge is not common sense. This is because the amount no longer exceeds the range of the "promoting material" and the sludge can be treated only by less than half of the capacity of the stirring dryer (for example, the mortar mixer or the ribbon mixer), which is presumed to be inefficient.

  However, as mentioned earlier, it is better to be able to treat sludge daily, even in small quantities. The inventors have repeated trial and error in search of a lower-cost drying method, and when the amount of sludge mixed with the drying accelerator is reduced to 1/3 or less by weight, only stirring without adding heat is required, and It has been found that the mixture can be dried to a moisture content of 25% or less in a short time. The moisture content of 25% is the moisture content that can be reached by natural drying, and if the moisture content falls to 25% or less, it becomes an odorless dried product that does not adhere to the hands at all, and even if it is stored, it has a moldless property. There is no outbreak or rot, which is sufficient for volume reduction. In particular, in the drying by the natural drying method, when the dried product is dried to 25% or less, almost no odor can be obtained. The dried mixture can be newly used as a drying accelerator. That is, a predetermined amount of sludge can be added again the next day after the mixture is dried by adding sludge having a weight ratio of 1/3 or less with respect to the drying promoting material. There is no need to tweak the dried mixture, it is only necessary to throw in new sludge every day and to stir and mix.

  If the amount of the drying accelerator is much larger than that of the sludge, it is presumed that the sludge is finely dispersed when agitated, and the drying is accelerated in combination with the appropriate cohesive force and the water resistance of the coffee slag. Further, since the particles are dispersed and granulated by stirring, drying is further promoted by the diffusion effect. The dried mixture becomes 3-5 mm or less in granular form. Each time the mixture obtained by mixing and agitating the sludge and the drying promoting material and drying is reused as a new drying promoting material, the ratio of the coffee residue decreases. However, the sludge dries quickly due to the widespread diffusion of the sludge into the bulk of the particulate matter (ie, the drying aid). As a result, it is better to repeat drying a small amount of sludge in a large amount of the drying promoting material, and the drying efficiency is better.

  Although the dried mixture cannot be reused permanently as a drying accelerator, if the amount of sludge is adjusted, the sludge can be dried continuously without component adjustment for 15 times or more. In other words, the dry accelerating material disclosed in the present specification is obtained by mixing and drying a sludge containing a high water content at a weight ratio of 1/3 or less of the initial dry accelerating material, and drying the mixed dry product. It can be reused at least 15 times as an accelerating material. Assuming that the working days excluding holidays from the 30th of the month are about 25 days, the sludge is dried every day only by adjusting the components less than twice a month (including replacement with a new drying promoting material). be able to.

  The drying accelerating material disclosed in the present specification has a moisture content of 25% or less mainly containing coffee grounds. The drying accelerating material disclosed in the present specification is preferably coffee slag alone or a mixture of coffee slag and sludge, and preferably contains coffee slag in a solid content ratio of 30% or more. The solid content weight ratio of 30% means that 30% or more of the total weight of the solid content of the coffee grounds and the solid content of the sludge is coffee grounds.

  The drying accelerating material disclosed in the present specification is obtained by mixing and stirring a high water content sludge at a weight ratio of 1/3 or less with respect to the drying accelerating material to dry the sludge. It can be reused more than 15 times. That is, new sludge is added daily to the first drying accelerating material and drying is continued for one month.

  The present specification also provides a sludge drying method using the above-mentioned drying accelerating material. First, a highly water-containing sludge is mixed and stirred with the drying promoting material disclosed in this specification at a weight ratio of 1/3 or less to reduce the water content to 25% or less (first step). Next, new sludge is mixed and stirred into the mixed dried product obtained in the first step at a weight ratio of 1/3 or less to reduce the water content to 25% or less (second step). In the second and subsequent steps, a part or all of the mixed dried product obtained in the previous step is further mixed and stirred with a new sludge at a weight ratio of 1/3 or less to reduce the water content to 25% or less. repeat. Here, after the second step, the amount of another sludge is adjusted so that the solid content weight ratio of the coffee slag in the mixture of the sludge and the coffee slag does not fall below 30%, or a new drying promoting material is added. Good. By keeping the solid content weight ratio of the coffee residue of 30% or more, the sludge does not clump and the sludge is finely dispersed when agitated, and the drying speed is accelerated due to the appropriate cohesion and water resistance of the coffee residue. Guessed.

  More specifically, as described above, it is considered a box capable of treating sludge every day, and an open-type agitator / dryer (such as a mortar mixer or a ribbon mixer) is filled with a drying accelerator in advance, and the weight ratio is added thereto. Then, sludge of 1/3 or less of the drying accelerating material is charged and dried by stirring and drying. The dried mixture after drying can be reused at least 15 times or more as a new drying accelerator. In the use of the stirring dryer, it is not necessary to add heat for drying, and the only energy required is electric energy for stirring (of course, this does not deny drying by heating).

  In order to prevent the solid content ratio of the coffee residue from falling below 30%, it is advisable to adjust another amount of sludge or add a new drying accelerator. In addition, since the capacity of the stirring device is limited, a predetermined amount may be periodically removed from the mixture obtained in the previous step. In the process, the solid content of the sludge remains in the dryer due to the continuous introduction of the sludge, so that the weight of the mixed dried product (drying promoting material) in the dryer gradually increases. Therefore, in order to adjust the amount of the mixed dried product (drying promoting material) in the dryer, the mixed dried product (drying promoting material) is extracted from the mixed dried product (drying promoting material) as needed. To an appropriate amount. Further, as the number of continuous sludge injections increases, the weight ratio of solid content between the sludge and the coffee slag in the mixed dried product continuously changes. That is, as the number of times of sludge feeding increases, the solid content weight ratio of the coffee residue decreases, and the solid content weight ratio of the sludge increases. At this time, when the weight ratio of the solid content of the coffee grounds is less than 30%, the drying promotion function gradually decreases. If this happens, use a new coffee grounds to restore the drying promotion function, or replace the entire drying promotion core material. Thereby, the fine-grain dispersion of sludge, which is a function as a drying promoting material, is restored, and drying is accelerated in combination with the appropriate cohesive force and water resistance of the coffee grounds.

  The details and further improvements of the technology disclosed in this specification will be described in the following “Detailed description of the invention”.

It is a figure explaining the drying method of an example. It is a table of a test result. It is a graph of a test result. It is a graph of another test result. It is a graph of a comparative example. It is a table | surface which shows the test result of a 2nd Example.

  The sludge to be dried includes sewage sludge, livestock manure sludge, food sludge and coagulated sludge discharged from various factories, grease trap sludge generated in food-related kitchens, paper sludge, and the like. These sludges have a very high moisture content (usually 70% to 90%) and are difficult to handle because they have an odor. Until now, such sludge has been requested to be picked up by a specialized trader, which required a considerable cost for treatment.

  According to the present invention, sludge can be dried quickly and inexpensively by using coffee slag, which is industrial waste, as a drying accelerator. No other effective recycling of coffee grounds has been established. Some say that deodorant function and use of fuel, but in reality most coffee slag is discharged as waste (minus raw material) to the disposal company and is treated with compost etc. Is reality. In addition, some problems have been pointed out regarding the use as compost, and at present, drainage drinking water manufacturers do not have effective recycling formulas.

  The dried mixture of coffee grounds and sludge (dry mixture) can be reused as a new drying accelerator. By repeating the process of mixing and stirring the sludge with the drying promoting material and mixing and stirring new sludge with the obtained dry mixture, the sludge can be treated at lower cost. When the process is repeated, the ratio of coffee grounds in the dry mixture decreases. However, as described later, when a new sludge in a smaller amount (weight ratio) than that of the dry mixture (that is, the drying accelerator) is added, the coffee grounds are reduced. The new sludge can be dried as much as compared with the case where the ratio is high. Naturally, the drying accelerator cannot be reused indefinitely. However, every time the recycling cycle is repeated several to several tens of times, a new drying accelerator (i.e., dried coffee grounds) is appropriately added, so that the drying accelerator can be reused. The drying promotion effect returns. As will be described later, the test shows that at least 15 or more repetitions are possible.

  Although the drying promoting material of the present invention can be reused, it is preferable that the drying promoting material to be initially introduced is mainly composed of coffee grounds having a water content of 25% or less. All of the drying promoting material may be coffee slag, or a mixture of sludge and coffee slag, wherein the ratio of the coffee slag to the total weight of the solids of the coffee slag and the sludge is 30% or more in terms of the solid content weight ratio. Good to be. Mixing and stirring a high water content sludge at a weight ratio of 1/3 or less with such a drying promoting material not only causes the sludge to dry quickly, but also makes the dried mixture a new drying promoting material about 25 times. Can be reused. The use of coffee grounds also eliminates odor in the dried mixture.

  One embodiment of the sludge drying method will be described with reference to FIG.

  (First Step) A new drying accelerator 3 is charged into the mixer 2 (A). As the mixer, for example, a general-purpose mixer such as a mortar mixer or a ribbon mixer may be used, but it is preferable that the mixer is an open type in which an input port is always open. The drying accelerating material 3 mainly composed of coffee residue has a water content of 25% or less, and has a granular shape of about 3 mm. A high water content sludge 4 having a weight ratio of 1/3 or less of the drying promoting material 3 is put into the mixer 2 (B). The mixture of the drying promoting material 3 and the sludge 4 is mixed and stirred by the mixer 2 to reduce the water content to 25% or less (C). Since the weight of the drying accelerating material 3 is more than three times as large as the weight of the sludge 4 to be charged, the sludge diffuses into the drying accelerating material 3 with the start of mixing and stirring, and is granular due to the cohesive force of the coffee scum and water resistance. It will become. When the sludge is in a kneaded state, it sticks to the blades of the mixer 2 and the drying efficiency is significantly reduced. By using a larger amount of the drying promoting material 3 than the sludge to be fed, the sludge is quickly granulated. The sludge dries to a moisture content of 25% or less in one day.

  (Second step) To the mixture having a water content of 25% or less obtained in the first step, new high water content sludge 4 is added, and the mixture is stirred. This step is the step of FIG. 1C and the step of FIG. That is, the mixed dried product obtained in the first step is reused as a new drying accelerator. The amount of the sludge 4 to be charged here is a weight ratio of 1/3 or less of the mixed and dried product having a moisture content of 25% or less obtained in the first step. Compared with the case of the first step, the ratio of the coffee residue in the new drying accelerating material is reduced, but the weight of the drying accelerating material is larger than the sludge 4 with high water content, so that the sludge 4 is dried. It diffuses into the accelerator and granulates without kneading. Also in the second step, mixing and stirring are performed until the water content of the newly added mixture of sludge and the drying promoting material becomes 25% or less (from FIG. 1 (B) to (C)). Also in this case, the water content falls to 25% or less in one day.

  (Third Step) To the mixed and dried product having a water content of 25% or less obtained in the second step, new sludge 4 having a high water content is further added and mixed and stirred. This third step is a repetition of the second step. The amount of the sludge 4 to be added here is also set to a weight ratio of 1/3 or less of the mixed dried product obtained in the previous step (second step), as in the case of the second step.

  Thereafter, the third step is repeated. That is, (B) and (C) of FIG. 1 are repeated. However, the volume of the mixed dried product in the mixer 2 will increase as it is. Before the volume of the mixed dried product in the mixer 2 exceeds the allowable value of the mixer 2, an appropriate amount of the mixed dried product is taken out of the mixer 2, and then the sludge 4 having a high water content is added. This step corresponds to the transition from (C) to (B) via (D) in FIG.

  Further, when the third step is repeated, the ratio of coffee residue in the drying accelerating material decreases. The third step cannot be repeated indefinitely. The degree of drying of the mixture of the sludge and the drying accelerating material is measured, and a new drying accelerating material 6 (containing a coffee residue having a water content of 25% or less in a solid weight ratio of 30% or more) is added at an appropriate timing and mixed and stirred. . This step corresponds to a transition from (B) to (C) via (E) in FIG.

  By repeating the mixing and stirring of the highly water-containing sludge with at least three times the weight of the drying accelerator and mixing and stirring, a large amount of sludge can be dried as a result.

  2 and 3 show test results of the drying method disclosed in the present specification. FIG. 2 is a table showing the test results, and FIG. 3 is a graph showing changes in the water content and the temperature on the next day of the mixture obtained by mixing and stirring the sludge and the drying accelerator. Only 30 kg of the drying accelerator was put into the mixer on the first day. The sludge to be introduced is sludge of food and has a water content of 90%. The third and tenth days corresponded to Sunday, and no new sludge was introduced.

  Every day except Sunday, 6 [kg] of sludge is added and mixed and stirred. The stirrer used was a mortar mixer whose capacity was 100 kg or more, so that the mixture was not taken out until the 11th day.

  Since the dry matter of the added sludge increases, the solid content weight ratio of the sludge and the drying promoting material increases every day. The weight ratio of the sludge to the drying promoting material after one day is sludge: drying promoting material = 0.1: 5. The weight ratio after 11 days is sludge: drying accelerator = 1: 5. The solid content of the added sludge remains in the drying accelerator, but the water evaporates.

  Since the average temperature was low on the second day, the moisture content of the next day increased to 23.38 [%], but on other days, the moisture content of the next day was approximately 20 [%] or less. Until the 11th day, 6 [kg] was injected every day except Sunday, but the moisture content on the day following the last day was 19 [%], indicating that the effect of the drying accelerating material was not reduced.

  FIG. 4 shows another test result. FIG. 4 shows the results of a test in which sludge was mixed with the drying promoting material of a single coffee residue every day at a ratio of drying promoting material / sludge = 3/1 and stirred. The graph shows the component ratio (the weight ratio of the solid content of coffee grounds to the solid content of sludge) after drying to a moisture content of 25% or less. FIG. 5 is a comparative example, and shows the result when the solid content weight ratio between sludge and coffee grounds is 74/26 as the initial drying promoting material. The “first time” graphs at the left end of FIGS. 4 and 5 show the ratio of sludge / coffee residue in the drying accelerating material before the sludge to be dried is charged. FIG. 5 also shows the results of a test in which mixing and stirring were performed every day at a ratio of drying accelerator / sludge = 3/1. That is, the comparative example of FIG. 5 is a result when a drying accelerating material having a solid content of less than 30% of coffee grounds is used. In the comparative example, the number of times that the material could be repeatedly used as the drying accelerator was limited to 5 times. At the fifth stage, the ratio of the solid content of the coffee grounds to the total weight of the solid material in the drying accelerator was 21.6%. From the sixth time, the water content became 26% or more, and the drying property was reduced.

  On the other hand, when coffee grounds alone was used as the initial drying accelerating material (FIG. 4), even if sludge was added continuously for 25 days, there was no change in the performance as the drying accelerating material. % Could be achieved. Further, the particle size of the dried product did not increase. The particle size after drying at the 25th time was 92% at 3 mm or less. In addition, at the start, the particle size of 3 mm or less is 100%.

  From the above results, when the content (solid content ratio) of coffee slag having a water content of 25% or less is 30% or more, good performance as a drying accelerating material is exhibited, and repeated use becomes possible. And, by adding a drying accelerator so that the content of coffee slag with a water content of 25% or less does not fall below 30%, the sludge should be dried / reduced every day (or every few days). Becomes possible.

  As another example, test results with a ribbon mixer are shown (FIG. 6). In this example, 50 kg of coagulated sediment sludge was treated per day.

The test conditions are as follows.
・ Agitating and drying equipment: Ribbon mixer of 0.8 m ³・ Drying accelerator: 200 kg input ・ Sludge input: 50 kg of sludge coagulated sediment sludge with a moisture content of 79% per day ・ Stirring drying time: 1 day 8 hours

  Here, more specifically, the coagulated sediment sludge is the coagulated sediment sludge generated when the emulsion or latex-containing wastewater is subjected to coagulation sedimentation treatment.

The measurement and check items are as follows.
・ Water content measurement: The day after the introduction, before the addition of sludge on the day ・ Ambient temperature: Continuous logger measurement ・ Weight measurement: Weight measurement in the stirrer (once a week)
・ Measuring period: 1 month (21 injections)

  In addition, the air temperature in the table of FIG. 6 is an average air temperature for 24 hours. With the increase in the number of times, the generation of powdered material of 0.1 mm or less was hardly observed, and it became clear that the ribbon-type mixer did not powder more than the mortar mixer. This time, the sludge was injected once a day (21 times in total) every day except Saturday and Sunday without sampling. Still no problem. That is, the water content could be suppressed to approximately 25% or less each time only by stirring for 8 hours per day.

  The drying accelerating material disclosed in the present specification can be obtained at a low cost because it mainly contains coffee waste, which is industrial waste. In addition, no other effective recycling process has been established for coffee grounds. Some say that deodorant function and use of fuel, but in reality most coffee slag is discharged as waste (minus raw material) to the disposal company and is treated with compost etc. Is reality. In addition, some problems have been pointed out regarding the use as compost, and at present, drainage drinking water manufacturers do not have effective recycling formulas. The drying promotion material disclosed in the present specification can reuse the obtained dry mixture as a new drying promotion material by mixing and stirring sludge having a smaller weight.

  Also in the case of reuse, the mixture can endure a large number of reuses by mixing and stirring the sludge having a weight ratio of less than the same amount to the drying accelerator. A portion of the mixture may be removed each time it is reused, or each time it is reused a specified number of times, to keep the total amount of the mixture below a predetermined tolerance. Further, it is preferable to add a new drying promoting material (mainly composed of dried coffee grounds) at an appropriate number of reuses while monitoring the particle size of the dried product.

The following effects can be expected from the drying promoting material disclosed in this specification and the sludge drying method using the same.
(1) In-situ treatment at a small-scale facility is possible at a site where sludge is generated.
(2) Since it can be treated at the sludge generation site, there is no need to carry it out in the sludge state.
(3) Conversion to dry matter by reducing the volume at the sludge generation site (easiness of handling and improvement of odor).
(4) Waste is reduced by sludge volume reduction (can be reduced to about 1/3 to 1/4).
(5) Room temperature drying is possible (the heating cost is unnecessary), and the odor in the facility is also improved.
(6) Treating the generated sludge continuously (daily) eliminates storage in sludge and is sanitary.
(7) The discharged dried product can be effectively used as a drying promoting material. The dried waste can be used for fuel, compost, etc.
(8) The equipment is simple and very inexpensive, and even small-scale facilities can reduce processing costs.
(9) It is an energy saving system and has an effect of reducing carbon dioxide.

  As described above, specific examples of the present invention have been described in detail, but these are merely examples, and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples illustrated above. The technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings can simultaneously achieve a plurality of objects, and has technical utility by achieving one of the objects.

Claims (6)

  A drying promoting material for sludge, comprising a coffee slag as a main component and having a water content of 25% or less.   The drying accelerating material according to claim 1, wherein the coffee slag is used alone or as a mixture of coffee scum and sludge, wherein the coffee slag contains a solid content ratio of 30% or more.   The mixed dried product obtained by mixing and drying a high water content sludge at a weight ratio of 1/3 or less with respect to the drying promoting material can be reused at least 15 times or more as a new drying promoting material. Or the drying accelerating material according to 2. A first step of mixing and stirring the highly water-containing sludge at a weight ratio of 1/3 or less to the drying accelerating material according to any one of claims 1 to 3, to reduce the water content to 25% or less,
In the mixed dried product obtained in the first step, new sludge is mixed and stirred at a weight ratio of 1/3 or less, and a second step of reducing the water content to 25% or less,
After the second step, a part or all of the mixed dried product obtained in the previous step is further mixed with a new sludge at a weight ratio of 1/3 or less and stirred to reduce the water content to 25%. %, A method of drying sludge repeatedly.   After the second step, in order to prevent the solid content weight ratio of the coffee slag in the mixed dried product from falling below 30%, add a new coffee slag or switch to a new drying accelerating material, The sludge drying method according to claim 4.   After the second step, since the weight of the mixed and dried product in the dryer increases due to continuous introduction of sludge, a predetermined amount of the dried product is sometimes withdrawn from the dryer so that the stirring and drying efficiency does not decrease. 6. The method for drying sludge according to 5.

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