JP5249504B2 - Method for producing porous material - Google Patents

Description

  The present invention is a raw sludge generated in a large amount in a sewage treatment plant, a wastewater treatment plant, a rural settlement wastewater treatment facility, etc. Alternatively, the present invention relates to a novel treatment method capable of treating these digested sludges safely, simply and at low cost, and a porous material obtained by the method.

  At present, most of sewage, manure, etc. are treated by the bioactive sludge method, and as a result, a large amount of raw sludge is generated. In the old days, raw sludge was simply deposited and reclaimed, dehydrated on a dry floor, or applied to farmland to help fertilize and improve soil. Although it is still an effective method for small-scale facilities, a large amount of raw sludge cannot be handled by such small-end technology. In particular, raw sludge contains many pathogenic bacteria, and strict care is required for its handling.

  Accordingly, concentration of raw sludge, chemical treatment, mechanical dehydration, drying, incineration, and the like are performed, and anaerobic digestion treatment is most suitable for various hygiene, work, and economic requirements. Digestion treatment is often used in combination with each of the above treatments, and is excellent in that it reduces the malodor of sludge and pathogenic bacteria, improves fertilizer value, and provides compost materials.

  However, a disadvantage of the anaerobic digestion treatment of sludge is that the equipment becomes very large and is expensive enough to account for 30 to 40% of the construction cost of a sewage treatment plant or the like. Anaerobic digestion takes about two months, and the tank capacity increases accordingly.

  Similarly, the treatment of many sludges in addition to sewage and sewage treatment sludge, such as bottom sediment mud dredged from lakes and dams, and shochu sludge whose production continues to increase, is also available. Is under pressure. In the former, there is a technology to reduce the sludge by introducing a purification material (Patent Document 1) and a technology to add a fixing agent to drowned sludge to increase the viscosity and return it to the lake bottom (Patent Document 2). Most of the soil is piled up on the site and air-dried and disposed of in landfills. However, there is a problem in that the contained plant material rots and gives off a bad odor, and the dry fine powder is blown by the wind.

The latter is difficult to concentrate except for special concentrators that are very fine and expensive, especially in the case of shochu shochu, where production is increasing. In the past, abandonment of the shochu process was common, but now it is forbidden. Each manufacturer concentrates it at high cost (Patent Document 3) or adsorbs it to dextrin (Patent Document 4). However, there is a demand for a method for treating shochu in large quantities and at low cost.
JP 2006-021157 A JP-A-9-085296 JP 2006-204107 A JP-A-2005-213157

The present invention provides a technique for treating sludges, which have conventionally had various problems, with an inexpensive, safe and simple method.

  That is, the present invention relates to sludge such as raw sludge, digested sludge, bottom sediment sludge, shochu sludge, etc. generated in sewage treatment plants, etc. At the same time, the mixture is stirred and mixed by a mixing device to reduce the water content and granulate, and then dried and fired.

  Mineral powders such as waiting stones used in the present invention are themselves wastes and surplus substances. And the water content of sludges is reduced using water absorption, such as visiting stone powder, and it granulates by mixing simultaneously. The granulated product is dried using natural heat or waste heat generated during firing. During drying (during storage), fermentation heat is also generated by fermentation of sludge-containing organic matter, and drying is accelerated.

  Further, when the granulated product is baked, the organic matter contained in the sludge is burned to form voids, and the obtained baked product becomes porous. A more porous material in which sawdust or rice husk is added as a porous forming material can be obtained. In the case of sawdust, it also acts as a water absorbing agent for sludge. Furthermore, if sawdust or rice husk is added, the firing temperature is lowered. This is particularly preferable in the case of a waste tile pulverized product having a high firing temperature because the cost can be reduced. In addition, inorganic auxiliary materials such as zeolite and crushed shell products also work as water-absorbing agents, and also act as phosphorus-absorbing materials when fired products are used as soil and water treatment agents.

  The most preferred mineral powder in the present invention is a visitor stone powder. This is particularly due to its large water absorption and moldability. Kurusuishi (Kurumachi rust stones) refers to the tuff sandstone that forms the lower layer of the Neogene Miocene Izumo Group in the southern coast of Lake Shinji in Shimane Prefecture, The high-quality ones are concentrated in the place where the rocky facies is particularly good among the massive tuff coarse sandstones, and they exist in the range of about 10km east-west from Yatsuka-gun Tamayu-cho to Shinji-cho and width 1-2km. This stone is soft and easy to mine and process, and Izumo stone lantern is designated as a traditional craft.

  This coming rust stone is composed of a wide variety of rock fragments and crystal fragments, and a matrix (matrix) that fills the space between them. The size of the rock fragments is often 0.5 mm to 1.0 mm in diameter, and is about 1.5 mm at the maximum. The proportion of rock and crystal fragments is as high as 80%. As rock fragments, andesite, quartz andesite, rhyolite, flowering rock, and various types of tuff have been confirmed. As crystal fragments, plagioclase, pyroxene, amphibole, biotite, opaque minerals, volcanic glass, and altered minerals have been confirmed. In addition, as a substrate (matrix), zeolite, chlorite, and carbonate mineral formed by alteration have been confirmed.

Many of these minerals are called clay minerals, and this is the reason why crushed rust stones can be formed. In addition, because it contains zeolite (zeolite), it is excellent in ammonia adsorption and moisture uptake and discharge. In addition to visiting rust stones, there is what is known as visiting shiroishi. This is chronologically old and has a lot of rhyolite-type montmorillonite, which cannot be used in the present invention. In addition, as shown in Table 1 (analog “Shimane Geology” published by Shimane Prefecture), a lot of iron is included in the incoming rust stone (6.13% as Fe ₂ O ₃ ). Therefore, the porcelain clay of the present invention is colored red, brown to black color when fired. However, in the case of the present invention, since it is used as a filter material or a greening material, the color of the fired product does not matter. In the table, the numerical value indicates weight percent. Further, as is apparent from Table 1, the incoming rust stone contains about 7% loss on burning (Ig. Loss). This is an ancient plant residue, which disappears during firing and creates micropores.

  By the way, stone materials are mined and then processed into various products, but a large amount of scrap materials and grinding / polishing waste are generated at the stage of mining and processing. In the past, these scraps have been disposed of in landfills where they have been disposed of, but stone processing companies in various regions are suffering from the decline in landfills and rising processing costs.

  This is also the case with Kuroshiki stone, a kind of tuffy sandstone. The powder was previously used for glaze of stone stone roof tiles, but its use is now decreasing. For this reason, many vendors deal with the processing waste by processing the processing waste and storing it on their premises, but this is not a drastic measure, and the processing of the processing waste is large. It is a problem.

  Furthermore, in the case of visiting stones, brittle parts (calcite) rich in calcium carbonate may be included due to insufficient metamorphosis, but such parts are not suitable for processing, so they remain as stone materials even if they are mined. There is also a significant proportion of bad stones that are discarded.

  Accordingly, the present inventors have developed a technique for pulverizing processed stones of visiting stones and using them for clay and the like. However, in the case of clay, the amount of consumption is small and it is insufficient for the treatment of waste. By using in the present invention, processing of a large amount of processing waste is promoted.

  However, although the processed waste of visiting stones contains powder, there are many pieces of crushed waste, which requires labor and cost to grind. Therefore, the present invention paid attention to andesite and andesitic tuff. Andesite and andesitic tuff are used in large quantities as crushed stone, and a large amount of crushed stone powder is generated along with it. This crushed stone powder is also an industrial waste, and its treatment is a big problem in the industry. There are two types of crushed stone: dry and wet, and in the case of dry, very fine powder is obtained. And in this invention, it uses as a water absorbing material of sludge as it is.

  In the present invention, waste tile ground products can be used as well as the above-mentioned powders of waiting stones and andesite. Research on the use of waste tiles for several percent of the production volume and crushing them for use as soil substitutes has been promoted, but there are problems such as lack of effective use due to low water absorption. Therefore, when the present inventor used the crushed product of the waste tile, if the water content is low, there is a certain amount of water absorption, and when mixed with sludge, the inferior stone powder is somewhat inferior. However, it turned out to be fully available. However, Ishizu tiles produced in the Iwami district of Shimane Prefecture have a high firing temperature (1200 to 1230 ° C), so the temperature for sintering is similarly high (1200 to 1230 ° C) even when mixed with sludge. ) To increase the cost. Therefore, it was found that when organic sub-materials such as sawdust and rice husk were mixed, the sintering temperature was reduced to the same level (1000-1180 ° C.) as that of Kuroshiki powder.

  The particle size of each powder is about sand (2 mm or less) or silt (0.02 mm or less). The water content of the powder is about 2-3%. The mixing ratio of each powder and sludge differs between sludges with a moisture content of 50 to 95% (90 to 95%) and dehydrated sludges (50 to 80%). The ratio should be such that it can be granulated by mixing in a mixing device (similar to a concrete mixer). Usually, the use ratio (weight ratio) of powder and sludge is about 1 to 1.5-6.

  Next, the granulated product is temporarily stored, fermented or dried during storage, and then fired. The firing temperature is 1100 to 1180 ° C. However, in the case of waste tile pulverized products, those containing 5 to 10% by weight of organic sub-materials can be sintered even when fired at the same temperature (1100 to 1180 ° C.). It is necessary to bake at a temperature of 1200 ° C to 1230 ° C. In addition, the temperature said here means the maximum temperature. That is, the temperature is gradually raised from room temperature to 1140 ° C., and then the temperature is lowered. The firing temperature in this case is referred to as 1140 ° C. The temperature is raised gradually from room temperature over 8 hours, and the power is turned off when the temperature reaches 1140 ° C. Then, it is allowed to cool naturally over 10 hours, and when the temperature reaches 300 ° C., the kiln lid is opened. The above is the tooth vertebra of the batch type kiln, but the continuous firing in the tunnel kiln is also performed in this temperature range.

  The porous material obtained by the present invention pays attention to its excellent porosity and water absorption, and can be used in many fields such as filter media, purification materials, ground improvement materials, roadbed materials, agricultural soil substitutes, etc. Is.

  As described in detail above, the present invention can be applied to raw sludge such as raw sludge and digested sludge generated in sewage treatment plants, bottom sediment sludge, shochu sludge, etc., granite, andesite, andesitic tuff powder. Alternatively, together with the waste ground pulverized product, the mixture is stirred and mixed by a mixing device to reduce the water content and granulate, and then dried and fired.

Therefore,
(1) Conventionally, it is possible to treat sludges that are burned in the same process as the powder of waiting stones, andesite crushed stone, and waste tile pulverized products that have been discarded without use.
(2) Moreover, since it can be formed simply by stirring and mixing them with a mixing device, almost no processing energy is required until this stage. The most consuming energy is the subsequent baking, which can also reduce the baking temperature by mixing organic substances.
(3) A filter medium for biological filtration having an excellent effect on removing ammonia from water in an aquarium, a creek, a pond, and the like can be obtained.
(4) Permeability and water retention due to continuous porosity, water purification capacity, filtering material for sewage and drainage, horticultural and greening materials such as pot and planter soil and rooftop greening soil, underground infiltration It can be widely used for civil engineering materials such as roadbed materials under permeable pavement materials and sand pile substitutes used for ground improvement.
It is possible to commercialize waste with a little effort and cost, and it will be a savior for the visiting stone-related industry, the crushed stone industry, and the tile industry.

  The raw sludge discharged from the sewage treatment plant (water content 95%) 1 is mixed with granite stone powder (water content 2%) in a mixing device at a rate of 5 and stirred and mixed for granulation and drying. And firing at a temperature of 1100 to 1180 ° C. to obtain a porous material.

(Gourmet stone powder)
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a conventional biological treatment facility A for wastewater, and FIG. 2 is a schematic diagram showing an example of a conventional sludge treatment facility B for digesting excess sludge discharged from this wastewater treatment facility. 3 is a schematic view showing an example of an apparatus 1 for treating surplus sludge by the method of the present invention.

  The apparatus 1 of the invention accepts sludge and granite stone powder at a predetermined ratio, stocks the mixing apparatus 2 for agitation and granulation, and the obtained granulated product 3 and dries it with exhaust heat of firing or natural circulating air. In addition, in some cases, the stock chamber 4 for natural fermentation, the tunnel chamber 5 for firing the granulated product 3 quantitatively fed from the stock chamber 4, and the fired product 3 'discharged from the tunnel chamber 5 are cooled. A cooling chamber 6 for sieving is included. Reference numeral 7 denotes a porous material (product).

  First, 4 kg of raw sewage sludge (moisture content 95%) and 15 kg of granite powder were sufficiently stirred with a mixing device to obtain a granulated product. The granulated product was dried and then fired at a temperature of 1140 ° C. to obtain a porous material.

(Andesite powder)
In the same manner as in Example 1, sewage dewatered raw sludge (water content 70%) and dry crushed stone powder (0.2 mm under 95% or more) were granulated with a mixing device at a ratio of 2 per body. Next, a porous material was obtained in the same manner as in Example 1.

(Waste tile ground product)
The waste tile shredded product (dried state) was crushed with a Los Angeles abrasion machine. The particle size distribution of the obtained powder is about 25% for 0.2 mm or less, about 50% for 0.2-2 mm, and about 25% for 5 mm or less. The waste tile ground product (water content 2%) and raw sewage sludge (water content 95%) were mixed, stirred and fired at the same ratio as in Example 1 to obtain a porous material.

It is a schematic diagram which shows an example of the conventional biological treatment facility of wastewater. It is a schematic diagram which shows an example of the conventional digestion treatment facility of the excess sludge discharged | emitted from the wastewater treatment facility of FIG. It is a schematic diagram which shows an example of the processing apparatus of the excess sludge of this invention. Example 1

Explanation of symbols

A Conventional biological treatment facility B Conventional sludge treatment facility 1 Sludge treatment device 2 of the present invention 2 Mixing device 3 Granulated product 3 ′ Firing product 4 Stock chamber 5 Tunnel chamber 6 Cooling chamber 7 Porous material

Claims (3)

Raw sludge, digested sludge, bottom sludge or shochu sludge produced in a sewage treatment plant having a moisture content of 90 to 95%, dehydrated sludge having a moisture content of 50 to 80%, and a moisture content of 2 to 3% The powder of Japanese stone, oresite and andesitic tuff is added to the mixing device at a ratio of 1.5 to 6 by weight, mixed with stirring, granulated, dried and then heated to 1000 ° C to 1180 ° C. A method for producing a porous material, characterized in that the material is fired. Raw sludge, digested sludge, bottom sludge or shochu sludge produced in a sewage treatment plant having a moisture content of 90 to 95%, dehydrated sludge having a moisture content of 50 to 80%, and a moisture content of 2 to 3 % The waste tile pulverized product is put into a mixing device at a ratio of 1 to 1.5 to 6 by weight, stirred and mixed, granulated, and dried and fired at a temperature of 1200 ° C to 1230 ° C. A method for producing a porous material. It is granulated and dried using 5 to 10% sawdust and rice husk with respect to the total amount (the dry weight of sludge and the dry weight of waiting stones, etc.), and is fired at a temperature of 1000 to 1180 ° C. A method for producing a porous material according to claim 2.

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