JP2000202499A - Waste sludge fiber composite material and its utilization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change waste sludge after dehydrated to have a component or a form suitable for the object for recycling by efficiently dehydrating to recycle water treatment sludge or industrial water waste sludge. SOLUTION: This waste sludge composite material is obtained by adding vegetable fiber to the waste sludge and dehydrating even waste sludge containing clay, is easily broken after dehydrated and has no harmful component to be used as a supporting body for plant culture or nursery bed for mushroom growing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for recycling purified or industrial water sludge containing clay or silt generated in the process of producing tap water or industrial water, and relates to a method for reusing the plant fiber in the waste water. The present invention relates to a sludge fiber composite obtained by mixing and dehydrating a mixture, a support for plant culture and a bacterial bed for mushroom cultivation using the same as a raw material.

[0002]

2. Description of the Related Art Purified sludge and industrial water sludge suspended in water are treated as industrial waste by adding appropriate chemicals, coagulating, dewatering, and then disposed of. This disposal requires a great deal of expense, and many of them are landfilled, and the lack of land at disposal sites is a serious problem.

[0003] Purified water sludge and industrial water sludge are originally derived from soil such as forests, green lands, and fields, and can be returned to the natural environment again. Attempts have been made to reuse as a support for plant culture and the like. At that time, it is necessary to dehydrate and dry the purified water sludge and the industrial water sludge to an appropriate moisture content, but if a general pressure dehydrator, gravity dehydrator, vacuum dehydrator, etc. Wastewater containing mineral clay or silt becomes extremely difficult to dewater due to clogging and formation of filtration, and requires a special dewatering device. However,
When used as a support for plant cultivation, it is necessary to contain clay and silt in order to improve fertilizer holding power and water retention and to support growing plants. Therefore, there is a demand for easily dewatering even sludge that is difficult to dewater and contains clay or silt.
In consideration of the transport efficiency and preservability of the sludge, it is preferable that the water content is as small as possible.However, the sludge cake formed by dehydration becomes very hard as the water content decreases, and the plant culture support In order to use as a floor, secondary processing such as pulverization and granulation is required.

Japanese Patent Application Laid-Open No. 7-29999 discloses a method for producing a dehydration aid using dewatered wastewater as a raw material for efficiently dewatering wastewater. It requires equipment and energy and cannot be easily realized.

Japanese Patent Application Laid-Open No. Hei 9-216000 discloses a method of mixing waste paper with crushed waste paper and dewatering it. However, heavy metals derived from printing ink and foreign substances such as plastics are mixed in the waste paper. This is a hindrance when it is reused as a support for plant culture or a bacterial bed.

When various synthetic fibers such as inorganic fibers such as glass fibers, polyester fibers, and polyamide fibers are mixed with sludge instead of vegetable fibers, dewatering is possible, but the water retention of the cake is low and the cake is discharged from the cake. It is not suitable for reuse as a support for plant cultivation or as a bacterial bed, because mud easily flows out. Furthermore, since these fibers are hardly decomposed in the natural environment and must be treated as waste after use, the object of the present invention of recycling sludge waste cannot be achieved.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems. In order to reuse sludge, even if the sludge is difficult to dewater including clay and silt, the efficiency of the sludge is reduced. It goes without saying that the dewatered sludge must be in a component and form suitable for the purpose of reuse, not to mention well dewatering.

[0008]

As a result of investigations to solve the above problems, it has been found that vegetable fibers become dehydration assistants by adding vegetable fibers during dewatering and dewatering, thereby improving the dehydration efficiency. And the cake formed after dehydration was found to collapse easily. In addition, it has been found that when the clay and silt fractions in the sludge are above 20%, they are particularly effective on plant growth. When pulp fiber is used as plant fiber during dewatering of sludge, it does not contain any harmful components for plants and fungi. It has been found that it can be used effectively. Furthermore, they have found that vegetable fibers can be used even if they are derived from waste such as agricultural products. In this case, waste such as agricultural products can be treated and reused together with the sludge, and the plant culture support and the bacterial bed can be manufactured at lower cost.

[0009] In the present invention, the term "sludge" refers to the solids removed from the water mixed with solids such as soil and soil, suspended solids, etc. taken from rivers and lakes when producing drinking water and industrial water. And water, the moisture content of which is generally between 50 and 99.9% by weight.

[0010] The vegetable fiber in the present invention is a fibrous substance consisting of cell wall components of plant cells and is used as a raw material for papermaking such as pulp fiber purified from wood and herbaceous plants, and cell wall components such as rice straw and fruit pomace. Any material may be used as long as it is made of a fibrous substance. However, the pulp fiber in the present invention does not include waste paper. This is because not only chemicals, inks, and plastics added to paper in the papermaking process, various processing processes, printing processes, etc. may inhibit the growth of plants and fungi, but also pulp recycled and isolated from waste paper. Since the fiber length is thinner and shorter than the pulp fiber before being processed into paper, the dewatering efficiency when added to the sludge becomes worse than when the pulp fiber before processing is added. This is because a sufficient effect cannot be obtained.

The vegetable fiber used in the present invention preferably has a maximum diameter of 0.001 to 10 mm and a maximum length of 0.1 to 50 mm. It is used after being subjected to a pretreatment so as to have a suitable size by various wet or dry cutting, pulverizing, and grinding devices such as a homogenizer.

The vegetable wastes in the present invention are the above-mentioned vegetable fibers discharged as agricultural wastes and forest wastes, and are, for example, fruits cakes in the juice industry and sugarcane and sugar beets in the sugar industry. Dust and pulp meal in the pulp manufacturing industry.

[0013] The sludge fiber composite of the present invention is obtained by adding the above-mentioned vegetable fiber to the above-mentioned sludge and dewatering it. When producing this sludge fiber composite, vegetable fiber is added to a slurry of sludge in an amount of 1 to 300% by weight based on the solid matter of sludge, stirred, and then dewatered by a belt press, a filter press or the like. Using a device, a solid-liquid separation device such as a decanter, and a drying device such as a drum dryer, until an appropriate moisture content is obtained.
You only have to dehydrate. The addition of various coagulants and filter aids within a range that does not inhibit the growth of plants and bacteria for more efficient dehydration can be appropriately selected by those skilled in the art.

In the present invention, clay and silt are soil particle fractions specified by the International Soil Society, and clay has a diameter of 0.
Particles of 002 mm or less, silt have a diameter of 0.02 to 0.0
02 mm particles. In the present invention, it is preferable that the sludge contains at least 20% or more of the clay and the silt fraction.
When the composition of the soil particles constituting the sludge is measured by the pipette method specified by the International Soil Society, the total weight of clay and silt is more than 20% of the total weight of the soil particles. In this sludge, clay or silt causes clogging of the dehydrating device or forms fine filtration, which hinders the movement of water, so that dewatering is particularly difficult, and the plant fiber according to the present invention is added. This significantly improves the filtration efficiency. In addition, when the sludge fiber composite produced from this sludge is used as a support for plant culture or as a bacterial bed, the clay and silt fractions absorb fertilizer components and nutrients of fungi, etc. Water retention due to the formation of fine voids and the ability to support the plant even when the plant grows, has the effect of preparing an environment suitable for plant growth and bacterial propagation .

The support for plant culture in the present invention is for planting plants and seeds such as trees, flowers, vegetables, fruits, etc., and plays the same role as soil in a natural environment.
And it is an alternative. When actually cultivating plants, it is the same as soil as to appropriately mix, prepare and use various materials such as fertilizers and soil improving materials suitable for individual plants. It is also possible to cultivate plants using a mixture of the plant culture support and soil according to the present invention.

The mushroom cultivation bed in the present invention is a culture medium for growing filamentous fungi artificially prepared for cultivating mushrooms. The waste fiber composite of the present invention contains vegetable fiber, which becomes a nutrient source for growing filamentous fungi that form mushrooms, and mushrooms are generated. Therefore, a bacterial bed can be manufactured at low cost without using materials such as sawdust generally used as a bacterial bed. It goes without saying that, similarly to the case of plant cultivation, nutrients and water corresponding to individual mushrooms can be appropriately mixed and prepared and used when the sludge fiber composite is used as a bacterial bed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a composite of sludge and plant fiber which can be reused as a support for plant culture or a fungal bed for mushroom cultivation. The sludge used in the present invention is a mixture of water and solids separated from water such as rivers and lakes when producing purified water or industrial water, for example, industrial waste generated in water purification plants and paper mills. It is.

The plant fiber used in the present invention is a fibrous substance composed of cell wall components of plant cells. Examples of such a fiber include wood pulp fiber, rice straw, and cotton. Wood pulp fiber is composed of polysaccharide mainly composed of cellulose, at least 90% of its constituent components, and contains no components that inhibit the growth of plants and fungi. It is suitable.

The plant waste used in the present invention is the above-mentioned plant fiber discharged as agricultural waste or forest waste, such as apples and tangerines discharged from food processing plants. Examples include grape pomace, sugarcane and sugar beet pomace discharged from a sugar factory, and wood chip dust and pulp plum discharged from a pulp manufacturing factory.

In the present invention, for dewatering in producing the sludge fiber composite, for example, a device such as a belt press, a filter press, a decanter, and a drum dryer can be used. Before dehydration, for example, flocculants such as cationized starch and polyacrylamide,
It is possible to add a filter aid such as microcrystalline cellulose or fine fibrous cellulose within a range that does not adversely affect the growth of plants and fungi.

The clay and silt contained in the sludge used in the present invention are mainly composed of minerals such as kaolinite, halloysite, smectite, vermiculite, chlorite, imogolite, allophane, gibbsite, hematite, goethite, and opaline silica. Among them, for use as a plant culture support or a bacterial bed, it is preferable to use sludge containing smectite or vermiculite.

As the fertilizer which can be added when the sludge fiber composite of the present invention is used as a support for plant culture, for example, nitrogenous fertilizer, phosphate fertilizer, potassium fertilizer, chemical fertilizer,
Compound fertilizer, fertilizer-controlling fertilizer, molded compound fertilizer, paste fertilizer, liquid fertilizer, porous lightweight fertilizer, calcareous fertilizer, malay fertilizer, siliceous fertilizer, trace element fertilizer, fertilizer with pesticide,
Organic fertilizers and composting materials. As soil improvement materials, for example, peat, peat, bark compost, shell fossils, V
Animal and plant materials such as A mycorrhizal fungal material and mineral materials such as zeolite, perlite, diatomaceous earth fired granules, fly ash, and gypsum are exemplified.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below, but the present invention is not limited thereto. Further,% in each example is% by weight.

Example 1 The clay and silt contents of the sludge generated during the production of industrial water were measured by the pipette method specified by the International Society of Soil Science. At that time, the clay and the silt fraction are added to the original sludge, or a predetermined amount is removed from the original sludge, whereby the clay, the silt fraction has a 10, 20, 50, and 80% sludge. Was prepared. To these sludges, bleached hardwood kraft pulp fibers are added to the dry weight of each sludge at 0, 25, 50, 10
It mixed so that it might be set to 0%, and 5 L of water suspensions which make dry weight only of sludge 10% of the total weight were prepared. Each suspension was subjected to suction filtration using a Buchner funnel having an inner diameter of 24 cm covered with one type of filter paper of JIS standard. As a result, the filtration could be performed by adding the pulp fiber regardless of the ratio of the clay and the silt fraction. Also, the higher the proportion of pulp fiber added, the shorter the time required for filtration. On the other hand, when the filtration was performed without adding pulp fiber, the filtrate could not be obtained immediately after the start of filtration, and the filtration could not be performed, regardless of the ratio of the clay and the silt fraction.

Example 2 The clay and silt contents of the sludge generated during the production of industrial water were measured by the pipette method specified by the International Soil Society. At that time, the clay and the silt fraction are added to the original sludge, or a predetermined amount is removed from the original sludge, whereby the clay and the silt fraction have a 10, 20, 50, and 80% sludge. Was prepared. The bleached hardwood bleached kraft pulp fiber was mixed with these sludges so as to be 50% of the dry weight of the sludge to prepare 5 L of an aqueous suspension in which the dry weight of the sludge alone was 10% of the total weight. . Each suspension was placed in a Buchner funnel with an inner diameter of 24 cm.
Suction filtration was performed using a filter paper of IS standard. After filtering until no more filtrate came out, the waste fiber composite formed on the funnel was taken out and dried at 50 ° C. using a dry heat dryer until the water content became 10%. The dried sludge fiber composite was destroyed by hand, packed in a No. 2 flowerpot, and seedlings of Komatsuna cultivated for two weeks after germination were planted. The flower pot was placed outdoors in a sunny place, and water to which a liquid fertilizer was added was appropriately sprinkled and cultivated for 2 weeks. As a result, Komatsuna grew smoothly in any of the sludge fiber composites, and no abnormalities were observed. However, when the clay and silt fraction contained 10% of sludge, lodging due to wind and rain and water sprinkling occurred, and it was difficult to support plants.

Comparative Example 1 An experiment was conducted in the same manner as in Example 2 except that pulp fibers were not added. As a result, it was not possible to destroy the dried sludge with the clay and the silt fraction of 20% or more of the sludge after drying, and it was not possible to pack the sludge in a flower pot. When the clay and silt fraction contained 10% of the sludge, the komatsuna grew smoothly, but it fell down due to wind and rain and water sprinkling, making it difficult to support the plant. In addition, in any of the sludges, almost no dehydration can be performed at the time of filtration, and most of the water is removed by a dry heat dryer.
It took 20 times or more as long as the case where the pulp fiber was added in Example 2.

Example 3 The dewatered, dried and pulverized sludge fiber composite of Example 2 was placed in a 500 ml Erlenmeyer flask, water was added so that the water content became 50%, and a mushroom growth promoter (New Weidel) was added. , Manufactured by Kitaken Co., Ltd.) in an amount of 10% based on the dry weight of the waste fiber composite. After capping the flask with a silicon stopper, the flask was sterilized at 120 ° C. for 30 minutes using an autoclave. The sterilized sample was inoculated in an aseptic state with 10 ml of a seed fungus for cultivation of Shiitake mushroom (Kitaken 603, Seedling Registration No. 4343) and cultured at a temperature of 20 ° C. for one month. As a result, in each of the sludges, white hyphae were spread throughout the sample, and it was confirmed that growth was successful.

Comparative Example 2 In Example 2, instead of bleached hardwood bleached kraft pulp fiber, polyethylene terephthalate fiber (manufactured by Teijin Limited) having a diameter of 0.01 mm was used at 50% of the dry weight of the sludge.
The dried sludge is mixed, dehydrated and dried so that
Placed in a 00 ml Erlenmeyer flask. The bacteria were cultured according to Example 3 below. As a result, filtration of the sludge was possible as in the case of adding the pulp fiber, but growth of mycelia was hardly observed in any of the sludges.

[0029]

As described above, according to the present invention, by adding vegetable fiber to wastewater and dewatering it, even wastewater containing clay and silt fraction which is difficult to dewater can be easily dewatered. It is possible. In addition, the sludge fiber composite obtained after dehydration can be easily pulverized and contains no harmful components, so that the plant culture support or mushroom can be processed without special pulverization or granulation. It can be used as a bacterial bed for cultivation.

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Claims (6)

[Claims] 1. A sludge fiber composite obtained by adding vegetable fibers to sludge containing clay or silt fraction and dewatering the sludge. 2. The wastewater fiber composite according to claim 1, wherein the vegetable fiber is vegetable waste. 3. The sludge fiber composite according to claim 1, wherein the vegetable fiber is a pulp fiber. 4. The sludge fiber composite according to claim 1, wherein the sludge contains at least 20% or more of a clay and a silt fraction. 5. A plant culture support comprising the sludge fiber composite according to any one of claims 1 to 4. 6. A fungus bed for cultivating a mushroom, comprising the sludge fiber composite according to any one of claims 1 to 4.