JP2969499B2 - Method for producing seedling culture soil using dewatered sludge as raw material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for reusing purified water sludge generated in a water purification plant in the process of producing tap water.
More specifically, the present invention relates to a method for producing a seedling culture using dewatered sludge obtained by dewatering the above-mentioned sludge as a raw material.

[0002]

2. Description of the Related Art Generally, in the agricultural field such as greenhouse horticulture, as sand for cultivation of plug seedlings in recent years, mountain sand or akadama soil widely existing in the Kanto region is dried and adjusted to a particle size of about 1 to 5 mm. Further, the acidity (pH) is adjusted to make the soil suitable for growing plants, or pearlite obtained by firing natural stones such as obsidian and perlite, or bamicarite obtained by firing mica minerals. Mix cultivated soil with various fertilizers,
The mixture is granulated and used as seedling cultivation soil.

[0003] Natural soils and rocks used as materials for these seedling cultivation soils are limited even though they are present in large quantities, are also localized, are uneven in quality, and have high processing costs. . In particular, natural mountain sand has been gradually depleted, and as a result, the price of product soil has also tended to soar.

On the other hand, most of the sludge settled in the sedimentation basin in the water purification plant has been landfilled after being subjected to dehydration treatment. In addition, sludge (sludge) accumulated in rivers and lakes is collected by mechanical means such as suction by a pump or excavation by a shovel, and is mixed with cement or a coagulant to be solidified and then landfilled. It had been.
As another disposal method of sludge, there has been a method of mixing fertilizer into dewatered sludge and using it as field soil.

[0005]

In recent years, the amount of sludge generated in water treatment plants has tended to increase (30 years per year on a dry basis).
(More than 10,000 tons), more than 70% of which is landfilled as industrial waste, but it is becoming increasingly difficult to secure landfills every year. Also, when fertilizer is mixed with dehydrated sludge and used as field soil, if the sludge contains harmful substances such as soluble aluminum and arsenic, it may become a source of pollution. Has limitations,
In fact, only a very small amount was used.

The present invention has been made in view of the above-mentioned circumstances, and has a high product value by using dewatered sludge obtained by dewatering sludge generated in a water purification plant or sludge deposited in rivers, lakes and marshes as a raw material. It is an object of the present invention to provide a method for producing cultivated soil and to effectively reuse sludge.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been devised in order to achieve the above object, and detoxifies a sludge cake containing harmful components by detoxifying and firing it at a temperature of 600 to 1100 ° C. The obtained fired product is crushed, and if necessary, other cultivation materials are added to the crushed material, and the baked material or a mixture of the calcination material and the other cultivation materials is subjected to humidity conditioning and granulated. This is a method for producing seedling cultivation soil using dewatered sludge as a raw material.

In the production method according to the present invention, purified water sludge generated in the process of producing tap water is used as a raw material.

[0009] The purified water sludge consists of turbid substances of river water and lake water generated in the process of producing tap water. This is a component obtained by adding aluminum or the like by adding a coagulant to a natural sand particle in terms of a component, and is mainly composed of an inorganic component and constitutes a relatively homogeneous clay. Purified water sludge may contain about 10 to 20% by weight of organic matter depending on tap water.

[0010] The dewatered sludge cake is obtained by dewatering the purified water sludge. Dehydration methods include gravity dehydration, pressure dehydration,
Methods include mechanical dehydration such as vacuum dehydration and solar drying.

In the firing step, the dehydrated sludge cake is fired at a high temperature, thereby rendering harmful components harmless and making it a raw material for a homogeneous and inorganic seedling culture. The harmful components are aluminum mainly derived from the coagulant, heavy metals that are naturally contained in raw water, and the like. In addition, components generally referred to as nutrients for plants, such as phosphorus and nitrogen introduced from agricultural water and domestic wastewater flowing into rivers and lakes, may also be harmful components for target plants. By baking the purified water sludge at a high temperature, these harmful components can be stabilized and / or evaporated and incinerated to reduce the amount thereof, and the burned material can be used as a raw material for growing seedlings harmless to plants. A preferred firing temperature is 60
0 ° C to 1100 ° C, more preferably 800 ° C to 1000 ° C
It is in the range of ° C. If the firing temperature is out of the range of 600 ° C to 1100 ° C, reduction of harmful substances such as soluble aluminum required for seedling culture cannot be sufficiently achieved. The obtained fired product is then pulverized. The pulverization of the fired product is preferably performed so that the average particle diameter is about 1 to 2 mm or less.

The seedling cultivation soil is required to have characteristics such as water permeability, water retention, air permeability, and fertilization. In addition, an optimum fertilizer for plant cultivation is required depending on a target plant. In order to include the characteristics and nutrients required for these plant cultivations, other cultivation materials are added to the crushed and fired sludge as necessary. Other soil material, vermiculite, or artificial soil, such as path Raito, peat moss, also calcium and potassium, nitrogen and various fertilizer and feed elements are exemplified.

The baked product or a mixture of the baked product and another cultivation material is subjected to humidity control and granulated.
Adjust H).

[0014] In this way, a non-polluting seedling cultivation soil excellent in water permeability, water retention, air permeability, fertilizer retention and the like and reduced in harmful substances such as soluble aluminum can be obtained.

[0015]

An embodiment of the present invention will be described below.

Embodiment 1 In this embodiment, a filter cake (dewatered sludge) obtained by dewatering sludge settled in a sedimentation basin to a water content of about 65% by a dehydrator installed in a water purification plant is used as a raw material.
The filter cake does not contain any additives such as a binder. Each step until a product is obtained is as shown in FIG. 1, and includes a dehydration step, a drying / firing step,
It consists of a pulverizing step, a mixing / humidifying step and a granulating step.

First, in the dewatering step, the purified water sludge is dewatered by vacuum dewatering to obtain a dewatered sludge cake. Then
The cake is dried and the dried product is fired at a temperature of about 1000 ° C. The obtained fired product is pulverized to an average particle size of 2 mm or less. Other soil material in the pulverized product is added vermiculite, or artificial soil, such as path Raito, peat moss, also calcium and potassium, nitrogen and various fertilizer and feed elements. The mixture thus obtained is humidified and granulated to obtain a seedling culture .

[0018]

According to the method for producing seedling culture soil of the present invention,
Contains harmful components such as soluble aluminum and arsenic
Detoxify sludge cake at a temperature of 600-1100 ° C
By baking, the above harmful substances are stabilized and / or
Or evaporate and incinerate to reduce the weight, and the burned material is transferred to plants.
Therefore, it can be used as a raw material for harmless seedling cultivation.

In the present invention, the fired product is pulverized, and if necessary, other cultivation material is added to the crushed material, and the calcination material or a mixture of the calcination material and the other cultivation material is humidified to form a mixture. The following effects can also be obtained by graining.

1) Quantitatively stable raw materials can be secured.
In addition, since water purification plants are distributed in various places, seedling cultivation soil can be produced in each place, and transportation costs of cultivation soil can be kept low.

2) Since the obtained soil is relatively stable in quality, the processing cost can be reduced.

3) The obtained soil is trace elements, for example, F
Since it contains e, Mn, etc., it acts effectively on plants.

4) Since the obtained soil is fired at a high temperature, it is harmless and odorless and is porous and water-permeable and air-permeable.
Due to its high water retention, it is the best soil for growing and growing plants.

5) The obtained cultivation soil can be mixed with other cultivation materials to obtain a seedling cultivation optimum for the target plant.

[Brief description of the drawings]

FIG. 1 is a process chart showing an embodiment of the present invention.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-64-34214 (JP, A) JP-A-64-34215 (JP, A) JP-A-4-108315 (JP, A) (58) Investigation Field (Int.Cl. ⁶ , DB name) A01G 1/00 303

Claims (1)

(57) [Claims] 1. A dewatered sludge cake containing harmful components is detoxified and fired at a temperature of 600 to 1100 ° C., and the obtained fired material is pulverized. If necessary, other cultivation material is added to the pulverized material. A method for producing a seedling culture using dehydrated sludge as a raw material, wherein the calcined product or a mixture of the calcined product and another culture material is subjected to moisture conditioning and granulation.