JPH0141762B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paving method that makes it possible to form paved surfaces for various competition facilities, promenades, etc. using clean water sludge collected from a water purification plant.

Water treatment plants carry out wastewater treatment with the aim of converting clean water sludge (also called sludge), which is an impurity in river water separated by sedimentation basins and filtration basins, into a solid substance that can be transported.

The basics of wastewater treatment are three operations: concentration, dehydration, and drying.In short, the water sludge is reduced, valuables are recovered if any, and the final product is solidified and minimized.

Typical sludge treatment methods include:
There are methods that use polymer flocculants, such as the polymer addition pelletization concentration method and the PAC (polyaluminum chloride) treatment method.

To explain this, for example, in the polymer-added pelletization and concentration method, water glass (sodium silicate) and a polymer such as polyacrylamide are mixed with collected clean water sludge to form pellets, which are then dried in the sun or in a roll press. After crushing, the sludge is dried in a drying oven to dehydrate it to the extent that it can be transported, producing solid sludge (also called cake).

The solid sludge obtained in this way is very similar in appearance to paving soil materials such as Arakida soil, but it has a relatively coarse particle size and has an extremely large amount of moisture and burnt residue, so it does not shrink when drying. It has the disadvantage of being intense. If tap water sludge were to be used as a paving material, it would harden as it dries and cause countless cracks, making it completely unusable.

Due to these circumstances, the current situation is that there is no effective way to use water sludge other than to use it for reclamation of gravel extraction sites.

On the other hand, the demand for soil materials for paving, such as loam, silty clay, fine sand, and Arakida soil, which is a mixture of these, which form the soil paved surfaces of tennis courts and promenades, is increasing as competition facilities become more popular. It is becoming more difficult every year.

The present invention was devised under these circumstances, and it solves the shortage of soil materials by mixing clean water sludge with general paving soil materials as an extender, and improves water resistance, permeability, and durability. The purpose of this project is to provide a paved surface that has the following features.

For this reason, in the present invention, first, water sludge treated by adding a polymer coagulant, such as polymer-added pelletized thickening method sludge or PAC method treated sludge, is processed into water sludge that is approximately fine sand or smaller (preferably particle size of approximately 200μ or less). )
Grind into granules.

The moisture content of treated sludge is approximately 20-60%,
As it is too plastic, it is difficult to crush it, so it is further dried and hardened and then mechanically crushed.

However, when the water content is 30 to 60%, water sludge has the property of breaking down into fine particles when pressurized using tire rollers, etc., so water sludge should not be laid on the pavement foundation. The pressurizing operation may be repeated while maintaining the above-mentioned moisture content (sprinkling water if necessary) until the particle size described above is achieved.

Next, for example, loam,
Paving soil materials having at least silt or clay, consisting of silty clay, fine sand, etc., are mixed so that the volume ratio of the whole is 20 to 80%, and thoroughly mixed using a kneader or the like.
In addition, when the water sludge is pressurized and ground on the pavement foundation as described above, it is excavated by a tractor or the like, and then the paving soil material is mixed and stirred.

A mixture of clean water sludge and soil material to which a polymer flocculant has been added hardens when the water evaporates and forms a strong paved surface, but the hardness and strength of the paved surface are determined by the flocculant. The higher the content, the higher the content. Therefore, the mixing ratio of the paving soil materials is appropriately determined within the above range depending on the amount of flocculant contained in the water sludge and the physical properties required of the paved surface.

The plastic mixture of water sludge and paving soil material is prepared into a paved surface by leveling the ground and applying compaction before the water evaporates and hardens, or while adding appropriate water.

In the soil paved surface formed in this way, the sludge particles and particles such as loam and fine sand that make up the soil are coated with the additives in the treated sludge, and the soil particles are further ground by compaction. At the same time, the silt or clay of the paving soil material binds the sludge and soil particles adhesively to each other, making it difficult to dissolve in water after drying and hardening, and does not break even when subjected to impact such as movement. It exhibits extremely high durability as it hardly turns into dust.

In addition, water permeability is maintained because gaps remain between soil particles, just like in conventional soil pavement, and therefore, depending on the amount of rainfall, rainwater is quickly absorbed into the underground layer after it rains. As mentioned above, it has high water resistance (does not become muddy), so it can be used immediately, and since it does not retain moisture, it is less susceptible to freezing damage in the winter.

Furthermore, it looks just like earthen pavement and maintains the appropriate elasticity characteristic of earth, making it extremely comfortable to use.

As described above, according to the present invention, it is possible to easily obtain a paved surface that has favorable properties unique to earthen pavement, is excellent in durability and water resistance, and is therefore easy to maintain, and is difficult to collect. This has the effect that water sludge can be used effectively as an extender for general paving soil materials, which are becoming increasingly popular.

Claims (1)

[Claims] 1. After pulverizing clean water sludge that has been treated with either the polymer addition pelletization concentration method or the polychlorinated aluminum treatment method into particles smaller than fine sand,
Paving soil materials having silt and/or clay are mixed and stirred so that the total volume ratio is 20 to 80%, and this mixture is leveled and compacted on a paving foundation to form a paved surface. A paving method characterized by forming. 2 Water sludge is laid on the pavement foundation and
2. The paving method according to claim 1, wherein the paving method comprises pressurizing and grinding the soil in a state in which it contains 100% water, and then digging it up and mixing and stirring the paving soil material.