JP2634846B2 - Coagulation separation method of suspension in water - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for clarifying river water and industrial water, and a method for coagulating sedimentation and separation of an aqueous suspension in a process of treating various types of industrial wastewater.

[Conventional technology]

In general, the step of treating service water or wastewater involves a clarification operation of separating a suspended solid and a liquid in a liquid to be treated to obtain a transparent supernatant. Many of the suspended solids in service water and wastewater are extremely fine and hard to settle by natural sedimentation.
Conventionally, it is led to a sedimentation separation tank, a coagulation sedimentation tank, where an inorganic coagulant or an organic polymer coagulant is added and coagulated in the tank,
It has been practiced to extract a floc formed from the bottom of the tank, further subject it to a solid-liquid separation treatment, and then dispose it in a cake form.

[Problems to be solved by the invention]

However, the floc formed by the action of the flocculant usually has water contained therein, and is precipitated in a highly water-swelling state due to binding water between the flocs, water attached around the flocs, etc. Is unstable and difficult to process. Therefore, a dehydration operation is still performed for stabilization. The dehydration operation can be performed, for example, by heat concentration, by using a vibrating sieve or a liquid cyclone, by a centrifuge, or by filtration under a pressure of about 3 to 5 kg / cm ² or suction with a filter press, a belt press, or the like. However, there is a great economic disadvantage such as initial costs required for equipment costs and running costs such as time, labor, and thermal power.

In addition, the dewatered cake is re-mudged when it is wetted by rainwater, groundwater, or the like, and thus has a drawback that it is unsuitable for open-field loading and transport without a lid. Therefore, except for extremely exceptional cases such as composting and incineration, the above dehydrated cake must be further solidified with lime, cement, etc. , And it is necessary to carry out a treatment such as solidification, preferably sun drying, which causes a problem of further increasing labor and cost.

In the present invention, a floc formed by coagulation and sedimentation is easily separated from clarified water by solidification and sedimentation as it is, and a very solid and easy-to-handle cake-like coagulate is obtained at a very economical advantage with a simple process. It is done for the purpose of.

[Means for solving the problem]

In order to achieve the above object, the method for coagulating and separating a suspension in water according to the present invention comprises at least one of inorganic and organic flocculants in service water or wastewater containing the suspension, mainly comprising alumina cement and gypsum. By adding 5 to 20% of a cement / gypsum-based hydraulic inorganic solidifying material as a mixture weight of the coagulant and the solidifying material with respect to the weight of the suspended solids in the above-mentioned water or wastewater. at least 0.1 kg / cm ^2, preferably 0.1 to 0 solidifies while flocculated.
The solidified product has a uniaxial compressive strength of 3 kg / cm ² .

The method of the present invention can be applied to the turbidity of rivers, lakes and marshes, reservoirs, industrial water, and the like, and the treatment of various industrial wastewaters, domestic wastewaters, and the like.

In the method of the present invention, a flocculant to be added to the water or wastewater containing the suspension includes, for example, an inorganic acidic flocculant such as aluminum sulfate and aluminum chloride, an inorganic base such as sodium aluminate, polyaluminum chloride and low basic aluminum. Known coagulants, such as inorganic coagulants, inorganic amphoteric coagulants using aluminum sulfate and polyaluminum chloride in combination, and organic polymer coagulants such as polyacrylamide, sodium polyacrylate, aminoester polyacrylate, diaminediamide, sodium alginate, etc. A sedimentation agent is used, and one or more of these are used as appropriate depending on the water quality, the properties of the suspension, and the like. As the condensing agent, activated carbon, a chlorine oxidizing agent such as sodium hypochlorite, an ion exchange resin or the like may be used in combination, as long as the performance is not impaired.

The greatest feature of the method of the present invention is that, in a coagulation sedimentation zone such as a sedimentation tank, a hydraulic inorganic solidifying material is added together with the coagulant to simultaneously achieve coarsening and sedimentation and solidification of the generated floc. The point is that the cake-like solidified solidified to an appropriate solidification strength is deposited and deposited.

The hydraulic inorganic solidifying material mainly contains Portland cement and alumina cement, which are generally called hydraulic cement. Hydraulic lime, natural cement and the like are also applicable, but the former two, especially alumina cement, are most preferable. When this is used in combination with an appropriate amount of gypsum, excellent solidification performance is exhibited. The optimal formula is alumina cement 90-80
% Of gypsum and 10-20% by weight of gypsum.

In the solidified material, the coagulant and the solidified material are 1/1 by weight.
凝集 1/5, preferably 〜 to し て, and used in advance, or when the flocculant is a liquid, used separately or mixed immediately before addition.

The amount of the coagulant and the solidifying agent added to the water to be treated is 5 wt.
-20%, preferably about 10-15%. If it is less than 5% by weight, the coagulation sedimentation and solidification effects are poor, and a solidified product having satisfactory solidification strength cannot be obtained. If the content exceeds 20% by weight, the effect is not increased, and it is rather economically disadvantageous.

(Operation)

In the sedimentation separation tank or the coagulation sedimentation tank, the fine particle suspension becomes a floc due to the action of the coagulant and the solidifying material,
Further, they rapidly aggregate and become coarse particles, and precipitate and deposit on the tank bottom. When a curing time of several hours elapses in this state, the material is solidified to a handleable state with a uniaxial compressive strength (qu) of at least about 0.1 kg / cm ² . This is, for example, a lime alumina cement (3CaO.Al ₂ O ₃ ) component and a gypsum (CaSO ₄ .2H ₂ O)
Component and from about 0.85: Looking at the case where a solidified material obtained by mixing with a weight ratio of 0.15, the cake coagulum settled, ettringite _{phase, Ca 6 Al 2 (SO 4} ) 3 (OH) 2 · 26H
Form an inorganic hydrate matrix composed mainly of ₂ O,
Solidification occurs simultaneously with sedimentation in water.

The upper supernatant water is discharged or released by sure to allow time for reaching the transportable solidification strength, cake coagulum tank bottom, uniaxial compressive strength if in the range of between 0.1 and 0.3 kg / cm ^2, Sosokohai From the exit, drop onto a suitable transport means such as a conveyor or a transport vehicle,
Alternatively, it can be easily taken out by a backhoe or other dredging means.

In order to further reduce the apparent volume of the cake-like coagulated product taken out, if the coagulated solidification material is appropriately added thereto and dewatered by a dehydrator, the dewatered cake itself has a solidifying ability, and the solidification strength gradually increases with time. , And the obtained solidified product has a feature that it is difficult to re-mud even if it contains water.

[Examples] The method of the present invention will be described below with reference to examples. In the examples, "parts" and "percent" are all based on weight.

Example 1 Autoset was used as a mixture for coagulating and solidifying a suspension. Solidification
Agent [Osaka City, manufactured by Autoset Co., Ltd., cement / gypsum system
Product name of solidified material] 8 parts and Mukifrock^TMFlocculant
Product name of aluminum-based flocculant]
Was.

Mud water generated from the sewer pipe shield construction site was led to the coagulation tank. The solid content in the mud was 1500 kg / Hr.
When the mixture was added to the muddy water at 10% of the solid content, the suspended solids rapidly formed flocs, further aggregated into coarse particles, and settled. The supernatant water was discharged at a curing time of 6 to 8 hours, and the uniaxial compressive strength (qu) of the cake-like solidified product at the bottom of the tank was measured. As a result, the handleable strength reached 0.2 kg / cm ² .

Example 2 Automatic set 7 parts of solidifying agent and Kim Flock^TMCoagulant 3
Prepare a mixture with the part, generated from the river dredging construction site
It was added to the mud in a storage tank. The solids concentration in the muddy water is 6%
Yes, based on the weight of this solid content,
Was set to 15%. After the suspended solids coagulate and settle, the supernatant water is removed.
It was released, and the solidified cake was cured for about 8 hours.
Roller, solidification strength that can be transported, that is, uniaxial compression strength qu
= 0.15-0.25 kg / cm^TwoWas secured.

〔The invention's effect〕

Since the present invention has the configuration and operation as described above, the following effects can be obtained.

Add a solidifying material together with the flocculant to the liquid to be treated,
Since flocking, flocculation, sedimentation, and solidification of the suspension can be achieved in a single operation in a single operation, a series of complicated processing steps such as extraction, dehydration, solidification, and drying of high water content flocs are not required as in the past. Becomes Therefore, equipment costs and operation costs required for the conventional process are greatly reduced, and the process is rationalized.

The obtained cake-like solidified product can be easily separated from the clarified water, and is in a very stable state without re-mudging even when it comes into contact with water again, so that it can be transported without a lid in the rain. There are many advantages, such as being able to be stored in the open-air and in the open state.

Further, since the cake-like solidified material has an appropriate solidification strength, it can be easily handled mechanically and does not pose any particular problem in moving and transporting.

Claims (2)

(57) [Claims] 1. The water or wastewater containing suspension contains a mixture of mainly 90 to 80% by weight of alumina cement and 10 to 20% by weight of gypsum together with 1 part by weight of at least one of inorganic and organic flocculants. 2 to 4 parts by weight of the cement / gypsum-based hydraulic inorganic solidifying material consisting of 5 to 20% based on the weight of the suspended solids in the above-mentioned water or wastewater as the weight of the mixture of the coagulant and the solidifying material A method of coagulating and separating a suspension in water, comprising coagulating and sedimenting a suspension to form a coagulate having a uniaxial compressive strength of 0.1 to 0.3 kg / cm ² . 2. The method according to claim 1, wherein the weight of the mixture of the coagulant and the solidifying material is 10 to 15% based on the weight of the suspended solids.