JPS59230692A - Treatment of dum muddy water and bank waste water - Google Patents

Abstract

PURPOSE:To conserve a neutralizing agent and to enhance treatment efficiency, by a method wherein dum muddy water is mixed with bank waste water having high alkalinity to neutralize the latter while a flocculant is added to the supernatant liquid formed after coarse particulate mud in the liquid mixture is separated by precipitation to separate the same into sludge and treated water. CONSTITUTION:Dum muddy water and bank waste water are simultaneously flowed into a water storage tank 20 and the high alkali component in the bank waste water is subjected to ion exchange and neutralizing reaction due to various minerals in the dum muddy water not only to neutralize the bank waste water but also to perform precipitative separation of coarse particulate soil in the water mixture. The supernatant liquid overflowed from the water storage tank 20 is sent to a cyclone 21 in a predetermined amount by a pump to separate particulate soil therein. PAC and an org. anionic high molecular agent are added to the water mixture flowed into a reaction tank 23 as flocculant while the water mixture having flocs formed therein is sent into an inclined plate precipitation tank 24 and separated into sludge and treated water. The greater part of the supernatant liquid in the precipitation tank 24 is refluxed to an aggregate producing plant to be reutilized.

Description

[Detailed Description of the Invention] This LyJ is capable of simultaneously and efficiently treating dam turbid water discharged from an aggregate production plant for dam construction and embankment body wastewater discharged from a concrete placement facility for dam construction. This study concerns methods for treating dam turbid water and dam body wastewater.

As is well known, a dam construction site has a plant for producing aggregates for dam construction, such as sand and gravel, and a concrete casting facility for forming the dam body. Turbid water containing clay, silicates, etc., with g: turbid suspended solids (8S) of 10.000 to 50.000 pI) m1 water cumulative ion concentration (1) H value) of 6.5 to 8.0 is discharged. The water from the latter concrete casting facility consists of washing wastewater from this facility, which has a highly alkaline pH value of 10 to 11, and contains suspended solids (SS) of 1000 to 2000 pp.
Since about 1.5 m of wastewater is discharged from the levee body, this wastewater must be treated.

Conventionally, the treatment of such wastewater is as described below.
This is done separately for dam turbid water and embankment body wastewater.

The former treatment of dam turbid water is carried out according to the process shown in Figure 1. First, the turbid water from the dam is sent to the reservoir 1 and Suikron, and the coarse grained soil therein is removed by natural settling, and the removed coarse grained soil is classified and separated by the classifier 3. The separated liquid is sent to reaction tank 4,
In this reaction tank 4, polyaluminum chloride (hereinafter abbreviated as PAC) and an anionic @island molecular agent are added as a flocculant and sent to a precipitation tank 5. The turbid water in the settling tank 5 is solid-liquid separated into flocculated sediment and supernatant water by the flocculant. Most of the treated water separated here is recycled to the aggregate manufacturing plant, and the rest is discharged.

On the other hand, the separated sludge is sent to the sludge storage tank 6 (sludge storage tank 6), and the sludge in the filter frame covered with filter cloth is pressurized (5).
~15 kg/crlt) l, is dehydrated by the filter press dehydrator 7 which feeds and filters the dehydrated cake into a dehydrated cake, and this dehydrated cake is carried out and disposed of together with the coarse sand produced by the above-mentioned classifier 3.

On the other hand, the latter treatment of embankment body wastewater is carried out according to the steps shown in FIG. First, the embankment body wastewater is sent to the settling pond 1, where the earth and sand in the wastewater is settled and removed. The wastewater (supernatant liquid) from which sediment has been removed is
It is sent to the neutralization flocculation tank 11, where PAC and anionic organic polymer agent are added as a flocculant, and carbon dioxide gas (COt) is added as a neutralizing agent.

In this way, a neutralizing agent and a coagulant are added to the wastewater, which is neutralized and forms aggregates.
2, where it is separated into solid and liquid into sludge and treated water.

The sludge is transferred to a sludge storage tank 13 and then turned into a dewatered cake by a filter press dehydrator 14. The treated water, on the other hand, is discharged into public waters.

By the way, the following drawbacks have been pointed out in the above-mentioned conventional methods for treating dam turbid water and embankment body wastewater, and a solution thereof is desired.

(b) Embankment body wastewater differs from dam turbid water in that its pH value is 10.
Because it is highly alkaline (~11), a neutralization process must be installed, and although the same equipment as the dam turbid water treatment process, such as settling tanks, sludge storage tanks, and dehydrators, is used, a separate treatment facility is required. Therefore, treatment facilities have to be built on a large scale, and the installation space and equipment costs are costly.

(b) Neutralization of wastewater in the embankment body wastewater is performed using carbon dioxide gas, which increases the cost of equipment for neutralization. In addition, even if excess carbon dioxide gas enters, there is no major change in the pH value of the treated water and it does not deviate from water quality standards. The drawback is that drug costs tend to be higher than planned.

(c) Filter press dewatering machines used in dam turbid water and embankment body wastewater treatment facilities stretch a filter cloth over a filter frame that forms a chamber, and send sludge into this chamber using a pressurized pump to surface the filter cloth. This is a type that presses and filtrates the entire filter. Therefore,
When the chamber is full of sludge, the filter frame must be dismantled and the dewatered cake in the chamber must be discharged.For subsequent use, the disassembled filter frame must be reassembled and the sludge removed using a pressure pump. It is necessary to filter the sludge. Therefore, in order to continue the treatment of turbid wastewater for a long time,
During the process, the room must be dismantled and cleaned many times, which reduces processing efficiency.In addition, with this filter press dehydrator, the moisture content of the dehydrated cake cannot be adjusted; and further 74μm
If the amount of sludge with the particle size below increases, the dewatering capacity will decrease, and in order to obtain a dehydrated cake with a predetermined moisture content, the pressing time must be increased, which also has the disadvantage of reducing the processing capacity per unit time. be.

In order to solve the drawbacks of these conventional methods for treating dam turbid water and embankment body wastewater, the present inventor conducted intensive research and came to the following findings.

(a) As is well known, dam turbid water is rich in clay with high adsorption capacity, the montmorillonite group that makes up the clay with high ion exchange capacity, and silicates that easily react with porcelain alkalis ( Therefore, by mixing the full dam water with the highly alkaline embankment wastewater,
It was assumed that the dam body wastewater could be neutralized, and when mixed in the middle and examined, it was found that the pH could be neutralized to 7 to 8.

It is necessary to adjust the mixing ratio so that the pH of the levee body wastewater is 11, while the amount of turbid water is such that the weight of sediment contained in it is 1,250 kg or more, and the pH of the mixed wastewater at that time is
It was found that H is represented by the following formula.

pH of mixed wastewater = Myo (Ra-1-6) However, The sludge dewatering machine is called a super press dewatering machine, and it has two functions: dewatering by capillary action that occurs on the filter cloth surface that comes in contact with sludge, and roll compression dewatering, and continuously dewaters sludge. A sludge-type dehydrator has been developed that can process sludge, and it has been found that the efficiency of the sludge dewatering process can be greatly increased by using this super press dehydrator.

This invention has been made based on the above findings.

That is, the floor of the present invention allows the dam turbid water discharged from the dam construction site and the dam body wastewater to flow into the water storage tank at the same time. In addition to neutralizing the embankment wastewater with various minerals to save on neutralizing agents, it also consolidated all treatment facilities into one facility to reduce equipment costs.In addition, a capillary-roll press type (super press) dehydrator was used to remove sludge. This method enables continuous operation and improves processing efficiency.

Hereinafter, this invention will be explained in detail with reference to the drawings.

First, dam turbid water and solid wastewater flow into the water storage tank 20 at the same time, and the high alkaline content of the dam body wastewater is neutralized through ion exchange, neutralization reaction, and adsorption by various minerals in the dam turbid water, and the mixed water is Separate coarse grained soil (2)
liquid temperature neutralization sedimentation step (hereinafter abbreviated as neutralization step). In this neutralization step, the mixed solution is brought to a state of I)) 16-8. In addition, the amount of inflow of dam turbid water and solid wastewater into the storage water [20] at this time is, as mentioned above, the amount of dam body wastewater! On the other hand, the amount of turbid water from the dam is 1.
It is important to adjust the voltage to 250v9 or higher.

A predetermined amount of the supernatant liquid overflowing from the water storage tank 20 is sent to the gold cyclone 21 by a pump, and further
Separate the above granular soil. The underflow water of the cyclone 21 is sent to a rotary classifier 22f to separate coarse sand, and the overflow water and the overflow water from the cyclone 21 are led to a reaction 4M23.

The mixed water flowing into the reaction tank 23 contains P as a flocculant.
A C and anionic 4'Nfjr molecular agent are added. The mixed water in which aggregates have been formed is transferred to the inclined plate sedimentation tank 2.
4 and is separated into sludge and treated water (solid-liquid separation process). The inclined plate sedimentation tank 24 has a single sedimentation structure in which a number of inclined plates are installed in the tank to promote the formation and sedimentation of aggregates, thus saving the amount of flocculant added in the reaction tank 23. This makes it possible to downsize the device and obtain stable treated water.

Most of the overflow water (treated water) from the upper DD sedimentation tank 24 is returned to the aggregate manufacturing plant for reuse, and the rest is discharged into public waters. On the other hand, the sludge settled at the bottom of the settling tank 24 is
A predetermined amount is transferred to the sludge storage tank 25 using a pump. The sludge temporarily stored in this sludge storage tank 25 is continuously sent to a super press dehydrator 26 to be dehydrated. The dehydrated cake produced here is carried out by a belt conveyor, and is carried out and disposed of by a truck or the like together with the coarse sand produced by the rotary classifier 22. The super press dehydrator 26 is
-As mentioned above, it is a type that can continuously dewater sludge by performing both functions: dewatering through capillary action that occurs on the filter cloth surface that comes in contact with sludge, and dewatering through roll compression. , sludge dewatering efficiency is extremely high.

Therefore, in the method of this invention, by providing a two-liquid temperature neutralization step, there is no or almost no need for a neutralizing agent, and the facility can be significantly reduced in scale.
Equipment costs can be reduced and treatment efficiency can be improved by employing the inclined plate sedimentation tank 242 and the super press type dehydrator 26.

In the above embodiment, the coarse-grained soil contained in the mixed water was sedimented and separated using the water storage tank 20 and the cyclone 21, but the present invention is not limited to this. (As shown in the figure, dam turbid water and embankment body wastewater flow into the settling basin 30f at the same time, neutralization is carried out in this settling basin 30, coarse particles t in the mixed water are sedimented and separated, and the supernatant liquid is reacted. It may be configured so that the tank 23 is fed.

As explained above, the present invention allows dam turbid water and embankment body wastewater discharged from a dam construction site to flow simultaneously into a storage tank to remove various minerals rich in neutralizing properties contained in the dam turbid water. This neutralizes highly alkaline embankment wastewater,
In addition, since the treatment method continuously dewaters the sludge produced in the solid-liquid separation process using a capillary-roll press type dehydrator, it is possible to save on neutralizing agents and reduce equipment costs by consolidating the entire treatment facility into one. It is possible to reduce the number of man-hours and increase processing efficiency.

In order to confirm the advantages of the treatment method of the present invention,
According to the process of the above example (Figure 3), $8 is reduced to 5000
Dam turbid water with a concentration of 0 ppm and levee body wastewater with pi (11) were treated in a total treated water f of 450 m'' at 7 o'clock, while the same dam turbid water and levee body wastewater were treated under the same conditions using the conventional method as a comparative example. The results are shown in the table below (Table C). As shown in the table above, in the present invention, the use of a neutralizing agent It was found that the total number of chemicals used, including chemicals, could be reduced to approximately 115 compared to the conventional method, and the quality of treated water was significantly more stable than that of the conventional method.

In addition, the facility cost required for the above actual operation is only 70 to 75 cm using the conventional method, and compared to the conventional method, the construction area of the facility according to the present method is 30%, and the equipment and machinery cost is 2,511 cm.
I got away with 6 less.

[Brief explanation of the drawing]

Figures 1 and 2 show flowcharts of conventional methods for treating dam turbid water and dam body wastewater. Flowchart 1 and FIG. 3 are flowcharts showing one embodiment of the present invention, and FIG. 4 is a flowchart showing another embodiment of the invention with some parts omitted. 20...water tank, 23...reaction borrowing, 2
6...Capillary-roll press type (super press) dewatering a, 30...Sand settling tank〇

Claims (1)

[Scope of Claims] Highly alkaline embankment body wastewater and mineral-rich dam turbid water having neutralizing properties are simultaneously introduced into a water storage tank or a settling pond, and the embankment body wastewater is neutralized by the dam turbid water,
A two-part heating, neutralization and sedimentation process in which coarse grained soil contained in the dam body wastewater and dam turbid water is sedimented and separated; and a supernatant liquid separated in this two-part warming, neutralization and sedimentation process or further subjected to sedimentation separation. A solid-liquid separation step in which a flocculant is added to the separated supernatant liquid to separate it into sludge and treated water, and a continuous sludge dewatering step in which the sludge is continuously dehydrated using a capillary-roll press type dehydrator. A treatment method for dam turbid water and embankment body wastewater.