KR20120040411A - Treatment method of the tunneling waste water - Google Patents

Abstract

The present invention relates to a method for treating tunnel drilling wastewater in which the suspended solids in the tunnel drilling waste water are flocculated by using a flocculant and separated and removed. Initiate and react with the polymer coagulant in the tubular agglomerator (2) to complete the coagulation reaction, precipitate the flocculated suspended solids in the sedimentation tank (3) to make a sludge, and remove the sludge to remove the suspended solids content in the tunnel wastewater The present invention relates to a method for treating tunnel excavation wastewater. The method of the present invention can shorten the treatment time of the tunneling wastewater and reduce the scale of the wastewater treatment plant, thereby contributing to the improvement of productivity.

Description

{Treatment method of the tunneling waste water}

The present invention relates to a method for treating wastewater generated during tunnel excavation. Specifically, the present invention relates to a method for separating and removing suspended solids in tunnel drilling wastewater.

In the construction of roads, a number of tunnels will be constructed. In tunnel excavation, a large amount of working water and chemicals are used, and a large amount of excavated wastewater is generated since fine soil such as dust is discharged together with groundwater. Although it varies depending on the size of tunnel excavation, tunnel excavation wastewater is generated on the scale of hundreds to thousands kl every day during the excavation period. Tunnel excavated wastewater contains a large amount of minerals such as stone powder, earth and sand, and contaminants that are mainly composed of strong alkaline substances in cement, which are introduced during concrete work. Pollution should be lowered and discharged to meet the standard. Korea's water pollutant emission standards are regulated according to the Water Environment Conservation Act (Law 4260), and the emission limit standards for pollutants emitted from wastewater discharge facilities are as follows.

end. Biochemical oxygen demand, chemical oxygen demand, suspended solids

I. Water pollutants such as panols

The concentration of suspended solids in tunnel wastewater varies depending on the region and working conditions, but it is generally in the range of 200 ~ 10000ppm and on average 1500 ~ 3000ppm (Ulsan-Pohang Expressway, Environmental Impact Assessment. Issued by the Korea Expressway Corporation). Tunnel wastewater must lower the acidity (PH) and suspended solids content of the wastewater in order to meet the emission limits. In order to lower the content of suspended solids, conventionally, the tunnel excavated wastewater extracted by the pump is sent to the reaction tank, the coagulant is introduced into the reaction tank, and the coagulation reaction is started. The suspended solids are precipitated to make sludge, and the sludge and water are separated by filtration and the sludge and wastewater separated from the sludge are discharged to the outside (FIG. 2).

In the conventional wastewater treatment method, three large structures such as a reaction tank, a condensation tank, and a sedimentation tank made of concrete structures must be provided, and thus, a large area of storage must be provided, and a lot of power costs are required for the stirring process in the agglomeration tank. The processing time also takes a long time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for treating tunneled wastewater, which can lower the content of suspended solids in tunneled wastewater within a short treatment time at a low cost while using a small-scale facility in a method for separating and removing suspended solids in tunneled wastewater. There is.

In the present invention, in the separation and removal of suspended solids in tunnel wastewater, the traditional method shown in FIG. The flotation material is formed into sludge in the settling tank and the method of separating and removing the sludge is improved so that the flocculation reaction is carried out using a pipe-shaped tubular reactor and a tubular flocculator instead of the conventional concrete reactor and the flocculation tank. The present invention relates to a method for treating tunnel wastewater by sending the completed wastewater to the sedimentation tank to make sludge of suspended solids into sludge and separating and removing the sludge.

The method of the present invention can accelerate the flocculation reaction of the suspended solids in the tunnel wastewater, thereby shortening the wastewater treatment time, eliminating the need for the installation of large-scale reactors and flocculation tanks, reducing the operating costs of the flocculation tanks and reducing the scale of the wastewater treatment facilities. Therefore, there is an effect that can contribute to productivity improvement.

1 is a process chart showing the treatment of wastewater according to the present invention.
2 is a process chart showing a treatment process of wastewater according to a comparative example.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

[ Example ]

The tunnel excavated wastewater with 185.5ppm COD and suspended solids (hereinafter referred to as ss) discharged by pumping from the work site with 700 tons of wastewater generated per day (29.2㎥ per hour) is provided with air inlet and coagulant inlet. It is introduced into a tubular reactor (1) made of polyvinyl chloride resin having a diameter of 120 mm and a length of 2 m.

Compressed air is injected through the air inlet 4 at a rate of 0.1 m 3 / min and polyaluminum chloride (coagulant) is injected through the coagulant inlet 5 so as to maintain a concentration of 100 ppm. Then, whirlpool (whirlpool) is formed in the wastewater conveyed by the bubbling effect by air bubbles by compressed air, and the flocculant (polyaluminum chloride) and S.S cause the flocculation reaction at a high speed.

The wastewater passed through the tubular reactor (1) is sent to a tubular agglomerator (2) having a diameter of 160 m and a length of 2 m provided with a polymer coagulant injection port (6) and maintained at a concentration of 0.2 ppm of polyacrylamide as a polymer coagulant. Insert as much as possible. The wastewater passed through the tubular reactor 1 and the tubular flocculator 2 for 2 minutes. The wastewater in which the flocculation reaction was initiated was sent to a sedimentation tank 3 having a size of 70 m 3 to precipitate the aggregate. The waste water was precipitated in the sedimentation tank for 2 hours. The entire work took two hours and two minutes. The COD content of the wastewater from which flocculated sludge was removed was 7 ppm and SS 3.5 ppm. The polyaluminum chloride took 70 kg per day and the polymer coagulant aid (polyacrylamide) took 1.4 kg per day.

[ Comparative example ]

COD 185.5ppm and SS 207.8ppm tunnel excavated wastewater discharged by pumping from the work site with 700 tons (29.2㎥ / hour) of wastewater per day was 2m × 2.4m × 2m with stirrer of 2.2kw × 3.8V It is sent to the reactor (7). While the wastewater is stirred with the stirrer (9), a flocculant (polyaluminum chloride) is injected to maintain a concentration of 100 ppm and stirred for 16 minutes to proceed with the flocculation reaction. The wastewater, in which the flocculation reaction is initiated, is sent to a 2m × 2.4m × 2m flocculation tank 8 equipped with a stirrer 10 having a capacity of 2.2kw × 3.8V. While stirring with a stirrer (10), a polymer coagulant (polyacrylamide) was added to maintain a concentration of 0.2 ppm, and stirred for 16 minutes, and then the wastewater was sent to a 70 m3 precipitation tank (3). After sedimentation was performed for 2 hours in the settling tank (3), the wastewater had a COD content of 8 ppm and an SS content of 18 ppm. The installation scale of the comparative example is based on the discharge allowance facility standard for permitting the discharge of pollutants determined by the Ministry of Environment. Compared with the wastewater treatment results of the Example and Comparative Example is shown in Table 1 below.

<Wastewater Treatment Results> Item Comparative example Example Wastewater Treatment Volume (tons / day) 700 700 Wastewater Pollution Degree COD (ppm) 185.5. 185.5 S.S (ppm) 207.8 207.8 Pollution degree after treatment COD (ppm) 8 7 S.S (ppm) 18 3.5 Coagulant Requirements Polyaluminum chloride 70 kg 70 kg Polyacrylimide 1.4 kg 1.4 kg Processing time 2 hours 32 minutes 2 hours 2 minutes

Equipment scale Reactor 2m x 2.4m x 2m 1 unit 12cm x 2m pipe Agglomeration tank 2m x 2.4m x 2m 1 unit 1 16cm x 2m Pipe Sedimentation tank 70㎥ 70㎥ agitator 2 x 2.2kw x 3.8v - Compressed air - 0.1㎥ / min

* The site area for facility maintenance takes more than three times compared to the example in the case of the comparative example.

In the present invention, by using the tubular reactor and tubular agglomerator, the wastewater pipe and the tubular reactor and tubular agglomerator which are pumped and discharged can be connected and used as a single pipe, and the tunnel excavated wastewater is discharged to the settling tank through one pipe. It will be able to increase the work efficiency. In a reactor connected by one line, there is an advantage in that the condensation reaction can be accelerated by vortexing the wastewater flow due to the bubbling effect of compressed air in a confined space, thereby shortening the aggregation reaction time. There is an advantage that can keep the scale of the waste water treatment plant small.

The tubular reactor may be referred to as a line reactor, and the tubular aggregate may be referred to as a line mixer.

" 는 폐수의 흐름 방향을 표시한 것이다.1: tubular reactor
2: tubular agglomerator
3: settling tank
4: air inlet
5: flocculant injection hole
6: injection of polymer coagulant aid
7: reactor
8: coagulation tank
9, 10: Stirrer
"

Indicates the flow direction of the waste water.

Claims (2)

In the tunneling wastewater treatment method in which suspended solids in the tunneling wastewater are flocculated by using a flocculant, separated and removed, the discharged tunneling wastewater is transferred to a tubular reactor (1) having an air inlet and the tubular reactor (1). In the vortex of the wastewater formed by the air injection, the flocculation reaction is initiated by reacting the flocculant with the flocculant in the tubular flocculator (2), and the flocculation flotation in the settling tank (3) after the flocculation reaction is completed. Sedimentation material to make a sludge, this sludge is separated and removed to remove the suspended solids in the tunnel wastewater treatment method
The method of treating tunnel excavation wastewater according to claim 1, wherein the flocculant is polyaluminum chloride and the polymer flocculent aid is polyacrylamide.

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