JP4839912B2 - Purification method of contaminated water - Google Patents

Description

  The present invention relates to a method for purifying contaminated water such as groundwater containing a volatile organic compound.

  Contamination of groundwater and factory wastewater with volatile organic compounds such as trichlorethylene and tetrachlorethylene has become a problem. There are methods for removing contaminants such as volatile organic compounds in the contaminated water in the aqueous phase, ultraviolet oxidation methods, and other various treatment and purification methods. Among these, the following purification methods are known. It has been.

The groundwater pumped up by the pump is introduced into the aeration apparatus through the water pipe, and the aerated gas is introduced into the activated carbon tank through the gas-liquid separation tank by the suction blower. Air in the atmosphere is introduced into the ozone gas generator through an air dryer, and the gas containing the generated ozone gas is introduced into the aeration apparatus. In the aeration apparatus, an ultraviolet lamp and a protective tube are provided around the ultraviolet lamp at a position where the groundwater is sprayed, and the groundwater becomes a thin liquid layer when flowing down the surface of the protective tube. At that time, ozone is absorbed into the groundwater, the ozone is radicalized by ultraviolet rays, and volatile pollutants contained in the groundwater are oxidatively decomposed (see, for example, Patent Document 1).
JP 2001-129540 A

  However, what is described in Patent Document 1 described above requires an aeration apparatus, an activated carbon tank, an ozone gas generation apparatus, an ultraviolet lamp and a protective tube, components of a contaminated groundwater spraying apparatus, and their connection, and the entire apparatus. However, there is a problem that man-hours are required to maintain and manage many different components to the optimum conditions. In addition, since groundwater flows down on the surface of the UV lamp protection tube at the position where the groundwater is sprayed and processed as a thin liquid layer, there is a limit to the ability to treat contaminated groundwater.

  The present invention solves the above-mentioned conventional problems and provides a purification method of contaminated water with excellent removal efficiency by simplifying the configuration of the purification device and improving the treatment capacity of the contaminated water with volatile organic compounds. It is intended.

The present invention solves the above-mentioned conventional problems. An aeration tank, an aeration chamber obtained by dividing the aeration tank into a plurality of partitions by a partition wall, a filler filled in each aeration chamber, and the respective aeration chambers Air supply means and an adsorbent that adsorbs volatile organic compounds, the contaminated water sequentially flows into each aeration chamber to promote gas-liquid contact with the filler, and the volatile organic compounds are separated from the contaminated water respectively. And a plurality of adsorption units having the adsorbent corresponding to each of the aeration chambers, and are volatilized from each of the aeration chambers. The contaminated water is purified by adsorbing the adsorbent of the adsorbing unit provided corresponding to different concentrations of the volatile organic compound transferred to the air for each aeration chamber. It is a method.

According to the purification method of the contaminated water of the present invention as described above, so as to correspond to different concentrations of volatile organic compounds has shifted to the air it can be optimally set the maximum adsorption capacity of the adsorbent for each aeration chamber Moreover, while simplifying the structure of a purification apparatus, the processing capability of the contaminated water by a volatile organic compound can be improved, and it can be set as the purification method of the contaminated water excellent in the removal efficiency.

The first invention includes an aeration tank, an aeration chamber obtained by dividing the aeration tank into a plurality of partition walls, a filler filled in each aeration chamber, air supply means to each aeration chamber, and volatile An adsorbent that adsorbs organic compounds is provided. Contaminated water is made to flow sequentially into each aeration chamber to facilitate gas-liquid contact with the filler, and volatile organic compounds are supplied to the air supplied to each aeration chamber from the contaminated water. And a plurality of adsorbing units having the adsorbents corresponding to the respective aeration chambers, the volatile organic compounds from the respective aeration chambers being removed from the respective aeration chambers. This is a method for purifying contaminated water, characterized in that it is adsorbed on the adsorbent of the adsorption unit provided corresponding to different concentrations of volatile organic compounds transferred to air for each chamber .

This makes it possible to optimally set the maximum adsorption capacity of the adsorbent corresponding to the different concentrations of volatile organic compounds transferred to the air for each of the multiple aeration chambers. And the adsorbent can be easily replaced. In addition to reducing the number of components and maintenance man-hours other than the aeration tank and the adsorbent, the volatile organic compound can be removed by flowing the contaminated water sequentially in the aeration chamber having the filler divided into a plurality of aeration tanks by the partition wall. The polluted water can be reliably transferred to the air. Therefore, while simplifying the structure of a purification apparatus, the processing capability of the contaminated water by a volatile organic compound can be improved, and it can be set as the purification method of the contaminated water excellent in the removal efficiency.

Invention of the second aspect, in the first invention is obtained by a method of purifying contaminated water, characterized in that the amount of air jetted from the lower portion of each aeration chamber and adjustable.

  This makes it possible to set the amount of air to the minimum necessary and optimum conditions for each of the aeration chambers, and to reliably transfer volatile organic compounds from groundwater to air. Moreover, noise due to aeration can be reduced, and the adsorption efficiency of the volatile organic compound by the adsorbent of the adsorption unit can be improved.

According to a third aspect of the invention, in the first or second aspect of the invention, a method for purifying contaminated water is characterized in that fine bubbles are ejected from the lower part of each aeration chamber.

  As a result, the gas-liquid contact can be further promoted, and the volatile organic compound can be reliably transferred from the groundwater to the air.

After the invention of the fourth aspect, in the first to third any one of the, where the underground water containing the pumping from the ground aquifer of volatile organic compounds, is passed through each of the aeration chamber, Obisui This is a method for purifying contaminated water, characterized by being introduced into a layer.

  Thereby, microbial decomposition of volatile organic compounds in the groundwater present in the aquifer can be promoted.

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a basic configuration diagram of an apparatus for carrying out the contaminated water purification method of Reference Example 1, and FIG. 2 is a basic configuration diagram of an apparatus for carrying out the contaminated water purification method of Example 1 .

( Reference Example 1)
In FIG. 1, a pumping well 3 reaching the aquifer 2 in the underground 1 is provided, and one end of the pumping pipe 4 is positioned in the pumping well 3. A filter 5 for removing foreign matter from the groundwater to be pumped and a pump 6 for suction are provided in the path of the pumping pipe 4, and groundwater that is contaminated water containing volatile organic compounds is supplied from the pumping well 3 to the aeration tank 7.

  The aeration tank 7 is divided by partition walls 8, 9, 10, 11, and 12, and constitutes a plurality of aeration chambers 13, 14, 15, 16, 17, and 18. Further, each of the plurality of aeration chambers 13, 14, 15, 16, 17, 18 is filled with fillers 19, 20, 21, 22, 23, 24. The fillers 19, 20, 21, 22, 23, and 24 are not particularly limited as long as they can sufficiently promote gas-liquid contact, but those having shapes such as Raschig rings and spheres are provided in the aeration chambers 13 and 14. , 15, 16, 17 and 18 are irregularly filled.

  Further, from the lower part of the plurality of aeration chambers 13, 14, 15, 16, 17, 18, a blower (air supply means) 25, a supply pipe 26, and a diffuser pipe 27, 28, 29, 30, 31, having a small hole, 32, aeration air is supplied through the flow rate adjusting valves 33, 34, 35, 36, 37, and 38. The groundwater pumped up is supplied to the aeration chamber 13 from a sprinkling pipe 39 having a large number of small holes located at multiple ends of the pumping pipe 4.

  A gas collecting plate 40 is provided so as to cover each upper space of the plurality of aeration chambers 13, 14, 15, 16, 17, and 18, and air (gas) containing a volatile organic compound transferred from groundwater by gas-liquid contact. Phase) is supplied via an exhaust pipe 41 and a switching valve 42 to an adsorption unit 44 having an adsorbent 43 such as activated carbon and an adsorption unit 46 having an adsorbent 45 such as activated carbon. The switching valve 42 supplies air containing a volatile organic compound to one or both of the adsorption unit 44 and the adsorption unit 46.

  Groundwater that has passed through the aeration chamber 18 is discharged from the drain pipe 47, and is supplied to the injection well 50 via the return pipe 49 by the switching valve 48 and returned to the aquifer. The arrows in the figure indicate the flow of groundwater.

  Next, the operation of the basic configuration apparatus will be described. Groundwater, which is contaminated water containing a volatile organic compound, is supplied to the aeration tank 7 from the pumping well 3. From the lower part of the aeration chamber 13, it enters the aeration chamber 14 through the gap between the lower end of the partition wall 8 and the aeration tank 7 and flows upward. It enters the aeration chamber 15 from the aeration chamber 14 beyond the upper end of the partition wall 9 and flows upward. Thereafter, the groundwater flows sequentially to the aeration chambers 15, 16, 17 and 18 over the gap between the lower ends of the partition walls 10 and 12 and the aeration tank 7 and the upper end of the partition wall 11. At this time, the groundwater flows through the gaps between the fillers 19, 20, 21, 22, 23, 24 filled in the aeration chambers 13, 14, 15, 16, 17, 18.

  Further, from the lower part of the aeration chambers 13, 14, 15, 16, 17, 18, a blower (air supply means) 25, a supply pipe 26, an air diffusion pipe 27, 28, 29, 30, 31, 32, and a flow control valve 33 are provided. , 34, 35, 36, 37, 38, the aeration air passes through the gaps between the filled fillers 19, 20, 21, 22, 23, 24 by buoyancy and rises.

  In the aeration chambers 13, 14, 15, 16, 17, and 18, the volatile organic compound is transferred from the groundwater to air by gas-liquid contact between the flowing groundwater and the rising aeration air. At this time, by the fillers 19, 20, 21, 22, 23, and 24, groundwater flows in various directions and trickles. Further, due to the fillers 19, 20, 21, 22, 23, and 24, the rising aeration air also becomes fine bubbles without causing bubble coalescence in the process of rising in the groundwater. Furthermore, drift of groundwater and air is prevented. By these actions, gas-liquid contact between groundwater and aeration air can be promoted, and volatile organic compounds can be efficiently transferred from groundwater to air.

  Furthermore, the air containing the volatile organic compound transferred from the groundwater by gas-liquid contact by the air collecting plate 40 provided so as to cover the upper spaces of the plurality of aeration chambers 13, 14, 15, 16, 17, 18 (Gas phase) is supplied to an adsorption unit 44 and an adsorption unit 46 having adsorbents 43 and 45 such as activated carbon through an exhaust pipe 41 and a switching valve 42. A volatile organic compound is adsorbed and removed by the adsorbents 43 and 45 made of activated carbon or the like of the adsorption unit 44 and the adsorption unit 46.

  The switching valve 42 supplies air containing a volatile organic compound to one or both of the adsorption units 44 and 46 having a certain adsorption capacity. For example, when air containing a volatile organic compound is supplied only to the adsorption unit 44, the other adsorption unit 46 is put in a standby state, and when the adsorption capacity of the adsorption unit 44 becomes below a certain level, the switching valve 42 Is operated to switch the flow path to the adsorption unit 46 side to supply air containing a volatile organic compound. Accordingly, it is not necessary to stop the operation of the purification process associated with the replacement of the adsorption unit or the desorption operation of the volatile organic compound from the adsorbent, as compared with an apparatus having only a single adsorption unit. Therefore, it is possible to improve the processing capability as the purification processing apparatus.

  Although it is possible to provide only a single large adsorption unit and increase the replacement period, the adsorption capacity gradually decreases and the use time near the limit is long, which is sufficient due to fluctuations in the concentration of volatile organic compounds. That can be difficult to remove.

  Further, when the concentration of the volatile organic compound in the groundwater is temporarily increased by allowing the air containing the volatile organic compound to be supplied to both the adsorption units 44 and 46 by the switching valve 42. For example, it is possible to ensure sufficient adsorption capacity for removal. In addition, although demonstrated by the example of 2 units | suction units 44 and 46, it is not limited to this, You may provide more adsorption units.

  The groundwater that has flowed through the aeration chambers 13, 14, 15, 16, 17, 18 and removed volatile organic compounds by gas-liquid contact is discharged from the upper portion of the aeration chamber 18 through the drain pipe 47, but the switching valve 48. Thus, the water can be supplied to the injection well 50 through the return pipe 49 and returned to the aquifer 2. In this case, by supplying groundwater aerobic in the aeration chambers 13, 14, 15, 16, 17, and 18 and the aerobic microorganisms propagated to the aquifer 2, It can promote microbial degradation of volatile organic compounds.

  Although the contaminated water is groundwater, it can also be applied to the purification treatment of contaminated wastewater from factories and the like. Furthermore, groundwater and contaminated wastewater from factories and the like are supplied to the aeration chambers 13, 14, 15, 16 through a storage tank. , 17 and 18 may be supplied.

  Further, a blower (air supply means) 25, a supply pipe 26, an aeration pipe 27, 28, 29, 30, 31, 32, supply for aeration from the lower part of the aeration chambers 13, 14, 15, 16, 17, 18 Aeration air is supplied through flow control valves 33, 34, 35, 36, 37, and 38 that adjust the amount of air. By providing the flow rate control valves 33, 34, 35, 36, 37, 38, the air amount is set to the minimum and optimum condition for each of the aeration chambers 13, 14, 15, 16, 17, 18. Can be set, and noise caused by aeration can be reduced. Furthermore, the adsorption efficiency of the volatile organic compounds by the adsorbents 43 and 45 made of activated carbon or the like of the adsorption unit 44 and the adsorption unit 46 can be improved.

  Further, even when the concentration of the volatile organic compound in the ground water or the flow amount of the ground water fluctuates, the supply air amount for aeration is adjusted by the flow control valves 33, 34, 35, 36, 37, 38, An organic compound can be reliably transferred from groundwater to air. Furthermore, by adjusting the supply air amount for aeration in each of the aeration chambers 13, 14, 15, 16, 17, 18 to an optimum condition, volatile organic compounds are converted from the groundwater flowing through the aeration chamber 18 in the subsequent stage to the air. It can be reliably transferred.

  The adjustment of the supply air amount by the flow rate adjusting valves 33, 34, 35, 36, 37, and 38 and the rotation speed control of the blower (air supply means) 25 may be used in combination. A more detailed response to the quantity is possible.

  Further, in the aeration tank 7 having a constant volume, the number or volume of the aeration chambers 13, 14, 15, 16, 17, 18 can be arbitrarily set according to the number of partition walls 8, 9, 10, 11, 12. Furthermore, by changing the position of each of the partition walls 8, 9, 10, 11, 12 to be constant, the aeration chambers 13, 14, 15, 16, 17, 18 each have a different volume (the width in the direction of groundwater flow). ). By these, optimal conditions can be set so that volatile organic compounds can be reliably transferred from groundwater to air. Changing the number or position of the partition walls 8, 9, 10, 11, 12 individually can be realized with a simple structure.

  As a result, it is not necessary to prepare a plurality of aeration towers or aeration towers of different sizes as in the prior art, and it is possible to simplify the apparatus and reduce equipment costs. Furthermore, volatile organic compounds can be reliably transferred from groundwater to air.

In the above-described configuration, aeration air is supplied from the diffusion tubes 27, 28, 29, 30, 31, and 32 having small holes located below the aeration chambers 13, 14, 15, 16, 17, and 18. Although it was made to supply, the surface area of the whole fine bubble is increased by refining the air and supplying the fine bubble (for example, about 10 to 40 μm) to the aeration chamber 13, 14, 15, 16, 17, 18. The residence time of the bubbles in the groundwater becomes longer, further promoting the gas-liquid contact, and the volatile organic compound can be reliably transferred from the groundwater to the air. As the fine bubble generating means, a two-fluid nozzle, a gas disperser, a gas-liquid stirrer or the like is used.
As described above, according to the contaminated water purification method of Reference Example 1, the aeration tank 7 and the aeration chambers 13, 14, in which the aeration tank 7 is divided into a plurality of partitions by the partition walls 8, 9, 10, 11, 12. 15, 16, 17, 18, filling materials 19, 20, 21, 22, 23, 24 filled in the respective aeration chambers 13, 14, 15, 16, 17, 18, and the respective aeration chambers 13, 14 15, 15, 17, 18, and a blower (air supply means) 25, and adsorbents 43, 45 that adsorb volatile organic compounds, and each aeration chamber 13, 14, 15, 16, 17, 18 is provided. The contaminated water is sequentially flowed to promote gas-liquid contact by the fillers 19, 20, 21, 22, 23, and 24, and volatile organic compounds are extracted from the contaminated water into the aeration chambers 13, 14, 15, 16, and 17, respectively. , 18 and then adsorbed to the adsorbents 43 and 45. It is obtained by the purification method of the contaminated water, and removing by.
As a result, components other than the aeration tank and the adsorbent and maintenance man-hours can be reduced, and the volatile organic compound is produced by sequentially flowing the contaminated water through the aeration chamber having the filler in which the aeration tank is divided into a plurality of partitions. Can be reliably transferred from the contaminated water to the air. Therefore, while simplifying the structure of a purification apparatus, the processing capability of the contaminated water by a volatile organic compound can be improved, and it can be set as the purification method of the contaminated water excellent in the removal efficiency.

(Example 1 )
Figure 2 is a basic configuration diagram of an apparatus for carrying out the method of purifying contaminated water of Example 1. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description of the configuration and operation is omitted. The difference from FIG. 1 is that an adsorbent of an adsorption unit provided with a plurality of adsorption units individually corresponding to a plurality of aeration chambers and provided with a volatile organic compound from each aeration chamber corresponding to each aeration chamber. It is made to adsorb to.

  The upper ends of the partition walls 8, 9, 10, 11, 12 of the aeration tank 7 are extended to the air collecting plate 40, and the upper spaces of the plurality of aeration chambers 13, 14, 15, 16, 17, 18 are partitioned. The exhaust pipes 51, 52, 53, 54, 55, 56 are connected to the air collecting plate 40 above the plurality of aeration chambers 13, 14, 15, 16, 17, 18, and the adsorption units 63, 64, 65 are connected thereto. , 66, 67, 68 are supplied with air (gas phase) containing a volatile organic compound transferred from groundwater by gas-liquid contact, and adsorbed on the adsorbents 57, 58, 59, 60, 61, 62 to be removed. Is.

  The concentration of the volatile organic compound transferred to the air is highest on the upstream side of the flowing groundwater and decreases as it flows downstream. For this reason, the density | concentration of the volatile organic compound which moved to the air in order of the aeration chamber 13, 14, 15, 16, 17, 18 will fall. In the configuration of FIG. 1, air (gas phase) containing volatile organic compounds from the aeration chambers 13, 14, 15, 16, 17, and 18 is collected and adsorbed by the adsorbent 43 or 45. In the present embodiment, the aeration chamber is provided by including a plurality of adsorption units 63, 64, 65, 66, 67, 68 individually corresponding to the plurality of aeration chambers 13, 14, 15, 16, 17, and 18. The maximum adsorption capacity of the adsorbents 57, 58, 59, 60, 61, 62 is optimally set corresponding to the different concentrations of the volatile organic compounds transferred to the air for every 13, 14, 15, 16, 17, 18 In addition, the adsorbent can be divided to reduce the size of the adsorbing unit, and the adsorbent can be easily replaced.

  Although the plurality of suction units 63, 64, 65, 66, 67, 68 individually associated with the plurality of aeration chambers 13, 14, 15, 16, 17, 18 are provided, for example, a plurality of adjacent aeration chambers are provided. It is good also as a structure provided with the some adsorption | suction unit corresponding to the aeration chamber.

  Applicable to the purification of contaminated water containing volatile harmful substances.

Basic configuration diagram of an apparatus for carrying out the contaminated water purification method of Reference Example 1 The basic block diagram of the apparatus for enforcing the purification method of the contaminated water of Example 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Underground 2 Aquifer 3 Pumping well 4 Pumping pipe 5 Filter 6 Pump 7 Aeration tank 8, 9, 10, 11, 12 Partition wall 13, 14, 15, 16, 17, 18 Aeration chamber 19, 20, 21, 22, 23, 24 Filler 25 Blower (air supply means)
26 Supply pipe 27, 28, 29, 30, 31, 32 Aeration pipe 33, 34, 35, 36, 37, 38 Flow control valve 39 Sprinkling pipe 40 Air collecting plate 41 Exhaust pipe 42 Switching valve 43 Adsorbent 44 Adsorption unit 45 Adsorbent 46 Adsorption unit 47 Drain pipe 48 Switching valve 49 Return pipe 50 Injection well 51, 52, 53, 54, 55, 56 Exhaust pipe 57, 58, 59, 60, 61, 62 Adsorbent 63, 64, 65, 66 , 67, 68 Adsorption unit

Claims (4)

An aeration tank, an aeration chamber obtained by dividing the aeration tank into a plurality of partition walls, a filler filled in each aeration chamber, an air supply means to each aeration chamber, and an adsorption for adsorbing volatile organic compounds The material is provided, the contaminated water is sequentially flowed into each aeration chamber, the gas-liquid contact is promoted by the filler, the volatile organic compound is transferred from the contaminated water to the air supplied to each aeration chamber, and then the adsorption A plurality of adsorbing units having the adsorbing material corresponding to each aeration chamber, and removing volatile organic compounds from each aeration chamber into air for each aeration chamber A method for purifying contaminated water, characterized in that the polluted water is adsorbed on the adsorbent of the adsorption unit provided corresponding to different concentrations of the transferred volatile organic compound . 2. The method for purifying contaminated water according to claim 1 , wherein the amount of air ejected from the lower part of each aeration chamber is adjustable. The method for purifying contaminated water according to claim 1 or 2 , wherein fine bubbles are ejected from the lower part of each aeration chamber. Groundwater containing and pumping from the ground aquifer of volatile organic compounds, after they were passed through each of the aeration chamber, any one of claims 1 to 3, characterized in that the introduction into the aquifer The method for purifying contaminated water described in 1.

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