JP2013075262A - Removing system and removing method of volatile substance in underground water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a removing system and a removing method of volatile substances in underground water by which effective utilization of energy can be attained.SOLUTION: The removing system 1 of volatile substances in underground water has a storage pump 2 for pumping up underground water containing the volatile substances, a heat pump 6 for heating underground water pumped up by the storage pump 2 and an aerator 10 which brings air into contact with the underground water heated by the heat pump 6 and makes the volatile substances contained in the underground water shift into the air to obtain treated water.

Description

  The present invention relates to a system and method for removing volatile substances in groundwater, and more particularly to a system for pumping groundwater and removing volatile substances in groundwater by aeration treatment.

  Countermeasures are required for organochlorine compounds such as trichlorethylene and tetrachloroethylene, or hydrocarbon compounds such as benzene as a causative substance for soil and groundwater contamination. Since these compounds are volatile, they are also called volatile organic compounds (hereinafter sometimes referred to as VOC). As a method for removing VOC from soil, particularly groundwater, a method using aeration is known (Patent Document 1). According to this method, groundwater containing VOCs is pumped, and air is supplied to the pumped groundwater with a blower to cause gas-liquid contact (aeration). VOCs contained in the groundwater are transferred to air, separated from the groundwater, and adsorbed by activated carbon or the like. The removal efficiency of VOC has a correlation with the temperature of groundwater at the inlet of the aeration apparatus. The higher the temperature of groundwater, the more the volatilization is promoted and the VOC is efficiently removed.

Japanese Patent No. 3214978

  In general, a heater is used to heat the pumped-up groundwater, but the power cost (electricity, oil, etc.) is enormous, and waste heat is released into the atmosphere as it is, from the viewpoint of effective use of energy. There is room for improvement.

  An object of this invention is to provide the removal system and removal method of the volatile substance in groundwater which can aim at the effective utilization of energy.

  The system for removing volatile substances in groundwater of the present invention includes a pump for pumping groundwater containing volatile substances, a heat pump for heating groundwater pumped by the pump, and air to the groundwater heated by the heat pump. An aeration apparatus that obtains treated water by transferring volatile substances contained in the groundwater to air by contacting them.

  The method for removing volatile substances in groundwater of the present invention includes pumping groundwater containing volatile substances, heating the pumped groundwater with a heat pump, and bringing air into contact with the groundwater heated with the heat pump. Thus, volatile substances contained in groundwater are transferred to air to obtain treated water.

  Since the heat pump is higher in energy efficiency than a heating device such as a heater, the energy can be effectively used.

  ADVANTAGE OF THE INVENTION According to this invention, the removal system and removal method of the volatile substance in groundwater which can aim at the effective utilization of energy can be provided.

It is a schematic block diagram of the removal system of the volatile substance in the ground water which concerns on one Embodiment of this invention. It is a schematic sectional drawing of a pumping well. It is a schematic block diagram of a heat pump. It is a schematic block diagram of an aeration apparatus. It is a schematic block diagram of the removal system of the volatile substance in the groundwater which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1: shows the schematic block diagram of the removal system of the volatile substance in groundwater which concerns on one Embodiment of this invention.

  The removal system 1 of the volatile substance in groundwater has the pump 2 which pumps up the groundwater containing a volatile substance. The pumping pump 2 is installed inside the pumping well 3 and connected to a pipe 22. FIG. 2 shows a schematic cross section of the pumped well 3. The pumping well 3 is formed by providing a vertical pit 31 on the ground by boring and providing a generally hollow cylindrical casing 32 therein. The casing 32 is formed of steel, stainless steel, vinyl chloride, or the like, and the side wall of the casing 32 has a large number of through holes 33 in order to allow communication of groundwater. The space between the inner wall of the vertical shaft 31 and the side wall of the casing 32 is filled with gravel, crushed stone, dredged sand 34, and the like in order to promote fixing of the casing 32 and communication of groundwater. The ground area where the groundwater exists is called an aquifer 35, and the water level inside the casing 32 substantially coincides with the water level WL of the surrounding aquifer 35. The pump 2 according to the present embodiment is installed at a position below the groundwater level inside the casing 32, but the pump is placed on the ground and the groundwater suction pipe is lowered from the ground into the aquifer 35 to the aquifer 35. Also good. The side wall above the aquifer 35 of the casing 32 may have a water shielding structure such as cement.

  The removal system 1 has a heat pump 6 that heats the groundwater pumped by the pump 2. FIG. 3 is a schematic configuration diagram of the heat pump 6. The heat pump 6 uses a vapor compression type in this embodiment. The heat pump 6 includes an evaporator 6a that evaporates refrigerant such as ammonia, carbon dioxide, chlorofluorocarbons, and alternative chlorofluorocarbons such as R410A, a compressor 6b that compresses the refrigerant, a condenser 6c that condenses the refrigerant, and a refrigerant. An expansion valve 6d for expansion, and these elements are arranged in this order on the closed loop 6e. The refrigerant undergoes a thermal cycle of evaporation, compression, condensation, and expansion while circulating in the closed loop 6e. The adjacent portion between the condenser 6 c and the pipe 22 forms a heat exchanging portion 7, and the adjacent portion between the evaporator 6 a and the heat source 8 forms a heat exchanging portion 9. Heat QC is taken from the heat source 8 through the heat exchanging portion 9 by the heat of vaporization when the refrigerant evaporates in the evaporator 6a. The evaporated refrigerant is compressed by the compressor 6b and becomes a high-temperature and high-pressure gas phase. The refrigerant is then sent to the condenser 6c. The condensation heat QH released during the condensation is given to the groundwater flowing through the pipe 22 via the heat exchange unit 7. The condensed refrigerant is cooled under reduced pressure through the expansion valve 6d. In this way, during one cycle of operation of the heat pump 6, heat absorption from the heat source 8 and ground water in the pipe 22 are heated.

  Although there is no upper limit of the groundwater temperature that can be heated by the heat pump 6, the general heat pump 6 can heat the groundwater to about 60 ° C.

  In addition to the vapor compression type, the heat pump 6 may be a thermoelectronic, chemical, adsorption, or absorption heat pump 6.

  The removal system 1 has an aeration apparatus 10 that transfers volatile substances contained in groundwater to air by bringing air into contact with groundwater heated by the heat pump 6. In FIG. 4, the schematic block diagram of two types of aeration apparatus 10a, 10b is shown.

  The aeration apparatus 10a illustrated in FIG. 4A includes a packed tower 11 and a blower (blower) 12 that supplies air to the packed tower 11. Groundwater is sprayed from the upper part of the packed tower 11 by the spray nozzle 13. A packed bed 14 is provided inside the packed tower 11, and groundwater is retained as a thin film on the surface of the packed bed 14. Air is supplied from the lower part of the packed tower 11 by the blower 12. The groundwater in the coated state comes into contact with air (indicated by white arrows) blown upward from below, and the VOC moves to air. The groundwater from which the VOC has been removed stays at the bottom 14 a of the packed tower 11 and is discharged from the packed tower 11 by the pump 15. The air that has absorbed the VOC is discharged from the upper part of the packed tower 11. The discharged air is sent to the activated carbon treatment device 17 filled with activated carbon, and VOC is adsorbed by the activated carbon.

  The aeration apparatus 10b shown in FIG. 4B includes a main body container 19 and a blower (blower) 12 that supplies air to the main body container 19. A plurality of planar trays 20 are arranged inside the main body container 19. On each tray 20, a flow path (not shown) extending two-dimensionally is formed by a side wall held on the bottom surface of the tray 20. Groundwater is supplied from the upper part of the main body container 19 to the uppermost tray 20 and flows along the flow path on the uppermost tray 20. The groundwater that has reached the outlet of the uppermost tray 20 falls to the next lower tray 20 and similarly flows along the flow path on the tray 20. In this way, the groundwater flows from the uppermost tray 20 to the lowermost tray 20, finally stays at the bottom 19 a of the main body container 19, and is discharged from the main body container 19 by the pump 15.

  On the other hand, a large number of aeration holes 21 are formed on the bottom surface of each tray 20, and the air blown upward from below by the blower 12 (indicated by white arrows) passes through the aeration holes 21 and flows through the tray 20. Enter. At this time, the air that has entered each tray 20 comes into gas-liquid contact with the groundwater flowing through the flow path of the tray 20, and the VOC moves to air. In this way, air rises from the lowermost tray 20 to the uppermost tray 20 while making gas-liquid contact with the groundwater flowing through each tray 20 and absorbing VOC, and finally discharged from the upper portion of the main body container 19. Is done. The discharged air and the activated carbon treatment device 17 filled with activated carbon are sent to the VOC and adsorbed on the activated carbon.

  Various things can be used as the heat source 8 of the heat pump 6. Referring to FIG. 1, in one example, groundwater that has passed through the aeration apparatus 10 and is heated can be used as the heat source 8 (heat source 1). The groundwater heated by the heat pump 6 and passed through the aeration apparatus 10 is still in a high temperature state although the temperature is somewhat lowered by the aeration apparatus 10. The temperature of groundwater is generally between 15 and 17 ° C. throughout the year, and the groundwater that has been heated and passed through the aeration apparatus 10 can be effectively used as a heating source for groundwater. Conventionally, groundwater treated by the aeration apparatus 10 has been discharged into sewage or the like as it is, but by recovering heat with the heat pump 6, it is possible to effectively use energy. Moreover, the heat pump 6 itself has high energy efficiency, and can heat groundwater with low energy as compared with a conventional heating device using an electric heater, a boiler, or the like.

  The air supplied from the blower 12 and contacting the ground water can be used as the heat source 8 of the heat pump 6 (heat source 2). Since the air supplied from the blower 12 is heated by the heat generated by the motor, the exhaust gas exiting the aeration apparatus 10 is in a high temperature state and can be effectively used as a heating source for groundwater. By making a part of the pipe 23 connecting the aeration apparatus 10 and the activated carbon treatment apparatus 17 into thermal contact with the heat pump 6, the energy of the exhaust gas can be used.

  The heat pump 6 can also use the atmosphere as the heat source 8 (heat source 3). Since the outside air temperature may reach 30 to 35 ° C. in summer, it can be effectively used as a heating source for groundwater. The heat absorption side piping of the refrigerant of the heat pump 6 is formed in a coil shape, and the thermal energy of the atmosphere can be efficiently recovered by exposing the coiled portion directly to the outside air. The air used as the heat source 8 can be reused for cooling.

  The heat pump 6 can also use hot waste water as the heat source 8 (heat source 4). Although the supply source of warm wastewater is not particularly limited, when a factory, a power plant or the like is adjacent, warm wastewater generated by these facilities can be used.

  Each embodiment described above can be combined in an arbitrary pattern. For example, the groundwater (heat source 1) that has passed through the aeration apparatus 10 and the exhaust gas (heat source 2) emitted from the blower 12 can be used simultaneously as the heat source of the heat pump 6. These heat source 8 and the heat exchanging section 9 for the refrigerant of the heat pump 6 may be provided in series or in parallel. In addition, when air or hot wastewater is used as a heat source (heat sources 3 and 4), a switching device (not shown) is provided, and a mode used as a heat source and a mode not used depending on the level of outside air temperature or the supply status of hot wastewater May be switched.

  In each above embodiment, the 2nd heat pump 23 which uses the groundwater which passed the aeration apparatus 10 as a heat source can also be provided. When the waste water of the aeration apparatus 10 is not used (when the heat sources 2 to 4 are used), the entire amount or a part of the waste water can be used as the heat source of the second heat pump 26 via the heat exchange unit 24. Although the utilization method of the heat | fever collect | recovered with the 2nd heat pump 26 is not specifically limited, Air, water, etc. can be heated via the heat exchange part 25, and it can use for uses, such as heating and hot water supply. When the waste water of the aeration apparatus 10 is used (when the heat source 1 is used), a part of the aeration apparatus 10 is supplied to the heat pump 6 for heating the ground water, and a part or the whole amount of the remaining ground water is secondly supplied. It can be used as a heat source for the heat pump 26.

  Furthermore, as shown in FIG. 5, a heat exchanger 27 is provided between the pumping pump 2 and the heat pump 6, and between at least a part of the groundwater that has passed through the aeration apparatus 10 and the groundwater before being supplied to the heat pump 6. Heat exchange can also be performed. Thereby, the ground water before being supplied to the heat pump 6 can be heated, and the load of the heat pump 6 can be reduced.

DESCRIPTION OF SYMBOLS 1 Removal system of volatile substance 2 Pumping pump 3 Pumping well 6 Heat pump 8 Heat source 10, 10a, 10b Aeration apparatus 12 Blower (blower)

Claims (8)

A pump for pumping groundwater containing volatile substances;
A heat pump for heating the groundwater pumped by the pump;
An aeration apparatus for obtaining treated water by transferring the volatile substances contained in the groundwater to the air by bringing the groundwater heated by the heat pump into contact with air;
A system for removing volatile substances in groundwater.   The removal system according to claim 1, wherein the heat pump uses the treated water as a heat source.   The removal system according to claim 1 or 2, wherein the aeration apparatus includes a blower that supplies the air, and the heat pump uses the air supplied from the blower and in contact with the groundwater as a heat source.   The removal system according to any one of claims 1 to 3, wherein the heat pump uses air as a heat source.   The removal system according to any one of claims 1 to 4, wherein the heat pump uses hot wastewater supplied from outside the removal system as a heat source.   The removal system of any one of Claim 1 to 5 which has a 2nd heat pump which uses the said treated water as a heat source.   The heat exchanger which heat-exchanges heat between at least a part of the treated water and the groundwater before being supplied to the heat pump, and heats the groundwater before being supplied to the heat pump. The removal system according to any one of the above. Pumping groundwater containing volatile substances;
Heating the pumped groundwater with a heat pump;
By bringing air into contact with the groundwater heated by the heat pump, the volatile substances contained in the groundwater are transferred to the air to obtain treated water;
A method for removing volatile substances in groundwater.

Images