JP4458469B2 - Anaerobic microorganism collection device and collection method - Google Patents

Description

  The present invention relates to an apparatus capable of accumulating and collecting anaerobic microorganisms living in the ground without changing the environmental conditions of the underground, and a collection method using the same. This technique is particularly effective for laboratory tests for evaluating the purification effect of bioremediation.

  In the past, physical techniques such as groundwater pumping treatment were common as technologies for remediating the environment by remediating soil and groundwater contamination by organochlorine compounds (such as trichlorethylene and tetrachlorethylene, or various organic solvents). Bioremation promotion technology is being used frequently. This is a technology for purifying pollution in situ by injecting a nutrient source (for example, an electron donor) of underground microorganisms into the ground to activate a natural purification function by local anaerobic microorganisms. In practice, a method is adopted in which groundwater is pumped up at a contaminated site, a nutrient source is dissolved therein, and natural injection or pressurized injection is performed from an injection well (for example, see Patent Document 1).

  In order to increase the purification effect in the bioremediation promotion technology, it is necessary to select an appropriate nutrient source type according to the contamination status and to inject an appropriate amount into the ground. Conventionally, the type and amount of nutrients are determined empirically based on past construction results, but the purification effect as expected is not always obtained. The reason is that soil and groundwater pollutants, pollution status, anaerobic microbe habitat status, etc. are various, and it is not possible to quantitatively evaluate the types and amounts of nutrient sources suitable for them.

  Therefore, the bioremediation effect confirmation test is currently being evaluated mainly by installing a pilot plant locally and injecting nutrient sources. This is because organochlorine-degrading microorganisms vary depending on the pollutant, and very few species of microorganisms may be involved in purification, so it is thought that proper evaluation cannot be made even if a small amount of groundwater is collected. . However, this method is very large, and there are problems that it takes cost and time to grasp the injection amount and the number of days until the purification effect appears, and the efficiency is low. Moreover, it is unclear what kind of microorganisms should be activated, what kind of nutrients should be injected at what rate (rate and concentration), and trial and error. I must. Depending on the nutrient source to be input and its amount, it is possible that microorganisms other than the target will propagate and the target microorganisms may be inhibited from growing.

In consideration of such circumstances, it has been attempted to collect soil by boring and perform an indoor test using the extract, but it is difficult to collect a boring core in an airtight state. Therefore, even if this method can be implemented, it becomes very expensive. In addition, when collecting a limited amount of soil, the amount of microorganisms contained is small, so that appropriate evaluation cannot be performed.
JP 2003-251331 A

  The problem to be solved by the present invention is that an environment in which local anaerobic microorganisms inhabit can be brought into the room in a state where microorganisms are accumulated, and an anaerobic culture test can be easily performed. That is.

  The present invention comprises a pump for pumping up ground water, a water quality check unit for confirming that the pumped-up ground water is in an anaerobic state, and a first filter medium through which the pumped-up ground water is passed. A microorganism collecting unit for collecting, and a microorganism collecting unit for backwashing and collecting the microorganisms accumulated on the first filter medium by the microorganism collecting unit by backwashing with the ground water, and the microorganism collecting unit includes groundwater in which microorganisms are concentrated. , A drain line connected to the container, and a second filter medium incorporated in the drain line to prevent outflow of microorganisms, the container being airtight with respect to the microorganism accumulation part An anaerobic microorganism collecting apparatus characterized in that it can be separated as it is.

  Here, the container of the microorganism recovery part is a culture container, and the culture container is equipped with a flexible bag for adjusting internal pressure filled with an inert gas, a sampling means, and a nutrient source injection device Is preferred.

  In addition, the present invention uses such anaerobic microorganism collection device, first tests the groundwater pumped up in the water quality check unit to confirm that it is in an anaerobic state, then uses the pumped groundwater to collect the microorganism accumulation unit and microorganism recovery. The inside of the section is washed and filled, and then the groundwater pumped up is passed through the microorganism accumulation section to accumulate microorganisms on the first filter medium, and the first filter medium is backwashed with the groundwater pumped up. It is a method for collecting anaerobic microorganisms, wherein the microorganisms accumulated on the filter medium are transferred to a container. Thereafter, when culturing is performed, a container separated from the microorganism accumulation part is used as a culture container, and a nutrient source of microorganisms (for example, an electron donor or an inorganic salt) is injected from an injection device.

  According to the present invention, anaerobic microorganisms that inhabit the ground contaminated with organochlorine compounds can be collected and collected as they are, can be brought into the room as they are, and anaerobic culture can be easily performed. This makes it possible to determine the type and amount of nutrients required for decontamination using bioremediation promotion technology, estimate the time required for removal, and accumulate costs, and carry out environmental remediation work based on this to minimize It is possible to obtain the maximum decontamination effect with a limited period and cost.

  FIG. 1 is a schematic diagram of an anaerobic microorganism collecting apparatus according to the present invention, which is an example to which a function capable of easily performing a culture test is added. This device draws groundwater by using a borehole formed in the ground and collects microorganisms, and is installed near the hole at the current position. This anaerobic microorganism collecting device includes a pump 12 that pumps ground water using the borehole 10, a water quality check unit 14 for confirming that the pumped ground water is in an anaerobic state, and a first passage through which the pumped ground water passes. The filter medium 16 and the microorganism collecting part 18 for collecting microorganisms with the first filter medium 16, and the microorganism collecting part 18 collecting the microorganisms collected on the first filter medium 16 by backwashing with the ground water. The microorganism collecting unit 20 is provided.

  The water quality check unit 14 includes a pH sensor 22, an oxidation-reduction potential (ORP) sensor 24, an electrical conductivity (EC) sensor 26, a dissolved oxygen amount (DO) sensor 28, and the like, and switches the water pumped up by the pump 12. The flow path is changed by V1, and it is configured to be guided to these sensors for measurement. This makes it possible to confirm that the groundwater pumped up is anaerobic water. Although four types of sensors are incorporated here, it is not always necessary to provide all of them, and other sensors may be incorporated.

  The microorganism accumulation unit 18 includes a first filter medium 16 for collecting microorganisms through a relatively large amount of groundwater pumped up. In addition, some switching valves V1 to V6 for switching the flow path are provided. Since the microorganisms collected here have a size of 0.3 μm or more, a filter medium having a filtration performance lower than that (for example, 0.22 μm) is used. By changing the flow path so as to pass through the switching valves V1, V2, V3, V4, and V6, and passing water of about 100 liters, microorganisms in the groundwater are accumulated on the first filter medium 16 and drained. . Further, the flow path is changed so as to pass through the switching valves V1, V2, V6, V4, and V5, and water is passed in the reverse direction with respect to the first filter medium 16, and the vibrator 22 transmits the first filter medium 16 to the first filter medium 16. Microorganisms are discharged by applying back vibration and backwashing the pumped-up groundwater.

  The microorganism collection unit 20 is incorporated in a culture vessel 30 that collects microorganisms discharged by backwashing the first filter medium 16 with ground water, a drain line 32 connected to the culture vessel 30, and the drain line 32. And a second filter medium 34 that prevents the outflow of microorganisms. The culture vessel 30 has an airtight structure in which, for example, a stainless steel vessel body and a lid are combined. The culture vessel 30 can be separated from the microorganism accumulation part 18 in an airtight state. For this purpose, the water stop valves 36 and 38 are provided at the connection part to the microorganism accumulation part 18 and the drain line 32, respectively. It has been incorporated. The second filter medium 34 prevents the microorganisms discharged during backwashing of the first filter medium 16 from being lost from the culture vessel 30 and has a filtration performance equivalent to that of the first filter medium 16. Use things.

  A flexible bag 42 can be connected to the culture container 30 via a shut-off valve 40. The flexible bag 42 is a bag-like body made of a sheet in which an aluminum foil is bonded to a synthetic resin film, for example, and has a structure that is filled with an inert gas such as nitrogen gas and can be easily deformed by atmospheric pressure. Thus, even when a part of the groundwater in the culture vessel 30 is extracted, the internal pressure of the culture vessel 30 is automatically adjusted so as to always coincide with the atmospheric pressure. In this embodiment, a liquid extraction port 46 is provided at the lower part of the culture vessel 30 via the water stop valve 44, and an atmospheric gas extraction port 50 is provided at the upper part via the valve 48.

  Further, the culture container 30 is provided with a nutrient source injection device 52. Therefore, if the culture container 30 is separated from the microorganism accumulation part 18, it can be carried indoors and an anaerobic culture test can be performed as it is. A magnet stirrer 54 is placed in the culture vessel 30 in advance so that the inside of the culture vessel 30 can be stirred after collecting groundwater containing microorganisms.

  The operation procedure is summarized as follows. First, by operating the switching valve V1, the groundwater pumped by the pump 12 is guided to the water quality check unit 14, and pH, oxidation-reduction potential (ORP), electrical conductivity (EC), dissolved oxygen amount (DO), etc. are measured. Make sure that the pumped water is anaerobic. Next, each of the switching valves V1 to V6 is operated to wash the entire system (the microbial accumulation unit 18 and the microbial collection unit 20) with the groundwater. In addition, groundwater is also filled into the culture vessel 30 using the bypass channel 60. Then, a flow path that passes through the switching valves V1, V2, V3, V4, and V6 is formed so that the groundwater passes through the first filter medium 16, and microorganisms are accumulated in the first filter medium 16. For example, about 100 liters of water is passed to collect microorganisms. Then, the flow path which passes along switching valve V1, V2, V6, V4, V5 is formed, the 1st filter medium 16 is back-washed with the pumped-up groundwater, The collected microorganisms are sent to the culture container 30, and are collect | recovered. At the time of collection, the first filter medium 16 is vibrated by the vibrator 22 to increase the collection efficiency. At this time, the groundwater is discharged from the drainage line 32 of the culture vessel 30. Since the second filter medium 34 is incorporated in the drainage line 32, microorganisms do not flow out together with the drainage. In this way, anaerobic microorganisms can be collected and collected in an airtight state.

  The culture vessel 30 can be separated from the microorganism accumulation unit 18 by closing the water stop valves 36 and 38 and can be carried into the room as it is. A flexible bag 42 filled with nitrogen gas is attached to the culture vessel 30 from which microorganisms have been collected, and the valve 40 is opened. As a result, when the sample water is withdrawn from the liquid extraction port 46 of the culture vessel 30, the internal pressure of the culture vessel 30 is always adjusted to be the same as the atmospheric pressure, so that the operation is easy and the structure of the culture vessel 30 The degree of freedom in selecting materials and materials increases.

  For example, the test water is extracted so that a space of about 20% is formed in the culture container 30, the nutrient source is dissolved with a part of the test water, and the anaerobic state is used. inject. Use the remaining sample water to identify and quantify microorganisms. After injecting the organochlorine compound into the culture vessel 30 (the groundwater contains an organochlorine compound, but adjust it so that sufficient measurement sensitivity is obtained if the amount is small), the same temperature as the groundwater ( For example, the culture is stirred at 20 ° C. Then, the material balance of the organochlorine compound (decomposition state) is measured periodically to determine the period until complete purification.

  In this way, anaerobic microorganisms that inhabit the ground contaminated with organochlorine compounds can be collected and collected in that state, and can be simply anaerobically cultured. This makes it possible to integrate the type and amount of nutrient sources necessary for decontamination, and the period and cost required for removal.

Using the above equipment, microorganisms that live in the field are collected and collected in culture vessels, and nutrients are administered to activate the microorganisms collected in the field. It verified with. Here, the microorganism to be cultured is an anaerobic microorganism. The water quality at the sampling point used in the experiment is as follows.
・ PH: 5.67
・ Redox potential: 244mV
-Electrical conductivity: 18.69 mS / m
・ Amount of dissolved oxygen: 0.28 mg / l

  Here, the culture temperature was about 20 ° C., which is approximately equal to the temperature of groundwater. As a nutrient source, a commercially available electron donor was used. This electron donor is a substance that activates microorganisms such as carbohydrates made from food materials. This is because it is decomposed into carbon dioxide and water by indigenous microorganisms that are generally present in contaminated groundwater, and is safe and does not contaminate groundwater. Measurement items were TCE (trichloroethylene), DCE (dichloroethylene), and the like, and in principle, measurement was performed once a day. The test cases are the three cases shown in Table 1. The analysis of TCE was performed by the headspace GC-MS method by collecting 0.4 ml of test water from the culture vessel to make a total volume of 10 ml (25 times). The initial concentration was adjusted so that sufficient detection sensitivity was obtained at this time.

  A flexible bag filled with nitrogen gas is attached to the culture container, and 200 ml of local groundwater collected in the culture container is extracted with an injection device. Among them, a predetermined electron donor is dissolved in 100 ml, and after anaerobic state with an injection device, it is injected into the culture vessel. The remaining 100 ml is used for water quality analysis. Then, a predetermined amount of TCE is injected into the culture vessel. Then, culture | cultivation is started in a 20 degreeC thermostat, and a measurement is performed once a day.

  An example of the test results is shown in FIGS. FIG. 2 shows the daily change of the TCE concentration, and FIG. 3 shows the daily change of the Cis-DCE concentration.

  In Case 2, the TCE concentration decreased sharply from around the 15th day of culture, and after 23 days, the concentration became 1/100 of the original level. On the other hand, decomposition components Cis-DCE and 1,1-DCE increased at the same timing. TCE fell below environmental standards 45 days after the start of culture. With respect to DCE, a significant decrease in concentration did not occur, but a tendency to decrease in concentration was observed. From this result, it was confirmed that there were microorganisms effective for purification of TCE.

  In case 1, since no nutrient source (electron donor) is administered, there is almost no change in the TCE concentration. Moreover, in case 3, although the nutrient source (electron donor) is administered, there is almost no change in the TCE concentration. This is thought to be because the microorganisms were killed because the pH was too low (below 5).

  What is important here is that nutrients (electron donors) are administered in case 2 and case 3, but the effects are completely different depending on the administration method. Moreover, the difference in the effect is not known at all at the time of administration, and can be understood only after a dozen days. Moreover, once microorganisms are killed, subsequent purification cannot be performed. By preparing a plurality of culture vessels in which microorganisms are collected according to the present invention in advance and cultivating and analyzing various nutrient sources and how to give them, the optimum conditions for nutrient source administration are minimized when actually performing purification operations. Can be found in the period.

Explanatory drawing which shows an example of the anaerobic microorganisms collection apparatus which concerns on this invention. The graph which shows an example of the daily change of a TCE density | concentration. The graph which shows an example of the daily change of a Cis-DCE density | concentration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Pump 14 Water quality check part 16 1st filter material 18 Microorganism accumulation part 20 Microbe collection | recovery part 30 Culture container 32 Drainage line 34 2nd filter medium 42 Flexible bag 52 Injection | pouring apparatus

Claims (3)

  A pump for pumping up groundwater, a water quality check unit for confirming that the pumped-up groundwater is in an anaerobic state, and a microorganism collecting unit for collecting microorganisms with the first filter medium, the first filter medium passing through the pumped-up groundwater And a microorganism recovery unit for backwashing and recovering the microorganisms collected on the first filter medium by the microorganisms collecting unit, and the microorganism recovery unit is a container for storing the groundwater in which the microorganisms are concentrated And a drainage line connected to the container and a second filter medium incorporated in the drainage line to prevent the outflow of microorganisms, the container being separable from the microorganism accumulation part while being airtight An apparatus for collecting anaerobic microorganisms.   The container of the microorganism collection part is a culture container, and the culture container is equipped with a flexible bag for adjusting internal pressure filled with an inert gas, sampling means, and a nutrient source injection device. Anaerobic microorganism collection device. 3. Using the anaerobic microorganism collecting device according to claim 1, firstly, the groundwater pumped up is tested in a water quality check unit to confirm that it is in an anaerobic state, and then the microorganism accumulation unit is used in the pumped groundwater. Then, the inside of the microorganism collecting part is washed and filled, and then the groundwater pumped up is passed through the microorganism collecting part to accumulate microorganisms on the first filter medium and backwashed with the groundwater pumped up the first filter medium. A method for collecting anaerobic microorganisms, wherein the microorganisms accumulated on the filter medium are transferred to a container.

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