Chemistry: molecular biology and microbiology – Apparatus – Bioreactor
Reexamination Certificate
1998-05-15
2001-11-20
Redding, David A. (Department: 1744)
Chemistry: molecular biology and microbiology
Apparatus
Bioreactor
C435S293200, C435S297400
Reexamination Certificate
active
06319706
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for remedying medium polluted by a pollutant, and to an apparatus for the same.
2. Description of the Related Art
A large quantity of environmentally unsafe chemical substances have been produced as a result of recent advances in technology. Environmental pollution by chemical substances is a globally serious problem, since water and air can circulate throughout the world. As examples of well-known pollutants, there may be mentioned halogenated aliphatic hydrocarbons (e.g., dichloroethylene (DCE), trichloroethylene (TCE), tetrachloroethylene (PCE) and dioxin), aromatic compounds (e.g., toluene, xylene and benzene), crude petroleum, gasoline and the like. By way of illustration, dichloroethylene, trichloroethylene, tetrachloroethylene and other halogenated aliphatic hydrocarbons have been employed in large quantities as solvents for cleaning of precision parts or for dry cleaning. It has been established that these substances leak into soil and pollute the soil and underground water. Since these pollutants are highly volatile in general, they are also considered to cause air pollution. In addition, they may seriously affect the biotic kingdom, since it has been recently revealed that such pollutants are carcinogenic and teratogenic. Accordingly, there is a demand to develop, promptly, technologies for remedying polluted media such as soil, air and water.
As one possible solution for the aforementioned problems, the technique to decompose pollutants with the aid of microorganisms has been advanced. As microorganisms having decomposing activities for TCE, there have been reported, for example, the following microorganisms.
Welchia alkenophila
sero 5 (ATCC 53570; U.S. Pat. No. 4,877,736),
Welchia alkenophila
sero 33 (ATCC 53571; U.S. Pat. No. 4,877,736),
Methylocystis sp. strain M (Agric. Biol. Chem., 53,2903(1989); Biosci. Biotech. Biochem., 56,486(1992); ibid. 56,736(1992)),
Methylosinus trichosprium
OB3b (Am. Chem. Soc. Natl. Meet. Dev. Environ. Microbiol., 29,365(1989); Appl. Environ. Microbiol., 55,3155(1989); Appl. Biochem. Biotechnol., 28,877(1991); Japanese Patent Laid-open No. 2-92274; Japanese Patent Laid-open No. 3-292970),
Methylomonas sp. MM2 (Appl. Environ. Microbiol., 57,236(1991)),
Alcaligenes denitrificans
subsp.
xylosoxidans
JE75 (Arch. Microbiol., 154,410(1990)),
Alcaligenes eutrophus
JMP134 (Appl. Environ. Microbiol., 56,1179(1990)),
Mycobacterium vaccae
JOB5 (J. Gen. Microbiol., 82,163(1974), Appl. Environ. Microbiol., 55,2960(1989) ATCC 29678),
Pseudomonas putida
BH (Journal of the Japan Sewage Works Association, 24,27(1987)),
Pseudomonas sp. strain G4 (Appl. Environ. Microbiol., 52,383(1986); ibid. 53,949(1987); ibid. 54,951(1988), ibid. 56,1279(1990); ibid. 57,1935(1991); U.S. Pat. No. 4,925,802; ATCC 53617; this microorganism was first classified into
Pseudomonas cepacia
, but reclassified into Pseudomonas sp.),
Pseudomonas mendocina
KR-1 (Bio. Technol., 7,282(1989)),
Pseudomonas putida
F1 (Appl. Environ. Microbiol., 54,1703(1988), ibid. 54,2578(1988)),
Pseudomonas fluorescens
PFL12 (Appl. Environ. Microbiol., 54,2578(1988)),
Pseudomonas putida
KWI-9 (Japanese Patent Laid-open No. 6-70753),
Pseudomonas cepacia
KK01 (Japanese Patent Laid-open No. 6-227769),
Nitrosomonas europaea
(Appl. Environ. Microbiol., 56,1169(1990)), and
Lactobacillus vaginalis
sp. nov. (Int. J. Syst. Bacteriol., 39,368(1989), ATCC 49540) and so on.
A practical example of a technique for decomposing pollutants and hence remedying media with the aid of such a microorganism includes the process of contacting the microorganism with a pollutant.
Decomposition of pollutants in media with the aid of microorganisms is not as yet a completely satisfactory technique. To be more specific, it is hard to decrease, for example, the trichloroethylene concentration in groundwater to below the environmental quality standard (0.03 &mgr;g/ml) in Japan in 1997, and even if possible, it takes a relatively long time for such reaction. To further enhance decomposition of a pollutant by a microorganism, techniques are required for improving decomposition efficiency on the pollutant or for shortening the required period of time for the microorganism to decompose the pollutant.
The present inventors have found that since a microorganism is damaged by an intermediate product or the like formed during decomposition of a pollutant, and its decomposition activity for a pollutant decreases with prolonged contacting time with the pollutant, such a microorganism requires a longer reaction time to decompose the pollutant lower to a given concentration. To further efficiently remedy a medium containing a pollutant in a concentration around the environmental quality standard, it is markedly helpful to contact a microorganism having a high decomposing activity for the pollutant.
SUMMARY OF THE INVENTION
The present invention has been completed based upon the above findings. It is, therefore, a principle object of the invention to provide a more efficient process of remedying a medium containing a pollutant and an apparatus used for the same.
It is another object of the present invention to provide a more efficient remedying process for a polluted soil.
To accomplish the above-mentioned objects, the present invention provides, in one embodiment, a process for remedying a polluted medium comprising the steps of:
(a) providing a membrane between a first medium containing a pollutant and a second medium containing a microorganism capable of decomposing the pollutant, the membrane permeable to the pollutant and impermeable to the microorganism; and
(b) transporting the pollutant from the first medium to the second medium through the membrane to permit the microorganism to decompose the pollutant.
In a second embodiment, the invention includes a process for remedying soil polluted with a pollutant comprising the steps of:
(a) providing an apparatus comprising (i) a tubular case having openings at each end thereof for transporting a first medium containing the pollutant and (ii) a tubular member for transporting a second medium containing a microorganism capable of decomposing the pollutant, the tubular member having an outer wall composed of a membrane permeable to the pollutant and impermeable to the microorganism and being spaced in the tubular case to interpose the membrane between the first medium and the second medium;
(e) embedding the apparatus in the soil containing the pollutant;
(c) conducting the pollutant from the soil into the tubular case through one of the openings; and
(d) introducing the second medium containing the microorganism into the tubular member, whereby the pollutant passes through the membrane to be decomposed by the microorganism.
In an additional embodiment the invention includes an apparatus for remedying a polluted medium comprising a housing having (a) a first passage for a first medium containing a pollutant; (b) a second passage for a second medium containing a microorganism for decomposing the pollutant, the second passage in fluid communication with the first passage; and (c) a membrane permeable to the pollutant and impermeable to the microorganism interposed between the first and second passages.
In yet another aspect the invention provides for a process for remedying a polluted medium comprising the steps of:
(a) providing a membrane between a first medium containing a pollutant and a second medium containing a microorganism capable of decomposing the pollutant, the membrane permeable to the pollutant and impermeable to the microorganism; and
(b) transporting the pollutant from the first medium through the membrane to the second medium to permit the microorganism to decompose the pollutant, wherein the transporting step is conducted by providing a flow of the first medium in an opposite direction to a flow of the second medium.
Finally, in an additional embodiment the present invention is directed to an apparatus for remedying a polluted medium comprising a housing having (a)
Imamura Takeshi
Kawaguchi Masahiro
Kuriyama Akira
Sugawa Etsuko
Toge Yoshiyuki
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Redding David A.
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