Liquid purification or separation – Processes – Treatment by living organism
Patent
1997-08-04
1999-09-07
Woo, Jay H.
Liquid purification or separation
Processes
Treatment by living organism
210615, 210631, 210682, 210688, 210723, 210805, 2101951, 210199, 210206, 210912, 423 2, 588 20, C02F 1102
Patent
active
059482591
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a process and apparatus for treating oils and solvents contaminated by radioactive substances.
2. Description of the Prior Art
Spent oils and solvents are treated by burning or by the action of pre-selected micro-organisms to decompose them into intermediate products and/or into simple substances, some of which naturally reform into CO.sub.2 and H.sub.2 O.
In general, these micro-organisms react in the presence of a very large quantity of water and in the presence of oxygen, the ratio between the respective volumes of water and of oil being about 100/5 (20/1).
Thus for a "black tide", spreading micro-organisms over the surface of the sea covered with petroleum products to decompose those products is known in itself: the volume of water and the oxygen content of the water broadly comply with the above conditions.
Using water treatment plant to treat oily water containing much less than 5% by volume of oil using micro-organisms is also known in itself.
In those two cases and in numerous other cases known in themselves, the quantity of water relative to the volume of oils or solvents to be treated is so far in excess and any by-products of such a decomposition of oils and solvents are so diluted and eliminated as they are created that there is no concern about such by-products.
In contrast, oils and solvents which are contaminated with radioactive substances are subject to regulations which are becoming more and more strict and which proscribe contamination of the atmosphere or waste water removal systems to prevent dispersion into the environment of radioactive substances which such oils and solvents contain.
Thus nuclear power stations in France and in other countries are storing increasing volumes of contaminated oils and solvents which have to be stored until a solution is found which satisfies the regulations currently in force for their treatment.
The aim of the present invention is to overcome the disadvantages of known processes and apparatus and to provide a process and an apparatus for treating oils and solvents which are contaminated with radioactive substances, the process and apparatus being adapted to allow discharge into the atmosphere or into collecting systems of air and water having characteristics which satisfy the requirements of the current regulations, the radioactive substances being collected in a very small volume of waste products which is easy to treat and store to prevent any contamination of the environment.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention, a process for treating oils and solvents contaminated by radioactive substances includes a step of subjecting the oils and solvents to the action of pre-selected micro-organisms in the presence of air and a very large volume of water, relative to the volume of oils and solvents to be treated, the micro-organisms being adapted to destroy organic molecules, in particular to transform them into CO.sub.2 and H.sub.2 O.
In accordance with the invention, this process further includes the following steps: characteristics of dissolved oxygen concentration, pH and redox potential; radioactive substances to this volume of water, the charge corresponding to a volume of oils and solvents which is a predetermined fraction of the predetermined volume of water; predetermined temperature and for a predetermined time period; water; effluent have been removed, so that it regains the predetermined characteristics;
While processes known in themselves can treat small quantities of non-radioactive oils and solvents in the presence of a large volume of water, the by-products of the treatment give no cause for concern, being in any case sufficiently dilute for the regulations to be satisfied, it is possible to recycle at least a portion of the water produced by decomposition of the oils and solvents provided that it is regenerated so that it continuously regains the conditions of step a).
Operating on a pilot scale, the present inventor has reco
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Deguitre Joanes
Stingre Maurice
Morrison Betsey J.
Richmond Agency Limited
Woo Jay H.
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