| 摘要 |
PROBLEM TO BE SOLVED: To prevent reduction in efficiency of organic matter decomposition due to dissolved oxygen and increase in biological and sitological toxicity due to an oxidation byproduct(s) from being caused by introducing a liquid to be treated, that contains refractory organic matter, into a treatment vessel and irradiating the introduced liquid with ultraviolet rays while exposing the liquid to an inert gas, to subject the refractory organic substance to oxidative decomposition. SOLUTION: This decomposition process comprises: introducing filtered water 6 containing refractory organic matter to UV irradiation equipment; allowing the filtered water 6 to flow downward within a treatment vessel 14 to expose the filtered water 6 to an inert gas 16 supplied from a gas exposure device 17; and concurrently, irradiating the filtered water 6 with ozonizing rays and other ultraviolet rays, radiated from a UV lamp 18, to volatilize and reduce dissolved oxygen in the filtered water 6, to effect an anaerobic state of the filtered water 6 and thereby to enable irradiation of the filtered water 6 with the ozonizing rays and germicidal rays without causing any consumption of these rays by dissolved oxygen. As a result, the refractory organic substance in the filtered water 6 can efficiently be decomposed by organic matter decomposition reaction such as dehalogenation, that is caused with the ozonizing rays. The UV-treated water 8 is allowed to flow out from the lower part of the treatment vessel 14 and recycled to the upper part of the treatment vessel 14, to retain the filtered water 6 within the treatment vessel 14 for a period of time required for decomposing the refractory organic matter.
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