Liquid purification or separation – Processes – Utilizing electrical or wave energy directly applied to...
Patent
1997-02-28
1999-08-03
McCarthy, Neil
Liquid purification or separation
Processes
Utilizing electrical or wave energy directly applied to...
210192, 2101981, 210205, 422 24, 4221863, C02F 132, C02F 148, C02F 172
Patent
active
059321113
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an apparatus, and aspects thereof, for the decomposition of organic materials, for example for the treatment of organic solutions, liquids containing waste organics rendered unsuitable for discharge in effluent and particularly, but not exclusively, for the purification of waste containing organic residues or compounds in the free phase or in aqueous solution.
For the avoidance of doubt, the apparatus of the invention relates to and can be applied to the disinfection of water with respect to particular end-users, for example it can be applied to the removal of micro-organisms such as bacterial pathogens from water supplies.
Waste organic liquids either in the free phase or in solutions, aqueous or otherwise, are a necessary by-product of many operations in chemical, nuclear and related industries. Their disposal is increasingly becoming a problem as traditional methods of disposal, for example, incineration, land fill, discharge to sewer etc become unacceptable with increasingly stringent environmental protection legislation.
For example, a large amount of industrial waste contains contaminants or pollutants such as organic residues and organic or inorganic electrolytes either in the free phase or in aqueous solution. The costs of cleaning such waste using traditional technologies such as extraction and combustion are very high. Moreover, stringent environmental protection legislation dictates the levels of acceptable effluent discharge and so the degree to which waste must be cleansed before it can be released into the environment. More recently, the Biological Oxygen Demand quotient has been replaced by the Total Organic Content quotient and thus the emphasis has been switched from monitoring the viable organic content of an effluent to the non viable, or synthetic organic content of an effluent. There is thus a need to provide an apparatus which cost effectively removes, at least, the organic contaminant from an effluent to such an extent that acceptable TOC values are provided, and also ideally destroys microorganisms such as bacteria and protozoa, including developmental stages of such organisms.
It is also significant to note that organic compounds tend to complex with other agents and therefore the removal or breakdown of organic compounds is a prerequisite to the removal or extraction of said agents. For example, the removal of heavy metals and radionuclides is effected using conventional techniques such as biodegradation, precipitation, ion-exchange, or evaporation, after heavy metals and radionuclides have been separated from organic complexing agents.
There are a number of methods currently available for the removal of organic contaminants.
For example, oxidation of the organic contaminant, either biologically or chemically using an oxidising reagent (such as chlorine, ozone, hydrogen peroxide, potassium permanganate etc) can be undertaken. Although biological treatment is widely used it is ineffective against those contaminants which are not easily oxidised or those contaminants which are too toxic for a biological species to be employed. The use of oxidising reagents is less favoured because the agents tend to be expensive and can produce unwanted intermediates which themselves require treatment.
An alternative method concerns photolysis, that is irradiation of a solution with UV or short wave length visible light. Unfortunately, this technique has limited use on a wide range of contaminants and is also a relatively slow process because of the nature of the reaction rates involved.
Alternatively, photo-oxidation can be practised. This is essentially a combination of the above two mentioned methods. In this process, contaminated aqueous solution is simultaneously dosed with oxidising reagents and irradiated with UV or short wavelength visible light. Typically, there is a synergistic effect and the oxidising rates achieved are thus dramatically increased. However, in general, the technology is expensive and can produce intermediates which are themselves contaminants and
REFERENCES:
patent: 5151252 (1992-09-01), Mass
patent: 5364508 (1994-11-01), Weres et al.
Christensen Paul A.
Hutson Graham V.
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