Cleaning and liquid contact with solids – Processes – Including application of electrical radiant or wave energy...
Patent
1998-03-06
2000-01-11
Gulakowski, Randy
Cleaning and liquid contact with solids
Processes
Including application of electrical radiant or wave energy...
134226, 134 30, 134 34, 134 37, 134 42, 422 21, B08B 704, A61L 200, A61L 212
Patent
active
060131373
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process and a device for treating screenings from the mechanical cleaning stage of a sewage treatment plant.
The screenings arising at the end of a mechanical cleaning stage of a sewage treatment plant are often infected with bacteria and viruses. These screenings therefore have to be disinfected, so that no risk to the environment, in particular to humans, occurs in the following treatment stages or in the case of landfill.
PRIOR ART
In order to disinfect screenings, it is known to use chemical agents, but this gives rise to the problem of how these agents can be mixed with the screenings without great outlay on apparatus. There are therefore always areas in which the chemical agents do not act on the screenings, and thus in these areas there is inadequate disinfection with the inherent hazard potential. However, admissible mixing may be achieved only with a great deal of outlay, which is generally not tolerable.
DESCRIPTION OF THE INVENTION
The present invention is based on the technical problem or, respectively, the task, proceeding from the cited prior art, of specifying an improved process and an improved device for treating screenings from the mechanical cleaning stage of a sewage treatment plant which, with an economically tolerable outlay on apparatus, ensures reliable disinfection as far as the killing of viruses and can be used commercially.
Accordingly, the method according to the invention is distinguished by the fact that, within the framework of a disinfection stage, the screenings have electromagnetic waves in the frequency range between 1 GHz (gigahertz) and 1 THz (terahertz), so-called microwaves, applied to them for a predeterminable period, during or after the treatment the screenings are subjected to an airstream, which results in convective drying of the screenings and the air is guided through in one pass or in a circulation, and the screenings are washed or pressed before the disinfection stage and are dried or compacted after the disinfection stage. In this case, the application takes place at the end of the cleaning stage, screenings themselves are disinfected and the water which is present at the start of the cleaning stage in the sludge/solid mixture is not simultaneously disinfected, since the "biology" present in this water is intended to be retained for the further sewage treatment process. The drawing process leads to a reduction in weight of the screenings that subsequently have to be transported further. Furthermore, the dry screenings lead to lower contamination of equipment coming into contact with the screenings following the drying.
Use is preferably made of microwaves which lie in the frequency range between 2.425 and 2.475 GHz (gigahertz), this range also commonly being used in a microwave cooker. During the disinfection operation, the screenings are heated by the action of the microwaves in a cavity formed by a housing, the microwaves being fed into the cavity resonator by a magnetron. As a result of dielectric losses in the screenings, energy is taken from the microwave field and the screenings are consequently heated, which results in the killing of viruses at sufficiently high temperatures.
A preferred design variant, which is used advantageously in particular with respect to a favorable energy balance, is distinguished by the fact that, in a heating-up phase, the screenings have a magnetic field with a high energy density applied to them and, in a heat-maintaining phase, have a magnetic field with a lower energy density applied to them.
The device according to the invention for treating screenings from the mechanical cleaning stage of a sewage treatment plant, having a screenings inlet area and a screenings outlet area, is distinguished by the fact that a device generating electromagnetic waves, a so-called microwave device, is provided, which generates electromagnetic waves in the frequency range from 1 GHz (gigahertz) to 1 THz (terahertz) and applies these to the screenings for a predeterminable period,
REFERENCES:
patent: 3523076 (1970-08-01), Goerz et al.
patent: 3670891 (1972-06-01), Allen
patent: 4565669 (1986-01-01), Collins et al.
patent: 4631133 (1986-12-01), Axelrod
patent: 5389114 (1995-02-01), Forder
Dictionary of Science and Technology, W & R Chambers, p. 757, 1974.
Egner Umwelttechnologie GmbH
Gulakowski Randy
Markoff Alexander
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