Liquid purification or separation – Processes – Treatment by living organism
Patent
1998-09-28
2000-07-25
Wyse, Thomas G.
Liquid purification or separation
Processes
Treatment by living organism
210770, 210806, C02F 1116, B09B 300
Patent
active
060933232
DESCRIPTION:
BRIEF SUMMARY
The invention deals with a process for the separation of a mixture of waste.
Mixtures of waste have to be separated in order to be able to dispose of the various fractions in an appropriate manner. The object of the separation processes to be applied consists of separating the mixture into individual types of substances, as far as possible. However, waste mixtures are from this aspect extremely difficult mixtures of substances. The constantly changing composition of waste calls for processes which make it possible to grade the heterogeneity of the multi-substance mixture "waste" before separating it. Processes have proved themselves which differentiate according to the substance density, whereby the transport media can be gases or liquids.
The so far known processes and devices become more expensive as the required degree of purity of the substances to be separated increases. The use of substances is restricted by the degree of purity of the substance and the market price which can be obtained in competition with fresh raw materials.
When treating municipal waste, residual fractions remain which have to be either taken to a refuse tip or incinerated and taken to a tip. According to future regulations, disposal on refuse tips is subject to a residual organic content of less than 3% in building debris and less than 5% in household refuse. In order to achieve this, a selection of inert substances and the processing of combustible substances have to be effected with the existing emission risks of erosion which also exist here.
The up to now practised biological-mechanical treatment of waste following elimination of usable substances by separate collection is intended largely to reduce the organic substances in the waste in order thus to approach the required values of 3% respectively 5% residual organic substances. However, this results in plants requiring considerable space, because the biological decomposition of organic substances which are hard to degrade only takes place very slowly (6 to 8 months) and the waste throughout this period is subject to technical checks and control. This is followed sometimes by a separation of substances with the aid of known sorting processes in a moist state (approximately 35%).
W L B Wasser, Luft und Boden, Nov. 12, 1995, page 60, shows a process for the mechanical-biological waste treatment using waste of organic content. This is a dynamic process of mechanical-biological, aerobic waste treatment operating by a multi-stage intensive rot in a rot drum.
DE-OS 44 34 611 discloses a process for biological mechanical treatment of waste by which the refuse supplied is screened, broken up and homogenised. The refuse is then subjected in a rot to a biological decomposition process. Following rotting, the rotted product is separated into an organic and an inorganic fraction.
DE-PS 32 48 494 discloses a process for the production of a fuel for a refuse incinerator plant. In order to render possible the production of a fuel free from harmful substances and of improved calorific value, household refuse is divided in a first screening drum into overflow and substances passing through the screen. The overflow is subjected to a metal separation. Following composting in a bioreactor, the substances having passed through the screen are separated in a second screen drum into a fine fraction obtained as compost and an overflow.
The problem to be solved by the invention consists of proposing processes of the above mentioned type which ensure that non combustible substances contained in waste do not reach an incinerator plant and are not taken to a refuse tip whilst containing more than 3% respectively 5% organic substances.
According to a first proposal, this problem is solved as follows. If applicable following breaking up and/or homogenisation, the mixture is treated biologically ie composted and/or stabilised under forced ventilation. This takes place preferably in a closed container. Following this, the components of the mixture thus treated are separated into a combustible fraction and
REFERENCES:
patent: 3847803 (1974-11-01), Fisk
patent: 4053394 (1977-10-01), Fisk
patent: 4159944 (1979-07-01), Erickson et al.
patent: 5531898 (1996-07-01), Wickham
WLB Wasser, Luft und Boden, Mechanisch-biologische Abfallbehandlung mit kalter Rotte; Nov.-Dec. 1995, p. 60.
T. Obermeier, "Abfallwirtschaftskonzept fur Berlin und sein Umland", Muell und Abfall., Bd. 22, No. 12, Dec. 1990, Berlin, Germany, pp. 753-765.
Herhof Umwelttechnik GmbH
Wyse Thomas G.
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