IE922947A1 - Method for the microbiological cleaning of materials¹containing ordinary and coarse clay and fine particles, with¹the aid of certain loosening agents - Google Patents

Abstract

The invention relates to a process for the microbiological purification of materials which contain usual or coarse clay and finely particulate materials with the aid of loosening agents which, after completion of the purification, can be recovered and, after appropriate pretreatment, can be reused for further purification processes, for which purpose loosening agents are used which are not subject to microbiological attack and degradation, or only to a very slight extent, have a specific surface area as high as possible for processing reasons, are light in order to be easily separable in the float-sink method, have a controllable microporosity which ensures that only small amounts of water or portions of fine matter can be absorbed and nevertheless the microorganisms capable of degradation can be established in the immobilised state.

Description

.Method for the microbiological cleaning of materials ig ordinary and coarse clay and fine -—particles, with the aid of certain loosening agents.

The subject of the present invention ie a method for the microbiological cleaning of materials containing ordinary and ooarse olay and fine part idea, with the aid of loosening agents which can be recovered again at the end of cleaning and, after suitable pretreatment, reused for further cleaning processes.

Materials of the kind mentioned hereinbefore are not to be treated by so-called peroolative methods, because the water permeability or availability is only very low. For this reason, to obtain availability, loosening agents such as bark mulch, sawdust, chopped straw or tha like are added. These additions of course rot during microbiological processes and can thus be put back into natural circulation, but conneoted with the use of them Is the disadvantage that the volumes to be treated increase considerably and hence at the end of cleaning the quantity of material to be dumped or recycled is always greater than the initial quantity of material to be treated.

It ie therefore endeavoured to use loosening agents internal to the process, which oan be recovered again at tha and of cleaning and, after suitable pretreatment, oan be reused for further cleaning processes.

It is further known that due to the peculiarity of microbiological processes, during cleaning the degradability of specific microorganisms may be subject to negative influences owing to the availability of readily accessible c-souroes. During degradation there are then breaks* of significant time in which the desired degradation of pollutants is interrupted. Instead, the loosening agents are microbiologioally degraded, lose their physical constitution in the process and therefore no longer have a loosening effect. As a result the system clogs up, supply of oxygen and nutrients is no longer possible, and the OPEN TO PUBIJC INSPECTION i SECTION ζλ SiMi·· RULE 23 Γ- 922947 a system con·» to a standstill. The degradation process can then be continued only by renewed loosening and reactivation. This is a very disadvantageous procedure with respect to time and coats, in which degradation does not take place ae desired.

Other methods therefore retort to bioreactors which operate exclusively in the dispersion phase. Materials containing fine and very fine particles are nixed with large quantities of water to for» dispersions or slurries in suitable reactors, e.g. rolling reactors, and pollutant degradation is accomplished by continuous movement while supplying oxygen and nutrient salta. However it turns out that this method is admittedly able to fulfil the desired conditions for microbiological treatment, but the energy input, throughput quantity and other cost parameters leave doubts about the economy of such methods. They are however suitable for use with polycyclic aromatic hydrocarbons which aa a rule are difficult to degrade, and here particularly for those with nuclear fractions > 4. According to present-day knowledge, such materials are accessible to microbiological degradation only by preliminary oxidative degradation with e.g. o3 or H20a/0j techniques, and must therefore be subjected to appropriate treatment beforehand. Oxidation takes place advantageously in the liquid or elurry phase. Ae a result, in cloeed systems association with the toxic osone is to be handled safely and air contamination avoided by appropriate outlet air techniques. Since however the microbiological flora are also considerably reduced or completely destroyed by oxidation, for further treatment there must be added a suitably adapted microorganism population which carries out the necessary pollutant degradation. If then the further procedure takes place as described above, the same restrictions apply with respect to economy and prospects of success.

Starting from thia state of the art, it is the object of the present invention to provide a method for the t. 922947 microbiological cleaning of material· containing ordinary and eoar·· clay and fin· particle·/ with the aid of loosening ag«nts which can be recovered again at th· end of cleaning and/ aft«r suitable pretreatment, reused for further cleaning processes.

This object is aohieved according to th· Invention by the faot that loosening agent· ar· used which: are not aoceesible to any microbiological attack and degradation, or only very little, for reasons of process technology have as large a epeoific •urfaoe area as possible, are light, in order to be easy to separate in sink-float processes/ have controllable microporosity which ensures that only small quantities of water or fine particle fraction· can be absorbed and yet the microorganisms capable of degradation can be settled in the immobilised state* With particular advantage/ polyformaldehyde foams (PF) and/or polyolefin foams (PP/PE), but preferably polyurethane foams (PUR), divided with a particle else distribution necessary for the application, are used as loosening agents for this.

The particular advantage of the loosening agents to be used according to the invention lies in thlt the abovementioned foams are already partly available from recycling processes (refrigerators, insulation). But the most advantageous ie the use of PUR. Due to the high variability in working out the recipe, the good availability, the individually variable density, and the possibility of incorporating epeolflo fillers and favourable adaptation possibilities, after use in microbiological precleaning is favoured by the agents, PUR offers Also reutilisation process·· and after possibility of using glycolysis or alcoholysis, as polyols obtained in this way can be reused as raw materials for PUR foams. a mixture of the above-mentioned foams, which is conceivable in itself, should be confined to case· with extraordinary process advantages, because selective . 92 294 •eparation of th· mixture if not easy and ·ο th· possibility of recycling for PVR i· greatly United. λ preferred embodiment of the method according to the invention proceed· ae follows! After determining the composition of the material with high fine-particle fractions to be treated and the definition of the pollutants to be degraded, first of all in a suitable mixer there is formed from the material and the previously determined necessary amount of process water a slurry dispersion, from which any heavy fractions present suoh as stones or other large-format inclusions can be separated by screening. By outlet air treatment, volatile constituents in this process phase oan be further treated physioally/ohemlcally or mioroblologloally, and so it can be ensured that there is no air contamination. If necessary for reasons of the pollutant composition, the slurry dispersion can now in suitable reactors be subjected to additional chemical or chemioal/physloal pretreatment which oan be made safe by a dosed process system. This means in particular the above-mentioned oxidative pretreatment with o3 or H3C2 for the degradation of polynuclear polycyclic aromatic hydrocarbons.

Outgoing air which is produced can be posttreated by adsorption, desorption, thermal or microbiological methods, the nature and quantity of whioh are determined by the respective contamination.

In a further step, the elurry dispersion after analytical testing is mixed with the optionally mlerebiologleally pretreated loosening agent, in a mixer, slurry dispersion is added to the loosening agent over a period of time until a moist but still free-flowing cavity-forming mass is produced. This can be produoed both discontinuously and continuously. The mass is dumped in beds or stacks for further microbiological treatment. Depending on process requirements, aeration, watering or heating may be provided. After the microbiological treatment, the mass nixed with the loosening agent ie mixed in a mixing device with bo much process water that the loosening agent le cleaned of adherent fine and very fine particle fractions in turbulent flow* The loosening agent which floats to the top is removed, and the remaining slurry ia drained end taken to the dump· This process can be repeated. For treatment of the process water, membrane or ultrafiltration oan be used, ao that only email quantities of fresh water ere needed for cleaning. ^particular advantage of this method lies in that the loosening agents are pretreated with pollutant-degrading microorganisms. As a result, pollution degradation begins already after a short time, and the decontamination time le kept short.

After degradation of the pollutant, for removal of the loosening agent vhioh readily floats to ths top the latter is removed in a water/ so lids dispersion by the sink-float or other separating method, and is available again after cleaning or a chemical recycling process.

Claims (11)

1. l. Method for the microbiological cleaning of material· containing ordinary and ooaree clay and fine particle·, with the aid of loosening agent· which can be recovered •gain at the end of cleaning and, after suitable pretreatment, reused for further cleaning processes, character lead in that looeenlng agent· ere used which: are not accessible to any microbiological attack and degradation, or only very little, for reason· of process technology have ae large a epeoific surface area as possible, are light, in order to be easy to separate in eink-float processes, have controllable microporoeity which ensure· that only small quantities of water or fine particle fractions can be absorbed and yet the microorganism· capable of degradation can be settled in the immobilised state.

2. Method according to claim 1, characterised in that polyformaldehyde foams and/or polyolefin foams, but preferably polyurethane foame, divided with a partiole site distribution necessary for the application, are used as loosening agent·.

3. Method for the microbiological cleaning of materials containing ordinary and ooaree olay and fine particles, with the aid of loosening agents according to claim l or 2, characterised in that in a firet step a slurry dispersion is formed in a suitable mixer from the material with a high fine-partiole fraction to be treated and process water, and in a eeoond step slurry dispersion ie added to the loosening agent in a suitable mixer until · moist but etill free-flowing cavity-forming maes ie produced, which is dumped in beds or stacks for further microbiological treatment. Γ 92 294 7 »

4. Method according to claim 3, characterised in that during formation of the slurry dispersion, any heavy fractions present suoh as stones or other large-format inclusions are separated.

5. Method according to claim 3, characterised in that during formation of the slurry dispersion, there is outlet air trjeatment by vhioh volatile constituents are further treated physically/chemically or microbiologically.

6. Method according to claims 3 to 5 or any thereof, characterised in that the slurry dispersion in a rsaotor is subjected to additional chemical or ohemioal/physical treatment.

7. Method acoording to claim 6, characterised in that treatment with 0 3 or h 2 o 2 takes place.

8. Method according to claim β or 7, characterised in that outlet air produced during treatment is posttreated by adsorption, desorption, thermal or microbiological methods.

9. » Method according to claims 3 to 8 or any thereof, characterised in that after the microbiological treatment, ths mass mixed with the loosening agent is mixed in a mixing devioe with so much process water that the loosening agent ie cleaned of adherent fine and very fine particle fractions in turbulent flow and the loosening agent which floats to the top is removed.

10. Method according to claim 9, characterised in that the prooase water is treated by membrane or ultrafiltration. 922947' -8

11. Method according to claim 1 for the microbiological cleaning of materials containing ordinary and coarse clay and fine particles, substantially as hereinbefore described.