DE2016494A1 - Wastewater treatment - Google Patents

Description

HF 116

Ilerr AZ

Wastewater treatment

The invention "relates to a method" for obtaining "and recovery of the wastewater sludge from wastewater. ■

The wastewater purification was seen as a pressing problem ■ recognized by civilized mankind. Especially in densely populated areas, such as in Europe, sewage pollution is already around it seized that fears even for drinking water needs become loud. The fact that it could come to this is due not least to the fact that wastewater purification costs a lot of money and also that it costs a lot of money Substances removed from wastewater can no longer be recycled. One hardly economically

OPIlQINAl

109846/1460

(HP 116) -2 -

The significant exception "is biologically treated sewage sludge, eggs for loosening soils can be used / grounded. The expensive wastewater treatment has therefore always been treated negligently, until now the contamination the water body calls for vigorous measures. There were also several clarification procedures for Wastewater is known that all actually bring the wastewater into a biologically harmless state however, always leave the question open what should be done with the sludge removed from the wastewater. .

To reduce the mud henge, it is often dried and burned; the incombustible residues, however, as a rule still make up 30 % of the dried hats, which of course have to be put back into place somehow.

The landfill of these dried materials generally fails due to a lack of space or in turn harbors dangers for the water pollution.

A solution to this problem and at the same time a solution which makes the construction of wastewater treatment plants economically more interesting can only be found if the The sludge removed from the wastewater is recycled in a meaningful way.

According to one that does not yet belong to the state of the art Process makes it possible to use fine and superfine fibers synthetically produced materials, such as chipboard, in add about 30% by weight, without including the physical Properties of these substances suffer. However, the large-scale application of this process fails

109846 / 146Ö OHlQlNAL INSPECTiÖ

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economic procurement of the necessary for the process Fine and fine fibers or the expensive, however, necessary accumulation of the for recycling ' necessary substances to these fibers.

The invention "eliminates this tendency and gives" starting "from the substances carried or dissolved in waste water Process how these substances are already in the wastewater necessary additives can be deposited and how from these substances the fibrous end product, which in turn is added to synthetically produced materials " can become, arises.

The procedure is characterized by the following ■ steps:

1. Hechanical size reduction in wastewater. profitability Substances with the simultaneous addition of Oppositely charged ions, which for the end product - desired additives;

2. Blocking of the dissolved substances by destabilizing the dispersion, preferably through metal salts and / or by, polyelectrolytes under simultaneous Addition of ions that are oppositely charged to the dissolved substances and that are desired for the end product Additives;

5. pre-drying; the comminuted or flocculated substances to a moisture content of 60 % by means of a filter device or centrifuge known per se ;;

4. Drying of the pre-dried fabrics to make them blownable Granules with a residual moisture content of 5% by means of drying devices known per se;

5. Defibration of the granules, preferably in the presence of dry powdery desired for the end product Additive substances.

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In addition to the sequence of the individual process steps, new features of the process according to the invention are in particular process steps 1, 2 and 5.

Both in process step 1 - which of course can be omitted if the wastewater does not need to be reduced in size Contains substances - as in process step 2, the shredded or flocculated substances are opposed charged ions of the additives added, which are desired for the end product. This can for example Be plastic dispersions if the end product

is to be further processed in the plastics sector or metals for the defined conductivity of a synthetically produced material and the like. As in general If the wastewater has a pH value below 7, this measure does not only prevent the accumulation the additives achieved in the sense of the process, but also a neutralization of the wastewater, which is only allows the dissolved substances to flocculate. This flake flow can of course be supported by Addition of metal salts known per se or by means of polyelectrolytes, which also have the advantage of that they the thread-like stringing together by main

. and draw out or support IT side ties.

If the wastewater is neutralized, then there is the possibility of reducing the pH value by that a decomposition by slowing down the flow velocity is brought about at temperatures between 10 ° and 35 ° G. With this it is possible to keep the pH value up lower about 5 »5; another humiliation of this The value is because of the then beginning evolution of hydrogen sulfide associated with an extraordinary odor nuisance. Since even up to this value is already disturbing

109846 / U69

OWQINAL

201649A

116). - 5 - '

Make smells noticeable recommends & s to carry out this procedure in a closed container or circulation. At the same time, bacteria or secondary sludge can be added to this primary sludge, whereby the floating constituents of the wastewater are bound and fed to the main mass of the sludge.,

In the last process step takes place again, this time however in the dry way, there is an accumulation of substances that are important for the end product, but that are cannot be deposited on the wet path. This includes, for example, resin that is attached to the fibers Permits the synthetic fabrics to be dry resin or boric acid mixed with chipboard, makes chipboard products made from it incombustible.

The intermediate process steps 3 ″ and 4 are used only the preparation of the sludge so that the process step 5 can be carried out. In particular, the consistency and IT color of the Be adjusted evenly.

The end product of wastewater treated using this process is, on the one hand, pure wastewater that goes without saying in the conventional way and; Way can still be treated, but on the other hand a fibrous one Product that is loaded with various additives or additive materials and fed back into the recycling cycle and, moreover, can cover at least part of the costs of the clarification. This is also an incentive to Work according to this procedure is given, so that financially weak companies or municipalities are also possible, ■ to operate an IC sewage treatment plant reasonably economically.

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As already mentioned, step 1 can then not applicable if no material to be shredded is carried along with the wastewater. Generally this is at Kommixnalsehlämmen not the case, the sewage of municipalities therefore there are crushing facilities in front of the sedimentation basin supplied, which are generally made up of Zerld.einerungspumpen or "arrows" and the like. exist. Because in these facilities a turbulent flow prevails, it is easily possible to introduce the additives here and so with the comminuted substances to bring together that they are sure to attach. This is supported by the fact that many in the crushing Areas become free to which the additive molecules adhere as a result of the van-der-V / aal s - London forces acting there can attach.

To remove the additives with the sludge removed Avoid wastewater can use the additives can also be added to the sludge that has already settled in special spray pumps. In these Ilischpunrpen will also use the mud again if necessary comminuted or frayed, which in turn frees areas whose van der Waals forces cause the additive molecules able to hold.

The "primary sludge" prepared in this way can then be fed directly to a filtering device or a centrifuge or it can also be boiled, as is already done in some sewage treatment plants. Ground when cooking the substances are further opened up so that they can be easily drained. Boiling the primary sludge brings furthermore the advantage that the sludge becomes sterile, so that afterwards not only all pathogenic agents, but also

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the particularly resistant Spulwairmeiea? are destroyed. In addition, the thermiseib. sensitive fabrics destroyed, which in turn the -iederverwerfciang after Procedure is useful as this is highly flammable Substances' could possibly ignore further use.

The method according to the invention is to be demonstrated using the example of wastewater purification and sludge removal from a paper mill's wastewater: the wastewater has a solids content of approx Dye particles and Mneralien composed. Since the treated sludge from this wastewater is to be added to chipboard, in order to make the finished chipboard products flame-retardant, the solid particles of the wastewater must already be provided with flame-retardant additives. For flotation, therefore, milk of lime is preferably added, or else metal salts, which allow the mineral or metal content of the solid particles to be maintained in the desired manner and at the same time destabilize the solution in such a way that flocculation can take place. The wastewater mixed with the flotation agent is fed to a sedimentation basin, in which, with slow movement of the mixture, the wastewater sludge settles on the bottom of the basin ^e are supplied inigung,

The now present sludge with a solid content from about 3 "to 5% is pumped into an oil pump where it again treated according to the later intended use, in any case set in consistency land earbe can be. This setting can of course then

109846/1469

2Ü1649A

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omitted if the paper mill always uses the same papers drives, as a result of which there is always a constant sludge.

The fiber suspension is now fed to a rotary filter which thicken the sludge to a pesticide content of around 40 % .If the product does not get a crumbly shape, a paste former or a similar device can be connected downstream of the rotary filter, which supplies a corresponding starting product.

The unevenly shaped and unevenly large, granulate-like solid bodies that have now formed are fed to a drying device which separates the water down to a residual moisture level of about 5 % . After this processing stage, there are thus solid bodies in granulate form with a moisture content of 5 ° / ° , which consist of cellulose fibers and these accumulated minerals in a ratio of about 60:40. The minerals are selected during the flotation in such a way that they already have a flame-retardant effect and can also partially - in this form, however, only at higher temperatures - form glass flux. However, in order to achieve the flame-retardant effect even at low temperatures, boric acid must be added to the material, which is done in an impact plate mill serving as a grinding and mixing device. The granulate is fed to this impact plate mill precisely dosed together with boric acid, for example in a ratio of 1: 1, so that the end result is a fiber consisting of about 30 parts by weight of cellulose, 20 parts by weight of minerals and 50 parts by weight of boric acid. The boric acid cannot be added to the wet sludge, as it is water-soluble and when it is dried, the water of crystallization, which also causes the flame-retardant effect

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'would give. When grinding the granulate to fibrous However, binding surfaces are freed up again, which are occupied by boric acid particles in the main or secondary valence bond * With a corresponding enlargement, a fiber can actually be recognized, which in its basic structure consists of a cellulose fiber with attached mineral Particles - minerals from papermaking or boric acid deposited - exist.

This end product can now be bagged or stored in silos and then in the production of chipboard 'the chipboard for heavy ·; to be added to make it flammable.

In the example given, process step 1, that is to say the mechanical comminution of Substances carried along in the wastewater are omitted because such 'coarse substances are not to be found here. However, already be Substances added to the wastewater as well as to the still liquid sludge for the later utilization of the end product are necessary and which are due to the forces acting in the liquid phase on the solid particles attach. Process step 3 is used, in particular To adjust the consistency and color of the product, while process step 5 is used to which cannot be dissolved in the water to attach to the fibers. .

109846/1469

Claims (5)

(HP 116) - 10 - Patent claim Process for the recovery and utilization of the wastewater sludge arising in wastewater, characterized by the following process steps: 1. Mechanical crushing of the substances carried in the wastewater with the simultaneous addition of substances carried along Ions of oppositely charged substances of the additives desired for the end product; 2. Flocculation of the dissolved substances via destabilization the dispersion preferably by metal salts and / or by polyelectrolysis with the simultaneous addition of Ions of the additives desired for the end product, which are oppositely charged to the dissolved substances; 3. Pre-drying of the comminuted or flocculated substances to a moisture content of 60% by means of known ones Drying facilities; 4β drying of the pre-dried substances to give blown granules with a residual moisture of 5 % by means of drying devices known per se; 5. Defibration of the granules, preferably in the presence of dry, powdery additive substances desired for the end product. 1098U / U6Ö