EP0377713A1

EP0377713A1 - Arrangement and process for purifying waste water

Info

Publication number: EP0377713A1
Application number: EP19890907080
Authority: EP
Inventors: Wilfried Dolkemeyer; Karin Schmidt; Hans Gierlich
Original assignee: Rheinische Braunkohlenwerke AG
Current assignee: Rheinbraun AG
Priority date: 1988-07-08
Filing date: 1989-06-24
Publication date: 1990-07-18
Also published as: DE3823127A1; DD285768A5; WO1990000525A1

Abstract

L'invention concerne l'élimination d'impuretés adsorbables, notamment d'impuretés organiques, au moyen d'un dispositif renfermant une couche de matière adsorbante qui est de préférence prétraitée avec de la vapeur et/ou de l'eau.The invention relates to the removal of adsorbable impurities, in particular organic impurities, by means of a device enclosing a layer of adsorbent material which is preferably pretreated with steam and / or water.

Description

Device and method for cleaning waste water

The present invention relates to the removal of adsorbable impurities, in particular organic impurities, by means of a device in which there is a layer of adsorbent material which has preferably been pretreated with steam and / or water.

The purification of polluted water to preserve the environment is one of the great challenges for modern industrial society. There are numerous processes known which work according to very different principles.

Examples include biological processes which are used primarily to aerobically remove organic contaminants and nitrogen-containing contaminants.

Only a few of the very extensive patent literature can

Examples are mentioned, such as DE-OS 35 23 844, EP-A-0 202 626,

EP-A-0 154 915, DE-PS 25 12 815.

Examples of anaerobic processes are:

DE-OS 33 07 796, EP 0 046 901, EP 0 119 430.

Reverse osmosis is also used to purify waste water (DE-OS 35 43 661, EP-A-0 229 414).

Adsorptive processes are also important for wastewater treatment. According to DE-PS 24 18 169 and DE-PS 28 19 572 used as an adsorbent. According to DE-OS 33 35 994, a filter cartridge system is used which contains a suitable adsorbent. According to DE-OS 34 01 867, an adsorbent resin is used. Carbon materials are also used as adsorbents. DE-OS 34 36 453, for example, discloses a two-stage process in which, in a first stage, powdered activated carbon is dispersed in the wastewater and the solids are then filtered off.

In a second stage, the pre-cleaned water is sprayed into an active carbon adsorption tower with simultaneous air supply.

According to DE-OS 32 21 451, activated carbon, preferably carbon black from gasification plants, is pressed with a flocculant and a polymer into pellets which are introduced into the waste water with stirring.

EP-A-0 134 271 discloses a wastewater treatment process according to which wastewater is moved upwards through a coal bed, the coal bed expanding by approximately 30%.

Despite the extensive prior art described, there is a need to purify wastewater in a simple, one-step, particularly economical process, the process also being intended to allow the cleaning device to be operated on-site, for example on a landfill site, operated and removed again . A particularly important task here is to economically clean even heavily contaminated wastewater at least to the extent that it can be further cleaned in conventional sewage treatment plants. It is known that landfill leachate is legally classified as wastewater as of 01.01.89 according to the amended wastewater law. Therefore, increasing requirements for the purification of such wastewater can be expected. The current methods used for the purification of leachate are biological purification with chemical / physical aftertreatment and reverse osmosis (see, for example, "Abwassertechnik, 1-2, 1988 pp. 34-38). The type of contamination in leachate can be very different depending on the waste materials with which groundwater and surface water come into contact. For example, landfill leachate from hazardous waste landfills contains a different composition of impurities than leachate from domestic waste landfills (Rubbish and Waste, 2, 1988, pp.67-71). The proportions of organic impurities are usually higher in the latter.

Important contaminants that have to be removed are, for example, phenol and phenol derivatives, hydrocarbons or adsorbable organic halogen compounds (AOX). The applicant has now succeeded in further developing the state of the art, in particular with regard to economy and simple feasibility, by a process for the purification of waste water, characterized in that a layer of adsorbing material is introduced into the device according to claims 1-7 , wherein the adsorbing material is pretreated by introducing hot gas and / or liquid and, in the case of heating with gas, is placed under water and / or a water / steam mixture that the wastewater to be purified is adsorbed by the layer of Material is passed and that the cleaned waste water flows out of the device.

FIGS. 1, 2 and 3 show results for the reduction of the COD value in a laboratory device.

FIGS. 4 and 5 show results with a technical device.

Figure 6 shows results with a high temperature coke.

Figures 1, 8 and 9 represent experiments in which the coke was not pretreated.

FIGS. 10-13 represent tests in which surface-active substances were added to the pretreatment water.

FIG. 14 shows an example of a device according to the invention. Figures 15-17 represent loading, operation and transport of devices according to the invention.

The device according to the invention is a container in which there is a water-permeable, sieve-type installation above the container bottom, above which adsorbent material is arranged, with purified water flowing off through at least one outlet or overflow.

In principle, the container can have any spatial shape, that is, it can be cylindrical and round, square, rectangular _/ trapezoidal or can also consist of composite spatial shapes, such as, for example, expanding trapezoidally in the upper part, but being rectangular or rectangular below.

The listed forms of space are to be regarded as exemplary, but not as limiting.

The container, which is generally closed at the bottom but provided with at least one drain, has a sieve-like, rust-like installation in the lower region above the container bottom. This permeable part can take up the entire surface of this floor or only a part of the surface, in the limit case it can only cover the surface before the drain. The layer of adsorbent material rests on the sieve-like base. In the event that the waste water is passed through the adsorption material from top to bottom, the sieve-like base has the function of letting the water flowing out of the adsorption layer pass, so that it passes beneath it via at least one Drain can be removed from the container. In principle, the sieve bottom can have any configuration, such as a wire mesh, rods, a perforated metal plate or any other arrangement. For example, it can also have elevations or depressions.

If the wastewater is passed from the bottom to the top through the adsorption material, the same can be fed in through a feed in the lower area and flow out of the device via an overflow. The device according to the invention can consist of different materials as are customary in container construction, ie of steel, cast iron, stainless steel, plastics, reinforced concrete, composite materials and others

In order to avoid or reduce corrosion, it is desirable to provide corrosive materials with a protective coating or paint.

In order to reduce channel formation in the adsorption layer and on the container walls, it is advantageous to install suitable internals for flow conduction in the container, such as baffles on the container walls.

Since it has proven to be very advantageous to heat the adsorption material with gases, in particular steam and / or liquids, in particular water and / or water / steam mixtures or hot water, there is at least one feed device on the container for Steam and / or water is provided, preferably in the lower area, and the outlet in the container can also be used for this purpose by connection to a steam and / or hot water line. However, a supply of steam and / or water is also possible according to the invention from top to bottom.

Another preferred embodiment of the pretreatment is carried out by evacuation. The evacuation can take place in such a way that a vacuum is applied to the container containing the coke and / or the activated carbon and the liquid, preferably water, is then allowed to flow into the adsorption material. However, it is also possible first to wet or cover the adsorption material with the liquid and then to apply a vacuum.

The removal of the gas adhering to the adsorbent material is an important preferred embodiment of the present invention, as is evident from the tests carried out. Can be very beneficial. ie already carried out, the degassing by treatment with steam or hot water or both, also in combination with a degassing by evacuation. Degassing and mixing with water can also be carried out in the same way, that the adsorption material, such as finely divided coke or activated carbon, are sucked in with the water jet of a water jet pump. Another degassing process is the cycle mode with water. The wastewater to be cleaned itself can also be used here. Here, the pH of the circulating water should rise to values> 10, preferably> 12, during the advantageously multi-hour cycle. Surface-active substances can also be added to the water used in the pretreatment.

In certain cases, the increase in pH in the alkaline or strongly alkaline range is undesirable, for example when contaminants have to be removed from groundwater. Here, the pH can either be adjusted by adding acids or one works with an acid-containing adsorbent, such as those containing SO _? contained in the cleaning of flue gases.

Accordingly, activated carbon or coke, for example, which is loaded by flue gas cleaning, can subsequently be used for wastewater treatment.

By adding surface-active agents to the pretreatment liquid, especially water, the pretreatment time can be shortened considerably.

According to the invention, the surface-active agents should meet the following requirements: poor adsorbability,

Alkaline surfactant properties, good biodegradability,

Low dosage activity, low foaming.

Suitable classes of compounds are: anionic surfactants, n-alkyl sulfates

Alkyl sulfonates Alkylbenzenesulfonates, preferably with non-ionic surfactants containing n-alkyl groups (ethylene oxide adducts), may be mentioned as examples:

Fatty alcohol polyethylene glycol ether, alkylphenyl polyethylene glycol ether, fatty acid polyethylene glycol ester.

According to the invention, 10 to 2000 ppm, preferably 20 to 1500 ppm and particularly preferably 20 to 1200 pp of surfactants are added to the pretreatment liquid.

The curves in FIGS. 10-13 were determined by way of example. For this purpose, 200 ml of a landfill leachate was stirred in a flask with 10 g of hearth furnace coke and the time course of the COD decrease was determined.

The water level in the container can be regulated by means of conventional regulating devices. A very simple advantageous device is, however, the laying of the line for the draining water at such a height that the desired water level in the container can be set thereby. A hose can be used as the drain line. However, a fixed line can also be used. The height of the drain line is advantageously adjustable so that any desired water level in the tank can be set.

A great advantage of the device according to the invention is its portability. For example, when using coke as an adsorbent in a coke production plant, it can be filled, treated with steam and / or hot water and / or water / steam mixture, transported to the landfill by truck, parked there and immediately in operation be taken. After the adsorbent has been saturated, the container can be taken to an incineration plant, to a landfill approved for this purpose or to a regeneration plant. A preferred embodiment of the device is therefore that which is also customary for waste containers which are open at the top. This has the advantage that the trucks suitable for loading, unloading and transporting are available.

Any adsorbing material can be used in the method according to the invention, but preference is given to materials based on carbon, in particular coke, since these are considerably more economical than activated carbon, for example. A suitable coke is e.g. Oven coke obtained from lignite, in particular from Rhenish lignite, but also coke and hard coal coke made by other processes are suitable according to the invention. Other adsorbents can also be used, e.g. based on SiO_ or aluminum silicate or Al-O -, - or plastic, e.g. Silica gels, clays, bleaching earths, molecular sieves, ion exchangers and magnesium oxide.

In the case of the use of coke in particular, the applicant has found that treating it with gases and / or liquids, if necessary accompanied by previous evacuation before putting into operation, brings substantially better results than without this pretreatment. The preferred gas is water vapor, the preferred liquid is water and / or a water / steam mixture. After the treatment, the adsorbent material is filled with a gas, water, in particular hot water and / or water / steam mixture in the event of heating.

The temperature range in which the coke is brought by heating is 20-200 ° C, preferably 50-180 ° C and particularly preferably 75-140 ° C. According to the invention, additional treatment with liquid, e.g. Water possible before heating.

The gas or the steam or the liquid or gas / liquid mixture is generally below the sieve-like one Installation initiated. However, initiation is also possible at other points. The treatment time is generally 1 minute to 20 hours, preferably 10 minutes to 10 hours, particularly preferably 10 minutes to 5 hours. However, this information is not to be regarded as limiting, but rather as preferred embodiments.

When the device is in operation, the waste water can be passed through the adsorption layer from top to bottom, a water level generally being maintained which is somewhat higher than the adsorption layer itself. However, a mode of driving can also be selected in which the waste water is passed from bottom to top through the device according to the invention.

The flow rate of the water flowing through the adsorption layer is> 0 to 1 m / h, preferably 0.01 to 0.8 m / h, particularly preferably 0.05 to 0.5 m / h. The residence time of the waste water in the coke layer is 1 minute to 10 hours, preferably 5 minutes to 7 hours, particularly preferably 10 minutes to 5 hours.

The wastewater treatment temperature is - 0 to 45 ° C, preferably 5 to 35 ° C. The specified temperature ranges are to be regarded here as operating temperatures, it having to be taken into account that the pretreatment described may initially result in a higher temperature. According to the invention, the adsorbent material can also be pretreated as described before being filled into the device.

It is advantageous according to the invention to work with a grain size of the adsorbent material from 0.01 to 100 mm, preferably from 0.05 to 20 mm and particularly preferably from 0.05 to 5 mm. However, the cheapest grain size also depends in part on the adsorption material used. For example, when using carbon black from gasification plants to produce synthesis gas, for example by shell or Texaco gasification, the grain size is usually 0.3 to 1 μm. When using such a carbon black, good results are obtained even without steam pretreatment. It is sufficient to use the soot filtered off from the aqueous suspension in the device according to the invention.

Very suitable adsorbent material is fine coke with the known grain size.

The concentration of organic impurities (COD) and the concentration of adsorbable organic halogen compounds (AOX) can be considerably reduced by the process according to the invention.

The device according to the invention and the method according to the invention are of particular importance for the cleaning of landfill leachate. Here, as described, the device and method can be operated on site according to the invention and the water pumped onto the device, for example from percolation shafts, can be cleaned directly in the landfill area. Depending on the requirements, the water purified in this way can also be used for other cleaning processes, e.g. be sent to a sewage treatment plant.

Of course, other cleaning methods corresponding to the prior art can also be combined with the method according to the invention, such as, for example, pretreatment by settling, sedimenting, filtering, precipitating, flaking, degassing, aerating, sterilizing and emulsion splitting or the use of ion exchangers.

The invention will now be explained in more detail with the aid of the figures.

FIG. 1 shows laboratory tests in which> 0 - 80 ml of landfill leachate per g of adsorbent are passed over it at a flow rate of 0.5 m / h, a residence time of approx. 27 minutes and a temperature of 23 ° C. A hearth coke made from Rhenish brown coal was used (surface area approx. 250 m ² / g). The oven coke was through 4 hours Circular procedure of wastewater to be cleaned (without the addition of surface-active agents) over the coke has been pretreated; The apparatus was generally carried out by flowing the waste water through a pipe filled with adsorbent material.

The test wastewater contained a concentration (COD) of 1470 mg / l wastewater of organic impurities in test 1 and a quantity of 860 mg / l in test 2.

The straight lines indicate the remaining COD value after cleaning in accordance with the invention with different amounts of wastewater passed through the cleaning device.

The curves show that the COD values can be reduced to 100-200 mg and below, the adsorption capacity decreasing with increasing load, accompanied by an increase in the COD in the purified wastewater.

Wastewater pre-cleaned in this way can, if necessary, be further cleaned in sewage treatment plants or, if permissible, can be fed directly into water.

Analog tests are shown in FIG. 2 which were carried out at a flow speed of 0.3 m / h and an oven coke made from Rhenish lignite. The pretreatment was carried out by evacuation and subsequent filling with water.

FIG. 3 shows analogous tests with a landfill leachate (test numbers DW 38, 39) and a hard coal coke. The COD value of the waste water used was 1690 mg / 1. The flow velocities were 0.1 m / h (DW 39) and 0.2 m / h (DW 38). The residence times were 2 hours (DW 38 and 39).

FIG. 4 shows tests in a technical installation with waste water from a special landfill. An oven coke was also used, which was pretreated with a steam / water mixture for 2 hours. The input COD values were 1045 mg / 1 and 1100 mg / l (flow rate: 0.3 m / h). These results also show that excellent results can be obtained with the method according to the invention.

FIG. 5 shows tests on an industrial scale with a large container as the device according to the invention (flow rate: 0.2 m / h, residence time: 3 hours). The pretreatment corresponded to that in FIG. 1. The COD values in the feed are 1380 and 1300 mg / l. The waste water came from a household waste landfill. As the curves show, the COD values could be reduced to <100 mg / 1 COD.

FIG. 6 shows an experiment which was carried out like the experiment according to FIG. 1, but in which a high-temperature lignite coke from the GDR was used (surface area: 200-250 m ² / g).

FIGS. 7, 8 and 9 show experiments which corresponded to experiments 1, 3 and 6, but without pretreating the adsorbent.

The following table shows the residual amounts of organic impurities in the wastewater according to FIGS. 1-9 after cleaning via various adsorbents. The flow velocities were varied between 0.1 m / h and 0.5 m / h. The initial COD values are given in mg / 1 waste water. In the two columns on the right, the remaining COD values in the treated wastewater are shown when the adsorbents are loaded with 10 ml / g adsorbent and 50 ml / g adsorbent. All tests were carried out at ambient temperature.

In tests 1, 2, 3, 5 and 6, the pretreatment of the adsorbent was carried out by cycling a certain amount of waste water over the adsorbent for several hours.

In experiment 1, wastewater with 1470 mg and 860 mg COD in the wastewater and a flow rate of 0.5 m / h was investigated.

With a 10 ml load, residual COD values of up to 60 mg were achieved. Similar good results at 10 ml loading were also achieved in test 2 with a somewhat lower flow rate of 0.3 m / h, while the values at 50 ml / h improved significantly compared to test 1.

In experiment 3, work was carried out at 0.1 m / h and 0.2 m / h flow rate.

In contrast to experiments 1 and 2, a coal coal coke was used.

Here too, comparably good results were obtained, albeit at a low flow rate.

In experiment 4, the oven coke was used as an adsorbent. The pretreatment consisted of a 2 hour treatment with a steam-water mixture. The results were particularly good with this pretreatment.

Experiment 5 was carried out on an industrial scale. The pretreatment corresponded to experiment 1.

In experiment 6, a high-temperature lignite coke was used. At a flow rate of 10 ml / g, worse results were obtained than in Experiment 1, but not at a load of 50 ml / g.

In tests 7, 8 and 9, tests 1, 3 and 6 were repeated, but without pretreatment, i.e. the wastewater to be cleaned was passed directly over the untreated adsorbent.

The results were significantly worse at 10 ml / g as well as at 50 ml / g loading than in tests 1, 3 and 6. table

1) of which 323 mg AOX; 2) of which 189 mg AOX; 3) of which 12 mg AOX; 4) of which 9 mg AOX; 5) of which 401 mg AOX; 6) of which 336 mg AOX; 7) of which 9.6 mg of AOX 8) of which 8.4 mg of AOX.

The results are explained in more detail in FIGS. 10-13.

In FIG. 10, 50 ppm of a surfactant with the identification ESP-5433 was added to the pretreatment water.

If one looks at the time in which the COD value decreased from originally 2000 ppm to 800 ppm, it is found that this decrease without surfactant after approx. 53 min. is reached with surfactant at 38 min.

Accordingly, the preheating coke is wetted by the pretreatment liquid as a prerequisite for the adsorption capacity of the coke when the surfactant is added.

This is evident from the experiment that the adsorption of the relatively small adsorbable COD fraction in the wetting test takes place much faster when the surfactant is added than without it.

An analogous result is achieved when 1000 ppm of surfactant is added (FIG. 11).

With surfactant 800 ppm COD is reached after 12 minutes, without surfactant after 23 minutes.

Similar clear results are obtained with the surfactant ESD-151 (Figure 12).

With 500 ppm addition, 800 mg COD is achieved after 35 minutes, without addition after 54 minutes.

In FIG. 13, with 1000 ppm of surfactant addition, 800 ppm of COD are reached after 12 minutes, without surfactant after 23 minutes.

FIG. 14 shows a preferred embodiment of a device (1) according to the invention. It has the shape and dimensions of a waste container. The container has a water-permeable sieve bottom (3) above the container bottom (2). The black layer represents the adsorbent bed. The water layer (4) stands over the adsorbent bed. Waste water to be cleaned is fed in via (5).

(6) represents the space between the sieve plate and the container bottom. An outlet is represented by (7). The height of the water in (1) can be adjusted using the height-adjustable pipe bend (8). The cleaned waste water runs off at (9). (10) represents a water distribution system.

FIG. 15 shows an example of a system consisting of several devices (1-3) according to the invention. The waste water is fed in via (4) and drawn off at (5) as purified water.

With device (1) the removal of used adsorbent is shown, with device (3) the filling with fresh adsorbent.

FIG. 16 shows an overview of the method according to the invention.

The adsorbent is delivered with the railway containers (1) and stored in (2).

The containers (3) according to the invention are filled from (2) and pretreated at (4) with steam and hot water and e.g. parked at a landfill where pumping from seepage shafts via (5) landfill leachate to the containers. The outflowing purified water is collected in a collecting container (6), from which it can be transported, for example, to a sewage treatment plant.

The used adsorbent materials can be tipped over in a suitable landfill (7) or can also be transported to a regeneration.

A further exemplary overview is shown in FIG. 17. Already pretreated adsorbent material is loaded from (1) into a truck (2) and transported to the devices (3) according to the invention.

Waste water (4) is directed onto the filled devices. Purified water is collected in container (5). Used adsorbent is dumped in landfill 6, for example. As the explanations show, the device and the method according to the invention represent a technically important further development of the state of the art, according to which effective wastewater treatment, in particular special highly polluted wastewater, can be carried out using inexpensive "disposable" adsorbents and in simple process steps how landfill leachate is possible.

Claims

1. Device for the purification of waste water, characterized by a container in which a water-permeable sieve is located above the container bottom and adsorbent material is arranged above the sieve, and by at least one outlet on the container for the water flowing through the sieve.

2. Device according to claim 1, characterized by internals for flow control.

3. Device according to claims 1 and 2, characterized gekenn¬ characterized in that the internals for flow control are baffles on the inner container walls.

4. Device according to claims 1-3, characterized gekennzeich¬ net that the same is designed as a transportable container.

5. Device according to claims 1-4, characterized gekennzeich¬ net that the same has at least one gas and / or liquid supply in the lower region.

6. Device according to claims 1-5, characterized gekennzeich¬ net that the same has a height-adjustable water-draining line for adjusting the water level.

7. Device according to claims 1-5, characterized gekennzeich¬ net that the same has an overflow in the upper part.

8. Process for the purification of waste water, characterized in that a layer of adsorbent material is introduced into the device according to claims 1-7, the adsorbent material being introduced by introducing hot gas and / or liquid before or after the introduction is pretreated and then in the case of heating with gas is placed under water and / or a water / steam mixture so that the wastewater to be cleaned is passed through the layer of adsorbing material and that the cleaned wastewater flows out of the device.

9. The method according to claim 8, characterized in that the liquid used for the pretreatment is water and / or a water / steam mixture.

10. The method according to claims 8 and 9, characterized gekennzeich¬ net that the adsorbent material is coke.

11. The method according to claims 8-10, characterized gekennzeich¬ net that the adsorbent material is hearth coke.

12. The method according to claims 8 - 11, characterized gekennzeich¬ net that the adsorbent material in the pretreatment to 20 - 200 ° C, preferably 50 - 180 ° C and particularly preferably to 75 - 140 ° C is heated.

13. The method according to claims 8 - 12, characterized gekennzeich¬ net that the pretreatment time is 1 minute to 20 hours, preferably 10 minutes to 10 hours, particularly preferably 10 minutes to 5 hours.

14. The method according to claims 8 - 13, characterized gekennzeich¬ net that the flow rate of the wastewater flowing through the layer of adsorbent material> 0 to

1 m / h, preferably 0.01 to 0.8 m / h, particularly preferably 0.05 to 0.5 m / h.

15. The method according to claims 8 - 14, characterized in ^¬ net, that the residence time of the waste water DES 1 minute to 10 Stun, preferably from 5 minutes to 7 hours, more preferably 10 minutes to 5 hours is. - λo -

16. The method according to claims 8 - 15, characterized gekennzeich¬ net that the wastewater treatment at - 0 - 45 ^C C, preferably 5 - 35 ° C takes place.

17. The method according to claims 8 - 16, characterized gekennzeich¬ net that the grain size of the adsorbent material is 0.01 to 100 mm, preferably 0.05 to 20 mm and particularly preferably 0.05 to 5 mm.

18. The method according to claims 8 - 17, characterized gekennzeich¬ net that the grain size corresponds approximately to that of fine coke ent.

19. The method according to claims 8 and 12 - 16, characterized ge indicates that soot from oil gasification is used as the adsorbing material.

20. The method according to claims 8 - 19, characterized gekennzeich¬ net that the same takes place in / at a landfill and landfill leachate is cleaned.

21. The method according to claims 8 - 20, characterized gekennzeich¬ net that the adsorbent material is subjected to pretreatment with hot gas and / or with a liquid.

22. The method according to claims 8-21, characterized gekennzeich¬ net that the pretreatment of the adsorbent material is carried out by circulating water over the material.

23. The method according to claims 8 - 22, characterized gekennzeich¬ net that the pretreatment with steam and water follows er¬.

24. The method according to claims 8-23, characterized gekennzeich¬ net that a surface active agent is added to the pretreatment liquid.