DE2920010A1 - METHOD FOR ELIMINATING IMPURITIES IN SURFACE AND SURFACE WATER BY OZONE - Google Patents

Description

Pall 3068

DIDIER-WEEKE AG

Lessingstrasse 16-18

6200 Wiesbaden

Process for the elimination of pollution in groundwater and surface water using ozone

The invention relates to a method for removing contaminants, in particular from Baffinery products and / or refinery residues in ground or surface water. Such impurities are organic and / or inorganic chemicals or substances, in particular from deposits and refineries of petroleum products, which by means of ozone are no longer interfering compounds can be dismantled.

From DE-OS 26 47 34-1 it is already known that wastewater, those from gas works, coke ovens, generator stations, oil refineries and certain areas of the chemical industry, treated with ozone can be used to decompose and remove such contaminants. According to this previously known procedure a special catalyst is used to bring an intimate mixture of contaminated water into contact with ozone is brought. In this case, the contacting takes place in the countercurrent between the one containing the impurities Waste water and the ozone-containing gas stream in a tubular reaction vessel which contains the catalyst.

030047/0476

Furthermore, from DE-OS 25 56 328 a method for water treatment and in particular for drinking water treatment and wastewater purification known, in which for oxidation unwanted water constituents with water under pressure Ozone is loaded and the reaction takes place in a packed column he follows. Further working methods for the treatment of water or aqueous liquids with ozone are in the DE-OS 26 37 418 and 26 18 338 described. According to this latter Irradiation with UV is carried out simultaneously with the ozone treatment.

The object of the present invention is to remove contaminants in groundwater or surface water, in particular in cases where these contaminants have polluted large volumes of ground or surface waters.

Such contamination occurs, for example, through leakage or overfilling containers or tanks with the chemicals, which then end up in the soil and groundwater or contaminate surface water.

In such cases, attempts have previously been made to remove the contaminants in the groundwater or surface water either chemically to bind or, with a sufficiently high concentration and good separating properties, the soiling from this by separators, e.g. B. oil separator to remove. The disadvantage of using so-called chemical binders lies in the fact that the impurities are often not really removed but only brought into a different distribution, Another disadvantage is that larger amounts of water only with great technical effort and great costs, if at all, can be treated. The use of separators is also not possible in many cases, if any for example form emulsions, or it just gives

030047/0476

■ SV

Partial parting of the main quantities, while still essential parts the impurities in the water leaving the separator are included. Another problem is that many organic chemicals and especially Ingredients in refinery products and / or refinery residues are soluble in water to a not inconsiderable extent, so that a complete removal by separators not possible.

The previously known method using ozone for Oxidation of such impurities in the form of organic chemicals and in particular refinery products and / or Eaffxnerxerrückstands in water were in special facilities, often packed columns, or carried out using catalysts, and the water treated with ozone was then placed in receiving waters or sewage disposal systems introduced.

In the method according to the invention, the elimination of the Pollution also carried out by a known treatment with ozone, but the contaminated Water is treated with ozone without a significant change in the water balance occurs, so that a 'water cycle is created in which the amount of water remains practically unchanged and, for example, in the case of contaminated Groundwater no significant lowering of the groundwater level occurs overall. This has a major advantage, because by practically keeping the water level constant, the pollution zone spreads further

03004770478

is avoided. Another advantage of the process according to the invention is that through the circulation of the Water adhering to the soil can be washed out. The same applies in the case of surface water, where through the Vi ed he recirculation of the treated water no lowering of the water level in the surface water takes place, e.g. B. in the case of pools or oaks.

The method according to the invention is characterized in that that the contaminated water in a known manner ozone in sufficient amount without significant change of the water balance is added.

According to a preferred embodiment, the invention Procedure carried out so that one

a) removes the contaminated water at one or more points of the contamination area,

b) introduces a sufficient amount of ozone into the withdrawn water , and

c) then the ozone treated water to one or more Reintroduces places of the contamination area.

In the process according to the invention, the contaminated Water is taken from one point, then ozone is added to it, and then the ozone-added water is added returned again.

The introduction of the ozone into the extracted, contaminated water, preferably as an injection, during the transport of the water in pipelines to the reintroduction points

030047/0476

Λ-

take place, this is expediently immediately after, the Suction point takes place so that water and ozone in the pipeline system during transport to the outlet at the re-introduction point can react with each other. Of course, the ozone can also be used in an intermediate Treatment station, e.g. B. an intermediate tank, if this is because of the Injection equipment used proves to be expedient, or in several places the contaminated water can sucked off and led to a central container for the injection of the ozone, in order then from this central container to be returned to the individual re-introduction points, so that the introduction of the ozone is only required at one point is.

The ozone is produced in ozone generators known per se, as for example in Ullmann, Enzyklopadie der technischen Chemie, 3rd edition, Volume 15 (1964), pp.98-103 are described. The ozone can be generated in air or in air enriched with oxygen or pure oxygen, higher ozone concentrations of up to about 14% are possible.

In the process according to the invention, the reaction must be between Ozone and the impurities contained in the water or impurities when the water re-enters at the re-introduction points not yet completed, rather it seems to be the case that what is still contained in the water, unused ozone also with the impurities in the groundwater or the surface water, which this with Water mixed with ozone is added, continues to react. In particular in the case of groundwater pollution with petroleum products, d. H. Refined products and / or refinery residues, these soiling or impurities also adhere

030047/0476

■ * ■ - * ■

Erdreich., In which the groundwater stands, and a reintroduction of unreacted ozone together with the treated and in the end area of the pollution zone reintroduced water appears to have a beneficial effect on the removal of such soil adhering contaminants to have.

When using the method according to the invention in contaminants or contaminants contained in the groundwater it has been found to be advantageous to have one or more centrally located lowering wells in the pollution zone to create and suck off the contaminated groundwater there, forming a subsidence of the groundwater, then to treat the contaminated, extracted groundwater and the treated groundwater via injection wells in the Edge area to reintroduce the contamination zone. Of the In such a case, the level in these absorption wells is of course higher than the level in the lowering well, see above that a lowering funnel is formed. This embodiment of the method according to the invention is in particular in the Pail from larger contaminated areas such as refinery land and in particular the areas for the product containers, such as heating oil containers or gasoline containers, which are usually surrounded by an earth wall indicated in which, in the event of a leakage of Eaffxnerieprodukte and / or Eaffinerierresidues a relatively large-scale contamination occurs and significant amounts of contaminating products enter the soil and eventually get into the groundwater.

However, it is not necessary in every case, so-called To create sump wells in the area of the pollution zone, but the water mixed with ozone can also by means of Lances in the end of the pollution zone into the Soil to be reintroduced. This makes it easier

030047/0476

A-

Way the amount of the place of reintroduction and hence adjust the height of the water level. It can be useful here, from the mixture of water and gas, the was obtained by introducing the ozone into the polluted water, the gas by means of suitable separation devices, z. B. in a degassing tank to be deposited. In the case of the introduction of the ozone-added water in Inlet wells, this degassing takes place automatically when the water exits the supply line again, so that no separate degassing device is required.

In addition, in the case of a larger, contaminated zone, it is possible to move the lances to a new location the use of swallowing wells would not be possible without further ado.

According to another preferred embodiment of the invention Procedure is the water mixed with ozone as soon as possible before the reintroduction, be it via injection wells or via lances or as surface water in the The edge area of the contamination zone contains the chemicals and in particular the refinery products and / or refinery residues from the surrounding soil displacing substance added. Such a substance can either be a single substance or a mixture of substances, the chemicals or refinery products adhering to it either in the case of underground groundwater and / or displace refinery residues, or those adhering to the soil in the case of surface water Make chemicals or refined products and / or refinery residues therefrom easier to detach. as Examples of such substances are surface-active substances or emulsifying substances, and this is often the case surface-active substances are mentioned. In such a

030 0 47/0476

! "All of the reintroduced, treated water should naturally contain as little as possible of unconverted ozone in order to avoid oxidative degradation of such displacing substances Re-introducing into surface water add a substance that dissolves the impurities from dp ™ soil, which is particularly advantageous in the batch of poorly water-soluble, polluting substances, e.g. in the case of pitch- or tar-like products It can even be a liquid hydrocarbon which dissolves these impurities and which is then broken down together with the dissolved, polluting substances during further treatment with ozone.

The process according to the invention is illustrated by the following examples explained in more detail with reference to the drawing. In the drawing are:

1 shows a diagram which shows the course over time of the degradation of groundwater contaminated with pyronaphtha;

Pig. 2 supervision of an area with polluted groundwater, which is treated by the method according to the invention;

Pig. 3 is a sectional view through the soil of the area according to Pig. 2.

In the pig. 1 shows the time course of the degradation of water contaminated with pyronaphtha. Such pyronaphtha contains about 55% benzene and the remainder toluene, phenol, xylene and styrene and is a product obtained in refineries.

030047/0476

—9—

The level of contamination of the water was around 53 mg pyronaphtha per liter of contaminated water, d. H. at 53 tpm (Tpm = parts per million).

In a "5-1 wide-mouth bottle of this contaminated water was filled in an amount of 3 1 at a temperature between 12 ⁰ C and 14 ⁰ C, then ozone-containing air was introduced with an ozone content of about 8% through a nozzle into the water.

The quantitative decrease in pyronaphtha over time is shown in FIG. 1, from this it follows that after about Decomposition had occurred to about 3 tpm for 20 minutes.

In Figs. 2 and 3, the application of the invention Method presented for the treatment of groundwater contaminated with pyronaptha.

In Fig. 2 a bordered by an earth wall (4) with tanks for the products of a refinery is shown, wherein Pyronaphtha had leaked from such a container. The area in question had a groundwater level roughly 5 m depth to which the pyronaphtha that had leaked penetrated and floated on the groundwater or had partially dissolved into it.

In the central area of the pollution zone, a total of four lowering wells (1), see Fig. 2, were drilled, and from this groundwater with floating or dissolved pyronaphtha is always pumped off the surface. Over time it subsided the groundwater level falls from 5 m to 11 m, see Fig. 3

030047/0476

■ 4t ·

At the edge of the pollution zone, a total of six injection wells (2) were created to a depth of 6 m, ie 1 m below the water table. Groundwater contaminated with pyronaphtha was pumped out of the lowering well (1) in an amount of 400 nr / h and combined. Each of the connection of the four suction lines, an ozone-containing gas stream can be introduced into the extracted, pyronaphtha-contaminated groundwater by means of pipe nozzles. The groundwater after pumping out contained an average of about 50 tpm pyronaphtha. In a preliminary experiment it could Pyronaphtha 50 Tpm by sufficient injection of ozone-containing air from a commercially available ozoniser up to 3 ^m Tp are degraded. It is advisable to have an excess of at least 0.1 g of ozone / nr treated water. The extracted water, mixed with ozone, is then returned to the suction well (2) via the pipe (3). Of course, it is also possible in the method according to the invention to first pass the sucked off, polluted water, if it contains impurities forming a separate phase, through a separator and here a phase separation as far as possible while removing a smaller or larger proportion of the impurities, depending on the circumstances to reach. This of course results in a saving in used ozone, since these impurities separated as a separate phase in the separator no longer have to be removed by oxidation using ozone.

030047/0476

Claims (7)

1 May 7, 1979. Pall 3068 DIDIER-WEREE AG Lessingstrasse 16 - 18 6200 Wiesbaden Patent claims 1. Process for removing contaminants, in particular refinery products and / or refinery residues in ground or surface waters, characterized that the polluted waters in a known manner ozone in sufficient amount without essential Change in the water balance is added. 2. The method according to claim 1, characterized in that one a) removes the contaminated water at one or more points in the contaminated area, b) introduces a sufficient amount of ozone into the withdrawn water, and c) then reintroduces the water treated with ozone at one or more points in the contamination area. 3. The method according to claim 1, characterized in that the contaminated groundwater through one or more lowering wells and with the formation of a lowering funnel sucks off the groundwater and, after treatment with ozone, reintroduces it via injection wells. 03004 7/0476 4-, method according to claim 2, characterized in that the water treated with ozone is reintroduced using lances. 5 · Method according to one of the preceding claims, characterized characterized in that before the introduction of the ozone-treated water one of the impurities adds displacing substance to the soil. 6. The method according to any one of the preceding claims, characterized in that prior to the introduction of the with Ozone-treated water adds a substance that dissolves impurities from the soil. 030047/0478