SK69393A3 - Method of reconditioning soil - Google Patents

Abstract

Proposed is a method of reconditioning soil, in which contaminants in the soil are removed by washing, screening, gravity separation and/or flotation. Before reconditioning, the content of organic contaminants, in particular polycyclic hydrocarbons, and the proportion of lightweight material and fine-particulate material is determined. An adsorption agent is then added as a function of the organic-contaminant and lightweight-material contents thus determined, and the adsorption agent is intimately mixed with the soil.

Description

The invention relates to a soil treatment method according to the preamble of claim 1.

BACKGROUND OF THE INVENTION

From the publication Curry. J. Thomé-Kozmiensky, Altlasten 3, EP-Verlag für Energie- und Umv / Eltech GmbH, Berlin, 1989, p. 561 to 578 it is known that contaminated soils, so-called old infestations, are cleaned by soil washing and subsequent sorting, stiffness and / or flotation sorting because it has been found that pollutants present in the soil may exist in the finest grain fraction, enrich light material.

In pilot plants it was possible to remove polycyclic hydrocarbons, chlorinated hydrocarbons and aromatic compounds according to items 3, 4 and 5 in the so-called Dutch List ("Ilolländische Liste"). Wood, slag, coal, coke and plastic fractions are mentioned as light materials.

According to this method, the soil is permeated with light material and that the pollutants are bound quantitatively in the light material. If a light material is present in the soil, it is usually contained only in the uppermost layers of the soil. At the sites of old contamination, however, soil layers that are deeper are also contaminated.

the soil to be treated according to one prior art method may have only a small proportion of the finest grain of fine-grained sand (2 to 63 m) and clay (> 2 m). For a proportion of the finest grain, for example 50%, such administration can be cleaned by separating the finest grain and the contamination contained therein only; , 50% · This is inappropriate.

<Therefore, it can't be removed using a known method. ’The prevalence of contaminated under.

Furthermore, DE-OS 40 04 368, which was not prcduve. cation of, known to the soil before or during mixing • the washing of fine grain coal-materials, in particular coke, and the carbonaceous material, enriched with pollutants separated by mechanical or physical spôsobj ^I of <3-washed materials.

in this method, it is advantageous that fine-grained carbonaceous substances can only be applied at high expense and

J, however, not quantitatively separated from the finest grain of the soil.

The present invention has as its primary object to achieve all soils and layers of soil, irrespective of the amount and the amount of soil; the type of light material and the proportion of the finest grain, použitie for which purpose the use of sufficient decontarnation.

The invention is the subject of the present invention

This object is solved by the features expressed in the anvil portion of claim 1.

It has been proven by experiments that by virtue of the method according to the invention practically all contaminated soils can be cleaned.

'! Contaminated soils from contaminated habitats may show large differences in species and con- centrations. · D

• í. .

and 1 1 j in the first step, an analysis of the soil properties that are important to the soil is carried out 4 1 decontamination. These characteristics include, in addition to the type, concentration and distribution of pollutants in the soil, the granulometric composition and determination of the proportion of light i ⁴ j material. Free content is found from the difference between the total pollutant content and the pollutant content in the light material • i 1 • '.i 'i and Ί 1 1 '1 ..i pollutants. From these analyzes the amount of adsorbent to be added is determined. The amount of adsorption agent added is calculated such that the capacity of the adsorption agent is sufficient to reduce the pollutant content in accordance with the desired remediation target. The amount of adsorption agent detected is added to the adsorbent soil and mix thoroughly with the soil. The addition can be carried out by pouring and mixing with conventional farm machinery or after digging the soil in mixers. After addition of the adsorbent and its mixing with the soil, the added amount is mixed constantly or in more or less frequent sequence to ensure rapid and perfect adsorption of the pollutants to the adsorbent. The time required can range from a few hours to several days, and is dependent on, as well as the necessity of mixing at the stage and the type of contamination and the type of soil. • J í in the next step of the process, the adsorbent and the Ί • 1. J • J Ί In this case, the light material contained in the soil is removed in a manner known per se by the soil washing method, such as sorting, stiffness sorting and / or flotation. Purified fraction

and

- 4 lands represent the largest share, harvest! which pollutants are concentrated in a small proportion of the total amount.

Suitable adsorbents are; coke, coal, a mixture of activated carbon with coke, crosslinked plastics with, large eyes, natural substances / bark, wood / and / or: debris.

’. In particular, activated carbon with its large adsorption capacity has proven to work well. Because of the relatively high cost of activated carbon, the other adsorbents mentioned may also be used in order to achieve the desired degree of decontamination for the desired soil recovery. This is particularly the case when a high adsorption capacity of activated carbon is not necessary, for example, such pollutants are present as contaminants which do not adsorb very little to the soil material, or if the process can only be carried out when only the upper layers of soil by in situ treatment at. at least more weeks.

<1

DETAILED DESCRIPTION OF THE INVENTION

The invention is described in greater detail below with reference to Examples j Comparative Example 1 i 'From soil which originates from the topmost layer of soil i <

> j found coke oven and contains 12% fine-grained sand, pre-sieving was removed. thick material> 10 mm. 1 kg of A sieved soil (soil 1) was supplemented with 1 liter of 50% by weight, potassium iodide solution (density 1.6 g / cnP) and shaken for 30 minutes. it is then graded according to geese and obtained a top-floating fraction of pollutants and

- sedimenting soil fraction (purified soil 1). To determine the degree of soil decontamination, poly. 1

cyclic aromatic hydrocarbons (PAK), listed by the US Environmental Protection Agency (EPA) as a priority pollutant, by gas chromatography or high pressure liquid chromatography of toluene extract in soil samples / M.A. Callahan et al. (1979) Waterrelated environmental fate of 129 priority pollutants, EPA-Report - 440/4 "79" 0296 /. The results of the analyzes are shown in Table 1.

Table 1; results of soil analyzes

Analysis of fraction 1 gives 1 fraction of purified pollutant light material

/ microscopy / very a little exclusively Body weights a lot dry matter / g / 1000 862 136 sum PAK according to EPA / Mg / kg 1177 191 6978 benz / a / pyrene 107 18 625 degree decon- tamination /% / 84

soil 1 contains a fraction of light material, the separation of which leads to a degree of decontamination of 84%. Accordingly, it can be purified according to the state of the art.

Reference Example 2 _Λ habitat land which is from the lower layer comprising a coking plant ^ 47% jeninozrného sand, was treated as described in comparative example 1st

The results of the analyzes are shown in Table 2. Administration 2 does not contain a light material fraction. It can be seen from Table 2 that soil decontamination cannot be achieved by density sorting.

Table 2: Results of soil analyzes

Analysis of the fraction of soil 1 gives 1 fraction of purified pollutants

light material / Microscopy / not not not sushi weight- ny / g / 1000 994 2

sum of PAK according to EPA

/ Mg / kg / 380 382 N. P. benz / a / pyrene / Mg / kg / 6 6 n. p. degree decon- soil tamination /% / 0

Example 3

To the dried contaminated soil material (soil 2) with a grain size <10 mm was added 10% by weight of activated carbon (bulk density 450 g / 1.2 mm),

For adsorption of PAK present in the soil, the mixture was rinsed with 50% by weight of water and shaken for 7 days. The separation of the soil from the adsorption agent was carried out as described in Comparative Example 1 by density sorting. The results of the analyzes are given in Table 3. Decontamination degree of 65% is achieved. The PAK value in the cleaned soil 2 is below the value of category C of the Dutch list.

Table 3: Results of soil analyzes

Fraction analyzes

filed 2 soil 2 cleaned fractions pollutants weight, su- shiny / g / 1110 994 108 PAK sum by · EPA / mg / kg 375 131 2161 benz / a / pyrene / Mg / kg / 5 2 29 degree deconta- land mines /% / 65

J ...... ................. -. 4 (Example 4); administered from the upper soil layer of the habitat. contains 36% fine-grained sand as well as 6%> 3% of lightweight material, divided by sorting according to the density described in Comparative Example 1.

According to Tables 4 and 4, 41% could be decontaminated. administered shows a PAK content of 603 mg / kg which matures; far exceeds the limit of category C of the Dutch

The list is 200 mg / kg.

j _and the same shall be supplemented with 10% by weight of an adsorption j

·; reagent / activated carbon, bulk density 450 g / l, 2 mm / j and the mixture was washed with 50% water and shaken for 7 days.

j Then it was divided by density sorting. The decontamination rate could be as shown in Table 4

increased to 86% · This example adds that in soil 3 containing light material, decontamination can be improved by a factor of about 2 by the method of the invention.

THEN the cleaned soil 3 is below the C of the Dutch list. Table 4; results of soil analyzes Analyzes fractions filed 3 soil 3 fractions purified pollutants

without adsorbent

light material / Microscopy / a lot a little exclusively weight- shiny / g / 1000 937 63 sum PAK po- according to EPA / mg / kg / 1022 603 6650 benz / a / pyrene 1.3 8 71 degree deconta- land mines /% / 41

with a sorbent

dry weight / G / 1110 934 176 sum of PAK according to EPA / mg / kg 94.1 131 5106 benz / a / p.yrén / ^m g / ^k g / 1.4 2 67 degree deconta- land mines /% / 86

- 9 Example 5

The two soils originating from the lower soil layer of the coking plant and containing 29% fine-grained sand (filed 4) or 47% fine-grained sand (filed 5) were supplemented with different adsorbents (10% _w / _w ). . After 7 days of treatment, the soils were separated by density sorting. The results are shown in Table 5. Depending on the soil and adsorption agent used, the degrees of soil decontamination ranged from 29 to 29. 93% ·

Table 5: Use of different adsorbents for soil decontamination

filed no. adsorbent grain size / mm / land Mg / mg / kg Λ, shall čiste- / na PAK / Mg / kg / degree of soil decontamination /% / 4 activated carbon 2 2990 183 93 4 brown coal coke 2-4 3005 870 71 5 silicone rubber 2-5 485 107 78 5 anthracies t 1.6-2.5 482 342 29

Example 6 filed from the top layer of the soil of the impregnation plant (filed 6, sandy filed with 3% fine-grained sand without a light weight fraction), with a water content of 5% mixed thoroughly with various adsorbs.

- 10 reagents / 10% by weight. and was stored for 42 days without further mixing. The separation of the adsorbent from the soil material was then done by sorting the soil by density. The results are shown in the table

6. By this treatment it was possible to achieve a decontamination degree> 85 for all adsorption agents used

Table 6: use of different adsorbents for soil decontamination adsorption size soil soil grade decontaminant grain / mm / PAK cleaned soil target /% / / mg / kg / PAK / mg / kg / active

coal 2-5 272 <10 > 96 hnedouhoľ- coke 2-4 279 <10 > 96 silicone rubber 2-5 291 24 92 anthracite 1.6-2.5 285 25 91 crust the straw <5 297 36 87

Example 7

Dry contaminated soil material (soil 4, without light material fraction) was supplemented with 10% by weight, activated carbon and 50% by weight, water and shaken for various periods. The results are shown in FIG. After 7 hours, 50% PAV was adsorbed on activated carbon, after 72 hours of treatment, a degree of decontamination of greater than 80% could be achieved. As can be seen from Table 5 (Example 5), after 168 hours / 7 days / duration; processing degree 93% decontamination.

Example 8; Dry contaminated soil material / handles 4 »without! fraction of the light material / the doolnil 50% by weight of water "and ⁵ * 1 and various amounts of activated carbon and shaken for 24 · it; · Dín. The results are shown in Fig. 2. With 1% by weight of activated carbon, a decontamination of 50% could be achieved after 24 hours. This example demonstrates that; when using small amounts of activated carbon, the maximum d can still be d. e contamination below, y.

and

It follows from Examples 7 and 8 that the reduction of the PAK content in the soil required for decontamination can be achieved by the following process variations;

'1

'] _{From the} extension _of the processing time it can be as obvious SW príkladu.7, increase the degree of decontamination.

It is also possible to achieve a higher degree of decontamination by repeating the treatment with fresh adsorbent per unit time.

From Example 8 it can be deduced that by increasing the amount; The amount of adsorption agent may increase the degree of decontamination:. Cie.

Depending on the time available for the remediation and the cost of the adsorbent, the most favorable process variant for the remediation is determined.

Claims (1)

1. A method according to which the contaminants contained in the soil are removed by washing the soil, sorting, sorting by density and / or flotation, adding to the soil depending on the found content of the soil. Glucine adsorption agent, and this is thoroughly mixed with the soil, characterized in that the content of the light material and the finest grain is first determined and a coarse adsorption is added to the soil, depending on the detected content of organic pollutants and light material. , A reagent. ^: Ϊ́ 2. The method according to claim 1, characterized by. ••• I / characterized z e as the adsorbent used in coke / 1 carbon, activated carbon was coke zosieíované • P a plastic mesh in capital, natural substances (A j) bark, wood / and / or slag.