CN103901181A - Experimental method for detoxifying chromium-contaminated soil through anaerobically-digested sludge - Google Patents
Experimental method for detoxifying chromium-contaminated soil through anaerobically-digested sludge Download PDFInfo
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Abstract
The invention relates to an experimental method for detoxifying chromium-contaminated soil through anaerobically-digested sludge. The method comprises the following specific steps: (a) preparing a mixed sample of the chromium-contaminated soil and the anaerobically-digested sludge according to a certain proportion, weighing quantitative anaerobically-digested sludge according to a preset proportion of the chromium-contaminated soil to the anaerobically-digested sludge, adding a certain amount of deionized water into the quantitative anaerobically-digested sludge to uniformly mix the sludge, respectively weighing quantitative chromium-contaminated soil, adding the soil into the uniformly-mixed sludge, and fully and uniformly mixing the soil and the sludge; (b) periodically sampling to determine the concentration of water-soluble hexavalent chromium in a mixture; (c) increasing the specific gravity of the anaerobically-digested sludge, determining the concentration of the water-soluble hexavalent chromium, drawinga change curve of the concentration of the water-soluble hexavalent chromium in the mixture and a reduction rate of the water-soluble hexavalent chromium, and analyzing to determine an optimum mixing proportion of the chromium-contaminated soil to the anaerobically-digested sludge. The chromium-contaminated soil is detoxified through the anaerobically-digested sludge and is remediated. The method has the advantages of low investment, low operation cost, diversified treatment mode and the like.
Description
Technical field
The present invention relates to pollute reparation field, relate in particular to a kind of experimental technique of anaerobically digested sludge removing toxic substances chromium-polluted soil.
Background technology
0.3～1.5% the solubility sexavalent chrome containing in chromium slag, can be along with rainfall enters surrounding soil, surface water and groundwater, severe contamination surrounding environment.Therefore, the reparation of chromium-polluted soil more and more causes people's attention.
Compared with polluting restorative procedure with tradition, biological restoration has the advantages such as investment is little, operating cost is low, processing mode is various; But the biotic component of in prior art, chromium-polluted soil being repaired and ratio also do not have effective achievement.
In view of above-mentioned defect, creator of the present invention has obtained this creation finally through long research and practice.
Summary of the invention
The object of the present invention is to provide a kind of experimental technique of anaerobically digested sludge removing toxic substances chromium-polluted soil, in order to overcome above-mentioned technological deficiency.
For achieving the above object, the invention provides a kind of experimental technique of anaerobically digested sludge removing toxic substances chromium-polluted soil,
This detailed process is: this detailed process is:
Step a, according to a certain percentage, the mixing sample of preparation chromium-polluted soil and anaerobically digested sludge;
According to the predetermined ratio of chromium-polluted soil and anaerobically digested sludge, take quantitative anaerobically digested sludge, add wherein a certain amount of deionized water that mud is mixed well, then take respectively quantitative chromium-polluted soil and join in the mud of mixing well, fully mix;
Step b, period sampling measuring is water-soluble chromic concentration wherein;
Pretreating sludge is sampling immediately after mixing with soil, and each sampling in the 2nd day, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 15 days, 20 days, 25 days, 30 days once; Before every sub-sampling, all first sample is fully mixed, sample take out after natural air drying, air-dry rear with three-head grinding machine grind make it cross 60 mesh sieves, and pack preserve, to be measured;
Step c, increases the proportion of described anaerobically digested sludge, samples and preserves according to above-mentioned steps b, measures water-soluble chromic concentration, draws water-soluble hexavalent chromium concentration and percent reduction change curve thereof in potpourri; The chromium-polluted soil of Analysis deterrmination the best and the mixing ratio of anaerobically digested sludge.
Further, in above-mentioned steps a, control the amount of the deionized water adding, guarantee to mix rear sample moisture and do not separate out.
Further, in above-mentioned steps a, it is the ratio of 10: 1 and 5: 1 according to chromium-polluted soil and anaerobically digested sludge weight in wet base ratio, take respectively 40g, 80g anaerobically digested sludge, add wherein a certain amount of deionized water that mud is mixed well, then take respectively 400g chromium-polluted soil and join in the mud of mixing well, fully mix, period sampling measuring is water-soluble chromic concentration wherein.
Further, in above-mentioned steps c, increase sludge quantity, make chromium-polluted soil and anaerobically digested sludge weight in wet base ratio increase to 2: 1 and 1: 1.
Further, as the replacement scheme of step c, in described step a under the constant condition of anaerobically digested sludge and chromium-polluted soil proportioning, add a certain amount of changing food waste, be made into the combined chromium-polluted soil toxinicide of anaerobically digested sludge and changing food waste, measure water-soluble chromic concentration, draw water-soluble hexavalent chromium concentration and percent reduction change curve thereof in potpourri.
Further, in above-mentioned steps c, be under the condition of ratio of 10: 1 and 5: 1 according to chromium-polluted soil in above-mentioned steps a and anaerobically digested sludge ratio, take the changing food waste that 100g rubs and join in the mud of mixing well, fully mix, sample and preserve according to above-mentioned steps b.
Further, in above-mentioned steps d, the measuring process of initial Cr (VI) concentration affects factor is:
Steps d 11, takes respectively 2098g anaerobically digested sludge, and dry weight 600g, then according to soil: the ratio that dry weight mud is respectively 2: 1,1: 1,1: 2,1: 3 adds successively 1200g, 600g, 300g, 200g chromium-polluted soil to mix in container;
Further, in above-mentioned steps d, the measuring process of water percentage influence factor is:
Steps d 22, sample time and sample pretreatment; After sample mix, carry out immediately the 1st sub-sampling, then 6h, 12h, sampling respectively in 1 day, 2 days, 3 days, 5 days, 10 days, 15 days, 25 days, 35 days, 45 days, 65 days, before every sub-sampling, first sample is fully mixed, natural air drying after sample takes out, air-dry rear with three-head grinding machine grind make it cross 60 mesh sieves, and pack preservation, to be measured.
Further, in above-mentioned steps d, the measuring process of temperature influence factor is:
Steps d 31, take respectively 250g containing chromium-polluted soil, 250g anaerobically digested sludge, first in mud, add 876mL deionized water, make 75% water percentage, mud is mixed well, then add load weighted contaminated soil to be mixed evenly, finally three groups of samples are placed in respectively to the incubator of 10 ℃, 20 ℃, 30 ℃;
Further, in above-mentioned steps d, the measuring process of initial pH influence factor is:
Steps d 41, take respectively four groups of 200g dry weight mud, add wherein certain water gaging to mix well, the ratio according to dry weight than 6: 1 is respectively to adding 1200g chromium-polluted soil in mud and fully mixing, and is respectively 5,6,7,8 with the pH of HC1 and NaOH adjusting compound sample;
Beneficial effect of the present invention is compared with prior art: the present invention adopts anaerobically digested sludge removing toxic substances chromium-polluted soil, and soil is repaired, and has again the advantages such as investment is little, operating cost is low, processing mode is various.And anaerobically digested sludge source is abundant, can belong to waste recycling technique for the treatment of chromium-polluted soil in batches.
Accompanying drawing explanation
Fig. 1 a is that the present invention tests water-soluble hexavalent chromium concentration change curve in a potpourri;
Fig. 1 b is that the present invention tests water-soluble sexavalence percent reduction change curve in a potpourri;
Fig. 2 a is that the present invention tests water-soluble hexavalent chromium concentration change curve in two potpourris;
Fig. 2 b is that the present invention tests water-soluble sexavalence percent reduction change curve in two potpourris;
Fig. 3 a is that the present invention tests water-soluble hexavalent chromium concentration change curve in three potpourris;
Fig. 3 b is that the present invention tests water-soluble sexavalence percent reduction change curve in three potpourris;
Fig. 4 a is water-soluble hexavalent chromium concentration change curve in chromium-polluted soil and anaerobically digested sludge potpourri under different blended composition and division in a proportion condition;
Fig. 4 b is water-soluble hexavalent chrome reduction rate change curve in chromium-polluted soil and anaerobically digested sludge potpourri under different blended composition and division in a proportion condition;
Fig. 5 a and be under different water cut condition, water-soluble hexavalent chromium concentration change curve in chromium-polluted soil and anaerobically digested sludge potpourri;
Fig. 5 b is under different water cut condition, water-soluble hexavalent chrome reduction rate change curve in chromium-polluted soil and anaerobically digested sludge potpourri;
Fig. 6 a is under condition of different temperatures, water-solubility Cr (VI) concentration curve in chromium-polluted soil and anaerobically digested sludge potpourri;
Fig. 6 b is under condition of different temperatures, water-solubility Cr (VI) percent reduction change curve in chromium-polluted soil and anaerobically digested sludge potpourri;
Fig. 7 a is under different initial pH conditions, water-solubility Cr (VI) concentration curve in chromium-polluted soil and anaerobically digested sludge potpourri;
Fig. 7 b is under different initial pH conditions, water-solubility Cr (VI) percent reduction change curve in chromium-polluted soil and anaerobically digested sludge potpourri.
Embodiment
Below in conjunction with accompanying drawing, technical characterictic and the advantage with other above-mentioned to the present invention are described in more detail.
The detailed process of the experimental technique of anaerobically digested sludge removing toxic substances chromium-polluted soil of the present invention is:
Step a, according to a certain percentage, the mixing sample of configuration chromium-polluted soil and anaerobically digested sludge;
According to the predetermined ratio of chromium-polluted soil and anaerobically digested sludge, take quantitative anaerobically digested sludge, add wherein a certain amount of deionized water that mud is mixed well, then take respectively quantitative chromium-polluted soil and join in the mud of mixing well, fully mix.
In experiment, control the amount of the deionized water that adds, guarantee that moisture do not separate out.
Step b, period sampling measuring is water-soluble chromic concentration wherein;
Pretreating sludge is sampling immediately after mixing with soil, and each sampling in the 2nd day, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 15 days, 20 days, 25 days, 30 days once.Before every sub-sampling, all first sample is fully mixed, sample take out after natural air drying, air-dry rear with three-head grinding machine grind make it cross 60 mesh sieves, and pack preserve, to be measured.
Step c, increases the proportion of described anaerobically digested sludge, samples and preserves according to above-mentioned steps b, measures water-soluble chromic concentration, draws water-soluble hexavalent chromium concentration and percent reduction change curve in potpourri; The chromium-polluted soil of Analysis deterrmination the best and the mixing ratio of anaerobically digested sludge.
First, respectively for different experiments, above-mentioned steps is described.
Experiment one:
(1) according to chromium-polluted soil and anaerobically digested sludge weight in wet base ratio be the ratio of 10: 1 and 5: 1, take respectively anaerobically digested sludge 40g, 80g, add wherein a certain amount of deionized water that mud is mixed well, then taking respectively 400g chromium-polluted soil joins in the mud of mixing well, fully mix, period sampling measuring is water-soluble chromic concentration wherein.In experiment, control the amount of the deionized water that adds, guarantee that moisture do not separate out.
(2) sample time and sample pretreatment mud sampling immediately after mixing with soil, each sampling in the 2nd day, 3 days, 4 days, 5 days, 10 days, 15 days, 20 days once.Before every sub-sampling, all first sample is fully mixed, sample take out after natural air drying, air-dry rear with three-head grinding machine grind make its cross 60 mesh sieves and pack preserve, to be measured.
(3) experiment is 5496mg/kg with water-soluble hexavalent chromium concentration in original soil, in this experiment, chromium-polluted soil and anaerobically digested sludge mixing ratio are 10: 1,5: 1, and in potpourri, water-soluble chromic initial concentration is respectively 5343mg/kg, 5199mg/kg.
Refer to shown in Fig. 1 a and 1b, under DIFFERENT WET anharmonic ratio condition, water-soluble hexavalent chromium concentration and percent reduction change curve in chromium-polluted soil and anaerobically digested sludge potpourri.
Can be found out by Fig. 1 a, 1b, through the processing of anaerobically digested sludge, in chromium-polluted soil, water-soluble hexavalent chromium concentration has downward trend gradually, and the rate of reduction of the chromium that mixing ratio is 5: 1 is greater than 10: 1.Incipient stage, water-soluble hexavalent chromium concentration suppression ratio was very fast, reaction is afterwards tending towards slow, by the 20th day, soil mud mixing ratio is 10: 1 and 5: 1 o'clock, water-soluble hexavalent chromium concentration is down to 2742mg/kg, 1738mg/kg from 5343mg/kg, 5199mg/kg respectively, and hexavalent chrome reduction rate is respectively 48.7% and 66.6%.
As can be seen here, anaerobically digested sludge removing toxic substances chromium-polluted soil has feasibility, and sludge quantity is higher, and after reaction, Cr (VI) concentration is lower, and hexavalent chrome reduction rate is higher, and treatment effect is better.But along with the prolongation of time, react more and more slower, during by the 20th day, percent reduction less than 70%.For this reason, on the basis of this experiment, proceed following experiment.
Experiment two:
(1) according to chromium-polluted soil and anaerobically digested sludge weight in wet base ratio be the ratio of 2: 1 and 1: 1, take respectively 200g, 400g anaerobically digested sludge, add wherein a certain amount of deionized water that mud is mixed well, then taking respectively 400g chromium-polluted soil joins in the mud of mixing well, fully mix, period sampling measuring is water-soluble chromic concentration wherein.In experiment, control the amount of the deionized water that adds, guarantee that moisture do not separate out.
(2) sample time and sample pretreatment mud sampling immediately after mixing with soil, each sampling in the 2nd day, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 15 days, 20 days, 25 days, 30 days once.Before every sub-sampling, all first sample is fully mixed, sample take out after natural air drying, air-dry rear with three-head grinding machine grind make it cross 60 mesh sieves, and pack preserve, to be measured.
(3) increase sludge quantity, make the mixing ratio of soil and mud be reduced to 2: 1,1: 1.Experiment is 5496mg/kg with water-soluble hexavalent chromium concentration in original soil, and in this experiment, chromium-polluted soil and anaerobically digested sludge mixing ratio are 2: 1,1: 1, and in potpourri, water-soluble chromic initial concentration is respectively 4808mg/kg, 4274mg/kg.
Refer to shown in Fig. 2 a and 2b, it is respectively water-soluble hexavalent chromium concentration and percent reduction change curve in potpourri.
Can be found out by Fig. 2 a and 2b, after anaerobically digested sludge mixes with chromium-polluted soil, in contaminated soil, hexavalent chromium concentration reduces rapidly.First day, mixing ratio is 2: 1 o'clock, water-soluble hexavalent chromium concentration is reduced to 2847mg/kg by initial 4808mg/kg; Mixing ratio is 1: 1 o'clock, and water-soluble hexavalent chromium concentration is down to 1430mg/kg by initial 4274mg/kg, and hexavalent chrome reduction rate is respectively 40.8%, 66.6%, probes into the percent reduction in experiment apparently higher than feasibility.
Mixing ratio is 2: 1 and 1: 1 o'clock, and percent reduction reached more than 90% at the 9th day and the 6th day respectively; After the 10th day, reaction becomes slowly, and water-soluble hexavalent chromium concentration and percent reduction in two groups of samples are more or less the same, and this is that reducing power reduces gradually because reducing substances is consumed; The 30th day, percent reduction reached respectively 97%, 98%, and water-soluble hexavalent chromium concentration is down to respectively 145mg/kg, 84mg/kg.As can be seen here, increase sludge quantity and can significantly improve chromic percent reduction, mud obviously strengthens the detoxifying effect of chromium-polluted soil.
Above-mentioned experiment is tested by increasing sludge quantity, followingly tests by adding a certain amount of changing food waste, and this process is:
In described step a under the constant condition of anaerobically digested sludge and chromium-polluted soil proportioning, add a certain amount of changing food waste, be made into the combined chromium-polluted soil toxinicide of anaerobically digested sludge and changing food waste, measure water-soluble chromic concentration, draw water-soluble hexavalent chromium concentration and percent reduction change curve thereof in potpourri.
Experiment three:
(1) take 40g anaerobically digested sludge, add wherein a certain amount of deionized water that mud is mixed well, then the changing food waste that takes respectively 400g chromium-polluted soil and 100g rubbing joins in the mud of mixing well, and fully mixes, and period sampling measuring is water-soluble chromic concentration wherein.In experiment, control the amount of the deionized water that adds, guarantee that moisture do not separate out.
(2) sample time and sample pretreatment mud sampling immediately after mixing with soil, each sampling in the 2nd day, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 15 days, 20 days, 25 days, 30 days once.Before every sub-sampling, all first sample is fully mixed, sample take out after natural air drying, air-dry rear with three-head grinding machine grind make it cross 60 mesh sieves, and pack preserve, to be measured.
Refer to shown in Fig. 3 a and 3b, it is respectively water-soluble hexavalent chromium concentration and percent reduction change curve in potpourri.
Can be found out by Fig. 3 a and 3b, add after changing food waste, water-soluble hexavalent chromium concentration significantly reduces, and the water-soluble sexavalent chrome fall off rate of experiment first day is the fastest, and concentration is reduced to 1468mg/kg by initial 4486mg/kg; During by the 5th day, be down to 254mg/kg, percent reduction is now 94.3%; After five days, reaction rate obviously slows down, and during by 20 days, concentration is reduced to 71mg/kg, and percent reduction has reached 98.4%.As can be seen here, add the reduction that changing food waste is conducive to chromium, and rate of reduction is obviously accelerated.
The present invention also measures anaerobically digested sludge removing toxic substances Cr (VI) influence factor, comprises initial Cr (VI) concentration, temperature, water percentage, the impact of initial pH on Cr (VI) percent reduction; The different condition value of each reaction conditions is all used with a collection of mud tests simultaneously, to guarantee the reliability of comparison.
Initial Cr (VI) concentration:
Get four groups of equivalent anaerobically digested sludges, mud and chromium-polluted soil are pressed to different proportion mixing, chromic variation in results of regular determination soil, analyzes the impact of initial Cr (VI) concentration on anaerobically digested sludge processing chromium-polluted soil effect.
Steps d 11, takes respectively 2098g anaerobically digested sludge, and dry weight 600g, then according to soil: the ratio that dry weight mud is respectively 2: 1,1: 1,1: 2,1: 3 adds successively 1200g, 600g, 300g, 200g chromium-polluted soil to mix in container;
Water-soluble sexavalent chrome initial concentration in soil and mud mixture is respectively 2957.1mg/kg, 2217.8mg/kg, 1478.5mg/kg, 1108.9mg/kg.
Experiment is by regulating chromium-polluted soil and the blending ratio (dry weight ratio) of anaerobically digested sludge to obtain the potpourri of different initial hexavalent chromium concentrations.4 ratios have been got in experiment, obtain the potpourri of 4 kinds of DIFFERENT Cr concentration.Concrete data are as shown in table 1.
The corresponding initial hexavalent chromium concentration of table 1 different blended composition and division in a proportion
Refer to shown in Fig. 4 a and 4b, it is respectively under different blended composition and division in a proportion condition water-soluble hexavalent chromium concentration and percent reduction change curve in chromium-polluted soil and anaerobically digested sludge potpourri;
From Fig. 4 a, in the potpourri of 4 kinds of different proportionings, the variation tendency of hexavalent chromium concentration is basically identical, and the first day chromium concn of experiment declines rapidly, and downtrending afterwards tends towards stability.When experiment finishes, in 4 kinds of potpourris, chromic concentration is more or less the same.Can be found out by Fig. 4 b, the ratio of mud is larger, faster to the rate of reduction of chromium, but final percent reduction is more or less the same, and has all reached more than 97%.
Sampling and measuring result shows for the first time, under four groups of different initial concentration conditions, percent reduction is all higher than 87%, when wherein initial concentration is 1108.9mg/kg, concentration drops to 30.88mg/kg, now percent reduction is 97%, when initial concentration is 2957.1mg/kg, 2217.8mg/kg, 1478.5mg/kg, concentration drops to respectively 356.4mg/kg, 185.1mg/kg, 106.9mg/kg, and percent reduction is respectively 87.9%, 91.7%, 92.8%.Incipient stage, sexavalent chrome is reduced rapidly; In 35 days afterwards, hexavalent chromium concentration slowly reduces, and finds that potpourri expands because producing gas while sampling simultaneously; After 36 days, water-soluble hexavalent chromium concentration drops to respectively 68.7mg/kg, 20.4mg/kg, 5.24mg/kg, 3.88mg/kg, and corresponding percent reduction is respectively 97.7%, 99.1%, 99.6%, 99.7%.As from the foregoing, sexavalent chrome initial concentration is higher, and the time that reduction needs is longer, but mixing ratio is 1: 1,1: 2,1: 3 o'clock, all higher than 97%, visible at the percent reductions of 36 days, can select the mixing ratio of 1: 1 in practical application.
With the rising of initial water dissolubility hexavalent chromium concentration, chromic rate of reduction and percent reduction are all on a declining curve, reason is that hexavalent chromium concentration is higher, need the reducing substances of consumption more, and sludge quantity is certain, sludge quantity becomes the factor that determines reaction speed, and chromium concn increase causes sludge quantity relative deficiency, and reaction rate reduces.
Water percentage:
Steps d 22, sample time and sample pretreatment; After sample mix, carry out immediately the 1st sub-sampling, then 6h, 12h, sampling respectively in 1 day, 2 days, 3 days, 5 days, 10 days, 15 days, 25 days, 35 days, 45 days, 65 days, before every sub-sampling, first sample is fully mixed, natural air drying after sample takes out, air-dry rear with three-head grinding machine grind make it cross 60 mesh sieves, and pack preservation, to be measured.
Refer to shown in Fig. 5 a and 5b, it is respectively under different water cut condition, water-soluble hexavalent chromium concentration and percent reduction change curve in chromium-polluted soil and anaerobically digested sludge potpourri;
From Fig. 5 a and, under 4 kinds of different water cut conditions, the variation tendency of chromium concn is basically identical, along with the increase of time, chromium concn reduces gradually.Moisture percentage in sewage sludge is higher, and in potpourri, chromic concentration is higher, and percent reduction is lower.After 85 days, water-soluble hexavalent chromium concentration all drops to below 30mg/kg, and percent reduction is all more than 98%.
Although reduce with water percentage, percent reduction raises to some extent, percent reduction corresponding to each water percentage condition is more or less the same.
Temperature:
Steps d 31, take respectively 250g containing chromium-polluted soil, 250g anaerobically digested sludge, first in mud, add 876m1 deionized water, make 75% water percentage, mud is mixed well, then add load weighted contaminated soil to be mixed evenly, finally three groups of samples are placed in respectively to the incubator of 10 ℃, 20 ℃, 30 ℃.
Refer to shown in Fig. 6 a and 6b, it is respectively under condition of different temperatures, water-solubility Cr (VI) concentration and percent reduction change curve in chromium-polluted soil and anaerobically digested sludge potpourri;
From Fig. 6 a and 6b, under three kinds of condition of different temperatures, the variation tendency of chromium concn is basically identical, and increase chromium concn in time reduces gradually.In the temperature range of research, chromic percent reduction raises with the rising of temperature.In the time that temperature is 30 ℃, hexavalent chrome reduction rate is the highest, and during by 59 days, concentration is reduced to 8.4mg/kg, and percent reduction can reach 99.6%; 10 ℃ time, hexavalent chrome reduction rate is minimum, is 96.4%; In addition, the vital movement of microorganism is made up of series of biochemical reactions, and it is very obvious that these reactions are subject to the impact of temperature, so occur that above-mentioned phenomenon may be because in the temperature range of research, with the rising of temperature, microbial activity strengthens, and chromic reduction is accelerated gradually.In actual application process, can adopt plastic sheeting to cover the heap body of anaerobically digested sludge and chromium-polluted soil, to improve the temperature of heap body, can also play the effect of moisturizing simultaneously.
Initial pH:
Steps d 41, take respectively four groups of 200g dry weight mud, add wherein certain water gaging to mix well, the ratio according to dry weight than 6: 1 is respectively to adding 1200g chromium-polluted soil in mud and fully mixing, and is respectively 5,6,7,8 with the pH of HC1 and NaOH adjusting compound sample.
Refer to shown in Fig. 7 a and 7b, it is respectively under different initial pH conditions, water-solubility Cr (VI) concentration and percent reduction change curve in chromium-polluted soil and anaerobically digested sludge potpourri;
Can be found out by figure Fig. 7 a and 7b, original ph has obvious impact to the chromic reaction of detoxifying.Initial pH is 5,6,7,8 o'clock, the first day of reaction, and water-soluble sexavalent chrome is reduced to 631mg/kg, 703mg/kg, 1089mg/kg, 1380mg/kg by 4122mg/kg respectively; During by the 9th day, concentration is respectively 21mg/kg, 38mg/kg, 105mg/kg, 218mg/kg, and percent reduction reaches respectively 99.5%, 99.1%, 97.4%, 94.7%.In the scope of research, with the rising of pH, the percent reduction of Cr (VI) reduces, and the initial pH of chromium-polluted soil and anaerobically digested sludge is that 5 o'clock treatment effects are best.
Research shows, pH can affect the reduction effect of microbial growth and Cr (VI).In experiment, initial pH is that the reduction effect of 5 o'clock is best, because pH reduces, Cr (VI) oxidation-reduction potential raises, and oxidability strengthens, and the ability of organic reduction of hexavalent chromium strengthens simultaneously; Meanwhile, within the scope of the pH of research, the activity of the microorganism in anaerobically digested sludge in weak acid environment is higher, is more conducive to that micro-reduction is chromic to carry out.
The foregoing is only preferred embodiment of the present invention, is only illustrative for invention, and nonrestrictive.Those skilled in the art is understood, and in the spirit and scope that limit, can carry out many changes to it in invention claim, revise, and even equivalence, but all will fall within the scope of protection of the present invention.
Claims (10)
1. an experimental technique for anaerobically digested sludge removing toxic substances chromium-polluted soil, is characterized in that, this detailed process is:
Step a, according to a certain percentage, the mixing sample of preparation chromium-polluted soil and anaerobically digested sludge;
According to the predetermined ratio of chromium-polluted soil and anaerobically digested sludge, take quantitative anaerobically digested sludge, add wherein a certain amount of deionized water that mud is mixed well, then take respectively quantitative chromium-polluted soil and join in the mud of mixing well, fully mix;
Step b, period sampling measuring is water-soluble chromic concentration wherein;
Pretreating sludge is sampling immediately after mixing with soil, and each sampling in the 2nd day, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 15 days, 20 days, 25 days, 30 days once; Before every sub-sampling, all first sample is fully mixed, sample take out after natural air drying, air-dry rear with three-head grinding machine grind make it cross 60 mesh sieves, and pack preserve, to be measured;
Step c, increases the proportion of described anaerobically digested sludge, samples and preserves according to above-mentioned steps b, measures water-soluble chromic concentration, draws water-soluble hexavalent chromium concentration and percent reduction change curve thereof in potpourri; The chromium-polluted soil of Analysis deterrmination the best and the mixing ratio of anaerobically digested sludge;
Steps d, carries out measuring to the impact of anaerobically digested sludge removing toxic substances Cr (VI), comprises Cr (VI) concentration, temperature, water percentage, initial pH.
2. the experimental technique of anaerobically digested sludge removing toxic substances chromium-polluted soil according to claim 1, is characterized in that, in above-mentioned steps a, controls the amount of the deionized water adding, and guarantees to mix rear sample moisture and does not separate out.
3. the experimental technique of anaerobically digested sludge removing toxic substances chromium-polluted soil according to claim 1 and 2, it is characterized in that, in above-mentioned steps a, it is the ratio of 10: 1 and 5: 1 according to chromium-polluted soil and anaerobically digested sludge weight in wet base ratio, take respectively 40g, 80g anaerobically digested sludge, add wherein a certain amount of deionized water that mud is mixed well, then take respectively 400g chromium-polluted soil and join in the mud of mixing well, fully mix, period sampling measuring is water-soluble chromic concentration wherein.
4. the experimental technique of anaerobically digested sludge removing toxic substances chromium-polluted soil according to claim 3, is characterized in that, in above-mentioned steps c, increases sludge quantity, makes chromium-polluted soil and anaerobically digested sludge weight in wet base ratio increase to 2: 1 and 1: 1.
5. the experimental technique of anaerobically digested sludge removing toxic substances chromium-polluted soil according to claim 1, it is characterized in that, as the replacement scheme of step c, in described step a under the constant condition of anaerobically digested sludge and chromium-polluted soil proportioning, add a certain amount of changing food waste, be made into the combined chromium-polluted soil toxinicide of anaerobically digested sludge and changing food waste, measure water-soluble chromic concentration, draw water-soluble hexavalent chromium concentration and percent reduction change curve thereof in potpourri.
6. the experimental technique of anaerobically digested sludge removing toxic substances chromium-polluted soil according to claim 5, it is characterized in that, in above-mentioned steps c, be under the condition of ratio of 10: 1 and 5: 1 according to chromium-polluted soil in above-mentioned steps a and anaerobically digested sludge ratio, the changing food waste that takes 100g rubbing joins in the mud of mixing well, fully mix, sample and preserve according to above-mentioned steps b.
7. the experimental technique of anaerobically digested sludge removing toxic substances chromium-polluted soil according to claim 1, is characterized in that, in above-mentioned steps d, the measuring process of initial Cr (VI) concentration affects factor is:
Steps d 11, takes respectively 2098g anaerobically digested sludge, and dry weight 600g, then according to soil: the ratio that dry weight mud is respectively 2: 1,1: 1,1: 2,1: 3 adds successively 1200g, 600g, 300g, 200g chromium-polluted soil to mix in container;
Steps d 12, sample time and sample pretreatment; Mud is sampling immediately after mixing with soil, each sampling in the 2nd day, 4 days, 6 days, 8 days, 15 days, 22 days once, all first fully mixes sample before every sub-sampling, natural air drying after sample takes out, air-dry rear with three-head grinding machine grind make it cross 60 mesh sieves, and pack preserve.
8. according to the experimental technique of the anaerobically digested sludge removing toxic substances chromium-polluted soil described in claim 1 or 7, it is characterized in that, in above-mentioned steps d, the measuring process of water percentage influence factor is:
Steps d 21, the blending ratio that is 1: 1 according to chromium-polluted soil and anaerobically digested sludge dry weight ratio, take respectively the anaerobic nitrification mud of 300g containing pollution of chromium soil sample and dry weight 300g, the water percentage according to 65%, 70%, 75%, 80% calculates the amount that obtains the deionized water that four groups of samples need to add and is respectively 365.3mL, 651mL, 1051mL, 1651mL; When sample preparation, first in mud, add respectively 365.3mL, 651mL, 1051mL, 1651mL deionized water, and mud is mixed well, then add load weighted contaminated soil to be mixed evenly;
Steps d 22, sample time and sample pretreatment; After sample mix, carry out immediately the 1st sub-sampling, then 6h, 12h, sampling respectively in 1 day, 2 days, 3 days, 5 days, 10 days, 15 days, 25 days, 35 days, 45 days, 65 days, before every sub-sampling, first sample is fully mixed, natural air drying after sample takes out, air-dry rear with three-head grinding machine grind make it cross 60 mesh sieves, and pack preservation, to be measured.
9. according to the experimental technique of the anaerobically digested sludge removing toxic substances chromium-polluted soil described in claim 1 or 7, it is characterized in that, in above-mentioned steps d, the measuring process of temperature influence factor is:
Steps d 31, take respectively 250g containing chromium-polluted soil, 250g anaerobically digested sludge, first in mud, add 876mL deionized water, make 75% water percentage, mud is mixed well, then add load weighted contaminated soil to be mixed evenly, finally three groups of samples are placed in respectively to the incubator of 10 ℃, 20 ℃, 30 ℃;
Steps d 32, sample time and sample pretreatment; After sample mix, carry out immediately the 1st sub-sampling, 6h, 12h, sampling respectively in 1 day, 2 days, 4 days, 9 days, 19 days, 29 days, 39 days, 59 days; Before sampling, all first sample is fully mixed, measures compound sample pH simultaneously, air-dry rear with three-head grinding machine grind make its cross 60 mesh sieves and pack preserve, to be measured.
10. according to the experimental technique of the anaerobically digested sludge removing toxic substances chromium-polluted soil described in claim 1 or 7, it is characterized in that, in above-mentioned steps d, the measuring process of initial pH influence factor is:
Steps d 41, take respectively four groups of 200g dry weight mud, add wherein certain water gaging to mix well, the ratio according to dry weight than 6: 1 is respectively to adding 1200g chromium-polluted soil in mud and fully mixing, and is respectively 5,6,7,8 with the pH of HC1 and NaOH adjusting compound sample;
Step 42, sample time and sample pretreatment; After sample mix, carry out the 1st sub-sampling, eight day thereafter every day timing sampling; Before sampling, all first sample is fully mixed, sample take out after natural air drying, air-dry rear with three-head grinding machine grind make it cross 60 mesh sieves, and pack preserve, to be measured.
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