CJ/T 428-2013Detection methods for the leachate from municipal solid waste (English PDF)

1 Scope 1

2 Normative references 1

3 Terms and Definitions 1

4 Chroma 3

5 total solids 4

6 Total dissolved solids and total suspended solids5

7 Sulfate 6

8 Ammonia nitrogen 8

9 Kjeldahl nitrogen 11

10 Total Nitrogen 13

11 Chloride 16

12 Total phosphorus 18 13 pH 22

14 Biochemical Oxygen Demand Five Days (BOD5) 24

15 Chemical Oxygen Demand (CODCr) 28

16 Conductivity31

17 Potassium and Sodium33

18 Total Mercury 35

19 total arsenic 40

20 Lead and Cadmium42

21 total chromium 48 22 total bacteria 50

23 Total coliforms 53

24 Fecal coliforms 59

25 Quality Assurance and Control 63

Appendix A (Informative Appendix) Sulfuric acid standard titration solution and methyl red-bromocresol green mixed indicator 64

Appendix B (Normative Appendix) The pH of the standard solution varies with temperature 65

Appendix C (Normative Appendix) Gram Stain and Microscopic Examination 66

Detection method of domestic waste leachate

1 Scope

This standard specifies the terms and definitions, color, total solids, total dissolved solids and total suspended solids, sulfuric acid Salt, ammonia nitrogen, Kjeldahl nitrogen, total nitrogen, chloride, total phosphorus, pH, BOD5, COD, conductivity, potassium and sodium, total mercury, total the detection methods and quality assurance and control of 21 items such as arsenic, lead and cadmium, total chromium, total bacterial count, total coliform group, and fecal coliform group.

This standard is applicable to the determination of domestic waste leachate.

2 Normative references the following documents are indispensable for the application of this document. For dated references, only the dated version applies to this document pieces. For undated references, the latest version (including all amendments) applies to this document.

GB/T 7485 Determination of total arsenic in water quality Silver diethyldithiocarbamate spectrophotometric method GB/T 7489 Determination of Dissolved Oxygen in Water Quality - Iodometric Method HJ168 Technical guidelines for formulation and revision of environmental monitoring analysis method standards HJ535 Water Quality Determination of Ammonia Nitrogen by Nessler's Reagent Spectrophotometry

3 Terms and Definitions the following terms and definitions apply to this document.

detection limit limitofdetection the minimum concentration or amount of analyte that can be detected in a sample by a specific analytical method within a given confidence level.

Standard curve standard curve with pure solvent as a reference, the curve drawn after directly measuring the signal value with a series of standard solutions. Then under the same operating conditions Determine the signal value of the sample, and check the content or concentration of the signal value of the sample from the standard curve.

working curve working curve when the interference caused by the pretreatment of the sample to the measured components cannot be ignored, a series of standard solutions should not be used to directly measure the signal value, and should be prepared.

Make the standard solution after the same pretreatment as the sample, and then measure the signal value to draw the curve. It can be found from the working curve that the phase the content or concentration of the signal value of the measured sample under the same operating conditions.

Accuracyaccuracy

The degree of agreement between the measured value and the true value. It can be analyzed by directly measuring the standard sample or measuring the recovery rate of the standard sample Evaluation.

3.4.1

Use a standard sample (generally artificially synthesized) with a known content of the substance to be tested for analysis, and compare the measured results with the known content (when as the difference between the true value), the relative error is calculated as the accuracy of the operation and the method [see equation (1)].

Z1=D-BB ×100%

In the formula.

Z1---accuracy (relative error);

D --- Measured value;

B --- standard sample content.

Calculation results should be expressed with plus or minus signs.

3.4.2

At the same time as the sample is taken, another part is taken and an appropriate amount of standard substance is added for measurement at the same time, and the addition of standard substance is calculated according to the measurement result.

The recovery rate is used as the accuracy of the method [see formula (2)].

Z2=E-FG ×100%

In the formula.

Z2---accuracy (standard addition recovery rate);

E --- spiked sample;

F --- original sample;

G --- plus scalar.

precision

Under certain conditions, the degree of consistency between the results obtained by implementing the experimental steps several times. The smaller the random error that affects the experimental results, the actual the higher the precision of the test results.

3.5.1

The percentage of the ratio of the standard deviation to the absolute value of the arithmetic mean. It is often used to evaluate the precision of a determination method [see formula (3)].

P1=S

×100% (3)

In the formula.

P1---the precision of the determination method (relative standard deviation);

S --- standard deviation;

X --- Arithmetic mean of multiple measurement results.

When a limited number of samples are measured (less than 10), the calculation formula of the standard deviation S is shown in formula (4).

S = sum

(Xi-X)2

In the formula.

S --- standard deviation;

Xi --- each single measured value;

X --- Arithmetic mean of multiple measurement results;

n --- Determination times.

3.5.2

Relative deviation the percentage of the ratio of the absolute value of the deviation of any value in the parallel double-sample measurement to the arithmetic mean of the two measured values the precision of the determined results can be checked for admissibility [see formula (5)].

P2=XX

×100% (5)

In the formula.

P2---the precision (relative deviation) of parallel double-sample determination;

X --- any one of the two measured values;

X --- Arithmetic mean of two measured values.

4 shades

The detection of chromaticity in leachate can adopt the dilution multiple method.

4.1 Principle

After clarification or centrifugation, dilute the leachate sample with distilled water until the color is just invisible when compared with distilled water when observed with the naked eye the dilution factor up to that time.

4.2 Instruments and equipment

a) Centrifuge. 5000r/min;

b) Standard colorimetric tube 50mL;

c) Porcelain plate. white;

d) Beaker..200mL;

e) pH meter.

4.3 Samples

The laboratory sample volume of leachate for colorimetric determination is about 300mL, and it should be measured as soon as possible after sampling, otherwise it should be stored in polyethylene or glass bottles Measured within 24 hours at a temperature of 2°C to 5°C in a dark place.

4.4 Analysis steps

4.4.1 Take 100mL~150mL clear water sample and place it in a beaker, with the white porcelain plate as the background, observe and describe its color type.

4.4.2 Take clear water samples and dilute them into different multiples with water. Separate 50mL into 50mL colorimetric tubes, and line the bottom of the tube with a white Porcelain plate, observe the color of the diluted water sample from top to bottom, and compare it with distilled water of the same volume, until the color is barely visible, record the times at this time number. Simultaneously measure the pH value.

4.5 Calculation and representation of results the chromaticity value in the leachate is expressed by combining the dilution factor value and the text description.

4.5.1 Calculate the dilution factor according to formula (6).

C1=2n (6)

In the formula.

C1---Dilution factor value;

n --- Dilution times.

4.5.2 Color Description when issuing the report, it is necessary to write the color of the tested sample at the same time. Available dark black, gray black, dark green, light green, blue-green, yellow-green, dark gray, light gray, Earthy yellow, orange and so on.

4.5.3 pH value

When issuing the report, the pH value of the tested sample should be reported at the same time.

5 total solids

The detection of total solids in leachate can be done by gravimetric method.

5.1 Principle

Use an evaporating dish of known mass to hold a definite volume of leachate sample, first place it on a water bath to evaporate to dryness, and then move it to the inside of the drying box.

Dry at 103°C~105°C until constant weight, the mass added to the evaporating dish is the total solid.

5.2 Instruments and Equipment

a) Analytical balance. graduation value 0.1mg, maximum weighing.200g;

b) drying oven;

c) water bath;

d) dryers;

e) Pipette. 50.0mL;

f) Evaporating dish. 100mL;

g) Gloves for weighing evaporating dishes. white spun gauze gloves.

5.3 Samples

The amount of leachate laboratory sample for total solids determination should include the amount used for the determination of total dissolved solids and total suspended solids.

500mL, it should be measured as soon as possible after sampling, otherwise it should be stored in a polyethylene or glass bottle at a temperature of 2°C to 5°C, and measured within 24h.

5.4 Analysis steps

5.4.1 Put the cleaned and numbered evaporating dishes in a drying oven, bake them at 103°C~105°C for about 1 hour, put them in a desiccator to cool for 30 minutes, and weigh them.

Heavy. Bake for another 30 minutes, cool, and weigh until constant weight (the difference between the two weighings is less than 0.4 mg).

5.4.2 Use a pipette to draw 50.0mL of sample solution that is shaken evenly, put it into an evaporating dish with constant weight, and place it in a water bath to evaporate to dryness.

Move it into a drying oven, bake at 103°C~105°C for 1h, cool in a desiccator for 30min, and weigh. Repeat drying and cooling until constant weight (to two the difference between each weighing is less than 0.4mg).

5.4.3 If it is found that suspended solids have settled due to coagulation during the storage period of the sample taken, use a 50mL graduated cylinder to measure the sample that has been shaken well into an evaporating dish of constant weight. The following operations are the same as 5.4.2.

5.5 Calculation and presentation of results the total solid mass concentration in the leachate is calculated according to formula (7).

(w2-w1)×106

In the formula.

c2 --- the mass concentration of total solids in the leachate, in milligrams per liter (mg/L);

w1---mass of empty evaporating dish, unit is gram (g);

w2---empty evaporating dish and total solid mass, unit is gram (g);

V --- The volume of the leachate sample, in milliliters (mL).

The results are expressed with 3 significant figures and rounded to integers.

5.6 Precision and Accuracy

5.6.1 For leachate samples with a total solid content of 1000mg/L~2400mg/L, the relative deviation of 5 batches of parallel double-sample measurements is small at 0.5%.

5.6.2 Analyze the leachate samples with a total solid content of 2358.7mg/L and 1069.8mg/L, divide them into two batches, and measure 5 the relative standard deviations were 0.37%, 0.59% and 0.67%, 0.87%, respectively.

6 Total dissolved solids and total suspended solids the detection of total dissolved solids and total suspended solids in leachate can be carried out by gravimetric method.

6.1 Principle

Pass the leachate sample through the filter paper of specified specifications, absorb the filtered filtrate quantitatively, place it in an evaporating dish of known quality, and first place it in a water bath.

Evaporate to dryness, and then bake in a drying oven at 103°C to 105°C until constant weight. The mass added to the evaporating dish is the total dissolved solids. Subtract from total solids the total dissolved solids are the total suspended solids.

6.2 Instruments and Equipment

a) Erlenmeyer flask. 250mL;

b) Long-necked glass funnel. 75mm in diameter;

c) Quantitative filter paper. medium speed, diameter 125mm;

d) water bath;

e) Dryers;

f) Pipette. 50.0mL;

g) Evaporating dish. 100mL.

6.3 Samples

The amount of leachate laboratory sample for the determination of total dissolved solids and total suspended solids should include the amount used for the determination of total solids, totaling about 500mL, should be measured as soon as possible after sampling. Otherwise, store it in a polyethylene or glass bottle at a temperature of 2°C to 5°C, and measure it within 24 hours.

6.4 Analysis steps

6.4.1 Pour the leachate laboratory sample solution through the medium-speed quantitative filter paper into the Erlenmeyer flask to obtain the filtrate.

6.4.2 Put the cleaned and numbered evaporating dishes in a drying oven, bake them at 103°C~105°C for about 1 hour, put them in a desiccator to cool for 30 minutes, and weigh them.

Weight, then bake for 30min, cool, weigh until constant weight (until the difference between the two weighings is less than 0.4mg).

6.4.3 Use a pipette to draw 50.0mL of the filtrate into an evaporating dish with constant weight, place it on a water bath to evaporate to dryness, and then transfer it to a drying oven Bake at 103°C~105°C for 1h, cool in a desiccator for 30min, and weigh. Repeat drying, cooling, and weighing until constant weight (difference between two weighings less than 0.4mg).

6.5 Calculation and presentation of results the mass concentration of total dissolved solids in leachate is calculated according to formula (8).

(w2-w1)×106

In the formula.

c3 --- the mass concentration of total dissolved solids in the leachate, in milligrams per liter (mg/L);

w1---mass of empty evaporating dish, unit is gram (g);

w2---Empty evaporating dish and total dissolved solids mass, unit is gram (g);

V --- The volume of the filtrate drawn, in milliliters (mL).

The result should be expressed with 3 significant figures and rounded to an integer. Total suspended solids is the difference between total solids and total dissolved solids.

6.6 Precision and Accuracy

6.6.1 For leachate samples with a total dissolved solid content of 1000mg/L~2300mg/L, the relative the deviation is less than 0.8%.

6.6.2 Analyze the leachate sample with a total dissolved solid content of 2278.9mg/L, divide it into 3 batches, and measure the relative standard deviation 5 times for each batch They are 0.30%, 0.57% and 0.60% respectively.

7 Sulfates

The detection of sulfate in leachate can be carried out by gravimetric method. This method determines the concentration range of sulfate in the sample is (10~5000)mg/L (calculated as SO2-4).

7.1 Principle

In a solution acidified with hydrochloric acid, barium sulfate crystals are precipitated by adding a warm barium chloride solution dropwise at a near-boiling temperature.

After aging, filter the precipitate, wash the precipitate with warm water until there is no chloride ion, then dry it, and weigh it after burning at 800°C.

Calculate the mass of BaSO4 as SO2-4.

7.2 Interference and cancellation Suspended matter, silicon dioxide, nitrate and sulfite, precipitant barium chloride, etc. can cause positive errors in the results; alkali metal sulfuric acid in the precipitation Salts, especially alkali metal bisulfates, can cause negative errors. The presence of chromium and iron, etc., affects the barium sulfate due to the formation of chromium and iron sulfate Complete precipitation also skewed the results.

7.3 Reagents and materials the reagents used, unless otherwise specified, should be analytical reagents that meet the current national standards, and the experimental water should be distilled water or deionized water.

Zishui.

7.3.1 Hydrochloric acid (HCl), 1 in 1 solution Mix hydrochloric acid (HCl, rho=1.18g/mL) and water in equal volumes.

7.3.2 Barium chloride (BaCl2 2H2O), 50g/L solution Dissolve 50g of barium chloride dihydrate (BaC12·2H2O) in water and dilute to 1000mL, this solution is equivalent to 20mgSO2-4 per milliliter.

7.3.3 Silver nitrate-nitric acid (AgNO3-HNO3) solution Dissolve 1.7g of silver nitrate (AgNO3) in 100mL of water, add 0.1mL of nitric acid (HNO3, rho=1.40g/mL), store in brown Store in the reagent bottle away from light.

7.3.4 Methyl red indicator, 1g/L solution Dissolve 50mg of water-soluble methyl red sodium salt in 50mL of water, pH4.4~6.2.

7.3.5 Filter pulp

Shred the quantitative filter paper and put it into water, stir well to form a paste, then filter with medium-speed quantitative filter paper, wash with water for 3 times, add water to make suspension liquid for use.

7.4 Instruments and equipment

a) muffle furnace;

b) crucible tongs;

c) Beaker. 400mL;

d) Watch glass. 100mm in diameter;

e) Long neck funnel. diameter 75mm;

f) Porcelain crucible. 25mL;

g) Quantitative filter paper. slow speed, diameter 125mm;

h) Gloves for weighing the crucible. white spun gauze gloves.

7.5 Samples

The laboratory sample volume of leachate for sulfate determination is about 600mL. If it cannot be measured in time after sampling, use polyethylene or glass bottle Store at a temperature of (2~5)°C, and measure within 7 days.

7.6 Analysis steps

7.6.1 After drying the cleaned porcelain crucible in a 105°C drying oven, number it (you can add a few milliliters of blue ink with a little crystalline ferric chloride prepared solution number), put it into a muffle furnace and burn it at 800°C for 30 minutes, take it out and cool it for a while, then clamp it into a desiccator with a crucible to cool it 30min, weighing. Then place the porcelain crucible repeatedly in the muffle furnace at the same temperature and burn for 15 minutes, then cool and weigh in the same way until to constant weight (the difference between the two weighings before and after is not more than 0.2mg).

7.6.2 Use a pipette to draw an appropriate amount of leachate sample (the solution should contain about 50mgSO2-4), transfer it into a 400mL beaker, and Dilute to a total volume of approximately 250 mL. Add 2~3 drops of methyl red indicator (7.3.4), adjust with hydrochloric acid (7.3.1) until the solution is reddish, Then add 2mL of hydrochloric acid, heat and boil for 5min (at this time, if the solution still contains insoluble matter, it should be filtered and then precipitated); slowly add warm Add the barium chloride solution (7.3.2) in the sample solution until no precipitation occurs, and then add 2mL in excess. Continue to boil for 20min and leave overnight.

7.6.3 Use slow quantitative filter paper to filter the precipitate treated in 7.6.2, and then wash the precipitate with warm water for several times until there is no chloride ion.

(Use a small beaker to collect about 2mL of the filtrate, add 2 drops of AgNO3-HNO3 solution until no turbidity appears). Finally take a small amount of filter the pulp and the sediment in the filter paper are mixed, and after the filtration is complete, fold the sediment in the funnel, the filter paper pulp and the filter paper in the funnel together into a small bag.

7.6.4 Put the filter paper packet folded in step 7.6.3 into the crucible with constant weight in step 7.6.1, dry in a drying oven and muffle After carbonization and ashing at the furnace mouth, push it into the furnace, burn it at 800°C for 1 hour, take it out and cool it for a while, then move it into a drying box to cool, and weigh it; the second time Burn for 15min, cool, and weigh again until constant weight (the difference between the two weighings before and after is less than 0.3mg).

7.7 Calculation and presentation of results the sulfate concentration in the leachate is calculated according to formula (9).

(w2-w1)×0.4116×106

In the formula.

c4 --- the mass concentration of sulfate in the leachate, in milligrams per liter (mg/L);

w1 --- the mass of the empty crucible, in grams (g);

w2 --- mass of empty crucible and BaSO4, unit is gram (g);

V ---Leachate sample volume, in milliliters (mL);

0.4116---BaSO4 conversion factor into SO2-4.

The results are expressed with 3 significant figures and rounded to integers.

7.8 Precision and Accuracy

7.8.1 For leachate samples with a sulfate content of 800mg/L~2500mg/L, the relative deviation measured by 5 batches of parallel double samples is less than 2.5%.

7.8.2 Use sodium sulfate standard solution with a sulfate concentration of 1000.9 mg/L, divide it into two batches, and measure the relative standard deviation for 5 times in each batch.

The recoveries were 0.28% and 0.34%, respectively, and the recoveries were 98.4%~100.2%.

7.8.3 Analyze the spiked samples of leachate containing 1557.2mg/L and 2467.9mg/L sulfate, after 5 times of determination respectively, the relative standard the deviations were 0.83% and 1.10%, respectively, and the recoveries of standard addition were 95.8%~99.3%.

8 ammonia nitrogen

Ammonia nitrogen in leachate can be detected by distillation titration and Nessler's reagent colorimetry. See HJ535 for the determination of Nessler's reagent colorimetric method.

The concentration range of ammonia nitrogen in the sample determined by distillation titration is 30mg/L~7000mg/L (calculated as N).

8.1 Principle

Use a phosphate buffer solution with a pH of 7.4 to make the sample in a slightly alkaline state. After heating and distillation, the ammonia that escapes with water vapor is replaced by boric acid.

The solution is absorbed, and the ammonium in the distillate is titrated with a standard acid using a mixture of methyl red and methylene blue as an indicator.

8.2 Interference and cancellation Volatile basic compounds, such as hydrazine and amines, will distill out together with ammonia, and react with acid during titration to make the measurement result higher.

8.3 Reagents and materials the reagents used, unless otherwise specified, should be analytical reagents that meet the current national standards, and the experimental water should be prepared according to 8.3.1 of ammonia-free water.

8.3.1 Ammonia-free water Add 0.10mL of concentrated sulfuric acid per liter of water for distillation, and collect the distillate in a stoppered glass container. It is also possible to use freshly prepared Zishui.

8.3.2 Anhydrous sodium carbonate (Na2CO3) benchmark reagents.

8.3.3 Phosphate buffer solution Dissolve 14.3 g of anhydrous potassium dihydrogen phosphate (KH2PO4) and 90.2 g of dipotassium hydrogen phosphate trihydrate (K2HPO4 3H2O) in water, Dilute to 1000mL. And measure its pH value with a pH meter, if necessary, add anhydrous potassium dihydrogen phosphate or dipotassium hydrogen phosphate trihydrate to adjust to pH7.4.

8.3.4 Methyl red-methylene blue mixed indicator Dissolve.200mg of methyl red and 100mg of methylene blue in 100mL and 50mL of 90% (volume fraction) ethanol, and then mix the two together and serve, valid for one month.

Methyl red-bromocresol green mixed indicator can also be used (see Appendix A).

8.3.5 Boric acid solution Dissolve 20g of boric acid (H3BO3) in warm water, cool to room temperature, and dilute to 1000mL, effective within one month.

8.3.6 Hydrochloric acid solution, c(HCl)=0.2mol/L Draw 16.7mL of hydrochloric acid (HCl, rho=1.1g/mL) in water and dilute to 1000mL.

8.3.7 Hydrochloric acid standard titration solution c(HCl)=0.02mol/L

a) Preparation. Take 100mL of 0.2mol/L hydrochloric acid (8.3.6) in water and dilute to 1000mL. Then use anhydrous sodium carbonate calibration. Commercially available certified standard solutions can also be used directly.

b) Calibration. Weigh about 30mg of anhydrous sodium carbonate (8.3.2) (dried at 250°C for 4h; or at 285°C for 1h) in 500mL Add.200mL of cooled boiled distilled water to the Erlenmeyer flask, add 50mL of boric acid solution (8.3.5) after dissolving, and add 2~3 drops of methyl red-methylene blue mixed indicator (8.3.4), titrate with hydrochloric acid standard titration solution [a)] until the solution color changes from green Change to purple as the end point. Concentration of hydrochloric acid standard titration solution (duplicate samples must be used to take the average value, and the relative deviation should be less than 1%) is calculated according to formula (10).

c5=w×2×1000106×V =

0.053×V

In the formula.

c5 --- the concentration of hydrochloric acid standard titration solution, the unit is mole per liter (mol/L);

w --- the weight of anhydrous sodium carbonate weighed, in grams (g);

V --- the volume consumed by the hydrochloric acid standard titration solution, in milliliters (mL);

2 --- The number of moles of HCl required to neutralize molNa2CO3;

106 --- The molar mass of sodium carbonate (Na2CO3), in grams per mole (g/moL).

Sulfuric acid (H2SO4) standard titration solution can also be used (see Appendix A).

8.4 Instruments and equipment

a) Distillation device. composed of a 500mL~800mL Kjeldahl flask, a nitrogen ball and a vertically placed serpentine with a length of 300mm~400mm.

The condenser tube is assembled. The end of the condenser tube should be connected with a conduit of appropriate length so that the outlet tip of the conduit is immersed in the liquid surface of the absorbing liquid.

the following;

b) Erlenmeyer flask. 500mL;

c) acid burette. 50mL;

d) pH meter.

8.5 Sample

The laboratory sample volume of leachate for the determination of ammonia nitrogen needs to be about 100mL, which should be collected in polyethylene or glass bottles with stoppers. As soon as possible after sampling Otherwise, add sulfuric acid (H2SO4, rho=1.84g/mL) dropwise to acidify to make the pH less than 2, store it at (2~5)°C, and measure it within 24 hours Attention should also be paid to prevent acidified samples from absorbing ammonia in the air and being polluted.

8.6 Analysis steps

8.6.1 Still cleaning Add 350mL of water, 10mL of phosphate buffered saline, and a few glass beads to the Kjeldahl flask. Install the instrument, heat and distill, use 20mL boric acid solution (8.3.5) to absorb, add 2~3 drops of methyl red-methylene blue mixed indicator to the boric acid solution before use, then distill to distillate Cool until there is no ammonia in the effluent, discard the distillate and the residual liquid in the bottle, and keep the glass beads.

8.6.2 Determination

8.6.2.1 Measure 50.0mL of boric acid solution (8.3.5) into the Erlenmeyer flask, and add 2~3 drops of methyl red-methylene blue mixed indicator, set Under the outlet of the condenser tube, and ensure that the tip of the outlet of the distillate conduit is 2cm below the surface of the boric acid absorption solution.

8.6.2.2 Use a pipette to suck up the leachate laboratory sample (the amount of suction should be such that the volume of the hydrochloric acid standard titration solution consumed by the titration of the sample is about 25mL) in a Kjeldahl flask, dilute with water to a total volume of about 350mL, then add 10mL of phosphate buffer solution, and immediately dissolve the the bottle is connected to the condenser tube.

8.6.2.3 Heat the Kjeldahl flask so that the distillation rate is controlled at 6mL/min~8mL/min. When the distillate is collected to a total volume of about 300mL , be prepared to stop the distillation. 1min~2min before the distillation stops, lower the conical receiving flask so that the tip of the distillate conduit is free from the boric acid Absorb the liquid level, and stop heating after distilling for 1min.

8.6.2.4 Titrate the distillate with hydrochloric acid standard titration solution (8.3.7), and the solution turns from green to purple as the end point. Record the amount of acid used.

8.6.3 Blank test

Carry out a blank test according to the operation steps in 8.6.2, but replace the sample with water.

8.7 Calculation and representation of results the concentration of ammonia nitrogen in the leachate is calculated according to formula (11).

(V1-V2)

c5×14.01×1000 (11)

In the formula.

c6 --- the mass concentration of ammonia nitrogen in the leachate, in milligrams per liter (mg/L);

V1 --- the volume of hydrochloric acid standard titration solution consumed when titrating the sample, in milliliters (mL);

V2 --- The volume of hydrochloric acid standard titration solution consumed during blank test titration, in milliliters (mL);

V0 --- the volume of the leachate sample, in milliliters (mL);

c5 --- the actual concentration of the hydrochloric acid standard titration solution, in moles per liter (mol/L);

14.01---The molar mass of nitrogen (N), in grams per mole (g/mol).

The result is represented by 4 significant figures, with a maximum of 2 digits after the decimal point.

8.8 Precision and Accuracy

8.8.1 For leachate samples with an ammonia nitrogen content of 40mg/L~600mg/L, the relative deviation of 5 batches of parallel double-sample measurements is less than 3.6%.

8.8.2 Use ammonium chloride to make a standard solution with an ammonia nitrogen concentration of 1000.8mg/L. After 5 measurements, the relative standard deviation is 2.3%.

The yield is 93.9%~99.8%.

8.8.3 Analyze the spiked sample of leachate containing 262 mg/L ammonia nitrogen. After 4 measurements, the relative standard deviation is 3.5%, and the spiked recovery rate is 95%~103%.