CN104089913A - Method for measuring total nitrogen content in sludge - Google Patents
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- CN104089913A CN104089913A CN201410311438.1A CN201410311438A CN104089913A CN 104089913 A CN104089913 A CN 104089913A CN 201410311438 A CN201410311438 A CN 201410311438A CN 104089913 A CN104089913 A CN 104089913A
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Abstract
The invention provides a method for measuring total nitrogen content in sludge. The method comprises the following steps: treating the sludge with a nylon sieve being 80-100 meshes; adding 5ml of concentrated sulfuric acid (H2SO4); performing high-temperature digestion boiling for 50-70 minutes on an adjustable-temperature electric furnace; after the digestion, transferring the treated sludge into a 250mL volumetric flask, diluting and making up the volume to a scale, shaking uniformly and standing for later use; adjusting the pH of the standby sample to be over 10 with a potassium hydroxide solution, mixing uniformly and arranging for precipitation; filtering with medium-speed filter paper flushed with non-ammonia water; putting 50ml of the filtered supernate into a ground glass colorimetric tube with a plug; operating in the same conditions as the standard solution, and measuring the absorbance; and performing a control experiment on the absorbance and the absorbance subjected to blank test correction so as to measure the total nitrogen content in the sludge. The method for measuring total nitrogen content in sludge provided by the invention is simple to operate, has high reproducibility and is not interfered easily, and also guarantees the accuracy of the measured data.
Description
Technical field
The present invention relates to environment monitoring field, particularly relate to the assay method of total nitrogen content in mud.
Technical background
Along with expanding economy, constantly the exaggerating of city size, a large amount of population constantly pours in city, and therefore the sewage in city be also on the increase, and the pollutant in sewage can be enriched in mud gradually.Pollutant in mud also can be discharged in water body easily, if nitrogen content exceedes certain value in pollutant, will cause body eutrophication, welding.At present the method for China's sludge disposal mainly contains landfill and agricultural, if agricultural sludge just must be measured to its nutriment in a fertilizer and nuisance, be therefore necessary total nitrogen in mud to measure, but existing assay method ratio is easier to be disturbed, and stability is not high.
Summary of the invention
In order to address the above problem, the invention provides that a kind of stability is high, the assay method of total nitrogen content in the mud that is not easy to be disturbed.
In above-mentioned mud, the technical scheme of the assay method of total nitrogen content is as follows:
(1) sample pretreatment: the mud sample that will wet is laid on this pallet, isobaric loose with glass bar, go out the foreign matter such as stone and plant and animal residues in mud sample, mix for subsequent use; Dewatered sludge sample is removed after the foreign matter such as stone and plant and animal residues, to obtaining required sample, is ground to sample all by nylon mesh (80 order to 100 order) with agate mortar with inquartation division, mixes for subsequent use.
(2) sample is taken on analytical balance to standard model 0.3-1g, put into round-bottomed flask; Then add the concentrated sulphuric acid (H
2sO
4) 5ml, and add a little funnel of curved neck at bottleneck, be placed on adjustable electric cooking stove high temperature and disappear and boil 50-70 minute, sulfuric acid is smoldered in a large number, in the time can't see black carbon granules and exist, if when the content of organic matter exceedes 5%, should add 1-2g potassium pyrosulfate, add the oxidability of strength sulfuric acid to improve temperature; After digestion finishes, cool to room temperature, adds a small amount of water to prolonging slowly a bottle wall in round flask bottle, after be transferred in 250mL volumetric flask, constant volume, to scale, shakes up, stand for standby use.
(3) get above-mentioned sample 100mL for subsequent use in 250mL beaker, more than utilizing potassium hydroxide solution adjusting pH to 10, add 1 ml solution of zinc sulfate, mix, place and make it precipitation, use the Medium speed filter paper rinsing through water to filter, discard just filtrate 20 ml, or to sample centrifugal treating after flocculating.
(4) drafting of calibration curve: add respectively 0.00 ml, 0.50ml, 1.00 ml, 2.00 ml, 4.00ml, 6.00ml, 8.00ml and 10.00 ml ammonia nitrogen standard operation solution in 8 50 ml color comparison tubes, its corresponding ammonia-nitrogen content is respectively 0.0 μ g, 5.0 μ g, 10.0 μ g, 20.0 μ g, 40.0 μ g, 60.0 μ g, 80.0 μ g and 100 μ g, adds water to graticule.Add 1.0 ml potassium sodium tartrate solutions, shake up, then add nessler reagent 1.0 ml, shake up.Place after 10 min, under wavelength 420 nm, with 20 mm cuvettes, make reference with water, measure absorbance.Taking the absorbance after blank correction as ordinate, taking its corresponding ammonia-nitrogen content as horizontal ordinate, draw calibration curve.
(5) if the supernatant 50mL(water sample concentration of getting after centrifugal or filtration exceedes 2mg/L, can suitably lack water sampling volume) put into tool plug grournd glass color comparison tube, operate with under condition with standard solution, measure absorbance; Proofread and correct absorbance with blank test and compare experiment, determine the content of full nitrogen in mud by formula.
Experimental apparatus and experiment reagent that technique scheme is required are as follows:
1, test apparatus
UV530 spectrophotometer, tetrad heating jacket, round flask, the little funnel of curved handle, broken ceramics, agate mortar, 80 or 100 order nylon mesh, electronic balance, beaker, volumetric flask, funnel.
2, test reagent
Except as otherwise noted, when analysis, agents useful for same all uses the analysis pure chemistry reagent that meets national standard, and experimental water, by (1) preparation, uses volumetric apparatus and measuring device through calibrating.
(1), without ammoniacal liquor, in without ammonia environment, prepare by one of following method.
1. ion exchange process
Distilled water, by storng-acid cation exchange resin (Hydrogen) post, is collected in efflux in the vial with ground glass stopper.Every up-flow fluid adds the same resin of 10 g, is beneficial to preserve.
2. the way of distillation
In the distilled water of 1 000 ml, add 0.1 ml sulfuric acid (ρ=1.84 g/ml), redistillation in full glass distiller, discards front 50 ml distillates, then approximately 800 ml distillates is collected in the vial with ground glass stopper.Every liter of distillate adds 10 g storng-acid cation exchange resins (Hydrogen).
3. water purifior method
Prepare before use with commercially available water purifior.
(2) nessler reagent, can select the one preparation of following method
1. mercuric chloride-potassium iodide-potassium hydroxide (HgCl
2-KI-KOH) solution;
Take 15.0 g potassium hydroxide (KOH), be dissolved in 50 ml water, be cooled to room temperature, take 5.0 g potassium iodides (KI), be dissolved in 10 ml water, under agitation, by 2.50 g mercuric chloride (HgCl
2) powder adds in liquor kalii iodide several times, until solution is buff or occurs that pale red precipitation dissolves when slow, is fully uniformly mixed, and changes into and drip mercuric chloride saturated solution, in the time occurring that a small amount of vermilion precipitation is no longer dissolved, stop dripping.Under agitation, cooling potassium hydroxide solution is joined lentamente in the mixed liquor of above-mentioned mercuric chloride and potassium iodide, and be diluted to 100 ml, leave standstill 24 h in dark place, incline and supernatant, store in polyethylene bottle, cover tightly with rubber stopper or tygon lid, deposit dark place, can stablize 1 month.
2. mercuric iodixde-potassium iodide-NaOH (HgI
2-KI-NaOH) solution
Take 16.0 g NaOH (NaOH), be dissolved in 50 ml water, be cooled to room temperature, take 7.0 g potassium iodides (KI) and 10.0 g mercuric iodixde (HgI
2), soluble in water, then by this solution under agitation, slowly join in above-mentioned 50 ml sodium hydroxide solutions, be diluted with water to 100 ml.Store in polyethylene bottle, cover tightly with rubber stopper or tygon lid, deposit the term of validity 1 year in dark place.
(3) potassium sodium tartrate solution, ρ=500 g/L
Take 50.0 g sodium potassium tartrate tetrahydrate (KNaC
4h
6o
64H
2o) be dissolved in 100 ml water, heating boils to drive away ammonia, is diluted to 100 ml after fully cooling.
(4) potassium pyrosulfate.
(5) solution of zinc sulfate, ρ=100 g/L
Take 10.0 g zinc sulfate (ZnSO
47H
2o) soluble in water, be diluted to 100 ml.
(6) potassium hydroxide solution, ρ=250 g/L
Take 25 g potassium hydroxide soluble in water, be diluted to 100 ml.
(7) concentrated sulphuric acid.
(8) ammonia nitrogen standard stock solution, ρ
n=1 000 μ g/ml
Take 3.8190g ammonium chloride (NH
4cl, top grade is pure, is dried 2 h) at 100～105 DEG C, soluble in water, moves in 1000 ml volumetric flasks, is diluted to graticule, can preserve 1 month at 2～5 DEG C.
(9) ammonia nitrogen standard operation solution, ρ
n=10 μ g/ml.Draw 5.00 ml ammonia nitrogen standard stock solutions (8) in 500 ml volumetric flasks, be diluted to scale.Preparation before use.
Result is calculated
Calculate sample and proofread and correct absorbance and blank test correction absorbance difference Ar, the content w(mg/kg of total nitrogen in sample) calculate by formula (1).
=
（1）
In formula:
W---the mass concentration of total nitrogen in sample (in N), mg/kg;
The difference of absorbance is proofreaied and correct in the correction absorbance of Ar---sample and blank test;
The intercept of a---calibration curve;
The slope of b---calibration curve;
M---sample sample weighting amount, the g of unit;
V---sample volume, Unit/mL;
F---sample water percentage, represents with radix point;
50---colorimetric constant volume, Unit/mL;
250---the constant volume of sample in volumetric flask, Unit/mL.
3, utilize soil constituent analytical standard material sample to do repeatability and accuracy testing.
3.1, as stated above, under the same conditions, take some parts of Soil standard samples, measure, calculate respectively measurement result, represent with RSD, the results are shown in Table 1.
The test of table 1 repeatability
| Sequence number | GSS-1 | GSS-3 | GSS-4 | GSS-6 |
| 1 | 1840 | 628 | 943 | 722 |
| 2 | 1873 | 627 | 1029 | 767 |
| 3 | 1862 | 592 | 933 | 710 |
| 4 | 1920 | 611 | 1019 | 785 |
| 5 | 1855 | 600 | 962 | 725 |
| 6 | 1890 | 660 | 974 | 756 |
| Mean value (mg/kg) | 1873 | 619 | 976 | 744 |
| RSD(%) | 1.38 | 3.59 | 4.04 | 3.97 |
| Guarantee value (mg/kg) | 1870 +67 | 640 +50 | 1000 +62 | 740 +59 |
Repeatability is respond well as seen from the above table.
3.2, recovery test
In order to verify the accuracy of this method, utilize the mud sample of Sewage Plant to do four serial recovery of standard addition tests.Result is as shown in table 2.
Table 2 recovery test
Table 2 recovery test
The full nitrogen recovery of this method, between 97.7%-104%, illustrates that this method accuracy is very reliable as seen from the above table.
In mud provided by the invention, the assay method of total nitrogen content is simple to operate, can be strong in existing property, be difficult for being disturbed, and can ensure again the accuracy of institute's determination data simultaneously.
Embodiment
Below in conjunction with specific embodiment, further set forth the present invention.
1. classic method is measured total nitrogen content
Except as otherwise noted, when analysis, agents useful for same all uses the analysis pure chemistry reagent that meets national standard, and experiment, with being without ammoniacal liquor, is used volumetric apparatus and measuring device through calibrating.
1.1 sample pretreatments: should gather representative sludge product, the mud sample that will wet is laid on this pallet, isobaric loose with glass bar, go out the foreign matter such as stone and plant and animal residues in mud sample, mix for subsequent use; Dewatered sludge sample is removed after the foreign matter such as stone and plant and animal residues, to obtaining required sample, is ground to sample all by nylon mesh (80 order to 100 order) with agate mortar with inquartation division, mixes for subsequent use.
1.2 tests: accurately take ready sample 0.01g(and be accurate to 0.1mg) in 250mL tool plug Erlenmeyer flask, add 100mL water, 50mL alkalescence potassium persulfate, mixes, and jam-pack grinding port plug is tightened bottle stopper with cloth and rope etc., in case ejection.Triangular flask is placed in to medical portable steam sterilizer, and heating, makes gauge hand to 1.1kg/cm2-1.4 kg/cm2, and now temperature reaches 120 DEG C-124 DEG C, keeps after this temperature 1h, stops heating.After band gauge hand is down to zero, open valve venting, remove enclosing cover, take out triangular flask and be chilled to room temperature.
To clear up sample filtering and move in 250mL volumetric flask, and the abundant drip washing triangular flask of water and funnel, move in the lump in volumetric flask, add (1+9) hydrochloric acid 10mL, be settled to scale, mix standing.
1.3 blank test
With 100.00ml water replacement sample, measure according to 1.1 steps.
The drafting of 1.4 calibration curves
Measure respectively 0.00ml, 0.20ml, 0.50ml, 1.00ml, 3.00ml and 7.00ml potassium nitrate standard solution in 25ml tool plug grournd glass color comparison tube, its corresponding total nitrogen (in N) content is respectively 0.00 μ g, 2.00 μ g, 5.00 μ g, 10.0 μ g, 30.0 μ g and 70.0 μ g.Be diluted with water to 10.00ml, then add 5.00ml alkalescence potassium persulfate solution, jam-pack pipe close, tightens pipe close with gauze and cotton rope, in case ejection.Color comparison tube is placed in to autoclave sterilizer, is heated to top pressure valve and blows, close valve, continue to be heated to 120 DEG C and start timing, maintain the temperature at 30min between 120～124 DEG C.Naturally cooling, open valve venting, remove enclosing cover, take out color comparison tube and be cooled to room temperature, pin pipe close the liquid in color comparison tube put upside down and mixed 2～3 times.
1.5 colorimetric
Use 10mm quartz colorimetric utensil, on ultraviolet spectrophotometer, make reference with water, measure absorbance respectively at wavelength 220nm and 275nm place.The correction absorbance A b of zero-dose, the correction absorbance A s of other standards series and difference Ar thereof calculate by formula (2), (3) and (4).In total nitrogen (taking N) content, (μ is g) as horizontal ordinate, and corresponding Ar value is ordinate, draws calibration curve.
A
b＝Ab
220－2Ab
275 （2）
As＝As
220－2As
275 （3）
Ar＝As－Ab （4）
In formula:
The correction absorbance of Ab---zero-dose (blank) solution;
Ab220---zero-dose (blank) solution is in the absorbance at wavelength 220nm place;
Ab275---zero-dose (blank) solution is in the absorbance at wavelength 275nm place;
The correction absorbance of As---standard solution;
As220---standard solution is in the absorbance at wavelength 220nm place;
As275---standard solution is in the absorbance at wavelength 275nm place;
Ar---standard solution proofreaies and correct absorbance and zero-dose (blank) solution is proofreaied and correct the poor of absorbance.
1.5 results are calculated
Total nitrogen content w in mud, numerical value one milligrams per kilogram (mg/kg) represents, calculates by following formula (5):
=
(5)
In formula:
The numerical value of C---the total nitrogen content that checks on calibration curve, the mg/L of unit;
V---sample constant volume 250mL;
M---take the weight of sample, the g of unit;
The numerical value of the water percentage of f---sample, represents with radix point.
Result of calculation is as shown in table 3.
Table 3 classic method is measured total nitrogen content
2.the inventive method is measured total nitrogen content
2.1 sample pretreatments: the mud sample that will wet is laid on this pallet, isobaric loose with glass bar, go out the foreign matter such as stone and plant and animal residues in mud sample, mix for subsequent use; Dewatered sludge sample is removed after the foreign matter such as stone and plant and animal residues, to obtaining required sample, is ground to sample all by nylon mesh (80 order to 100 order) with agate mortar with inquartation division, mixes for subsequent use.
2.2 take standard model 0.3-1g on analytical balance, put into round-bottomed flask; Then add the concentrated sulphuric acid (H
2sO
4) 5ml, and add a little funnel of curved neck at bottleneck, be placed on adjustable electric cooking stove high temperature and disappear and boil 50-70 minute, sulfuric acid is smoldered in a large number, in the time can't see black carbon granules and exist, if when the content of organic matter exceedes 5%, should add 1-2g potassium pyrosulfate, add the oxidability of strength sulfuric acid to improve temperature; After digestion finishes, cool to room temperature, adds a small amount of water to prolonging slowly a bottle wall in round flask bottle, after be transferred in 250mL volumetric flask, constant volume, to scale, shakes up, stand for standby use.
2.2 get above-mentioned sample 100mL for subsequent use in 250mL beaker, more than utilizing potassium hydroxide solution adjusting pH to 10, add 1 ml solution of zinc sulfate, mix, place and make it precipitation, use the Medium speed filter paper rinsing through water to filter, discard just filtrate 20 ml, or to sample centrifugal treating after flocculating.
The drafting of 2.3 calibration curves: add the blank solution identical with volume of sample in 8 50 ml color comparison tubes, add respectively 0.00 ml, 0.50ml, 1.00 ml, 2.00 ml, 4.00ml, 6.00ml, 8.00ml and 10.00 ml ammonia nitrogen standard operation solution, its corresponding ammonia-nitrogen content is respectively 0.0 μ g, 5.0 μ g, 10.0 μ g, 20.0 μ g, 40.0 μ g, 60.0 μ g, 80.0 μ g and 100 μ g, adds water to graticule.Add 1.0 ml potassium sodium tartrate solutions, shake up, then add nessler reagent 1.0 ml, shake up.Place after 10 min, under wavelength 420 nm, with 20 mm cuvettes, make reference with water, measure absorbance.Taking the absorbance after blank correction as ordinate, taking its corresponding ammonia-nitrogen content as horizontal ordinate, draw calibration curve.
If the 2.4 supernatant 50mL(water sample concentration of getting after centrifugal or filtration exceed 2mg/L, can suitably lack water sampling volume) put into tool plug grournd glass color comparison tube, operate with under condition with standard solution, measure absorbance; Proofread and correct absorbance with blank test and compare experiment, determine the content of full nitrogen in mud.
2.5 results are calculated
Calculate sample and proofread and correct absorbance and blank test correction absorbance difference A
r, the content w(mg/kg of total nitrogen in sample) calculate by formula (1).
=
（1）
In formula:
W---the mass concentration of total nitrogen in sample (in N), mg/kg;
The difference of absorbance is proofreaied and correct in the correction absorbance of Ar---sample and blank test;
The intercept of a---calibration curve;
The slope of b---calibration curve;
M---sample sample weighting amount, the g of unit;
V---sample volume, Unit/mL;
F---sample water percentage, represents with radix point;
50---colorimetric constant volume, Unit/mL;
250---the constant volume of sample in volumetric flask, Unit/mL.
Result of calculation is as shown in table 4.
Table 4 the inventive method is measured total nitrogen content
Conclusion: can find out that from two kinds of different assay methods the content that uses classic method to measure full nitrogen is starkly lower than measured value of the present invention, and use traditional assay method to be easily disturbed, stability is not high.
Claims (2)
1. the assay method of total nitrogen content in mud, is characterized in that: described method is carried out as follows:
(1) sample pretreatment: the mud sample that will wet is laid on this pallet, isobaric loose with glass bar, go out the foreign matter such as stone and plant and animal residues in mud sample, mix for subsequent use; Dewatered sludge sample is removed after the foreign matter such as stone and plant and animal residues, to obtaining required sample, is ground to sample all by nylon mesh (80 order to 100 order) with agate mortar with inquartation division, mixes for subsequent use;
(2) sample is taken on analytical balance to standard model 0.3-1g, put into round-bottomed flask; Then add the concentrated sulphuric acid (H
2sO
4) 5ml, and add a little funnel of curved neck at bottleneck, be placed on adjustable electric cooking stove high temperature and disappear and boil 50-70 minute, sulfuric acid is smoldered in a large number, in the time can't see black carbon granules and exist, if when the content of organic matter exceedes 5%, should add 1-2g potassium pyrosulfate, add the oxidability of strength sulfuric acid to improve temperature; After digestion finishes, cool to room temperature, adds a small amount of water to prolonging slowly a bottle wall in round flask bottle, after be transferred in 250mL volumetric flask, constant volume, to scale, shakes up, stand for standby use;
(3) get above-mentioned sample 100mL for subsequent use in 250mL beaker, more than utilizing potassium hydroxide solution adjusting pH to 10, add 1 ml solution of zinc sulfate, mix, place and make it precipitation, use the Medium speed filter paper rinsing through water to filter, discard just filtrate 20 ml, or to sample centrifugal treating after flocculating;
(4) drafting of calibration curve: add the blank solution identical with volume of sample in 8 50 ml color comparison tubes, add respectively 0.00 ml, 0.50ml, 1.00 ml, 2.00 ml, 4.00ml, 6.00ml, 8.00ml and 10.00 ml ammonia nitrogen standard operation solution, its corresponding ammonia-nitrogen content is respectively 0.0 μ g, 5.0 μ g, 10.0 μ g, 20.0 μ g, 40.0 μ g, 60.0 μ g, 80.0 μ g and 100 μ g, adds water to graticule;
Add 1.0 ml potassium sodium tartrate solutions, shake up, then add nessler reagent 1.0 ml, shake up;
Place after 10 min, under wavelength 420 nm, with 20 mm cuvettes, make reference with water, measure absorbance;
Taking the absorbance after blank correction as ordinate, taking its corresponding ammonia-nitrogen content as horizontal ordinate, draw calibration curve;
(5) if the supernatant 50mL(water sample concentration of getting after centrifugal or filtration exceedes 2mg/L, can suitably lack water sampling volume) put into tool plug grournd glass color comparison tube, operate with under condition with standard solution, measure absorbance; Proofread and correct absorbance with blank test and compare experiment, determine the content of full nitrogen in mud by formula.
2. the assay method of total nitrogen content in mud as claimed in claim 1, is characterized in that: described formula is:
=
In formula:
W---the mass concentration of total nitrogen in sample (in N), mg/kg;
The difference of absorbance is proofreaied and correct in the correction absorbance of Ar---sample and blank test;
The intercept of a---calibration curve;
The slope of b---calibration curve;
M---sample sample weighting amount, the g of unit;
V---sample volume, Unit/mL;
F---sample water percentage, represents with radix point;
50---colorimetric constant volume, Unit/mL;
250---the constant volume of sample in volumetric flask, Unit/mL.
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| CN106932352A (en) * | 2017-04-14 | 2017-07-07 | 河海大学 | A kind of method for determining activated sludge coefficient of stabilization |
| CN107192683A (en) * | 2017-07-25 | 2017-09-22 | 福建海峡环保集团股份有限公司 | A kind of method of total phosphorus in measure sludge |
| CN107340249A (en) * | 2017-07-05 | 2017-11-10 | 安徽皖仪科技股份有限公司 | A kind of method of total nitrogen content in on-line checking environmental water sample |
| CN112362604A (en) * | 2020-10-22 | 2021-02-12 | 江苏锦测环保科技有限公司 | Method for detecting biological toxicity of chemical wastewater |
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Cited By (5)
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| CN106932352A (en) * | 2017-04-14 | 2017-07-07 | 河海大学 | A kind of method for determining activated sludge coefficient of stabilization |
| CN107340249A (en) * | 2017-07-05 | 2017-11-10 | 安徽皖仪科技股份有限公司 | A kind of method of total nitrogen content in on-line checking environmental water sample |
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Application publication date: 20141008 |