1. A method for quantitative calculation of phosphorus migration and conversion in a pipeline sediment-water system, comprising the steps of:

s1, constructing a test device, which comprises a plurality of identical containers, wherein the bottom of each container is filled with sterilized sediment, and the upper water is poured into each container;

s2, sampling sediments and overlying water in each container, wherein the containers are marked in sequence, and sampling is carried out in the marked sequence every preset number of days;

s3, determining the sample, specifically comprising:

a. the TP and DRP concentration in the overlying water sample is measured by adopting a molybdate colorimetric method;

b. centrifuging the sediments in each sample at the rotating speed of 5000r/min for 20min, filtering to obtain interstitial water, and measuring the interstitial water TP and DRP by a molybdate colorimetric method;

c. drying and grinding the sediment residues obtained by centrifugation, and dividing into two parts;

wherein, one part is sieved by a 200-mesh sieve, is added with 10ml of 5 percent potassium persulfate solution and 5ml of 30 percent sulfuric acid solution for digestion, is cooled and stands overnight, and is measured by a molybdenum-antimony anti-spectrophotometry method the next day to obtain TP in the sediment;

sieving the other part with a 100-mesh sieve, adding 10ml of 5% potassium persulfate solution and 50ml of 1mol/L ammonium chloride solution, adjusting the pH value of the sample to be neutral, then performing shaking extraction at 25 ℃ for 2h, pouring the extracted liquid into a centrifuge tube, centrifuging for 20min at the rotating speed of 10000r/min, filtering the supernatant through a 0.45-micron glass filter membrane, and determining by a molybdenum-antimony anti-spectrophotometry method to obtain Ex-P in the sediment;

s4, calculating the variation of TP, DRP and Ex-P according to the measurement result, and the migration rate and the conversion rate of TP and DRP.

2. The method of claim 1, wherein the method comprises the steps of: in step S1, the containers are uniformly divided into a sterilization group and a control group, wherein the containers in the sterilization group are filled with the sterilization deposit and poured with the topping water, and the containers in the control group are filled with the original deposit and poured with the topping water.

3. The method of claim 2, wherein the method comprises the steps of: and (4) flatly spreading the sediments, putting the sediments into a superclean bench, and irradiating for 48 hours under an ultraviolet lamp to obtain the sterilized sediments.

4. The method of claim 2, wherein the method comprises the steps of: and the opening of each container is wrapped by a PVC preservative film, so that an anoxic environment is formed in the container.

5. The method of claim 1, wherein the method comprises the steps of: in step S2, the sampled area of the sediment is 0-20mm below the sediment-water interface.

6. The method of claim 1, wherein the method comprises the steps of: in step S4, the variation calculation formulas of TP, DRP, and Ex-P are:

ΔC＝C-C⁰；

wherein Δ C isConcentration variation of TP, DRP and Ex-P at different positions in the sterilized group, C is concentration of TP, DRP and Ex-P at different positions in the last sampling of the sterilized group⁰Concentrations of TP, DRP and Ex-P at different positions in the first sampling;

the migration amount calculation formula of TP or DRP is as follows: Δ M ═ Δ C, where Δ M is the transport volume of TP or DRP in the overlying water, interstitial water;

the mobility calculation formula of TP or DRP is:wherein r is_MIs the mobility;

the conversion amount calculation formula of TP or DRP is as follows: delta T is-delta C '-delta M, wherein delta T is the biological transformation amount of TP and DRP in the overlay water or interstitial water of the control group, and delta C' is the concentration variation amount of TP, DRP and Ex-P at different positions of the control group;

the conversion formula for TP or DRP is:

Background

The drainage system is used as an important component of urban infrastructure and is used for collecting and conveying domestic sewage, rainwater and industrial wastewater; however, suspended particles carried in rain and sewage can be settled under the influence of factors such as water flow factor change in the pipeline, so that the deposition phenomenon in the drainage pipeline is very common; the pipeline sediment can reduce the conveying space of the pipeline and reduce the water conveying capacity of the pipeline, microorganisms in the sediment can generate harmful compounds in metabolism to cause peculiar smell and corrosion, and phosphorus pollutants in the sediment enter a receiving water body along with overflow sewage and wastewater, so that water body eutrophication is easily caused.

At present, no simple and feasible method for measuring and calculating the migration and conversion processes of phosphorus pollutants exists, so that a quantitative calculation method for migration and conversion of phosphorus in a pipeline sediment-water system is urgently needed to solve the problems

Disclosure of Invention

The invention provides a quantitative calculation method for phosphorus migration and conversion in a pipeline sediment-water system, which is used for solving the problem caused by phosphorus pollutants in pipeline sediments.

In order to achieve the purpose, the invention provides the following technical scheme: a method for quantitative calculation of phosphorus migration and conversion in a pipeline sediment-water system, comprising the steps of:

s1, constructing a test device, which comprises a plurality of identical containers, wherein the bottom of each container is filled with sterilized sediment, and the upper water is poured into each container;

s2, sampling sediments and overlying water in each container, wherein the containers are marked in sequence, and sampling is carried out in the marked sequence every preset number of days;

s3, determining the sample, specifically comprising:

a. the TP and DRP concentration in the overlying water sample is measured by adopting a molybdate colorimetric method;

b. centrifuging the sediments in each sample at the rotating speed of 5000r/min for 20min, filtering to obtain interstitial water, and measuring the interstitial water TP and DRP by a molybdate colorimetric method;

c. drying and grinding the sediment residues obtained by centrifugation, and dividing into two parts;

wherein, one part of the precipitate is sieved by a 200-mesh sieve, is added with 10ml of 5 percent potassium persulfate solution and 5ml of 30 percent sulfuric acid solution for digestion, is cooled and stands overnight, and is measured by a molybdenum-antimony anti-spectrophotometry method the next day to obtain TP in the precipitate;

sieving the other part with a 100-mesh sieve, adding 10ml of 5% potassium persulfate solution and 50ml of 1mol/L ammonium chloride solution, adjusting the pH value of the sample to be neutral, then performing shaking extraction at 25 ℃ for 2h, pouring the extracted liquid into a centrifuge tube, centrifuging for 20min at the rotating speed of 10000r/min, filtering the supernatant through a 0.45-micron glass filter membrane, and determining by a molybdenum-antimony anti-spectrophotometry method to obtain Ex-P in the sediment;

s4, calculating the variation of TP, DRP and Ex-P according to the measurement result, and the migration rate and the conversion rate of TP and DRP.

Preferably, in step S1, the containers are uniformly divided into a sterilization group and a control group, wherein the containers in the sterilization group are filled with the sterilization deposit and poured with the topping water, and the containers in the control group are filled with the original deposit and poured with the topping water.

Preferably, the sediment is placed into a super clean workbench after being laid flat, and is irradiated for 48 hours under an ultraviolet lamp, so that the sterilized sediment is obtained.

Preferably, each opening of the container is wrapped by a PVC preservative film, so that an anoxic environment is formed in the container.

Preferably, in step S2, the sampling area of the sediment is 0-20mm below the sediment-water interface. Preferably, in step S4, the variation calculation formulas of TP, DRP, and Ex-P are:

ΔC＝C-C⁰；

wherein, deltaC is the concentration variation of TP, DRP and Ex-P at different positions of the sterilization group, C is the concentration of TP, DRP and Ex-P at different positions of the last sampling of the sterilization group, C is⁰Concentrations of TP, DRP and Ex-P at different positions in the first sampling;

the migration amount calculation formula of TP or DRP is as follows: Δ M ═ Δ C, where Δ M is the transport volume of TP or DRP in the overlying water, interstitial water;

the mobility calculation formula of TP or DRP is:wherein r is_MIs the mobility;

the conversion amount calculation formula of TP or DRP is as follows: delta T is-delta C '-delta M, wherein delta T is the biological transformation amount of TP and DRP in the overlay water or interstitial water of the control group, and delta C' is the concentration variation amount of TP, DRP and Ex-P at different positions of the control group;

the conversion formula for TP or DRP is:

compared with the prior art, the invention has the beneficial effects that: according to the invention, the migration and conversion of phosphorus in the drainage pipeline are simulated by constructing the test device, and the migration path and the biotransformation path of phosphorus are analyzed by sampling and measuring sediments and water in the pipeline, so that the migration amount and the conversion amount are calculated, and further the migration rate and the conversion rate are calculated.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.

In the drawings:

FIG. 1 is a schematic diagram of a phosphorus migration and conversion test simulation apparatus in a sediment-water system according to the present invention;

FIG. 2 is a graph of the amount of change in phosphorus in various forms in a sediment-water system of the sterilization unit of the present invention;

FIG. 3 is a graph showing the variation of phosphorus in each form in the sediment-water system of the control group of the present invention.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

Example (b): a method for quantitative calculation of phosphorus migration and conversion in a pipeline sediment-water system, comprising the steps of:

s1, constructing a test device, which comprises a plurality of identical containers, wherein the bottom of each container is filled with sterilized sediment, and the upper water is poured into each container;

s2, sampling sediments and overlying water in each container, wherein the containers are marked in sequence, and sampling is carried out in the marked sequence every preset number of days, and the sampling area of the sediments is 0-20mm below a sediment-water interface;

s3, determining the sample, specifically comprising:

a. the TP and DRP concentration in the overlying water sample is measured by adopting a molybdate colorimetric method;

b. centrifuging the sediments in each sample at the rotating speed of 5000r/min for 20min, filtering to obtain interstitial water, and measuring the interstitial water TP and DRP by a molybdate colorimetric method;

c. drying and grinding the sediment residues obtained by centrifugation, and dividing into two parts;

wherein, one part of the precipitate is sieved by a 200-mesh sieve, is added with 10ml of 5 percent potassium persulfate solution and 5ml of 30 percent sulfuric acid solution for digestion, is cooled and stands overnight, and is measured by a molybdenum-antimony anti-spectrophotometry method the next day to obtain TP in the precipitate;

sieving the other part with a 100-mesh sieve, adding 10ml of 5% potassium persulfate solution and 50ml of 1mol/L ammonium chloride solution, adjusting the pH value of the sample to be neutral, then performing shaking extraction at 25 ℃ for 2h, pouring the extracted liquid into a centrifuge tube, centrifuging for 20min at the rotating speed of 10000r/min, filtering the supernatant through a 0.45-mu m glass filter membrane, and determining by a molybdenum-antimony anti-spectrophotometry method to obtain weak adsorption state total phosphorus Ex-P in the sediment;

s4, calculating the variation of TP, DRP and Ex-P according to the measurement result, and the migration rate and the conversion rate of TP and DRP.

Uniformly dividing a middle container of the test device into a sterilization group and a control group, filling sterilization sediments into the bottom of the container in the sterilization group, and pouring overlying water, wherein the sterilization sediments are obtained by flatly laying the sediments, then placing the sediments on an ultra-clean workbench, and irradiating for 48 hours under an ultraviolet lamp to obtain the sterilization sediments; filling original sediments at the bottom of the containers in the control group, pouring overlying water, and wrapping the openings of the containers with PVC preservative films in order to simulate an anoxic environment in an actual rainwater pipeline, so that an anoxic environment is formed in the containers;

in step S4, the variation calculation formulas of TP, DRP, and Ex-P are:

ΔC＝C-C⁰；

wherein, deltaC is the concentration variation of TP, DRP and Ex-P at different positions of the sterilization group, C is the concentration of TP, DRP and Ex-P at different positions of the last sampling of the sterilization group, C is⁰Concentrations of TP, DRP and Ex-P at different positions in the first sampling;

the migration amount calculation formula of TP or DRP is as follows: Δ M ═ Δ C, where Δ M is the transport volume of TP or DRP in the overlying water, interstitial water;

the mobility calculation formula of TP or DRP is:wherein r is_MIs the mobility;

the conversion amount calculation formula of TP or DRP is as follows: delta T is-delta C '-delta M, wherein delta T is the biological transformation amount of TP and DRP in the overlay water or interstitial water of the control group, and delta C' is the concentration variation amount of TP, DRP and Ex-P at different positions of the control group;

the conversion formula for TP or DRP is:

referring to fig. 1, in one embodiment, there are 10 containers, 5 containers in each of the sterilized group and the control group, and the containers are respectively numbered 1 to 5, wherein each of the containers is filled with sterilized sediment with a thickness of 50mm in the sterilized group, each of the containers is filled with raw sediment with a thickness of 50mm in the control group, the sterilized group tests simulate the migration process of phosphorus in the pipeline, the control group tests simulate the migration and biotransformation process of phosphorus in the rainwater pipeline, and 250ml of simulated rainwater, i.e., cover water, is slowly poured into each of the containers in turn, and the concentrations of various pollutants in the simulated rainwater are as follows:

during sampling, the upper water sample and the sediment sample are respectively taken from the two groups of containers marked with the marks 1 on the same day of the test, then the samples are sequentially taken from the two groups every 3 days until the sampling is finished at 12 days, wherein 3 samples are respectively taken in parallel when the upper water sample and the sediment sample are taken each time.

In the sterilized group, the migration amount of each form of phosphorus in the sterilized group was measured according to the above procedure, and the results are as follows:

table of concentration variation of TP at different positions in the sterilized sediment-water system:

concentration variation table for DRP/Ex-P at different positions in the sterilized sediment-water system:

as can be seen from the above table, in the sterilized sediment-water system, the concentrations of TP and DRP in the overlying water and interstitial water were both slightly decreased, and TP and Ex-P in the sediment were increased by a small amount;

referring to fig. 2, the measurement results were calculated:

calculated TP and DRP migration amounts in overlying water were about:

ΔM_TP＝-ΔC_TP＝0.046mg·L^-1

ΔM_DRP＝-ΔC_DRP＝0.031mg·L^-1；

similarly, the migration amounts of TP and DRP in interstitial water calculated by the method are about 0.025 mg.L respectively^-1And 0.025 mg. L^-1And calculating the mobility of TP and DRP in the overlying water according to the above calculation formula, as shown in the following table:

in the control group, the biotransformation amount of each form of phosphorus in the control group was measured according to the above procedure, and the results are as follows:

table of concentration changes of TP at different positions in the control sediment-water system:

concentration variation table for DRP/Ex-P at different positions in the control sediment-water system:

as can be seen from the above table, in the sterilized sediment-water system, TP and DRP decreased in the overlying water and interstitial water, and TP and Ex-P increased in the sediment; under the combined action of the concentration gradient and the microorganisms, part of phosphorus migrates and is converted into sediment from overlying water and interstitial water.

Calculating the variation of the TP of the water coating on the control group according to the calculation formula:

ΔO_TP＝0.234-0.295＝-0.061mg·L^-1

referring to FIG. 3, the variation of phosphorus at different positions in the control group is calculated, wherein the microorganism in the control group plays an important role, and the variation of TP and DRP concentration is the result of the combined action of position migration and biotransformation;

and (3) calculating and calculating the TP bioconversion amount in the overlying water according to the conversion amount calculation formula: Δ T ═ - (0.061) -0.046 ═ 0.015mg · L^-1The same principle is used to calculate the amount of TP and DRP bioconversion in the overlying water and interstitial water, as shown in the following table:

and calculating the conversion rates of TP and DRP in the overlying water and interstitial water according to the conversion rate formula, wherein the conversion rates are shown in the following table:

finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.