US 12,339,259 B1 · Monitoring method and device of dissolved greenhouse gases in wastewater

Abstract

A monitoring method of dissolved greenhouse gases in wastewater includes: S1, collecting a wastewater sample, performing mud-water separation, and collecting a supernatant after the mud-water separation; S2, adding dilute sulfuric acid solution to the supernatant collected in a headspace vial to adjust pH of the supernatant to 1-4, and then tightening a cap of the headspace vial; S3, inverting the headspace vial, and checking whether there are air bubbles in the headspace vial; S4, injecting 5-10 mL of pure nitrogen into the headspace vial through a syringe, and discharging 5-10 mL of the wastewater sample through a conduit; S5, placing the headspace vial in a water bath constant temperature shaker, and shaking the headspace vial for 20-30 minutes; S6, extracting gases from an upper part of the headspace vial, and measuring concentrations of the gases; S7, quantitatively calculating concentrations of the dissolved greenhouse gases in the wastewater sample.

A monitoring method of dissolved greenhouse gases in wastewater, comprising the following steps:

S1, collecting a wastewater sample by using a wastewater collection device, performing mud-water separation on the wastewater sample, and collecting a supernatant after the mud-water separation by using a headspace vial;
S2, adding a dilute sulfuric acid solution to the supernatant collected in the headspace vial to adjust pH of the supernatant to 1-4, and then tightening a cap of the headspace vial;
S3, inverting the headspace vial, checking whether there are air bubbles in the headspace vial, discarding the wastewater sample and repeating the step S1 and the step S2 to recollect another wastewater sample when there are air bubbles in the headspace vial, and storing the headspace vial in a refrigerator when there are no air bubbles in the headspace vial;
S4, injecting 5-10 milliliters (mL) of pure nitrogen into the headspace vial by using a syringe, and discharging 5-10 mL of the wastewater sample from the headspace vial through a conduit;
S5, placing the headspace vial in a water bath constant temperature shaker, and shaking the headspace vial for 20-30 minutes to make a gas phase and a liquid phase in the headspace vial to reach headspace equilibrium;
S6, measuring a temperature of the headspace vial in the step 5, measuring volumes of the gas phase and the liquid phase in the headspace vial in the step 5, extracting gases from an upper part of the headspace vial in the step S5, and measuring concentrations of the gases by using a gas chromatograph;
and
S7, quantitatively calculating concentrations of the dissolved greenhouse gases in the wastewater sample of the step S1 based on Henry's Law and the concentrations of the gases as greenhouse gases in the gas phase measured in the step S6;
wherein the dissolved greenhouse gases comprise nitrous oxide (N2O) and methane (CH4);
wherein a concentration calculation equation for the N2O is:
C
0
=
(
C
l
×
V
l
)
+
(
C
g
×
P
R
×
T
×
V
g
)
V
l
+
V
g
C
l
=
C
g
×
exp
(
(
A
1
+
A
2
×
(
1
⁢
0
⁢
0
T
)
+
A
3
×
ln
⁡
(
T
1
⁢
0
⁢
0
)
+
A
4
×
(
T
1
⁢
0
⁢
0
)
2
)
)
where C0 represents a concentration of the N2O in the wastewater sample, Cg represents a concentration of the N2O in the gas phase after the headspace equilibrium, Cl represents a concentration of the N2O in the liquid phase after the headspace equilibrium, and P and R respectively represent an atmospheric pressure and a gas constant;
T represents an absolute temperature, Vg and Vl respectively represent the volumes of the gas phase and the liquid phase in the headspace vial, and A1, A2, A3 and A4 respectively represent constants −165.8806, 222.8743, 92.0792, and −1.48425;
and
wherein a concentration calculation equation for the CH4 is:
C
0
=
C
g
(
β
⁢
RT
V
m
+
V
g
V
l
)
where C0 represents a concentration of the CH4 in the wastewater sample, Cg represents a concentration of the CH4 in the gas phase after the headspace equilibrium, β represents a solubility coefficient for the CH4, R represents a gas state constant, T represents the absolute temperature, Vm represents a molar volume of the CH4 under a standard condition, and Vg and Vl respectively represent the volumes of the gas phase and the liquid phase in the headspace vial.

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Monitoring method and device of dissolved greenhouse gases in wastewater

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Monitoring method and device of dissolved greenhouse gases in wastewater

Life of this patent

Abstract

Claims7