CN115180722B - Method for determining pollution-reducing and carbon-reducing working conditions of micro-polluted water surface flow constructed wetland - Google Patents
Method for determining pollution-reducing and carbon-reducing working conditions of micro-polluted water surface flow constructed wetland Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/32—Biological treatment of water, waste water, or sewage characterised by the animals or plants used, e.g. algae
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/08—Chemical Oxygen Demand [COD]; Biological Oxygen Demand [BOD]
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/14—NH3-N
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/15—N03-N
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/16—Total nitrogen (tkN-N)
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/18—PO4-P
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Abstract
The invention discloses a method for determining the pollution-reducing and carbon-reducing working conditions of a micro-polluted water surface flow constructed wetland, which comprises the following steps: building a surface flow constructed wetland small test system; configuring a wetland operation condition; collecting water samples of water inflow and water outflow of each surface flow constructed wetland test system and greenhouse gas samples; measuring the water quality index and the greenhouse gas concentration of each surface flow constructed wetland small test system; accounting the pollutant removal rate, the greenhouse gas release flux and the global warming potential value of each surface flow constructed wetland test system; and determining the optimal operation condition of each surface flow constructed wetland small test system. The invention combines the current research situation of the treatment technology of the micro-polluted water, quantitatively evaluates the purification effect of the micro-polluted water surface flow constructed wetland, determines the optimal operation condition of the surface flow constructed wetland, has the advantages of strong applicability, easy operation and the like, is suitable for popularization and use, and has guiding significance for the design and construction of the micro-polluted water, the operation management of the surface flow constructed wetland and the reduction of greenhouse gas emission.
Description
Technical Field
The invention relates to a technology for evaluating the treatment effect of micro-polluted water and surface flow constructed wetland, in particular to a method for determining the pollution and carbon reduction working conditions of the micro-polluted water surface flow constructed wetland.
Background
The micro-polluted water is water body polluted by organic matters, part of water quality indexes exceed class III water standards of GB3838-2002 'surface Water environmental quality standards', the phenomenon of seasonal exceeding of the concentration of ammonia nitrogen and total phosphorus is presented, and the micro-polluted water has the water quality characteristics of low carbon and high nitrogen. Aiming at the characteristic of low concentration of pollutants in the micro-polluted water body, the surface flow constructed wetland is a common effective measure for improving and maintaining the water quality of the micro-polluted water source. However, the surface flow artificial wetland treatment effect can be influenced by natural conditions and artificial regulation, the operating conditions such as the inlet water nitrogen composition, the hydraulic retention time, the plant density and the like are different, and the wetland treatment efficiency, the plant growth and the microbial reaction are also different. When the artificial wetland is used for wastewater treatment, oxygen kinetics, hydrologic conditions and microbial processes can be changed, and the generation and emission of air in the artificial wetland greenhouse are promoted or inhibited, so that the contribution amount to global warming is correspondingly increased or reduced. The existing researches show that the greenhouse gas emission of the constructed wetland is approximately 2-10 times of that of the natural wetland, and the constructed wetland has the suspicion of transferring water pollution into atmospheric pollution, so that the comprehensive environmental effect of the constructed wetland is greatly reduced. The difference in greenhouse gas emissions may be related to various factors such as the type of constructed wetland, operating conditions, hydraulic load, water level, carbon-nitrogen ratio, and climate environment. Therefore, quantitative research on the water quality purifying effect of the surface flow constructed wetland and the influence of factors such as the nitrogen composition of the inflow water, the plant density, the hydraulic retention time and the like on the greenhouse gas emission is particularly necessary.
Disclosure of Invention
The invention aims to: the invention aims to provide a method for determining the pollution and carbon reduction working conditions of a micro-polluted water surface flow constructed wetland.
The technical scheme is as follows: the invention discloses a method for determining the pollution-reducing and carbon-reducing working conditions of a micro-polluted water surface flow constructed wetland, which comprises the following steps:
s1, building a surface flow artificial wetland small-scale system, which comprises the steps of determining an experimental device, collecting sediment to remove impurities, homogenizing, spreading the homogenized sediment in the experimental device, transplanting emergent aquatic plants with similar growth vigor into the experimental device, and performing water inlet pre-culture on the surface flow artificial wetland small-scale system;
s2, configuring the operation working condition of the surface flow constructed wetland small test system, and determining the COD of the inflow water according to experimental requirements Mn Concentration, TN concentration, TP concentration and prepared wastewater medicine name, inlet water pH value of 7-8, and determining inlet water nitrogen composition including inlet water NH 4 + -N and NO 3 - -N ratio; determining plant density; determining hydraulic retention time;
s3, collecting water samples and greenhouse gas samples of each surface flow artificial wetland small test system, collecting water quality samples of water inflow and water outflow of each small test system in the set corresponding hydraulic retention time, and collecting greenhouse gas samples of each small test system at the same time, wherein a plurality of parallel samples are arranged in each experimental group;
s4, measuring the water quality index concentration and the greenhouse gas concentration of each surface flow constructed wetland small test system, wherein the water quality monitoring index is a basic physical and chemical index and COD (chemical oxygen demand) Mn 、NH 4 + -N、NO 3 - N, TN and TP, the greenhouse gas index is CO 2 、CH 4 And N 2 O；
S5, accounting pollutant removal rates composed of different plant densities, different hydraulic retention times and different inflow nitrogen elements of each surface flow constructed wetland small scale system, wherein the pollutants comprise COD Mn 、NH 4 + -N、NO 3 - N, TN and TP accounting for greenhouse gases CH 4 、CO 2 And N 2 O release flux, accounting for global warming potential values;
s6, determining the optimal operation condition of each surface flow artificial wetland small-scale system, including determining the plant density and hydraulic retention time of the highest removal rate of pollutants of each surface flow artificial wetland small-scale system under the conditions of different inflow nitrogen elements, and determining the minimum greenhouse gas release amount under the corresponding conditions.
Further, the step S1 specifically includes:
bottom mud with preset thickness is paved at the bottom of an experimental device, emergent aquatic plants with similar heights and growth vigor are selected to be transplanted into the experimental device to serve as experimental groups, 3 groups of parallel samples are arranged in each experimental group, 3 groups of non-plant control groups are arranged in each experimental group, a plurality of groups of experimental groups and the non-plant control groups are placed in an artificial greenhouse for pre-culture for 1-3 months, and simulated micro-polluted water is injected to start an experiment after the system is stable.
Further, the step S2 specifically includes:
the inflow water adopts artificial micro-polluted water, the composition of inflow water nitrogen is set according to experimental requirements, and the pH value of inflow water is kept between 7 and 8; setting each experimental group by adopting a single variable principle, respectively setting different plant densities in a plurality of groups of experimental devices, and respectively setting different hydraulic retention time and different inflow nitrogen compositions in a plurality of groups of experimental devices with the same plant density; all experimental groups have different water retention time, water nitrogen composition and plant density, other conditions are consistent, and the water inlet concentration of all plant-free control groups is consistent with the corresponding experimental group concentration.
Further, in the step S3, the greenhouse gas sample is collected by a static box-weather chromatography method, and the temperature and the air pressure in the box are recorded while the greenhouse gas sample is collected.
Further, COD in step S4 Mn Measured by potassium permanganate oxidation titration method, NH 4 + N is determined by Nardostat spectrophotometry, NO 3 - N is determined by inorganic anions in water, TN is determined by alkaline potassium persulfate digestion spectrophotometry, TP is determined by ammonium molybdate spectrophotometry, and a monitoring method of greenhouse gas monitoring indexes is gas chromatography.
Further, in step S5, the calculation formula of the pollutant removal rate is as follows:
wherein R is the pollutant removal rate; c (C) in The water inlet concentration of the system; c (C) out The water outlet concentration of the system is obtained.
Further, CH in step S5 4 、CO 2 And N 2 The O release flux change calculation formula is:
wherein F is gas flux; m is the molar mass of gas, P is the pressure of a sampling point, T is the absolute temperature at the time of sampling, V0, P0 and T0 are the molar volume of gas, the air pressure and the absolute temperature under the standard state of ideal gas respectively, and dc/dt is the slope of the change of the concentration of the gas with time at the time of sampling; h is the height of the gas in the sampling box.
Further, the global warming potential calculation formula in step S5 is:
C CO2-eqv ＝25C CH4 +298C N2O +C CO2 ；
wherein C is CO2-eqv C is the emission of greenhouse gases CH4 Is CH 4 Seasonal accumulative quantity, C N2O Is N 2 Cumulative O season, C CO2 Is CO 2 Seasonal cumulative amount.
The invention relates to a system for determining the pollution-reducing and carbon-reducing working conditions of a micro-polluted water surface flow constructed wetland, which comprises the following components:
the surface flow constructed wetland small-scale test system comprises a plurality of groups of experiment groups and a plant-free comparison group, wherein the plurality of groups of comparison experiment groups are respectively arranged according to different wetland operation conditions, the wetland operation conditions comprise plant density, hydraulic retention time and inflow nitrogen composition, and the inflow nitrogen composition comprises inflow NH (NH) 4 + -N and NO 3 - -N ratio;
the data acquisition module is used for acquiring water samples and greenhouse gas samples of each surface flow artificial wetland small test system, acquiring water inflow and outflow quality samples of each surface flow artificial wetland small test system at the set corresponding hydraulic retention time, simultaneously acquiring greenhouse gas samples of each surface flow artificial wetland small test system, recording the temperature and air pressure of the current day of sampling and the temperature and air pressure in a greenhouse gas acquisition box, and setting 3 parallel samples for each experimental group;
the test module is used for measuring the water quality index concentration and the greenhouse gas concentration of each surface flow artificial wetland small test system, and the water quality monitoring index is a basic physicochemical index and COD Mn 、NH 4 + -N、NO 3 - -N, TN, TP, greenhouse gas index CO 2 、 CH 4 、N 2 O；
And the data accounting module is used for accounting the pollutant removal rate, the greenhouse gas release flux and the global warming potential value of each surface flow artificial wetland small-scale system and determining the optimal operation working condition of each surface flow artificial wetland small-scale system.
The beneficial effects are that: compared with the prior art, the invention has the technical effects that: (1) The invention determines a method for processing the determination of the operation conditions of pollution reduction and carbon reduction of the micro-polluted water surface flow constructed wetland, and establishes the system drop of the surface flow constructed wetlandA pollution reduction carbon benefit evaluation system; (2) The operation condition of the micro-polluted water surface flow artificial wetland system is treated by configuration: plant density, hydraulic retention time, influent nitrogen composition (influent NH) 4 + -N and NO 3 - -N proportion), according to the surface flow constructed wetland pollution-reducing and carbon-reducing effect accounting system, the working condition that the pollutant removal rate of the surface flow constructed wetland system is highest and the release amount of greenhouse gas is minimum is optimized, so that the pollution-reducing and carbon-reducing effect of the micro-polluted water surface flow constructed wetland system is achieved; (3) The invention combines the research current situation of purifying micro-polluted water by the surface flow constructed wetland, quantitatively evaluates the purification effect and the greenhouse gas emission of the surface flow constructed wetland for treating the micro-polluted water, determines the optimal operation condition of the surface flow constructed wetland, has the advantages of strong applicability, easy operation and the like, is suitable for popularization and use, and has guiding significance for the micro-polluted water treatment, the design and construction of the surface flow constructed wetland, the operation management and the reduction of the greenhouse gas emission.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a schematic diagram of a test apparatus according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an artificial greenhouse in an embodiment of the invention.
Detailed Description
The invention will now be described in detail with reference to the drawings and specific examples.
The invention relates to a method for determining the pollution-reducing and carbon-reducing working conditions of a micro-polluted water surface flow constructed wetland, which is characterized in that the plant density, the hydraulic retention time and the water inlet nitrogen composition (water inlet NH) of a surface flow constructed wetland system are configured 4 + -N and NO 3 - -N proportion), collecting water samples and greenhouse gases of each surface flow constructed wetland system, measuring water quality indexes and greenhouse gas concentration, accounting the pollutant removal rate, greenhouse gas release flux and global warming potential value of the system, and further determining the optimal operation condition of each surface flow constructed wetland system. As shown in fig. 1, the method specifically comprises the following steps:
s1, building a surface flow artificial wetland small-scale system, wherein the surface flow artificial wetland small-scale system comprises sediment homogenization, transplanting emergent aquatic plants with similar growth vigor, and water inlet preculture of the surface flow artificial wetland small-scale system; specific:
determining an experimental device, collecting bottom mud, removing impurities such as stones, homogenizing, spreading the bottom mud at the bottom of the experimental device, wherein the thickness is 10-15cm, selecting reed with similar height and growth vigor, transplanting the reed into the experimental device, setting a plant-free control group and a standby plant group, pre-culturing for 2-3 months in an artificial greenhouse, taking tap water as water after 1-3 weeks in the early stage of pre-culturing, supplementing natural evaporation water amount every day at 5:00 pm, keeping the water depth of the water inlet at 5cm, cleaning dead plants in time and cultivating standby plants with similar growth vigor in a complementary manner. After the plant growth condition is good, the simulated micro-polluted water is injected, the pre-experiment is carried out for 1-3 weeks, the hydraulic retention time of the pre-experiment is 5-7 days, the water inlet depth is 10cm, the water inlet and outlet quality is measured, the water outlet quality is considered to be stable after no obvious statistical difference is found, and the formal experiment can be started;
s2, configuring the operation condition of the surface flow artificial wetland small test system, and determining the COD of the inflow water according to experimental requirements Mn The concentration, TN concentration and TP concentration and the names of the prepared wastewater medicines are stored, the pH value of the inlet water is between 7 and 8, and the nitrogen composition of the inlet water (inlet water NH) is determined 4 + -N and NO 3 - -N ratio); determining plant density; determining hydraulic retention time; specific:
preparing water simulating micro-polluted water into pure water, wherein carbon is provided by glucose or sucrose, phosphorus is provided by potassium dihydrogen phosphate, and nitrogen is provided by ammonium chloride and potassium nitrate (or sodium nitrate); the plant density is 0, 25 plants/m 2 50 plants/m 2 And the like, and can be adjusted according to actual conditions; the hydraulic retention time is 1, 3, 5, 7, 14 days, etc., and can be adjusted according to actual conditions.
S3, collecting water samples and greenhouse gas samples of each surface flow artificial wetland test system, wherein the water samples comprise water quality samples of inflow water and outflow water and greenhouse gas samples; specific:
different compositions of nitrogen in water (NH in water) are collected at the corresponding hydraulic retention time 4 + -N and NO 3 - -N ratio) And coating 500ml of water samples on each surface flow artificial wetland small test system of different plant densities and corresponding no-plant control groups, collecting 10-100ml of greenhouse gas samples, arranging 3 parallel samples on all the surface flow artificial wetland small test systems, and rapidly transferring to a refrigerator for refrigeration after collecting.
S4, measuring the water quality index concentration and the greenhouse gas concentration of each surface flow constructed wetland small test system, wherein the water quality monitoring index is a basic physical and chemical index and COD (chemical oxygen demand) Mn The indexes of the greenhouse gases are CO, ammonia nitrogen, TN and TP 2 、CH 4 、N 2 O, all samples were assayed as much as possible within 48 h; specific:
(1) Water quality monitoring index as basic physical and chemical index and COD Mn 、NH 4 + -N、NO 3 - N, TN and TP. The basic physicochemical index can be detected by a portable multiparameter water quality analyzer, including water temperature, DO, pH, ORP, turbidity, conductivity and the like, and COD Mn Measured by potassium permanganate oxidation titration method, NH 4 + N is determined by Nardostat spectrophotometry, NO 3 - N adopts the determination of inorganic anions in water (ion chromatography), TN adopts the digestion spectrophotometry of alkaline potassium persulfate, TP adopts the spectrophotometry of ammonium molybdate, and specific methods refer to methods for monitoring and analyzing water and wastewater (national environmental protection agency, 2002);
(2) The monitoring index of the greenhouse gas is CO 2 、CH 4 、N 2 O, the monitoring method is gas chromatography;
s5, accounting the pollutant removal rate, the greenhouse gas release flux and the global warming potential value of each system;
calculating pollutant removal rates of the water quality indexes according to a pollutant removal formula, and calculating greenhouse gas release flux and global warming potential values according to greenhouse gas monitoring concentration; the method comprises the following steps:
(1) The pollutant removal rates of different water depths, different plant densities and different hydraulic retention times of each system are calculated, and the calculation formula of the pollutant removal rates is as follows:
wherein R is the pollutant removal rate (%); c (C) in The concentration of the water fed into the system (mg.l) -1 )；C out For the concentration of the effluent (mg.l) -1 )；
(2)CH 4 、CO 2 And N 2 The O flux change calculation formula is:
wherein F is the gas flux (mg.m -2 ·h -1 ) The method comprises the steps of carrying out a first treatment on the surface of the M is the gas molar mass (g.mol) -1 ) P is the pressure (Pa) of the sampling point, T is the absolute temperature (K) at the time of sampling, and V0, P0 and T0 are the gas molar volumes (L.mol) of the ideal gas in the standard state -1 ) Air pressure (Pa) and absolute temperature (K), dc/dt being the slope of the gas concentration over time at the time of sampling; h is the height (cm) of the gas in the sampling box;
(3) The global warming potential calculation formula is:
on the scale of hundred years, CH in greenhouse gases released by a wetland ecosystem 4 The greenhouse effect of (2) is CO 2 25 times, N 2 The greenhouse effect of O is CO 2 298 times of (2). According to this standard, CO released during the growth phase of the wetland 2 、CH 4 、N 2 O three greenhouse gas emissions (CO) 2 Gas meter) and contribution rate are calculated as follows:
C CO2-eqv ＝25C CH4 +298C N2O +C CO2 (3)；
wherein C is CO2-eqv Is the emission of greenhouse gases (CO 2 Meter) (g.m) -2 )，C CH4 Is CH 4 Seasonal cumulative amount (g.m) -2 )， C N2O Is N 2 Cumulative O season (g.m) -2 )，C CO2 Is CO 2 Seasonal cumulative amount (g.m) -2 )。
S6, determining the optimal operation condition of each surface flow constructed wetland small test system, including determining the optimal hydraulic retention time and the optimal plant density;
plant density and hydraulic retention time of the highest removal rate of each wetland system pollutant under different water inflow conditions are determined, and the minimum greenhouse gas release amount under corresponding conditions is determined.
The invention relates to a system for determining the pollution-reducing and carbon-reducing working conditions of a micro-polluted water surface flow constructed wetland, which comprises the following components:
the surface flow constructed wetland small-scale test system comprises a plurality of groups of experiment groups and a plant-free comparison group, wherein the plurality of groups of comparison experiment groups are respectively arranged according to different wetland operation conditions, the wetland operation conditions comprise plant density, hydraulic retention time and inflow nitrogen composition, and the inflow nitrogen composition comprises inflow NH (NH) 4 + -N and NO 3 - -N ratio;
the data acquisition module is used for acquiring water samples and greenhouse gas samples of each surface flow artificial wetland small test system, acquiring water inflow and outflow quality samples of each surface flow artificial wetland small test system at the set corresponding hydraulic retention time, simultaneously acquiring greenhouse gas samples of each surface flow artificial wetland small test system, recording the temperature and air pressure of the current day of sampling and the temperature and air pressure in a greenhouse gas acquisition box, and setting 3 parallel samples for each experimental group;
the test module is used for measuring the water quality index concentration and the greenhouse gas concentration of each surface flow artificial wetland small test system, and the water quality monitoring index is a basic physicochemical index and COD Mn 、NH 4 + -N、NO 3 - -N, TN, TP, greenhouse gas index CO 2 、 CH 4 、N 2 O；
And the data accounting module is used for accounting the pollutant removal rate, the greenhouse gas release flux and the global warming potential value of each surface flow artificial wetland small-scale system and determining the optimal operation working condition of each surface flow artificial wetland small-scale system.
Examples:
s1, building a surface flow constructed wetland small test system;
the experiment is carried out on a saline dragon lake drinking water source, the test device is a water bucket with the diameter of 40cm and the height of 50cm, and a circular hole with the diameter of 1cm is formed at the position 10cm away from the bottom of the water bucket so as to be convenient for water discharge (as shown in figure 2). Collecting bottom mud with the original surface layer of 0-15cm, sampling, covering the container with a cover, wrapping with tinfoil, and rapidly transporting back to a laboratory. Removing impurities such as stones, homogenizing, and spreading bottom mud at the bottom of the barrel to 15cm. The emergent aquatic plants are selected from reed, reed with similar height and growth vigor is transplanted into the barrel, and a non-plant control group is arranged at the same time. All plants were pre-cultivated in an artificial greenhouse (as shown in fig. 3), and after the system had stabilized, simulated slightly contaminated water was injected to start the experiment.
S2, configuring a wetland operation condition;
and (3) configuring operation conditions of the wetland: the plant density was 2, 6, 10 plants/barrel, and the hydraulic retention time was 1d, 3d, 5d, 7d.
Preparing wetland water inlet conditions: the water inlet adopts artificial simulated micro-polluted water, the experimental water is pure water, the water inlet C/N is 4:1, TN is 1.5mg/L, and TP is 0.15mg/L. Simulation of COD in slightly polluted water Mn 、NH 4 + -N、NO 3 - N and TP are each composed of sucrose, NH 4 Cl、KNO 3 And KH 2 PO4 was provided. The nitrogen composition of the water inlet is set to be high in NO 3 - group-N (NH) 4 + /NO 3 - =0:1), high NH 4 + group-N (NH) 4 + /NO 3 - =0.7:1) and mean value of saline lake water inflow over years (NH 4 + / NO 3 - =4:1), the specific parameters are shown in table 1.
Table 1 test water inlet parameters
S3, collecting water samples and greenhouse gas samples of each surface flow artificial wetland test system;
and respectively collecting water samples and gas samples at 11:00 am of experiments 1, 3, 5 and 7d, wherein each experiment group is provided with 3 parallel samples, all samples are refrigerated after being collected and immediately sent to a laboratory, the gas samples are collected by a static box-weather chromatography method, the height of the box is customized according to the plant height, a 100ml injector is used for collecting the first sample after the box is buckled and sealed, then 1 gas sample is collected every 20min within 1h, 3 times of gas samples are collected, and the temperature and the air pressure in the box are recorded while the gas samples are collected.
S4, measuring the water quality index concentration and the greenhouse gas concentration of each surface flow constructed wetland small-scale test system;
monitoring basic physicochemical indexes and COD of each surface flow artificial wetland small test system according to water quality index measurement method Mn 、NH 4 + -N、NO 3 - -N, TN and TP concentrations, CO monitoring according to greenhouse gas determination methods 2 、CH 4 、N 2 The O concentration is as follows:
table 2 tests of water basic physicochemical index
Table 3TN Water inlet and outlet concentration (mg/L)
TABLE 4NH 4 + N Water in and out concentration (mg/L)
TABLE 5NO 3 - N Water in and out concentration (mg/L)
TABLE 6COD Mn Concentration of water inlet and outlet (mg/L)
TABLE 7TP Water in and out concentration (mg/L)
TABLE 8 greenhouse gas concentration (plant Density 6 plants) (ppm) for different influent nitrogen compositions
TABLE 9 greenhouse gas concentrations for different plant densities (intake Nitrogen composition 0.7:1)
S5, accounting the pollutant removal rate, the greenhouse gas release flux and the global warming potential value of each surface flow constructed wetland test system;
calculating the removal rate of various pollutants of each surface flow constructed wetland small-scale test system under the working conditions of different water inlet nitrogen compositions, different hydraulic retention times and different plant densities according to a formula (1), wherein the pollutant removal rate data are shown in tables 10-14; the different inflow nitrogen compositions, the different plant density greenhouse gas concentrations and the corresponding global warming potential values of each surface flow artificial wetland small-scale system are calculated according to the formula (2) and the formula (3), and are specifically shown in tables 15 and 16.
Table 10TN removal Rate (%)
TABLE 11NH 4 + N removal Rate (%)
TABLE 12NO 3 - N removal Rate (%)
TABLE 13COD Mn Removal rate (%)
TABLE 14TP removal (%)
TABLE 15 different feed Nitrogen composition CO 2 、CH 4 、N 2 O release flux and global warming potential values
| Nitrogen composition of water inlet | CH 4 /(mg/m 2 /h) | CO 2 /(mg/m 2 /h) | N 2 O/(μg/m 2 /h) | GWP/(g/m 2 ) |
| 0:1 | 13.80 | -776.449 | -9.03756 | -434.196 |
| 0.7:1 | 20.48 | -400.256 | 124.726 | 149.0237 |
| 4:1 | 8.81 | 75.49722 | -0.01495 | 295.656 |
TABLE 16 different plant densities CO 2 、CH 4 、N 2 O release flux and global warming potential values
| Plant density | CH 4 /(mg/m 2 /h) | CO 2 /(mg/m 2 /h) | N 2 O/(μg/m 2 /h) | GWP/(g/m 2 ) |
| 0 | 1.55 | 406.8345 | 118.62 | 480.9867 |
| 2 | 13.59 | -489.372 | -0.55 | -149.771 |
| 6 | 3.62 | -592.004 | -51.36 | -516.841 |
| 10 | 6.25 | -1243.77 | -120.40 | -1123.42 |
S6, determining the optimal operation condition of each surface flow constructed wetland small test system;
analysis of the above data led to the following conclusion:
(1) Different water inflow nitrogen elements form a wetland system, and TN and NH are prolonged along with the hydraulic retention time under the same plant density 4 + -N、NO 3 - The removal rates of N all showed a tendency to rise gradually, the maximum removal rate being reached on the fifth day, the optimal hydraulic retention time being determined to be 5 days.
(2) The wetland system composed of different inflow nitrogen elements has better effect of removing pollutants when the plant density is 2 plants under the same hydraulic retention time condition, and determines that the optimal plant density is 2 plants/barrel, and is converted into 25 plants/m 2 。
(3) When the hydraulic retention time is 5 days and the plant density is 2 plants/barrel, the NH is high under three water inlet nitrogen forms 4 + N groups of TN have better removal effect and lower global warming potential.
The working conditions of the wetland system comprising different inflow nitrogen elements, namely the highest pollutant removal rate, the lowest greenhouse gas release amount and the global warming potential value, are that the hydraulic retention time is 5 days, and the plant density is 2 plants/barrel.
Claims (7)
1. The method for determining the pollution and carbon reduction working conditions of the micro-polluted water surface flow constructed wetland is characterized by comprising the following steps of:
s1, building a surface flow artificial wetland small-scale system, which comprises the steps of determining an experimental device, collecting sediment to remove impurities, homogenizing, spreading the homogenized sediment in the experimental device, transplanting emergent aquatic plants with similar growth vigor into the experimental device, and performing water inlet pre-culture on the surface flow artificial wetland small-scale system;
s2, configuring the operation working condition of the surface flow constructed wetland small test system, and determining the COD of the inflow water according to experimental requirements Mn Concentration, TN concentration, TP concentration and prepared wastewater medicine name, inlet water pH value of 7-8, and determining inlet water nitrogen composition including inlet water NH 4 + -N and NO 3 - -N ratio; determining plant density; determining hydraulic retention time; the method comprises the following steps:
the inflow water adopts artificial micro-polluted water, the composition of inflow water nitrogen is set according to experimental requirements, and the pH value of inflow water is kept between 7 and 8; setting each experimental group by adopting a single variable principle, respectively setting different plant densities in a plurality of groups of experimental devices, and respectively setting different hydraulic retention time and different inflow nitrogen compositions in a plurality of groups of experimental devices with the same plant density; other conditions are kept consistent except that the water force retention time, the water inlet nitrogen composition and the plant density of all experimental groups are different, and the water inlet concentration of all plant-free control groups is kept consistent with the corresponding experimental group concentration;
s3, collecting water samples and greenhouse gas samples of each surface flow artificial wetland small test system, collecting water quality samples of water inflow and water outflow of each small test system in the set corresponding hydraulic retention time, and collecting greenhouse gas samples of each small test system at the same time, wherein a plurality of parallel samples are arranged in each experimental group;
s4, measuring the water quality index concentration and the greenhouse gas concentration of each surface flow constructed wetland small test system, wherein the water quality monitoring index is a basic physical and chemical index and COD (chemical oxygen demand) Mn 、NH 4 + -N、NO 3 - N, TN and TP, the greenhouse gas index is CO 2 、CH 4 And N 2 O；
S5, accounting pollutant removal rates composed of different plant densities, different hydraulic retention times and different inflow nitrogen elements of each surface flow constructed wetland small scale system, wherein the pollutants comprise COD Mn 、NH 4 + -N、NO 3 - N, TN and TP accounting for greenhouse gases CH 4 、CO 2 And N 2 O release flux, accounting for global warming potential values;
the global warming potential calculation formula is:
C CO2-eqv =25C CH4 +298C N2O +C CO2 ；
wherein C is CO2-eqv C is the emission of greenhouse gases CH4 Is CH 4 Seasonal accumulative quantity, C N2O Is N 2 Cumulative O season, C CO2 Is CO 2 Seasonal cumulative amount;
s6, determining the optimal operation condition of each surface flow artificial wetland small-scale system, including determining the plant density and hydraulic retention time of the highest removal rate of pollutants of each surface flow artificial wetland small-scale system under the conditions of different inflow nitrogen elements, and determining the minimum greenhouse gas release amount under the corresponding conditions.
2. The method for determining the pollution and carbon reduction conditions of the micro-polluted water surface flow constructed wetland according to claim 1 is characterized in that the step S1 is specifically as follows:
bottom mud with preset thickness is paved at the bottom of an experimental device, emergent aquatic plants with similar heights and growth vigor are selected to be transplanted into the experimental device to serve as experimental groups, 3 groups of parallel samples are arranged in each experimental group, 3 groups of non-plant control groups are arranged in each experimental group, a plurality of groups of experimental groups and the non-plant control groups are placed in an artificial greenhouse for pre-culture for 1-3 months, and simulated micro-polluted water is injected to start an experiment after the system is stable.
3. The method for determining the pollution and carbon reduction conditions of the micro-polluted water surface flow constructed wetland according to claim 1, wherein the greenhouse gas sample collection in the step S3 is a static box-gas chromatography method, and the temperature and the air pressure in the box are recorded while the greenhouse gas sample is collected.
4. The method for determining the pollution and carbon reduction conditions of the micro-polluted water surface flow constructed wetland according to claim 1, wherein the COD (chemical oxygen demand) in the step S4 is Mn Measured by potassium permanganate oxidation titration method, NH 4 + N is determined by Nardostat spectrophotometry, NO 3 - N is determined by inorganic anions in water, TN is determined by alkaline potassium persulfate digestion spectrophotometry, TP is determined by ammonium molybdate spectrophotometry, and a monitoring method of greenhouse gas monitoring indexes is gas chromatography.
5. The method for determining the pollution and carbon reduction conditions of the micro-polluted water surface flow constructed wetland according to claim 1, wherein the pollutant removal rate in step S5 is calculated by the following formula:
；
wherein R is the pollutant removal rate; c (C) in The water inlet concentration of the system; c (C) out The water outlet concentration of the system is obtained.
6. The method for determining the pollution and carbon reduction conditions of the micro-polluted water surface flow constructed wetland according to claim 1, wherein in step S5, CH is 4 、CO 2 And N 2 The O release flux change calculation formula is:
；
wherein F is gas flux; m is the molar mass of gas, P is the pressure of a sampling point, T is the absolute temperature at the time of sampling, V0, P0 and T0 are the molar volume of gas, the air pressure and the absolute temperature under the standard state of ideal gas respectively, and dc/dt is the slope of the change of the concentration of the gas with time at the time of sampling; h is the height of the gas in the sampling box.
7. The utility model provides a little pollution water surface flow constructed wetland pollution reduction reduces carbon operating mode determining system which characterized in that includes:
the surface flow constructed wetland small-scale test system comprises a plurality of groups of experiment groups and a plant-free comparison group, wherein the plurality of groups of comparison experiment groups are respectively arranged according to different wetland operation conditions, the wetland operation conditions comprise plant density, hydraulic retention time and inflow nitrogen composition, and the inflow nitrogen composition comprises inflow NH (NH) 4 + -N and NO 3 - -N ratio;
the data acquisition module is used for acquiring water samples and greenhouse gas samples of each surface flow artificial wetland small test system, acquiring water inflow and outflow quality samples of each surface flow artificial wetland small test system at the set corresponding hydraulic retention time, simultaneously acquiring greenhouse gas samples of each surface flow artificial wetland small test system, recording the temperature and air pressure of the current day of sampling and the temperature and air pressure in a greenhouse gas acquisition box, and setting 3 parallel samples for each experimental group;
the test module is used for measuring the water quality index concentration and the greenhouse gas concentration of each surface flow artificial wetland small test system, and the water quality monitoring index is a basic physicochemical index and COD Mn 、NH 4 + -N、NO 3 - -N, TN, TP, greenhouse gas index CO 2 、CH 4 、N 2 O；
And the data accounting module is used for accounting the pollutant removal rate, the greenhouse gas release flux and the global warming potential value of each surface flow artificial wetland small-scale system and determining the optimal operation working condition of each surface flow artificial wetland small-scale system.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ZA852151B (en) * | 1984-03-24 | 1985-12-24 | Perfluktiv Consult Ag | Process and apparatus for the manufacture of activated form coke |
| EP2130426A2 (en) * | 2008-06-05 | 2009-12-09 | Institut für Gemüse- & Zierpflanzenbau e.V. | Method and assembly for carbon dioxide supply of plants cultivated in a greenhouse |
| US8252182B1 (en) * | 2008-09-11 | 2012-08-28 | University Of Central Florida Research Foundation, Inc. | Subsurface upflow wetland system for nutrient and pathogen removal in wastewater treatment systems |
| CN203513429U (en) * | 2013-07-25 | 2014-04-02 | 东华大学 | Compound water purification system of algal-bacterial symbiotic surface flow wetland |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ZA852151B (en) * | 1984-03-24 | 1985-12-24 | Perfluktiv Consult Ag | Process and apparatus for the manufacture of activated form coke |
| EP2130426A2 (en) * | 2008-06-05 | 2009-12-09 | Institut für Gemüse- & Zierpflanzenbau e.V. | Method and assembly for carbon dioxide supply of plants cultivated in a greenhouse |
| US8252182B1 (en) * | 2008-09-11 | 2012-08-28 | University Of Central Florida Research Foundation, Inc. | Subsurface upflow wetland system for nutrient and pathogen removal in wastewater treatment systems |
| CN203513429U (en) * | 2013-07-25 | 2014-04-02 | 东华大学 | Compound water purification system of algal-bacterial symbiotic surface flow wetland |
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