CN116903133A

CN116903133A - Treatment method of cadmium-and/or lead-containing wastewater

Info

Publication number: CN116903133A
Application number: CN202311074905.9A
Authority: CN
Inventors: 曾涛涛; 王亮钦; 沙海超; 符彧淞; 刘清; 张�杰
Original assignee: University of South China
Current assignee: University of South China
Priority date: 2023-08-24
Filing date: 2023-08-24
Publication date: 2023-10-20

Abstract

The invention provides a method for treating wastewater containing cadmium and/or lead, and belongs to the technical field of wastewater treatment. During the activated sludge treatment process, the microbial groups in the sludge can participate in the conversion and removal process of heavy metals through their own metabolism. The present invention performs SBR activated sludge treatment on heavy metal wastewater, and adds signal molecules to the activated sludge treatment wastewater system. Signaling molecules are molecules that guide intercellular or intracellular communication. They can regulate physiological processes such as cell growth, differentiation, movement, metabolism, and death. The microbial quorum sensing effect mediated by signaling molecules can promote most functionalities in sewage treatment. microbial activity, thus improving the sewage treatment effect. The results of the examples show that adding signaling molecules can significantly improve the removal rate of cadmium and lead in wastewater compared to not adding signaling molecules.

Description

Treatment method of cadmium-and/or lead-containing wastewater

Technical Field

The invention relates to the technical field of wastewater treatment, in particular to a method for treating wastewater containing cadmium and/or lead.

Background

With the rapid development of modernization and industrialization, cadmium (Cd), lead (Pd) have been widely used in many industrial applications and discharged from industrial wastewater. Lead and cadmium are used as extremely toxic pollutants, can not be biodegraded in wastewater, and have adverse effects on organisms, plants and human bodies. Therefore, the treatment of the cadmium and lead wastewater has important significance for social development and human health.

At present, cadmium and lead wastewater is mainly treated by a physicochemical method, so that the cost is high and the energy consumption is high. The activated sludge can be used for treating cadmium and lead wastewater, but the method has low cadmium and lead removal rate in the wastewater. Therefore, a method for promoting the treatment effect of SBR activated sludge on cadmium and lead wastewater is needed to improve the removal rate of cadmium and lead in the wastewater.

Disclosure of Invention

The invention aims to provide a treatment method of cadmium-and/or lead-containing wastewater. The treatment method has better cadmium lead removal rate.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a treatment method of cadmium-and/or lead-containing wastewater, which comprises the following steps:

performing SBR activated sludge treatment on the cadmium-and/or lead-containing wastewater in the presence of signal molecules, wherein a single cycle of SBR activated sludge treatment comprises water inflow, reaction, precipitation, drainage and idling which are sequentially performed; the signal molecule is added after water inflow is finished.

Preferably, the signaling molecule is an AHLs signaling molecule.

Preferably, the concentration of the signal molecules in the SBR activated sludge treatment system is 0.1-1 mu mol/L.

Preferably, the concentration of cadmium in the cadmium-and/or lead-containing wastewater is 8-12 mg/L.

Preferably, the concentration of lead in the cadmium-and/or lead-containing wastewater is 8-12 mg/L.

Preferably, the pH value of the cadmium-and/or lead-containing wastewater is 3-5.

Preferably, the volume ratio of the cadmium-containing and/or lead-containing wastewater to the activated sludge is 7: (2-4).

Preferably, the cycle number of the SBR activated sludge treatment is 28-32.

Preferably, a single cycle of the SBR activated sludge treatment comprises 2 to 4 cycles.

The invention provides a treatment method of cadmium-and/or lead-containing wastewater, which comprises the following steps: performing SBR activated sludge treatment on the cadmium-and/or lead-containing wastewater in the presence of signal molecules, wherein a single cycle of SBR activated sludge treatment comprises water inflow, reaction, precipitation, drainage and idling which are sequentially performed; the signal molecule is added after water inflow is finished. In the activated sludge treatment process, a microorganism population in the sludge can participate in the heavy metal removal process through self metabolism. The invention processes SBR activated sludge treatment on cadmium and/or lead-containing wastewater, adds signal molecules into an activated sludge treatment wastewater system, wherein the signal molecules are molecules for guiding intercellular or intracellular communication, can regulate physiological processes such as growth, differentiation, movement, metabolism, death and the like of cells, and the group induction of microorganisms mediated by the signal molecules can improve the activity of partial functional microorganisms in the wastewater treatment, thereby improving the wastewater treatment effect. The results of the examples show that the addition of signal molecules can significantly improve the removal rate of cadmium and lead in wastewater relative to the addition of no signal molecules during the simulated SBR treatment process.

Drawings

FIG. 1 is a schematic view of the SBR activated sludge treatment process of the present invention;

FIG. 2 shows lead removal rates in wastewater treated in example 1 and comparative example 1 of the present invention;

FIG. 3 shows the cadmium removal rate of wastewater treated in example 2 and comparative example 2 of the present invention;

FIG. 4 shows lead removal rates in wastewater treated in example 2 and comparative example 2 of the present invention;

FIG. 5 shows the EPS content of the extracellular polymeric substances of the activated sludge treated in example 1 (R0), example 1 and comparative example 1 according to the present invention;

FIG. 6 shows the EPS content of the extracellular polymeric substances in the activated sludge treated in example 1 (R0), example 2 and comparative example 2 according to the present invention;

FIG. 7 shows the activities of catalase in the activated sludge treated in example 1 of the present invention (R0), example 1, and comparative example 1;

FIG. 8 shows the activity of catalase in the activated sludge treated in example 1 (R0), example 2, and comparative example 2 according to the present invention;

FIG. 9 shows the urease activity of the activated sludge treated in example 1, and comparative example 1 according to the present invention;

FIG. 10 shows the urease activity of the activated sludge treated in example 1, example 2 and comparative example 2 according to the present invention.

Detailed Description

In the present invention, the activated sludge concentration MLSS is preferably 3000 to 4000mg/L.

In the present invention, the signal molecule is preferably an N-acyl homoserine lactone AHLs signal molecule. In the present invention, the length of the acyl linkage in the N-acyl homoserine lactone AHLs signal molecule is preferably C4 to C18.

In the present invention, the concentration of the signal molecule in the SBR activated sludge treatment system is preferably 0.1 to 1. Mu. Mol/L, more preferably 0.2 to 0.8. Mu. Mol/L, and most preferably 0.4 to 0.6. Mu. Mol/L. The invention limits the types and the concentration of the signal molecules in the range, can better promote the activity of microorganisms and improve the removal rate of cadmium and lead.

In the present invention, the cadmium-and/or lead-containing wastewater preferably further comprises carbon-, nitrogen-and phosphorus-containing compounds, ferrous ions, magnesium ions, calcium ions and yeast extract.

In the invention, the concentration of cadmium in the cadmium-and/or lead-containing wastewater is preferably 8-12 mg/L, more preferably 10mg/L; the concentration of lead in the cadmium-and/or lead-containing wastewater is preferably 8-12 mg/L, more preferably 10mg/L; the pH value of the cadmium-and/or lead-containing wastewater is preferably 3-5, more preferably 4; the concentration of ammonia nitrogen in the cadmium-containing and/or lead-containing wastewater is preferably 30-40 mg/L, more preferably 35mg/L; the total phosphorus concentration in the cadmium-and/or lead-containing wastewater is preferably 3-5 mg/L, more preferably 4mg/L; the COD concentration in the cadmium-and/or lead-containing wastewater is preferably 500-700 mg/L, more preferably 600mg/L; the concentration of ferrous ions in the cadmium-and/or lead-containing wastewater is preferably 0.03-0.04 mmol/L; the concentration of magnesium ions in the cadmium-and/or lead-containing wastewater is preferably 0.1-0.3 mmol/L; the concentration of calcium ions in the cadmium-and/or lead-containing wastewater is preferably 0.1-0.3 mmol/L; the concentration of the yeast extract in the cadmium-and/or lead-containing wastewater is preferably 5-15 mg/L. The invention limits the parameters in the wastewater containing cadmium and/or lead to the above range, so that the wastewater has better treatment effect.

In embodiments of the invention, cadmium and/or lead containing wastewater is preferably simulated by adding a cadmium source and/or lead source, a carbon source, a nitrogen source, a phosphorus source, a ferrous salt, a magnesium salt, a calcium salt, a yeast extract, and an acid to water. In the present invention, the cadmium source preferably includes one or more of cadmium chloride, cadmium nitrate, and cadmium sulfate; the lead source preferably comprises one or more of lead nitrate and lead acetate; the carbon source preferably comprises one or more of sodium lactate, peptone, glucose, sucrose and starch; the nitrogen source preferably comprises one or more of ammonium chloride, ammonium bicarbonate, peptone and sodium nitrate; the phosphorus source preferably comprises one or more of disodium hydrogen phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate and adenine nucleoside triphosphate; the ferrous salt preferably comprises ferrous sulfate heptahydrate; the magnesium salt preferably comprises magnesium sulfate heptahydrate; the calcium salt preferably comprises calcium chloride heptahydrate. The source of the yeast extract is not particularly limited in the present invention, and may be a commercially available product known to those skilled in the art or a product prepared by a conventional preparation method. The kind of the acid is not particularly limited in the present invention, and the pH of the wastewater may be ensured within the above range by using an acid well known to those skilled in the art.

In the invention, the volume ratio of the cadmium-containing and/or lead-containing wastewater to the activated sludge is preferably 7: (2-4), more preferably 7:3. The invention limits the volume ratio of the wastewater containing cadmium and/or lead to the activated sludge within the above range, so that microorganisms in the activated sludge can better participate in the fixation and removal of the cadmium and the lead, and the removal rate of the cadmium and the lead is improved.

In the present invention, the cycle number of the SBR activated sludge treatment is preferably 28 to 32, more preferably 30; the single period preferably comprises 2 to 4 cycles, more preferably 3 cycles; the single cycle includes sequentially performing water inlet, reaction, precipitation, water discharge and idling.

In the present invention, the signal molecule is added after the water inflow is completed.

In the present invention, the flow rate of the wastewater at the time of water inflow and water drainage is independently preferably 1300 to 1500mL/h, more preferably 1400mL/h.

In the present invention, the reaction time is preferably 4 to 6 hours, more preferably 5 hours; the reaction is preferably carried out under stirring. The stirring manner and rate are not particularly limited in the present invention, and stirring manner and rate well known to those skilled in the art may be employed. In the invention, in the reaction process, microorganisms in the activated sludge participate in the fixation and removal of cadmium and lead through self metabolism, and signal molecules mediate the quorum sensing effect of the microorganisms so as to promote the activity of most functional microorganisms in the activated sludge and improve the wastewater treatment effect. The present invention can sufficiently proceed the reaction by limiting the reaction time to the above-described range.

In the present invention, the time of the precipitation is preferably 1.5 to 2.5 hours, more preferably 2 hours. In the invention, in the precipitation process, sludge is separated from wastewater by precipitation. The invention limits the sedimentation time to the above range, and can fully separate the sludge from the wastewater.

In the present invention, the idle time is preferably 0.4 to 0.6 hours, more preferably 0.5 hours. The invention limits the idle time to the above range, can adjust the activity of microorganisms in the activated sludge, and is beneficial to the subsequent reaction.

The invention limits the parameters of the cycle number, the time of each step in single cycle and the like of the activated sludge treatment in the above range, can lead microorganisms in the activated sludge to fully react with cadmium and lead, and improves the removal rate of cadmium and lead in wastewater.

According to the invention, the signal molecules are added into the activated sludge wastewater treatment system, and the microbial quorum sensing effect mediated by the signal molecules can promote the activity of most functional microorganisms in the wastewater treatment, so that the wastewater treatment effect is improved.

The schematic diagram of the SBR activated sludge treatment process is shown in figure 1, the reaction stage is carried out under the condition of stirring, and the precipitation stage, the drainage stage and the idle stage are carried out after the reaction stage is completed.

The technical solutions of the present invention will be clearly and completely described in the following in connection with the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1

(1) Manually preparing simulated lead-containing wastewater, wherein the lead concentration is 10mg/L, the pH value is 4, the ammonia nitrogen concentration is 35mg/L, the total phosphorus concentration is 4mg/L, the COD concentration is 600mg/L, the ferrous ion concentration is 0.036mmol/L (ferrous sulfate heptahydrate 10 mg/L), the magnesium ion concentration is 0.2mmol/L (magnesium sulfate heptahydrate 50 mg/L), the calcium ion concentration is 0.23mmol/L (calcium chloride heptahydrate 50 mg/L), and the yeast extract is 10mg/L; the carbon source is sodium lactate; the nitrogen source is ammonium chloride; the phosphorus source is disodium hydrogen phosphate;

(2) A 500mL conical flask was used to simulate an SBR reactor, 150mL of activated sludge (mlss=3000 mg/L) was added thereto, SBR activated sludge treatment was performed on the lead-containing wastewater in step (1) (the volume ratio of lead-containing wastewater to activated sludge was 7:3, although a 500mL conical flask was used, the activated sludge and lead-containing wastewater could be contained because the scale line of the conical flask was below the upper edge), and each cycle comprised 5 steps: adding 350mL of lead-containing wastewater into a conical flask at the adding rate of 1400mL/h, adding a C6-HSL signal molecule after water inflow is finished for 0.25h, wherein the concentration of the C6-HSL signal molecule in an activated sludge wastewater treatment system is 0.5 mu mol/L, reacting for 5h under stirring, then precipitating for 2h, discharging the treated wastewater at the discharging rate of 1400mL/h, wherein the discharging time is 0.25h, and finally idling for 0.5h, wherein 3 cycles are one cycle, and the total operation is 30 cycles, wherein 1-10 cycles are the first stage, 11-30 cycles are the second stage, and the treated wastewater is denoted as R3.

Example 2

(1) Manually preparing simulated wastewater containing cadmium and lead, wherein the concentration of cadmium is 10mg/L, the concentration of lead is 10mg/L, the pH value is 4, the concentration of ammonia nitrogen is 35mg/L, the total phosphorus concentration is 4mg/L, the COD concentration is 600mg/L, the concentration of ferrous ion is 0.036mmol/L (ferrous sulfate heptahydrate is 10 mg/L), the concentration of magnesium ion is 0.2mmol/L (magnesium sulfate heptahydrate is 50 mg/L), the concentration of calcium ion is 0.23mmol/L (calcium chloride heptahydrate is 50 mg/L), and the concentration of yeast extract is 10mg/L; the carbon source is sodium lactate; the nitrogen source is ammonium chloride; the phosphorus source is disodium hydrogen phosphate;

(2) A 500mL conical flask is adopted to simulate an SBR reactor, 150mL of activated sludge (MLSS=3000 mg/L) is added into the reactor, the cadmium-and lead-containing wastewater in the step (1) is subjected to SBR activated sludge treatment (the volume ratio of the cadmium-and lead-containing wastewater to the activated sludge is 7:3), and each cycle comprises 5 steps: the water inflow time is 0.25h, after water inflow is finished, C6-HSL signal molecules are added, the concentration of the C6-HSL signal molecules in an activated sludge wastewater treatment system is 0.5 mu mol/L, the reaction time is 5h (under stirring), the sedimentation time is 2h, the drainage time is 0.25h, the idle time is 0.5h,3 cycles are one cycle, and the total operation is 30 cycles, wherein 1-10 cycles are the first stage, 11-30 cycles are the second stage and are recorded as R4.

Comparative example 1

The C6-HSL signal molecule in step (2) of example 1 was omitted, and the other conditions were the same as in example 1 and designated R1.

Comparative example 1

The C6-HSL signal molecule in step (2) of example 2 was omitted, and the other conditions were the same as in example 2 and designated R2.

The lead removal rates in the wastewater treated in example 1 and comparative example 1 were measured, and the results are shown in fig. 2, and the cadmium removal rates in the wastewater treated in example 2 and comparative example 2 are shown in fig. 3, and the lead removal rates in the wastewater treated in example 2 and comparative example 2 are shown in fig. 4. Wherein the concentration of cadmium and lead is measured by flame atomic absorption spectrophotometry, and the specific operation procedure is implemented according to the water and wastewater detection analysis method.

As can be seen from fig. 2, in the Pb (II) -only environment, in the stage I, in the case where AHL (R1) and AHL (R3) are not added, the average removal rate of Pb (II) is 99.8% and 98.0%, respectively, and the removal effects are not great; the average removal of Pb (II) in R1 and R3 in stage II was 17.4% and 70.7%, respectively. From this, it was found that the addition of AHL (R3) promotes the Pb (II) removal effect compared with the case where no AHL (R1) was added, and that the removal rate of R1 was originally high in the first stage, which resulted in insignificant promotion of AHL, whereas the removal rate of R3 was about 53.3% higher than that of R1 in the second stage, which indicates significant promotion of Pb (II) removal by AHL.

As can be seen from fig. 3, in the presence of both Cd (II) and Pb (II), the average removal rate of Cd (II) in the case of no addition of AHL (R2) and no addition of AHL (R4) in the I-stage was 98.0% and 99.8%, respectively; average removal of Cd (II) in R2 and R4 in stage II was 17.4% and 70.6%, respectively. Compared with R2, the removal effect of Cd (II) in R4 is respectively improved by 1.8% in the stage I and 53.2% in the stage II.

As can be seen from fig. 4, in the presence of both Cd (II) and Pb (II), the average removal rate of Pb (II) in the case of no addition of AHL (R2) and no addition of AHL (R4) in the stage I was 97.0% and 99.8%, respectively; the average removal rate of Pb (II) in R2 and R4 in the II stage was 17.1% and 71.5%, respectively. Compared with R2, the Pb (II) removal effect of R4 is improved by 2.8% in the I stage and by 54.4% in the II stage. From this, it can be seen that the addition of AHL can greatly improve the removal effect of Cd (II) and Pb (II).

The initial activated sludge (R0), the activated sludge treated in example 1 and comparative example 1 were tested for the EPS content of the extracellular polymer in the activated sludge treated in example 1, and the results are shown in fig. 5, and the initial activated sludge (R0), the activated sludge treated in example 2 and the activated sludge treated in comparative example 2 were tested for the EPS content of the extracellular polymer in the activated sludge treated in example 1, and the results are shown in fig. 6.

Wherein the EPS assay method comprises:

(1) EPS heat extraction

1) Measuring 50mL of muddy water mixed solution by using a measuring cup, putting the muddy water mixed solution into a 50mL centrifuge tube, setting 4000rpm at 4 ℃ for centrifugation for 5min, filtering supernatant to obtain a Soluble Microorganism Product (SMP) extracting solution, and continuously carrying out subsequent treatment on a muddy sample; 2) The mud sample in 1) was made up to 50mL with 70℃0.05% NaCl solution, vortexed for 2min, and centrifuged at 4000rpm at 4℃for 10min. Filtering the supernatant to obtain LB layer extract, and continuously treating the mud sample; 3) Supplementing the mud sample in the step 2) to 50mL with 0.05% NaCl solution, heating in a water bath at 60 ℃ for 30min, vortex shaking for 2min, centrifuging at 4000rpm at 4 ℃ for 15min, and filtering the supernatant to obtain TB layer extract.

(2) EPS determination

In EPS, the polysaccharide content was determined by anthrone colorimetry using glucose as a standard solution. The concentration of protein was also determined using the BAC protein concentration determination kit.

As can be seen from fig. 5, in the Pb (II) -only environment, in the I-stage, the contents of PN and PS in R1 to which AHL is not added are increased from the initial contents of 13.02mg/gVSS and 7.81 mg/gVSS in R0 to 23.71mg/gVSS and 24.47mg/gVSS, respectively; the PN and PS content in R3 to which AHL was added increased from the corresponding initial content of R0 to 33.03mg/g VSS and 24.24mg/gVSS. PN in R3 is increased by 39.3% compared with R1, and PS is reduced by 0.94% compared with R1. In phase II, the PN and PS contents in R1 gradually decrease to 6.89mg/gVSS and 3.03mg/gVSS; PN and PS content in R3 gradually decreased to 30.97mg/gVSS and 6.41mg/gVSS. PN in R3 is 349% higher than R1, PS is 112% higher than R1.

As can be seen from FIG. 6, in the presence of both Cd (II) and Pb (II), the PN and PS contents in R2 without AHL added in stage I increased from the corresponding initial contents in R0 to 19.67mg/g VSS and 23.45mg/g VSS, respectively; the PN and PS content in R4 to which AHL was added increased from the corresponding initial content of R0 to 34.15mg/g VSS and 21.18mg/g VSS. PN in R4 is increased by 73.44% compared with R2, and PS is reduced by 9.68% compared with R2. Stage II, wherein the PN and PS contents in R2 are gradually reduced to 4.38mg/gVSS and 3.69mg/gVSS; PN and PS content in R4 gradually decreased to 30.77mg/gVSS and 13.82mg/gVSS, PN in R4 was higher than R2603% and PS was about 275% higher than R2.

The results of measuring the activity of catalase in the activated sludge treated in example 1 (R0), example 1 and comparative example 1 are shown in FIG. 7, and the results of measuring the activity of catalase in the activated sludge treated in example 1 (R0), example 2 and comparative example 2 are shown in FIG. 8, wherein the activity of catalase is obtained by using KMnO ₄ Back-titrating unreacted H ₂ O ₂ Is analyzed by the method of (2). The principle of this experiment is to determine the catalase activity by measuring the amount of hydrogen peroxide which is not decomposed when soil interacts with hydrogen peroxide by a volumetric method (usually titration of hydrogen peroxide which is not decomposed using potassium perchlorate). The chemical equation of the reaction is as follows:

2KMnO ₄ +5H ₂ O ₂ +4H ₂ SO ₄ →2MnSO ₄ +2KHSO ₄ +8H ₂ O+5O ₂

and (3) preparation of a reagent:

a.0.3％H ₂ O ₂ solution

b.10％H ₂ SO ₄ ；

c.0.1mol/LKMnO ₄ Standard solution

d.0.2mol/LpH 7.8.7.8 phosphate buffer

e.0.1mol/L oxalic acid;

the operation steps are as follows: into a 100mL Erlenmeyer flask, 2g of air-dried sludge was placed, 40mL of distilled water and 5mL of 0.3% hydrogen peroxide solution were added, after 60 minutes of shaking, 5mL of 10% sulfuric acid was added, and the filtrate was treated with 0.1mol/LKMnO ₄ Standard solution was titrated to the light pink (no discoloration over 30 minutes) endpoint.

And (3) calculating results: will beA was recorded as titration 25mL of initial H ₂ O ₂ KMnO for mixed liquor consumption ₄ Amount (mL), record B as KMnO used to titrate soil filtrate consumption ₄ Amount (mL).

Catalase Activity= (A-B) ×T

1g of soil was depleted of 0.1mol/LKMnO after 1 hour ₄ The volume of the standard solution is expressed as mL. Wherein T is KMnO ₄ Calibration values for titre.

As can be seen from fig. 7, in the Pb (II) -only environment, the catalase activity in the non-added AHL (R1) in the I-stage increased from 6.56mL corresponding to the initial activity in R0 to 10.46mL, respectively; the catalase activity in the added AHL (R3) increased from the initial activity corresponding to R0 to 16.62mL. The catalase activity in R3 was increased by 59% as compared to R1. Whereas in stage II, the catalase activity in R1 gradually decreased to 9.85mL; the catalase activity in R3 gradually decreased to 8.20mL, and the catalase activity in R3 was about 16.8% lower than that in R1.

As can be seen from fig. 8, in the presence of both Cd (II) and Pb (II), the catalase activity in the non-added AHL (R2) was increased from the corresponding initial activity in R0 to 12.92mL in stage I, respectively; the activity of catalase in AHL (R4) was increased from the initial activity corresponding to R0 to 15.39mL, and the activity of catalase in R4 was increased by 19.12% compared to R2. Stage II, the catalase activity in R2 gradually decreases to 9.44mL; the catalase activity in R4 gradually decreased to 9.37mL, while R2 was essentially leveled with R4 at this stage.

The activity of urease in the activated sludge treated in example 1 (R0), example 1, and comparative example 1 was measured, and the results are shown in fig. 9, and the activity of urease in the activated sludge treated in example 1 (R0), example 2, and comparative example 2 was measured, and the results are shown in fig. 10, wherein the urease activity was measured by indigo colorimetry according to the procedure of the soil urease (solid urease, S-UE) measuring kit (Solebro, china). Generates 1 microgram of NH per gram of sample per day ₃ N is defined as 1 unit of enzyme activity.

The operation steps are as follows: specific experimental procedures refer to the instructions of the kit.

And (5) carrying out related operation on the obtained test sample according to the instruction, and uniformly mixing for later use. After the ultraviolet spectrophotometer is started to preheat, the wavelength is adjusted to 630nm, and after distilled water is zeroed, the value A is measured. Note that each measurement tube is provided with a control tube.

Δa=a assay tube-a control tube

Drawing a standard curve: referring to the steps on the specification, corresponding standard curves are drawn according to the concentration (y) and absorbance (x) of the standard tube.

And (3) calculating results:

the ΔA is taken into the formula derived from the standard curve and the concentration of the sample in the assay (μg/mL) is calculated.

Wherein, the unit represents: each g of soil sample per day produced 1gNH ₃ N is considered as an enzyme activity unit.

Urease activity (U/g soil) =y×10×v inverse total ≡w ≡t=80×y

As can be seen from FIG. 9, in Pb (II) only environment, in stage I, the urease activity in R1 without AHL added was reduced from 11.08mg/g to 9.37mg/g of the initial activity of R0; whereas the urease activity in R3 with AHL added increased from the initial activity of R0 to 12.32mg/g. The urease activity in R3 was increased by 31.48% over R1. Whereas in stage II the urease activity in R1 gradually decreased to 5.34mg/g; whereas the urease activity in R3 gradually decreased to 6.53mg/g, the urease activity in R3 was about 22.3% higher than R1.

As can be seen from FIG. 10, the change in urease activity was very remarkable in the presence of both Cd (II) and Pb (II). In stage I, the urease activity in the non-added AHL (R2) is reduced from 11.08mg/g of R0 to 5.92mg/g; the urease activity in the added AHL (R4) is obviously increased from 11.08mg/g to 14.13mg/g, and the urease activity in the R4 is 138 percent higher than that in the R2. Stage II, the urease activity in R2 gradually decreases to 3.51mg/g; the urease activity in R4 gradually decreased to 8.54mg/g. Although the urease activity is reduced at this stage, the urease activity in R4 is still obviously higher than that of R2. From the overall trend, the urease activity in the blank groups (R1 and R2) without AHL was reduced in the 30d run period, while the urease activity in the experimental groups (R3 and R4) with AHL was reduced in the early stage (stage I) and the later stage (stage II).

Genomic DNA was extracted from bacterial 16S rDNAV3-V4 region fragments using the E.Z.N.A.Soil DNAKit kit (OMEGA, bioTek, winooski, VT, USA) from the initial activated sludge (R0) of example 1 and the sludge samples of examples 1-2 after two reaction stages using the universal primer 338F/806R. The sequences were species classified using RDP classification software (version 2.13) and the dominant flora composition and abundance at the phylum and genus level was recorded for each sample. The results are shown in tables 1 and 2.

Table 1 analysis of microbial community structure at the gate level

As can be seen from Table 1, the relative abundance of Proteus (Proteus) increased significantly with the addition of AHL, from 21.3% (R0) to 44.0% (R4_10d) and 95.2% (R4_30d). The relative abundance of campylobacter viridis (Chloroflexi) was significantly reduced from 28.4% (R0) down to 5.6% (r4_10d) and 0.4% (r4_30d).

TABLE 2 microbial community structural analysis at the genus level

As can be seen from table 2, the addition of AHL significantly increased the relative abundance of Stenotrophomonas and Bordetella. In particular Enterobacteriaceae, whose relative abundance increases from 1.1% for R2_10d, 1.6% for R2_30d to 6.7% for R4_10d and 59.3% for R4_30d, respectively.

In conclusion, the invention adds signal molecules into the wastewater treatment system of activated sludge, so as to improve the removal rate of cadmium and lead in wastewater.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims

1. A treatment method of cadmium-and/or lead-containing wastewater comprises the following steps:

2. The method of claim 1, wherein the signaling molecules are AHLs signaling molecules.

3. The method according to claim 1, wherein the concentration of the signal molecule in the SBR activated sludge treatment system is 0.1 to 1. Mu. Mol/L.

4. The method according to claim 1, wherein the concentration of cadmium in the cadmium-and/or lead-containing wastewater is 8-12 mg/L.

5. The method according to claim 1, wherein the concentration of lead in the cadmium-and/or lead-containing wastewater is 8-12 mg/L.

6. The method according to claim 1, wherein the pH of the wastewater containing cadmium and/or lead is 3-5.

7. The treatment method according to claim 1, wherein the volume ratio of the cadmium-and/or lead-containing wastewater to the activated sludge is 7: (2-4).

8. The method according to claim 1, wherein the cycle number of the SBR activated sludge treatment is 28 to 32.

9. The process according to claim 1, characterized in that the single cycle of SBR activated sludge treatment comprises 2 to 4 cycles.