Patent Application
20240190717
This application is based on and claims priority to Chinese Application No. 202211569342.6, filed Dec. 8, 2022, the entire contents of which are incorporated herein by reference.
The invention relates to the field of water treatment technology, in particular to a method for promoting rapid precipitation of travertine crystals by algae.
The main component of travertine is CaCO3 precipitation. According to the water temperature of its formation place, travertine is divided into cold water type travertine and hot water type travertine. The formation of travertine is mainly the CO2 overflow of the water body, which leads to the supersaturation of CaCO3 in the water body, thus the precipitation is formed. The crystal structure of travertine is mainly calcite or aragonite. The main factors for travertine formation are the influence of geomorphic conditions, temperature and climate, hydrodynamic conditions, and biological effects. The current mainstream school believes that travertine is dominated by hydrodynamic factors. It is believed that under the influence of hydrodynamics, the water body emits CO2, and the following equation occurs in the solution rich in Ca2+ and HCO3−: Ca2++2HCO3−→CO2↑+CaCO3↓+H2O, resulting in the precipitation of CaCO3 in the solution, thus the landscape travertine is formed. However, in the scientific research of recent years, scholars Rogerson, M et al. and Shiraishi. F have simulated the sterilization of the water body without biological addition in the laboratory experiments, which only added the travertine system, and created the hydrodynamic conditions. However, there was no obvious travertine precipitation after the experiment, and a large amount of travertine precipitation was produced after adding the biomembrane, which proved that the biological factors are the main reason for the travertine formation.
Huanglong travertine landscape is mainly divided into the following four stages: the spring water rich in calcium ions overflows to form a thick layer of travertine sedimentations; the calcarenite sedimentation dissolution stage; the dynamic equilibrium stage of travertine sedimentation dissolution; the travertine degradation stage.
The travertine in Huanglong valley scenic spot has been degraded, such as the loose travertine surface layers, the travertine soil loss, and the blackening of travertine surface water. Due to the degradation of travertine in recent years, travertine conservation is extremely important. To conserve travertine and prevent travertine from degradation, it is of great significance to propose a method for rapid travertine sedimentation.
The purpose of this invention is to provide a method for promoting the rapid precipitation of travertine crystals by algae, which can significantly improve the sedimentation rate of travertine crystals. At the same time, there is pseudomonas in the calcified water body of algae, which can be used for algae-lysing bacteria isolation and purification.
To achieve the above purpose, the invention provides a method for promoting the rapid precipitation of travertine crystals by algae. Microalgae is added to the water body with a calcium ion concentration of 100-500 mg/L for stirring, and the amount of microalgae is 0.1-8×108 cells/L.
The optimal selection is that the concentration of magnesium ion in water is 31.87 mg/L, and the concentration of bicarbonate ion is 796.8 mg/L.
The optimal selection is that the water pH is 7.5.
The optimal selection is that the concentration of calcium ion in water is 300 mg/L.
The optimal selection is that the added quantity of microalgae is 5.31×107 cells/L.
The optimal selection is that the microalgae are one or several kinds of Chlorella and diatoms.
Therefore, the invention adopts a method for promoting the rapid precipitation of travertine crystals by algae, which significantly improves the sedimentation rate of travertine crystals. At the same time, there is pseudomonas in the calcified water body of algae, which can be used for algae-lysing bacteria isolation and purification.
A further detailed description of the technical solution of the invention through the drawings and embodiments is as follows.
The technical solution of the invention is further explained by drawings and embodiments as follows.
1) Prepare 5 portions of compound water with a calcium concentration of 100 mg/L.
2) Add the Chlorella into the compound water respectively. The adding quantities of Chlorella are 1.98×107 cells/L, 5.31×107 cells/L, 1.08×108 cells/L, 4.86×108 cells/L and 7.36×108 cells/L, respectively.
3) Extract 15 ml water every two days for the detection of Ca2+ concentration change six times in total.
4) Calculate the sedimentation rate of travertine crystals in compound water by the exponential decay equation. The results are shown in Table 1.
1) Prepare 5 portions of compound water with a calcium concentration of 300 mg/L.
2) Add the Chlorella into the compound water respectively. The adding quantities of Chlorella are 1.98×107 cells/L, 5.31×107 cells/L, 1.08×108 cells/L, 4.86×108 cells/L and 7.36×108 cells/L, respectively.
3) Extract 15 ml water every two days for the detection of Ca2+ concentration change six times in total.
4) Calculate the sedimentation rate of travertine crystals in compound water by the exponential decay equation. The results are shown in Table 2.
1) Prepare 5 portions of compound water with a calcium concentration of 500 mg/L.
2) Add the Chlorella into the compound water respectively. The adding quantities of Chlorella are 1.98×107 cells/L, 5.31×107 cells/L, 1.08×108 cells/L, 4.86×108 cells/L and 7.36×108 cells/L, respectively.
3) Extract 15 ml water every two days for the detection of Ca2+ concentration change six times in total.
4) Calculate the sedimentation rate of travertine crystals in compound water by the exponential decay equation. The results are shown in Table 3.
1) Prepare 5 portions of compound water with a calcium concentration of 100 mg/L.
2) Proceed with the natural sedimentation.
3) Extract 15 ml water every two days for the detection of Ca2+ concentration change six times in total.
4) Calculate the sedimentation rate of travertine crystals in compound water by the exponential decay equation. The results are shown in Table 4.
1) Prepare 5 portions of compound water with a calcium concentration of 300 mg/L.
2) Proceed with the natural sedimentation.
3) Extract 15 ml water every two days for the detection of Ca2+ concentration change six times in total.
4) Calculate the sedimentation rate of travertine crystals in compound water by the exponential decay equation. The results are shown in Table 4.
1) Prepare 5 portions of compound water with a calcium concentration of 500 mg/L.
2) Proceed with the natural sedimentation.
3) Extract 15 ml water every two days for the detection of Ca2+ concentration change six times in total.
4) Calculate the sedimentation rate of travertine crystals in compound water by the exponential decay equation. The results are shown in Table 4.
Extract 15 mL water and measure the Ca2+ concentration by ICP. The exponential decay equation is used to fit the process of travertine sedimentation. The exponential decay equation is expressed by equation 1, and the exponential decay equation after the logarithm is expressed by equation 2.
[Ca2+]=ekt+b (1)
In[Ca2+]=kt+b (2)
Where [Ca2+] represents the calcium ion concentration, t represents the sampling time, k represents the travertine rate constant, d[Ca2+]/dt represents the travertine rate.
After 15 days, the deposited travertine crystals in the experiment were detected by XRD and SEM.
When the initial concentration of Ca2+ is 100.00 mg/L or 300.00 mg/L, the sedimentation rate of travertine crystals was the fastest in the compound water of microalgae solution with the initial concentration of 5.31×107 cells/L. When the initial concentration of Ca2+ was 500.00 mg/L, the calcification rate went faster as the increase of microalgae concentration. The sedimentation rate of travertine crystals in comparison cases 1-3 is significantly lower than that of travertine crystals in embodiments 1-3. At different microalgae concentrations, when the Ca2+ concentration in the water was 300.00 mg/L, the calcification rate is the fastest.
Therefore, in low and medium concentrations of Ca2+ water, the calcification rate is the fastest when the initial concentration of microalgae solution is 5.31×107 cells/L. At this time, when the concentration of microalgae increases, the calcification rate decreases instead. In high concentrations of Ca2+ water, the increase of microalgae concentration will increase the calcification rate. When the concentration of Ca2+ is about 300.00 mg/L, it is beneficial to increase the sedimentation rate of travertine crystals in water when the concentration of microalgae is about 5.31×107 cells/L.
Samples of embodiments 1-3 and comparison cases 1-3 are numbered, as shown in Table 5, and analyzed by XRD. The X-ray diffraction (XRD) cell parameters of travertine sedimentation are shown in table 6.
It can be seen from the unit cell parameter table that in the experimental groups of D2, D3, D4, D5, D6, and C6, the fresh travertine contains the characteristic diffraction peaks of calcite (the main chemical composition is CaCO3), and the corresponding main advantage surfaces are (012), (104), (110), (113), (202), (018) and (116). The space groups of D2, D3, D4, D5, D6, and C6 are all R-3c (167), the number of unit cell molecules is 6, the 20 corresponding to the main advantage surface is similar, and the cell spacing corresponding to the main advantage surface is not much different. The cell volume is 0.36785 nm3, 0.36776 nm3, and 0.36778 nm3. The cell density is 2.71080 g/cm3, 2.71120 g/cm3, and 2.71140 g/cm3. The average grain size of travertine crystal is less than 100.
The grain sizes corresponding to the main advantage surfaces of D2, D3, D4, and D5 are partially greater than 100, and the grain sizes corresponding to the main advantage surfaces of D6 and C6 are less than 100.
The B6 fresh travertine contains calcite characteristic diffraction peaks (the main chemical composition is CaCO3(H2O), and the corresponding main advantage surfaces are (100), (101), (012), (111), (021), (022), (211), etc. The B6 space group is P3121 (152), and the number of unit cell molecules is 3. The 20 corresponding to the main advantage surface and the cell spacing corresponding to the main advantage surface are different from those of the D2, D3, D4, D5, D6, and C6 groups. The cell volume is 0.24292 nm3, the cell density is 2.42530 g/cm3, and the average grain size of the travertine crystal is 25.0. The grain size corresponding to the main advantage surface of B6 is less than 100.
The XRD results show that at the same calcium ion concentration, the travertine crystals produced by different concentrations of microalgae have the same structure as calcite. When the concentration of microalgae increases to 7.36×108 cells/L, the cell size of calcite decreases. The results of calcine sedimentation in water with different Ca2+ concentrations under the same microalgae concentration showed that when the Ca2+ concentration in the solution decreases to 79.68 mg/L, the structure of calcite will change and may become calcite monohydrate (CaCO3·H2O).
By observing the electron microscope images of the blank group without microalgae solution under different Ca2+ concentrations (as shown in
When Ca2+ is 100.00 mg/L, the calcite travertine is observed, but at this time, it is mainly in small crystal travertine form with a small amount of standard calcite.
When Ca2+ concentration increases to 300.00 mg/L, the proportion of small crystal travertine increases.
When the concentration of Ca2+ increases to 500.00 mg/L, the size of small crystal travertine increases, and filamentous algae imprinting is observed.
Comparing the D2-D6 experimental groups with different microalgae concentrations at the same calcium ion concentration (500.00 mg/mL), it was found that when the microalgae concentration increases, the shape of the formed travertine will be closer to the standard and mature calcite, and at the same time, due to the high concentration of microalgae, its dead body was covered on the surface of the travertine crystal, resulting in only a very small amount of travertine seen in the electron microscope picture. In the case of low-concentration microalgae, more travertine crystals can be observed by scanning electron microscope. However, other salt crystals appeared in the lowest concentration of microalgae solution.
By observing the electron microscope images of the experimental groups with different Ca2+ concentrations under the same microalgae concentration (as shown in
By observing all samples (
In summary, this method can be used to repair travertine in degraded or damaged areas of the travertine landscape by cultivating microalgae.
Finally, it should be noted that the above embodiments are only used to explain the technical solution of the invention rather than to limit it. Although the invention is described in detail with references to the better embodiments, ordinary technicians in this field should understand that they can still modify or replace the technical solution of the invention, and these modifications or equivalent replacements cannot make the modified technical solution out of the spirit and scope of the technical solution of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202211569342.6 | Dec 2022 | CN | national |
