CN110627220B

CN110627220B - Method for efficiently inhibiting effluent microalgae of sewage plant by using submerged plants

Info

Publication number: CN110627220B
Application number: CN201910935982.6A
Authority: CN
Inventors: 胡洪营; 陆轶峰; 郭昉; 王胜楠; 刀国华; 张琳; 潘国强
Original assignee: Kunming Dianchi Water Co ltd; Tsinghua University
Current assignee: Kunming Dianchi Water Co ltd; Tsinghua University
Priority date: 2019-09-29
Filing date: 2019-09-29
Publication date: 2020-11-17
Anticipated expiration: 2039-09-29
Also published as: CN110627220A

Abstract

The invention discloses a method for efficiently inhibiting effluent microalgae of a sewage plant by using submerged plants, which comprises the following steps: (1) selecting a water sample of a sewage plant effluent test and placing the water sample in a container; (2) selecting hydrilla verticillata and myriophyllum pratense as submerged plants for controlling algae, removing attached phytoplankton, planting in a container filled with a test water sample, placing in a greenhouse for growing for at least 2 weeks, selecting plants which are healthy in growth and consistent in size and condition, removing attached phytoplankton again, and carrying out aeration culture for planting; (3) combining submerged plants at a ratio of 13 + -0.5 kg (wet weight)/m³The total mixed planting density is jointly cultivated in an effluent river channel of a sewage plant, and the planting ratio of the hydrilla verticillata to the foxtail spicatum is (1-1.1): 1. the inhibition rate of the invention on the maximum biomass of microalgae is up to more than 90%, the removal rate of TN is up to more than 60%, and the removal rate of TP is up to more than 95%.

Description

Method for efficiently inhibiting effluent microalgae of sewage plant by using submerged plants

Technical Field

The invention relates to the technical field of water body restoration, in particular to a method for efficiently inhibiting effluent microalgae of a sewage plant by using submerged plants, and particularly relates to a treatment method for restoring a water body by using a combination of hydrilla verticillata and watery plants.

Background

Since the 30 s of the 20 th century, the water resource crisis is aggravated by the gradually-highlighted global eutrophication and water bloom problems. The sewage recycling is the best way to solve the water resource shortage and complete the natural restoration of water ecological cycle. Because the background value of the pollutants of the effluent of the sewage plant is higher, the effluent is more easily eutrophicated than natural rivers and lakes after being reused in landscape water bodies, and most of the urban landscape water bodies are still water landscapes or are under the conditions with very weak self-purification capacity, and the unfavorable conditions are very easy to cause black and stink phenomena and bloom. However, the water bloom cannot be controlled only by reducing the nitrogen and phosphorus concentration of the effluent of the sewage plant, and other comprehensive measures are needed to inhibit the growth of microalgae in the effluent of the sewage plant.

The algae inhibiting technology can be divided into the following three categories according to different using means: (1) the physical method mainly solves the problem of excessive propagation of algae from two aspects, on one hand, starting from the source of nutrient element input, and reducing the inflow of nutrient elements such as nitrogen and phosphorus in a water body by means of dilution, closure, dredging, sewage diversion and the like; on the other hand, the method is to directly remove the algae in the water body and remove the harmful algae from the water body by adopting the modes of mechanical pumping, filtering, flocculating settling and the like. However, the physical method has a fatal disadvantage of expensive treatment cost, so that the application range of the method can be limited to a small water body or a local water body of a large water body. (2) The chemical method is a means of adding a chemical reagent into a water body subjected to microalgae bloom and killing algae cells by oxidation or other actions so as to inhibit the growth of the algae, but has the defects of large using amount, low applicable concentration of the algae and risk of secondary pollution. (3) The biological method for inhibiting algae mainly comprises two types of biological manipulation and allelopathy, wherein the biological manipulation method is a method for repairing polluted water bodies by selecting some organisms which can eat algae and have resistance or degradation effect on algal toxins by utilizing predation relation among organisms; allelochemical effect algae inhibiting is to inhibit the growth of algae with allelochemical matter released from aquatic plant so as to restore and purify polluted water. However, the algae control effect of the biological manipulation method in different water bodies is uncertain, and because allelochemicals secreted by submerged plants belong to natural organic compounds, the allelochemicals can be generally degraded in the natural environment, the risk of secondary pollution is basically avoided, and the biological manipulation method has good ecological safety. Therefore, the submerged plant is more suitable for being used as a pioneer species for ecological restoration of the water bloom water body.

The submerged plant is used as a pioneer species in aquatic ecological environment restoration, can effectively inhibit the growth of the water bloom microalgae, is a key link for treating the water bloom problem, and is a method for effectively establishing a clear water stable biological community because the submerged plant community has a high-efficiency synergistic algae inhibition effect and is beneficial to the healthy development of a water ecosystem. But at present, no scheme for effectively inhibiting the water bloom by combining submerged plants is provided. Therefore, the research on the influence of the combination of the submerged plants on the growth characteristics of the water bloom microalgae under the water outlet condition of the sewage plant is of great significance.

Disclosure of Invention

In order to solve the problems, the invention aims to provide a method for efficiently inhibiting the effluent microalgae of a sewage plant by using a submerged plant combination, the key of adopting the algae-controlling submerged plant combination is to screen out purified plants which can adapt to eutrophic water and have the algae inhibiting effect, and the plants are properly combined and matched, so that the hydrilla verticillata and the myriophyllum spicatum have the following advantages compared with other aquatic plants: (1) has strong algae inhibiting capacity; (2) the composite material has strong nitrogen and phosphorus removal capacity and strong stain resistance; (3) the microbial community of the plant attached with the biological membrane and the rhizosphere is rich, and the plant attached with the biological membrane has certain removal capability on pollutants such as nitrate nitrogen, heavy metal, organic matters and the like in a water body; (4) the water-based paint has wide distribution and strong environment adaptation capability, is widely distributed in ponds, lakes and ditches, and is distributed in wide areas such as various provinces in the south and north of China; (5) is suitable for shallow water greening and is a good submerged ornamental plant; (6) the growth speed is high, the influence of plant harvesting on the plants is small, the harvested plants can have the recycling capability to a certain extent, the recycling economy is realized, and the feed can be used as feed for aquatic animals such as crayfishes and fishes, so that the feed has good economic feasibility.

Based on the fact that the quality of the effluent of the sewage plant is different from the natural quality, the sewage plant has higher pollution load and is easy to explode to generate microalgae bloom, the two submerged plants are very suitable for being applied to the control of the effluent microalgae of the sewage plant, and experiments prove that the combined algae inhibiting and purifying functions of the two plant communities are obviously better than the effects of a single plant under the same planting density, and the load resisting capacity of the system is improved to adapt to the fluctuation of the water quality.

The invention is realized by the following technical scheme:

a method for efficiently inhibiting effluent microalgae of a sewage plant by using submerged plants comprises the following steps:

(1) selecting a water sample of a sewage plant effluent test and placing the water sample in a container;

(2) selecting hydrilla verticillata and myriophyllum pratense as submerged plants for controlling algae, rinsing to remove attached phytoplankton, then planting in a container filled with a test water sample, placing in a greenhouse for at least 2 weeks, selecting plants which are healthy in growth and consistent in size and condition, removing the attached phytoplankton, and carrying out aeration culture for planting;

(3) adding submerged plant at a ratio of 13 + -0.5 kg (wet weight)/m³The total mixed planting density is jointly cultivated in an effluent river channel of a sewage plant, and the planting ratio of the hydrilla verticillata to the foxtail spicatum is (1-1.1): 1.

in the invention, compared with other submerged plants, the hydrilla verticillata has stronger competitive power on nitrogen and phosphorus, and the hybrid cross planting of the hydrilla verticillata and the foxtail alga can combine respective algae inhibition advantages except that the foxtail alga competes with algae for nutrient salt, so that the effect of synergistically inhibiting the growth of microalgae can be achieved through the conditions of secreting allelochemicals, competing nutrient salt, illumination and the like, and the plant combination has stronger denitrification and dephosphorization effects, is favorable for constructing a stable aquatic ecological community (for example, providing a growth environment for zooplankton, fish, microorganism and the like), and maintains the biomass algae at a lower level, namely, water bloom can not occur.

The influence of the planting density of the submerged plants on the algae control effect is large, but when the planting density is too small, the impact resistance of the submerged plants in the eutrophicated water body is poor, the growth of the submerged plants is easily influenced by population competition, the algae control effect cannot be achieved, but when the planting density is too large, the nutrition area of the submerged plants is small, the living space is insufficient, the plants are poor in growth vigor, the growth of the plants is limited, the plants die and rot easily, secondary pollution of the water body is serious, the plants cannot be used for ecological restoration of the water body, and in addition, the planting proportion of the two plants can also realize the algae control effect and stable growth of the plant combinationInfluence is caused, if the proportion is improper, a certain plant is easy to form a dominant species in the interspecific competition process, and the biological diversity of the aquatic ecotype is reduced; therefore, the planting conditions of the submerged plants can seriously influence the algae inhibiting effect and the ecological restoration cost ratio, and the inventor obtains the optimal algae control density of 13 +/-0.5 kg (wet weight)/m for the combined planting of the two plants according to a curved surface model designed by a response surface experiment³The optimal planting proportion is (1-1.1): 1, such as 1:1, 1.02:1, 1.05:1, 1.08:1, 1.1:1, etc., and verifies the conclusion on the basis of a large number of experiments, so that the final microalgae inhibition rate reaches more than 90%; the difference of water depths of different water bodies is large, so that the error of the planting density of the aquatic plants is large, and kg/m is selected³The unit can be converted into kg/m after the water depth of a suitable water body is determined²Units.

The algae inhibiting method provided by the invention is suitable for the first-grade A standard of the discharge standard of a sewage plant and above, wherein the first-grade A standard is the basic requirement of the effluent of the urban sewage plant as reuse water.

Preferably, the hydrilla verticillata is hydrilla verticillata.

Preferably, in the step (2), tap water is adopted for washing when floating swimming plants are removed, the floating swimming plants are used for planting after three days of aeration culture, and withered stems and leaves on the plants are picked off before the aeration culture. Algae can be attached to the surface of the submerged plant, so that the aeration culture is selected and then used for planting in order to avoid the influence of the algae attached to the plant on the test result.

Preferably, in the step (2), when the hydrilla verticillata and the foxtail spicatum are planted in the container filled with the test water sample, the soilless culture cup bottom and cobblestones are used for fixing the submerged plants, so that the submerged plants are convenient to adapt to the growth in the effluent environment of the sewage plant.

Preferably, in the step (3), indexes of total nitrogen content TN, total phosphorus content TP and chlorophyll concentration in water are measured before and after the submerged plant is planted; after the submerged plant is planted, the method for measuring the indexes comprises the following steps: sampling is carried out at regular time every 3 days, the determination index is completed within 1 day after sampling, after continuous determination is carried out for 30 days, the growth of the submerged plant combination in the river tends to be stable, and sampling determination is carried out at regular time every 7 days. Further preferably, the sampling time is selected from 10 a.m.: between 00 and 3:00 pm, the algae are more affected by light during this time period and are most susceptible to bloom.

Further, TN is measured by potassium persulfate oxidation ultraviolet spectrophotometry, TP is measured by molybdenum antimony spectrophotometry, and chlorophyll concentration is measured by a phyto-PAM instrument.

In order to realize resource recycling, further, the method for inhibiting the effluent microalgae of the sewage plant further comprises the following steps:

(4) and (4) harvesting the submerged plants in the step (3) every 14-20 days, wherein the harvesting amount of the hydrilla verticillata is 17% -36% of the biomass of the hydrilla verticillata in the total system, and the harvesting amount of the foxtail preputita ear is 10% -23% of the biomass of the foxtail preputita in the total system. In order to ensure efficient algae inhibiting effect, the harvesting amount of hydrilla verticillata and foxtail algae need to be controlled within a specified range.

Compared with the prior art, the method for efficiently inhibiting the effluent microalgae of the sewage plant by using the submerged plant has the following beneficial effects:

(1) the invention utilizes the combination of the hydrilla verticillata submerged plants to inhibit the growth of the effluent microalgae of the sewage plant, has obvious effect, has the inhibition rate of more than 90 percent on the microalgae, has the TN removal rate of more than 60 percent and the TP removal rate of more than 95 percent, has good ecological and attractive benefits, and provides theoretical basis for the selection of utilizing the submerged plants to control the algal bloom of the microalgae for building artificial wetlands and artificial composite ecological beds;

(2) the invention selects 13 plus or minus 0.5kg/m³The mixed planting total density is used for co-cultivating hydrilla verticillata and foxtail algae with the planting proportion of (1-1.1): 1, the inhibition rate of the plant growth regulator on microalgae reaches 90%, compared with the same gradient level of single plant planting density, the maximum effects of inhibiting algae and repairing water are achieved, the planting cost is saved, the growth condition of the plant growth regulator is good, and the relative growth amounts of hydrilla verticillata and myriophyllum spicatum respectively reach over 86% and 47%; to achieve 90% of algae inhibiting effect, the planting density of a single plant needs to reach 20kg/m³The total planting density of the hydrilla verticillata-foxtail algae combination only needs to reach 13 +/-0.5 kg/m³Therefore, not only is the cost saved, but also the stability of water ecology is facilitated;

(3) the hydrilla verticillata-foxtail algae combination can be used for deeply absorbing and purifying pollutants such as nitrogen and phosphorus in the effluent water of a sewage plant, and the harvested and caught hydrilla verticillata and foxtail algae can be recycled to a certain extent, so that circular economy is realized, and the hydrilla verticillata-foxtail algae combination has better economic feasibility;

(4) the method has the advantages of simple operation, low construction and operation management cost, obvious effect and no secondary pollution, and is suitable for being used as a new process for ecological restoration of effluent of a sewage plant.

Drawings

FIG. 1 is a graph showing the change in chlorophyll concentration in the first embodiment;

FIG. 2 is a graph showing the change in TN and TP concentrations in the first embodiment;

FIG. 3 is a graph showing the change in chlorophyll concentration in the second embodiment;

FIG. 4 is a graph showing the change in TN and TP concentrations in the second example.

Detailed Description

The present invention is described in detail with reference to the following specific embodiments, but the scope of the present invention is not limited to the specific scope of the present invention, and all other embodiments obtained by those skilled in the art without any inventive work based on the embodiments of the present invention belong to the scope of the present invention.

The method for efficiently inhibiting the microalgae in the effluent of the sewage plant by utilizing the submerged plant combination is suitable for various scenes of the effluent of a sewage treatment system, such as an effluent riverway of the sewage plant and a landscape pool after the effluent of the sewage plant is recycled, wherein the recycled landscape pool is mostly in a still water state, so that the landscape pool is more likely to burst water bloom compared with a flowing effluent recharging riverway of the sewage plant, after the algae inhibiting method provided by the invention is adopted, the inhibiting rate of the microalgae is up to more than 90%, the TN removing rate is up to more than 60%, and the TP removing rate is up to more than 95%.

Example 1

The embodiment is used for investigating the inhibiting effect of the invention on the microalgae discharged from a certain water quality purification plant in Beijing, and specifically comprises the following steps:

(1) selecting first-grade A standard effluent of a certain sewage plant, and measuring related indexes of the first-grade A standard effluent: the total nitrogen content TN is 15mg/L, the total phosphorus content TP is 0.5mg/L, and the chlorophyll concentration is 5.86 mug/L;

(2) selecting hydrilla verticillata and myriophyllum pratense as submerged plants for controlling algae, rinsing with tap water to remove attached phytoplankton, planting in a 20L glass water tank filled with test water samples, fixing the submerged plants with soilless culture cup bottoms and cobblestones, placing in a greenhouse for at least 2 weeks to adapt to test conditions, before the test, selecting plants which are robust in growth and consistent in size, washing with tap water to fully remove the attached phytoplankton, picking off withered stems and leaves on the plants, and culturing for three days by tap water aeration for testing;

(3) combining submerged plants of hydrilla verticillata and myriophyllum spicatum at a ratio of 13 + -0.5 kg (wet weight)/m³The mixed planting total density is jointly cultivated in a landscape pool for replenishing the effluent of a 1.5m multiplied by 1.2m sewage plant, the hydrilla verticillata and the myriophyllum spicatum are distributed at intervals, the planting proportion of the hydrilla verticillata to the myriophyllum spicatum is 1:1, setting three groups of parallel experiments according to the experimental scheme, simultaneously setting three groups of controls, adding no submerged plant in the control group, placing the experimental group and the control group in an outdoor natural environment (water bloom is easy to burst), wherein the experimental period is 50 days, after about 30 days, the growth of the submerged plant in a river tends to be stable, sampling is carried out at a rate of 10:00 every 3 days in the first 30 days, all measurement indexes are finished within 1 day after sampling, and all measurement indexes are finished at fixed points every 7 days in the last 20 days, wherein the measurement indexes comprise TN, TP and chlorophyll concentration; and the fresh weight of the plants was measured at the early and late stages of the experiment.

The corresponding measurement data (including the indexes before and after adding submerged plants and the fresh weight of the plants) are shown in table 1 below:

TABLE 1

After the test period is finished, the inhibition rate of the hydrilla verticillata-watery plant combination on the maximum biomass of the microalgae is more than 90%, the TN removal rate in the water body is as high as 71.3%, the TP concentration in the water body is as low as 0.012mg/L, the removal rate is as high as 97.6%, the growth conditions of the two plants are good, the relative growth amounts of the hydrilla verticillata and the watery plant combination respectively reach 89.8% and 47.2%, therefore, the use of the hydrilla verticillata-watery plant combination has obvious inhibition capability on the yielding water microalgae of the sewage plant and the removal effect of nitrogen and phosphorus, the growth of the yielding water of the sewage plant can be efficiently controlled, and the method is suitable for ecological restoration of the yielding water replenishing water of the sewage plant.

Example 2

The embodiment is used for investigating the inhibiting effect of the invention on the effluent microalgae of a certain water quality purification plant in Kunming city, and specifically comprises the following steps:

(1) selecting first-grade A standard water of a certain water quality purification plant in Kunming city, and measuring relevant indexes of the first-grade A standard water: the total nitrogen content TN is 14.3mg/L, the total phosphorus content TP is 0.42mg/L, and the chlorophyll concentration is 5.79 mug/L;

(3) combining submerged plants of hydrilla verticillata and myriophyllum spicatum at a ratio of 13 + -0.5 kg (wet weight)/m³The mixed planting total density is jointly cultivated in a landscape pool for effluent recharging of a 3.0m multiplied by 1.5m multiplied by 1.2m sewage plant, the hydrilla verticillata and the myriophyllum spicatum are distributed at intervals, the planting proportion of the hydrilla verticillata to the myriophyllum spicatum is 1.1:1, setting three groups of parallel experiments according to the experimental scheme, simultaneously setting three groups of controls without adding submerged plants in the controls, placing the experimental group and the controls in an outdoor natural environment, wherein the experimental period is 50 days, sampling is carried out 10:00 every 3 days in the first 30 days, and sampling is finished within 1 day after samplingAll measurement indexes are obtained, and all measurement indexes are fixed at a point every 7 days after 20 days, wherein the measurement indexes comprise TN, TP and chlorophyll concentration; and the fresh weight of the plants was measured at the early and late stages of the experiment.

The corresponding measurement data (including the indexes before and after adding submerged plants and the fresh weight of the plants) are shown in table 2 below:

TABLE 2

After the test period is finished, the inhibition rate of the hydrilla verticillata-watery plant combination on the maximum biomass of the microalgae is more than 90%, the TN removal rate in the water body reaches 65.1%, the TP concentration in the water body is as low as 0.015mg/L, the removal rate reaches 96.4%, the growth conditions of the two plants are good, the relative growth amounts of the hydrilla verticillata and the watery plant combination respectively reach 86.36% and 54%, and therefore, the use of the hydrilla verticillata-watery plant combination has obvious inhibition capability on the yielding water microalgae of a sewage plant and removal effect of nitrogen and phosphorus, the growth of the yielding water microalgae of the sewage plant can be efficiently controlled, and the method is suitable for ecological restoration of the yielding water recharging water of the sewage plant.

The above embodiments are merely illustrative of various embodiments of the present invention, and the description is specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.

Claims

1. A method for efficiently inhibiting effluent microalgae of a sewage plant by using submerged plants is characterized by comprising the following steps:

(2) selecting hydrilla verticillata and myriophyllum pratense as submerged plants for controlling algae, removing attached phytoplankton, planting in a container filled with a test water sample, placing in a greenhouse for growing for at least 2 weeks, selecting plants which are healthy in growth and consistent in size and condition, removing attached phytoplankton again, and carrying out aeration culture for planting;

(3) adding submerged plant at wet weight of 13 + -0.5 kg/m³The mixed planting total density is jointly cultivated in a landscape pool for effluent recharging of a sewage plant, and the planting ratio of the hydrilla verticillata to the foxtail spicatum is (1-1.1): 1;

the hydrilla verticillata is hydrilla verticillata;

in the step (2), tap water is adopted when floating plants are removed, the floating plants are used for planting after being subjected to aeration culture for three days, and withered stems and leaves on the plants are picked off before the aeration culture;

in the step (3), indexes of total nitrogen content TN, total phosphorus content TP and chlorophyll concentration in the effluent of the sewage plant are required to be measured before and after the submerged plant is planted; the method for measuring the indexes after the submerged plant is planted comprises the following steps: sampling regularly every 3 days, finishing the determination index within 1 day after sampling, and sampling regularly every 7 days for determination after 30 days when the growth of the submerged plant tends to be stable; the sampling time is selected from 10 am: between 00 and 3:00 pm;

and (4) harvesting the submerged plants in the step (3) every 14-20 days, wherein the harvesting amount of the hydrilla verticillata is 17% -36% of the biomass of the hydrilla verticillata in the total system, and the harvesting amount of the foxtail preputita ear is 10% -23% of the biomass of the foxtail preputita in the total system.

2. The method for efficiently restraining effluent microalgae of a sewage plant by using submerged plants as claimed in claim 1, wherein in the step (2), when the hydrilla verticillata and the foxtail spicatum are planted in the container filled with the test water sample, the submerged plants are fixed by using a soilless culture cup bottom and cobblestones.

3. The method of claim 1, wherein TN is measured by potassium persulfate oxidation ultraviolet spectrophotometry, TP is measured by molybdenum antimony spectrophotometry, and chlorophyll is measured by phyto-PAM.