CN103265145B - Method for purifying river water with low load and low temperature by using natural biofilm reactor - Google Patents

Abstract

The invention belongs to the field of ecology and environmental protection, relates to the field of low-load river water purification in farmland areas, and particularly relates to a method for purifying low-load low-temperature river water using a natural biofilm reactor, including the following steps: (1) natural biofilm enrichment and cultivation : Directly use the river water body as the "provenance" to enrich and cultivate microorganisms such as algae and bacteria; (2) Low-temperature natural biofilm domestication: reduce the cultivation temperature of the pre-cultivated natural biofilm in stages, and the temperature decrease gradient is Decrease 1 degree every 2 days until the culture temperature is between 0-4°C; (3) Low-temperature natural biofilm is inoculated into the reactor; (4) Natural biofilm reactor commissioning: by adjusting the weight of the floating body and the reactor , adjust the hydraulic load and residence time of the reactor; (5) water purification of natural biofilm reactor. The invention is simple and easy to implement, has a good purifying effect on the water quality of river courses in farmland areas, is easy to popularize, and simultaneously solves the problem of low removal efficiency of pollutants in winter.

Description

Method for purifying low-load low-temperature river water by using natural biofilm reactor

technical field

The invention belongs to the field of ecology and environmental protection, relates to the field of low-load river water purification in farmland areas, and particularly relates to a method for purifying low-load low-temperature river water by using a natural biofilm reactor.

Background technique

At present, the eutrophication of water body is seriously affecting the living environment of human beings. In the past 10 years, the eutrophication of rivers and lakes in my country has been very serious and showing a worsening trend. Of the more than 700 rivers (100,000 kilometers in length) in my country, 70.6% of them are polluted. More than 300 million people in rural my country have unsafe drinking water, of which about 63 million people drink high-fluorine water, 2 million people drink high-arsenic water, more than 38 million people drink brackish water, 190 million people drink water with excessive levels of harmful substances, schistosomiasis More than 11 million people in the disease area have unsafe drinking water; a considerable number of urban water sources are seriously polluted, threatening the quality of drinking water.

Farmland non-point source pollution is one of the main forms of pollution load in rivers and lakes in my country. The discharge of farmland non-point source pollution has brought a lot of low-load pollutants to nearby rivers. Due to the low load of such pollutants, many new challenges have been brought to conventional treatment methods, such as the low cost performance of traditional activated sludge treatment.

At present, the treatment methods for such low-load river water are divided into two categories, one is in-situ water purification method, and the other is bypass purification method (also known as ex-situ treatment method). The bypass purification method is to use the open space on both sides of the river to build a river water purification system, such as a wetland treatment system, a biological pond, and soil infiltration. For example, in order to reduce the pollution load of Dianchi Lake, a biological stabilization pond system including aquatic plant ponds and breeding ponds was designed and constructed based on the idea of bypass purification, and the removal effect of nitrogen and phosphorus was investigated. The results show that the average removal rates of TN, TP, NO ₃ ^- -N and NH ₃ -N are 25.3%, 50.6%, 38.4% and 35.6%, respectively, and it also has certain ecological landscape benefits while improving water quality , which can provide a demonstration for the purification of other water bodies. The feature of the bypass purification method is that it can combine the characteristics of river water quality to build an economically feasible treatment system. However, this type of bypass purification method usually requires power to lift water, which increases treatment costs and requires additional manpower management and maintenance.

Therefore, there are studies to upgrade this bypass purification method, such as combining the bypass system with the traditional sewage purification system (such as nitrogen and phosphorus removal system). Invention patent (application number 201110159014.4) proposes a bypass sludge reduction and silt separation for the problems of high influent sediment content, low VSS/MLSS, and insufficient carbon source often encountered in the current nitrogen and phosphorus removal process A sewage treatment system and method for nitrogen and phosphorus removal are composed of two parts: a main sewage treatment system and a bypass system with functions of nitrogen and phosphorus removal. The main sewage treatment system includes a grit chamber and a sewage treatment system with nitrogen and phosphorus removal functions. The bypass system is composed of hair separator, sludge reduction tank, sludge silt separator, silt dewatering system and chemical phosphorus removal system. This construction method combined with the bypass purification system can prevent the accumulation of silt in the sewage treatment system, increase the sludge VSS/MISS ratio in the biochemical reaction tank, and add chemical phosphorus removal in the embedded bypass system, which can Achieving low-cost chemical removal and recovery of phosphorus in sewage.

However, for river sewage with low pollution load, this method involving a bypass purification system requires a large area of wasteland to construct a purification project, which is not suitable for areas with insufficient land resources or areas with expensive land resources.

In view of this, in the case of actual river water purification, the in-situ water purification method is widely used and has a good prospect. From an ecological point of view, improving the water quality in situ and improving the self-purification capacity and resilience of the river aquatic ecosystem are also the only way for the sustainable and healthy development of the river ecosystem.

The in-situ water purification method mainly uses the principle of biofilm method to purify river water quality. The biofilm method is an important wastewater biological treatment method, which relies on the microbial community attached to the carrier to absorb and degrade N, P, COD and other pollutants in the wastewater to achieve the purification effect. Under anaerobic conditions, anaerobic microorganisms can treat high-concentration wastewater in a short period of time and degrade macromolecular organic substances into low-molecular compounds, and then convert them into methane and carbon dioxide; under aerated conditions, aerobic microorganisms can reduce COD in water and absorb N, P to achieve the effect of purifying sewage.

Because the bioreactor can well fix the biofilm and adjust the structure of the biofilm; the biomass and activity of the biofilm can be controlled by adjusting the setting of the reactor. Therefore, the bioreactor is widely used in in-situ water purification. It also has a good prospect in the field of in-situ purification of river water. By induction, such typical cases of using reactors to purify sewage include the following:

Sequencing batch type integrated membrane bioreactor (invention patent number: 03133571.3), realizes aerobic, anoxic and anaerobic environments in the same reaction tank, so that nitrogen and phosphorus pollutants can be fully removed.

Sequencing batch membrane-bioreactor sewage treatment process and device (invention patent number: 03100398.2) put membrane modules in the bioreaction tank, and make the outlet connect to the inlet pipe and outlet pipe respectively through two sets of control valves. The whole system is in Alternately experiencing anaerobic, aerobic, and anoxic states in time can effectively remove carbon-containing organic pollutants and nutrients such as nitrogen and phosphorus simultaneously.

Multi-stage bioreactor (invention patent number: 201080057245.8) A multi-stage bioreactor in a sedimentation tank, each chamber includes a hollow frame and a plurality of mesh substrates mechanically fixed to the frame, the substrate is configured to grow microorganisms thereon .

Upflow microbial reactor treatment process for manganese-containing wastewater (invention patent number: 201210176953.4) Manganese-containing wastewater first enters the primary sedimentation tank through a submersible pump, and then enters two series-connected aerobic biological reactions through pipeline pumps after primary sedimentation treatment The water intake is controlled by the water inlet pump, and the water discharged from the series reaction tanks then enters the three-layer filter tank, and the water discharged from the three-layer filter tank is the clean water after treatment.

The regulation method of microbial activity in membrane bioreactor (invention patent number: 201210014485.0) solves the problem that the existing membrane bioreactor treats micro-polluted surface water due to the low concentration of organic matter in raw water or low temperature. The activity and biomass decrease, and the water treatment effect becomes poor.

The non-woven floc dynamic membrane bioreactor (invention patent number: 201010512396.X) includes a reaction zone, a floc growth zone and a non-woven membrane module. The non-woven membrane module is equipped with a non-woven membrane. On the surface and inside of the cloth membrane, there is a dynamic membrane composed of flocs produced by the coagulation of colloidal substances in sewage.

Fluidized bed membrane bioreactor (invention patent number: 201010571203.8) utilizes the process of combining biological fluidized bed and membrane bioreactor, that is, the reactor is filled with waste rubber powder, activated carbon and adhesive self-made with a diameter of about 5mm. For the carrier particles, the filling ratio is 10%-30% of the effective volume of the reactor. Relying on the synergistic effect of the carrier and the sludge, the film hanging is completed, and the microorganisms grow on the filler, which reduces the sludge concentration in the reactor, changes the environmental operating conditions of the reactor, and slows down the membrane fouling, thereby prolonging the service life of the membrane and improving the efficiency of the membrane. processing capacity.

A membrane bioreactor and its method for purifying sewage (invention patent number: 201010571203.8) discloses a membrane bioreactor in which the microbial reactor and the membrane filter are separately set, which prolongs the service life of the membrane bioreactor and avoids Eliminate the troublesome cleaning of the membrane filter by the operator, and improve the water production efficiency.

Although, these representative bioreactors have purified the sewage well to a certain extent and protected the environment. However, temperature is an important factor affecting the physiological activities of microorganisms. Usually, too low temperature in a low temperature environment may delay or destroy the normal physiological activities of some microorganisms, thereby affecting the sewage treatment effect. Therefore, the microorganisms on the carrier can be screened before operation, and the microorganisms resistant to low temperature can be selected to finally form a biofilm, so that it can purify sewage under low temperature conditions.

At the same time, for river water quality with low pollution load, although the invention patent (publication number 201210014485.0) proposes a method for regulating microbial activity in membrane bioreactors for the treatment of slightly polluted surface water, the effect of purifying water quality remains to be tested. In addition, the water quality with low pollution load may not provide enough nutrients for the survival of active microorganisms. Therefore, cultivating biofilm communities that can survive and recycle themselves is a prerequisite for achieving low pollution load sewage treatment.

Contents of the invention

The purpose of the present invention is to overcome above-mentioned shortcoming, provide a kind of method that utilizes natural biofilm reactor to purify low-load low-temperature river water. The invention produces a natural biofilm that can survive and recycle itself. This biofilm can tolerate low temperature and treat low-temperature low-load sewage. This is a new design and construction model, which will achieve the dual purpose of cultivating natural biofilms composed of autotrophic and heterotrophic microorganisms and purifying low-temperature river water with low pollution load in farmland areas. The present invention aims at treating river sewage with low pollution load in winter, adopts the working idea of "division, classification, multi-stage" and "domestication of natural biofilm first, then immobilization of natural biofilm, and construction of bioreactor", based on "influent- The process route of primary sedimentation - aerobic (light) - anaerobic (light) - overflow - water out" is designed.

In order to achieve the above object, the technical solution of the present invention is: a method for purifying low-load low-temperature river water using a natural biofilm reactor, which is characterized in that it includes the following steps:

(1) Enrichment and cultivation of natural biofilm: Soak the purchased artificial aquatic plants in 0.1M hydrochloric acid for 2 hours, dry them, and place them in eutrophic water bodies under the conditions of light intensity greater than 3600 Lux and temperature 20-40°C Enrichment and cultivation of natural biofilms;

(2) Low-temperature natural biofilm acclimatization: The natural biofilm enriched and pre-cultured at a temperature of 20-40°C will continue to be cultivated, and the culture temperature will be reduced in stages until the culture temperature is reduced to between 0-4°C; Within the temperature range of ℃, continue to cultivate for a period of time, and the low-temperature natural biofilm is regarded as domestication success, for future use;

(3) Low-temperature natural biofilm is inoculated into the reactor: the reactor includes anaerobic reaction tank, aerobic reaction tank, sedimentation tank, filler, light source, and aeration device;

(4) Commissioning and running of the natural biofilm reactor: fix the natural biofilm reactor on the floating body, so that the water inlet of the reactor is just as far as the water surface, and the river water flows into the reactor under the condition of aeration, and the aerobic section of the reactor is under negative pressure , the river water reacts with the natural biofilm, and the pollutants are transformed, degraded, adsorbed and absorbed;

(5) Water purification with natural biofilm reactors: multiple natural biofilm reactors are arranged in the river water body to purify the river water in situ.

Further technical solutions include:

In step (1), the eutrophication index of the eutrophic water body is greater than 50, and the volume ratio of the artificial aquatic plants to the eutrophic water body is less than 1:2.

For the natural biofilm enrichment and cultivation described in step (1), the eutrophic water used to enrich and cultivate the natural biofilm needs to contain microorganisms such as algae and bacteria. "It actually comes from the nutrient-rich water that is taken. The eutrophic water collected in different locations may have different composition of natural biofilm microbial community, and its removal effect on pollutants is also different, but the removal efficiency of organic matter, nitrogen, phosphorus and other basic pollutants is not much different.

In step (2), the specific method of reducing the culture temperature in stages is as follows: the temperature gradient is reduced by 1 degree every two days until the culture temperature is reduced to between 0-4°C, and the culture is continued within the temperature range of 0-4°C a week.

The low-temperature natural biofilm described in step (3) is inoculated into the reactor, and the dissolved oxygen content in the water body of the anaerobic reaction pool in the reactor remains below 0.2 mg/L; the dissolved oxygen content in the water body of the aerobic reaction pool remains at 6.0 mg /L or more; the filler is composed of activated carbon, peat, sponge, fiber, and non-woven fabric, and the weight percentage ratio is 0.1:0.5:0.1:0.2:0.1; the light source is arranged below the water surface and is composed of ordinary incandescent waterproof lamps. The intensity is greater than 3600 Lux; the aeration device is composed of a fish farming pump (that is, a small aeration pump).

Further, the specific steps of inoculating the natural biofilm into the reactor in step (3) are as follows: the carrier enriched with natural biofilm (that is, the aforementioned artificial aquatic plants) is shortened to 0.1-0.5 cm long with scissors, and then placed in the reaction In the filler of the container, the amount of the carrier enriched with natural biofilm is 0.5-5% of the total filler.

In step (4), the hydraulic load and residence time of the reactor are adjusted by adjusting the weight of the floating body and the reactor.

Further, the natural biofilm reactor described in step (4) is commissioned and operated. When the eutrophication degree of river water is low, that is, when the eutrophication index is between 30 and 50, the hydraulic retention time is generally set at 12- 24 hours; when the degree of eutrophication of the river water is high, that is, when the eutrophication index is between 50 and 70, the hydraulic retention time is generally set at 24-48 hours; When the trophic index is greater than 70, the hydraulic retention time is generally set at 48-72 hours.

For the water purification of the natural biofilm reactor described in step (5), take the natural biofilm reactor out of the river during the rainy season (usually summer) and place it in a cool place indoors (with a temperature lower than 15°C) to ensure Natural biofilm microbial activity avoids the need to domesticate microorganisms again when using natural biofilm reactors to purify river water in the next winter. At the same time, the removal of natural biofilm during the rainy season is also conducive to river flood discharge, drainage and irrigation.

Further, in step (5), a natural biofilm reactor is arranged for every 100 square meters of river water.

In winter, the river water is purified in situ by natural biofilm reactors, the nutrients in the river water body are continuously reduced, the organic pollution load is continuously decomposed and degraded, and some heavy metal pollutants with low pollution loads are also removed or transformed, finally reaching the low temperature in winter The purpose of river water purification.

The technical effects before and after the implementation of the present invention are as follows (the average result of 6 samplings in winter): before the implementation, the river water contains a large amount of total suspended solids (TSS), organic matter (expressed by COD and UV ₂₅₄ nm-matter ultraviolet absorbance), nitrogen and phosphorus content and a small amount of heavy metals such as Hg, Cr, Cu, Cd, after the application of the natural biofilm reactor of the present invention, these pollutants are basically purified, and the pollutant reduction rate reaches more than 75% (see Figure 2).

The method of the invention is simple and easy to implement, and has good effect of purifying river water quality in winter. Compared with the traditional river water purification technology (such as artificial floating bed, adding chemical agents, etc.), the method of the present invention has the characteristics of stable effect, treatment efficiency not affected by low temperature, low construction cost and low operation cost. The natural biofilm invented has the characteristics of one-time investment and multi-year use. The domesticated natural biofilm can be used for a long time and can reproduce microbial populations with similar properties, further reducing operating costs. In addition, during the application of the natural biofilm reactor, it will not affect the normal flood discharge and drainage and irrigation of the river, which is convenient for promotion.

Description of drawings

Fig. 1 is the structural diagram of natural biofilm reactor;

Fig. 2 is the effect diagram of natural biofilm of the present invention purifying river channel sewage in winter;

Among them, 1 sedimentation tank, 2 anaerobic reaction tank, 3 aerobic reaction tank, 4 sedimentation tank, 5 water outlet, 6 filler, 7 light source, 8 aeration device.

Detailed ways

The technical solution of the present invention will be described in detail below in conjunction with FIG. 1 and FIG. 2 .

The method for purifying low-load low-temperature river water using a natural biofilm reactor is characterized in that it includes the following steps:

(1) Enrichment and cultivation of natural biofilm: Soak the purchased artificial aquatic plants in 0.1M hydrochloric acid for 2 hours, dry them, and place them in eutrophic water bodies under the conditions of light intensity greater than 3600 Lux and temperature 20-40°C Enrichment and cultivation of natural biofilms;

(2) Low-temperature natural biofilm acclimatization: Continue to cultivate the natural biofilm enriched and pre-cultured at a temperature of 20-40°C, and reduce the culture temperature in stages until it is reduced to a culture temperature between 0-4°C; Within the temperature range of ℃, continue to cultivate for a period of time, and the low-temperature natural biofilm is regarded as domestication success, for future use;

(3) Low-temperature natural biofilm is inoculated into the reactor: the reactor includes sedimentation tank 1, anaerobic reaction tank 2, aerobic reaction tank 3, sedimentation tank 4, water outlet 5, filler 6, light source 7, and aeration device 8;

(4) Debugging and operation of natural biofilm reactor: fix the natural biofilm reactor on the floating body, so that the water inlet of the reactor is just as far as the water surface, and the river water flows into the reactor under the condition of aeration, and the aerobic section of the reactor is under negative pressure , the river water reacts with the natural biofilm, and the pollutants are transformed, degraded, adsorbed and absorbed;

(5) Water purification with natural biofilm reactors: multiple natural biofilm reactors are arranged in the river water body to purify the river water in situ.

Example 1: A lake near Youfang Bridge in Nanjing is a typical eutrophic lake. The river water collected from the rivers entering the lake is used to enrich and cultivate natural biofilm, and artificial aquatic plants are used as the carrier of natural biofilm. After the natural biofilm was enriched and cultured for 35 days, the culture temperature was lowered by 1 degree every 2 days until the culture temperature reached 4°C, and the culture was continued at this temperature for 7 days. The bioreactor includes sedimentation tank, anaerobic reaction tank, aerobic reaction tank, sedimentation tank, and artificial filler. The total volume ratio of the above parts is 10%, 30%, 30%, 10%, and 20%. The artificial filler is composed of activated carbon, peat, sponge, fiber, and non-woven fabric, and the composition weight ratio is 0.1:0.5:0.1:0.2:0.1. Use ordinary LED waterproof lights as light sources, and use ordinary fish farming pumps as air pumps (power 3.2W). Use scissors to cut the carrier attached with the natural biofilm, and inoculate it into the filler of the bioreactor, and the inoculum amount is about 1% of the total filler. Since the eutrophication index of the river channel was between 30 and 50 during the experiment, the hydraulic retention time of the natural biofilm reactor was set to 24 hours by adjusting the size of the floating body.

Through a two-month winter experiment, the results show that the application of natural biofilm reactors can better purify river sewage and remove low-load pollutants. The average removal rates of TSS, COD, UV254nm-matter, TN, TP, Hg, Cr, Cu and Cd were 89.3%, 75.4%, 80.3%, 81.2%, 79.6%, 84.4%, 80.6%, 83.2% and 89.3%, respectively %.

Example 2: The Daqing River in Kunming is the main river entering the Dianchi Lake. On both sides of the river are leek and flower planting agricultural areas. The water quality of the river is in a state of severe eutrophication. The eutrophication index is greater than 70 and contains a small amount of low-load heavy metal pollutants. In order to purify this kind of sewage, an experimental study was carried out indoors. The collected river water was placed in a water tank of 1.2 cubic meters, and the natural biofilm reactor in Example 1 was used for purification. The removal efficiency of each pollutant was TSS 87.2 %, COD 82.5%, UV254nm-matter 79.1%, TN 67.4%, TP 71.2%, Hg 80.6%, Cr 79.4%, Cu83.3% and Cd 85.2%. In a word, after the implementation of the natural biofilm reactor of the present invention, the river sewage in winter is significantly purified, and the problem of low removal efficiency of low-temperature pollutants is solved.

The above embodiments do not limit the present invention in any form, and all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (8)

1. utilize natural biology membrane reactor to purify the method for underload low temperature river, it is characterized in that, comprise the steps:

(1) enrichment of natural biology film and cultivation: the artificial aquatic weed purchased, is dried after 2 hours by 0.1M salt acid soak, be placed in eutrophication water, in intensity of illumination, to be greater than 3600 Lux, temperature be enrichment under 20-40 ℃ of condition, cultivate natural biology film;

(2) low temperature natural biology film domestication: will continue to cultivate at the pre-incubated natural biology film of temperature 20-40 ℃ enrichment, and reduce stage by stage culture temperature, until be reduced to culture temperature between 0-4 ℃; In the temperature range of 0-4 ℃, continue to cultivate for some time, low temperature natural biology film is regarded as and is tamed successfully, for future use;

(3) low temperature natural biology film is seeded to reactor: reactor comprises anaerobic reation pool, aerobic reaction pond, settling tank, filler, light source, aerating apparatus;

(4) natural biology membrane reactor commissioning test: natural biology membrane reactor is fixed on buoyancy aid, make reactor water inlet just as for the water surface, in aeration situation, go to river in water inflow reactor, reactor aerobic section is negative pressure, river produces and reacts with natural biology film, and pollution substance is converted, degrades, adsorbs and absorbs;

(5) natural biology membrane reactor purification of water quality: a plurality of natural biology membrane reactors are laid in river water body, river is carried out to original position purification;

The described low temperature natural biology film of step (3) is seeded to reactor, and in the anaerobic reation pool water body in reactor, dissolved oxygen content remains on below 0.2 mg/L; More than in the water body of aerobic reaction pond, dissolved oxygen content remains on 6.0 mg/L; Filler is comprised of gac, peat, sponge, fiber, non-woven fabrics, and forming weight percentage ratio is 0.1:0.5:0.1:0.2:0.1; Light source is laid in below the water surface, and intensity of illumination is greater than 3600 Lux; Aerating apparatus consists of the pump of breeding fish.

2. the method for utilizing natural biology membrane reactor to purify underload low temperature river according to claim 1, it is characterized in that, natural biology film is inoculated into the concrete step of reactor and is in step (3): by enrichment the carrier of natural biology film cut short long to 0.1-0.5 cm after, put into the filler of reactor, access amount is the 0.5-5% of total filler amount.

3. the method for utilizing natural biology membrane reactor to purify underload low temperature river according to claim 1, is characterized in that, in step (4), by regulating buoyancy aid and reactor weight, regulates hydraulic load and the residence time of reactor.

4. the method for utilizing natural biology membrane reactor to purify underload low temperature river according to claim 3, it is characterized in that, the natural biology membrane reactor commissioning test concrete steps of step (4) are: when river eutrophication index circle is between 30 and 50, hydraulic detention time is set to 12-24 hour; When river eutrophication index circle is between 50 and 70, hydraulic detention time is set to 24-48 hour; When river eutrophication index is greater than 70, hydraulic detention time is set to 48-72 hour.

5. the method for utilizing natural biology membrane reactor to purify underload low temperature river according to claim 1, it is characterized in that, the described natural biology membrane reactor purification of water quality concrete steps of step (5) are: when rainy season or summer, natural biology membrane reactor is taken out from river course, be placed on temperature lower than the indoor shady and cool part of 15 ℃, active to guarantee natural biology membrane micro, while avoiding next use in winter natural biology membrane reactor purifying river water, need acclimated microorganism again.

6. the method for utilizing natural biology membrane reactor to purify underload low temperature river according to claim 1, it is characterized in that, in step (1), the eutrophication index of eutrophication water is greater than 50, artificial aquatic weed and eutrophication water volume ratio are less than 1:2, and eutrophication water contains algea and bacteria.

7. the method for utilizing natural biology membrane reactor to purify underload low temperature river according to claim 1, it is characterized in that, in step (2), reduce stage by stage the concrete mode of culture temperature as follows: it is within every two days, to reduce by 1 degree that temperature reduces gradient, until be reduced to culture temperature between 0-4 ℃, in the temperature range of 0-4 ℃, continue to cultivate one week.

8. the method for utilizing natural biology membrane reactor to purify underload low temperature river according to claim 1, is characterized in that, in step (5), every 100 square meter rivers are laid a natural biology membrane reactor.

Images