CN107055775A - Processing system and processing method for low ratio of carbon to ammonium aquiculture waste water - Google Patents

Abstract

The invention discloses a treatment system and a wastewater treatment method for aquaculture wastewater with a low carbon-to-nitrogen ratio, belonging to the technical field of wastewater biological treatment. The treatment system includes a nitrification device and a denitrification device connected together, a waste water storage device, a pipeline for communication, and a circulation pump for circulating the waste water in the above-mentioned devices; the treatment method includes ① microbial film formation ② circulation treatment and ③ repeating steps, the wastewater treatment system and wastewater treatment method are suitable for the treatment of aquaculture wastewater with low carbon and nitrogen ratios, and can generate biofilms composed of bacterial communities on the filler, and the removal of ammonia nitrogen, nitrite nitrogen and total nitrogen The rate can basically be kept above 90%, the system runs stably, no secondary pollution occurs, and it is easy to maintain and operate.

Description

Treatment system and treatment method for aquaculture wastewater with low carbon-to-nitrogen ratio

technical field

The invention relates to the technical field of wastewater biological treatment, in particular to a treatment system and method for aquaculture wastewater with a low carbon-to-nitrogen ratio.

Background technique

my country's aquaculture is mostly carried out in a high-density intensive factory farming model. The ammonia nitrogen and nitrite nitrogen content in the water of this farming model often seriously exceeds the standard, which has a destructive impact on the development of aquaculture. Initially, in order to maintain a good In such a breeding environment, farmers increase the frequency of water changes, which not only wastes water resources, but also directly discharges wastewater that endangers the surrounding water ecological environment.

Among the two main methods for denitrification of aquaculture wastewater, the biological denitrification method has the advantages of low cost, no secondary pollution, and no damage to the ecological balance of aquaculture compared with physical and chemical methods, and is the preferred method for treating aquaculture wastewater; at present, the traditional The biological denitrification process with nitrification/denitrification as the core has been widely used. For example, the Chinese invention patent with the application publication number of CN105692900 A discloses a short-range nitrification-denitrification intermittent aeration sequence batch biological reaction device and treatment The method of high ammonia nitrogen sewage realizes the efficient treatment of high ammonia nitrogen sewage and reduces the nitrogen and phosphorus content of sewage.

However, most of the aquaculture wastewater has the characteristics of low carbon-nitrogen ratio, especially the wastewater from greenhouse soft-shelled turtle farming, and more than 70% of the water samples have a carbon-nitrogen ratio of less than 2. Studies have shown that under the condition of low carbon-to-nitrogen ratio, the nitrogen removal rate of the traditional process is significantly reduced, and the process needs to be improved to ensure the nitrogen removal effect.

Contents of the invention

The purpose of the present invention is to provide a treatment system and wastewater treatment method for aquaculture wastewater with a low carbon-to-nitrogen ratio, which is suitable for aquaculture wastewater treatment with a lower carbon-to-nitrogen ratio (C/N, C in COD). The removal rates of ammonia nitrogen, nitrite nitrogen and total nitrogen can basically be kept above 90%.

In order to achieve the above object, a treatment system for aquaculture wastewater with a low carbon-to-nitrogen ratio designed by the present invention is used to treat aquaculture wastewater, including a nitrification unit and a denitrification unit connected together, a waste water storage unit, for The connected pipeline and the circulating pump that circulates the wastewater in the above-mentioned device, the wastewater first flows through the nitrification device, and then flows through the denitrification device; the nitrification device is composed of a nitrification grid, and the nitrification The grids are filled with nitrification fillers, the denitrification device is composed of denitrification grids, and the denitrification grids are filled with solid-phase carbon source fillers.

The nitrifying filler is used to provide the attachment surface of nitrifying bacteria, promote its enrichment and growth, and become a "nitrifying field" for nitrifying bacteria to transform ammonia nitrogen substances. Generally speaking, the larger the surface area, the better; the solid-phase carbon source filler is suitable for low-carbon nitrogen It is more important than the denitrification and denitrification of aquaculture wastewater, which can provide the carbon source required by denitrifying bacteria and enhance the removal efficiency of nitrogen.

As a preference of the above technical solution, the nitrifying filler is several suspended fillers, the suspended fillers include several concentric circles and connecting parts connecting the circles, which are hollow structures, and under the action of water flow and aeration, In a suspended fluidized state. As a preference of the above technical solution, the nitrification filler is an elastic filler suspended in the nitrification grid, and several branches extending from the periphery of the elastic filler are arranged.

The specific surface area of the suspended filler is >100m ² /m ³ , which provides space for a large number of microorganisms to attach and grow, especially for the growth of autotrophic and attached growth characteristics of nitrifying bacteria. At the same time, the easy fluidization of the filler increases the impact and cutting of the bubbles, improves the utilization rate of oxygen, makes the microorganisms in a logarithmic growth period of high activity, and improves the removal of organic matter and the conversion efficiency of ammonia nitrogen and other substances.

The suspended elastic filler has the characteristics of integration, its loading and unloading is convenient and quick, the filler itself has a large specific surface area, a large space for microorganisms to attach, and is easy to hang a film. The oxygen transfer rate and utilization rate are improved, which is beneficial to the nitrification reaction.

As a preference of the above technical solution, both the nitrification grill and the denitrification grill are composed of an upper opening grill and a lower opening grill arranged alternately, the bottom of the upper opening grill is sealed, and the upper opening The horizontal position is lower than the upper end of the lower opening grille; the bottom opening of the lower opening grille is open, and the horizontal position of the upper end is higher than the upper end of the upper opening grille.

The purpose of such setting is to prolong the flow path and residence time of the aquaculture wastewater, so that the nitrification and denitrification reactions in the aquaculture wastewater can be fully carried out, and the removal efficiency of nitrogen is improved.

As a preference of the above technical solution, the solid-phase carbon source filler is cylindrical particles made of PHBV material.

Methanol, ethanol, acetic acid, and glucose can also be used as carbon sources, but they are prone to insufficient or excessive dosage, unstable denitrification effect, and troublesome maintenance; some natural solid-phase carbon sources, such as: straw. Bark, reed, etc. are cheap, but when they degrade, they will produce a large amount of ammonia, which is accompanied by the environmental pollution problem of deepening the color of the effluent.

PHVB (polyhydroxybutyrate valerate) is an organic high molecular polymer obtained by bio-fermentation engineering. It is an aliphatic polymer produced by microorganisms in a state of non-equilibrium (such as lack of nitrogen and phosphorus), storing certain organic compounds as their own energy and carbon sources in the body, and is essentially an energy reserve for microbial growth. PHBV has a wide range of sources because it can use various organic substances such as starch sugar, food industry waste, discarded fruits, vegetables, and plant debris as raw materials. PHBV has good biodegradability, and it degrades and releases carbon sources under the action of microbial enzymes.

When the concentration of nitrogen in the water body is high, denitrifying bacteria are active, the amount of enzymes related to degrading PHBV increases relatively, and more carbon sources are released; as the concentration of nitrogen decreases, the activity of denitrifying bacteria decreases, and the related enzymes The amount of carbon will decrease accordingly, and the release of carbon sources will also decrease accordingly. Therefore, PHBV not only provides a continuous carbon source for biological denitrification, but also acts as a slow-release carbon source, whose degradation rate can be adjusted accordingly with changes in the environment, without deteriorating water quality due to the release of excessive organic carbon. . On the one hand, PHBV as a solid matrix is conducive to the formation of biofilms. On the other hand, during the operation of denitrification and denitrification, frequent maintenance is not required, and only carbon sources need to be added or replaced on time. The cycle can be counted annually, which is to a considerable extent It simplifies the control process and operating costs. In actual use, the solid-phase carbon source filler made of PHVB is divided into mesh bags, and then put into the denitrification grid.

As a preference of the above technical solution, the outlet end of the denitrification device is provided with a water intake.

As a preference of the above technical solution, an aeration device is arranged in the nitrification grid of the nitrification device.

As a preference of the above technical solution, an oxygen reduction device is provided between the nitrification device and the denitrification device, the oxygen reduction device includes several grids, and there is no filler in the grids.

The purpose of the oxygen reduction device is to reduce the dissolved oxygen in the water body. The aeration of the nitrification device will increase the dissolved oxygen in the feed liquid, which will inhibit the reaction of the denitrification device, thereby reducing the denitrification efficiency.

A method for treating wastewater, comprising the steps of:

①Microbial growth: Inject aquaculture wastewater into the treatment system, turn on the circulation pump to keep the treatment system in operation, keep the operating environment temperature at 25~30°C, replace half of the aquaculture wastewater every 3 days, and take water samples to detect other The concentration of NH ₄ -N, NO ₂ -N and TN, the film formation will be completed after the concentration of the above substances is stable;

②Cyclic treatment: Inject the aquaculture wastewater to be treated, circulate it in the treatment system, control the circulation period of the aquaculture wastewater at 8 hours by setting the flow rate of the circulation pump, and discharge the aquaculture wastewater after treatment;

③Repeat: Repeat step ②.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The wastewater treatment system and wastewater treatment method are suitable for the treatment of aquaculture wastewater with a low carbon-nitrogen ratio. It can form a biofilm composed of bacterial communities on the filler, and the removal rate of ammonia nitrogen, nitrite nitrogen and total nitrogen can basically be achieved. Keep above 90%;

This application uses Miseq high-throughput sequencing technology to analyze the bacterial community composition and structure of the biofilm a on the packing in the nitrification device and the biofilm b on the PHBV packing in the denitrification device. The following table:

Among them, Proteobacteria was the most dominant phylum in a and b, accounting for 93.26% in a sample and 65.68% in b. Nitrospira is the unique dominant species in a. Firmicutes, Bacteroidetes, Spirochetes and Chlorobacteria were identified in both biofilm samples, but their proportion in b was much higher than that in a.

(2) The wastewater treatment system operates stably without secondary pollution;

(3) The wastewater treatment system is easy to maintain;

(4) The wastewater treatment system and treatment method are easy to operate.

Description of drawings

Fig. 1 is a schematic structural diagram of a treatment system for aquaculture wastewater with a low carbon-to-nitrogen ratio.

Fig. 2 is a schematic diagram of the structure of the aquaculture wastewater flow channel formed by the upper opening grille and the lower opening grille.

Figure 3 is a schematic diagram of the structure of the suspended filler.

Figure 4 is a schematic diagram of the structure of the elastic filler.

Fig. 5 is the variation trend graph of each substance concentration and pH value over time in the microbial film hanging stage described in embodiment 3;

Fig. 6 is the variation trend diagram of nitrogenous substance concentration and pH value over time in the process described in embodiment 3;

Fig. 7 is the variation trend diagram of nitrogenous substance concentration and pH value over time in the process described in embodiment 4;

In the figure: nitrification device 1, nitrification grid 11, nitrification filler 12, suspension filler 12-a, elastic filler 12-b, denitrification device 2, denitrification grid 21, solid-phase carbon source filler 22, water intake 23, Upper opening grill a, lower opening grill b, waste water storage device 3, pipeline 4, circulation pump 5, aeration device 6, oxygen reduction device 7.

detailed description

Below in conjunction with accompanying drawing and specific embodiment the present invention will be described in further detail:

Embodiment 1: With reference to Fig. 1 ~ Fig. 3, the treatment system for aquaculture wastewater with low carbon-to-nitrogen ratio includes nitrification device 1, oxygen reduction device 7 and denitrification device 2, waste water storage device 3, for The connected pipeline 4 and the circulating pump 5 that circulates the waste water in the above-mentioned device also include an aeration device 6 arranged in the nitrification grid 11 of the nitrification device 1, the waste water flows through the nitrification device 1 first, Then flow through the denitrification device 2;

The nitrification device 1 is composed of a nitrification grid 11, and the nitrification grid 11 is filled with a nitrification filler 12, and the nitrification filler 12 is a plurality of suspension fillers 12-a, and the suspension filler 12-a includes several circles with the same center and a connecting portion connecting said circles;

The denitrification device 2 is composed of a denitrification grid 21, and the denitrification grid 21 is filled with a solid-phase carbon source filler 22, and the solid-phase carbon source filler 22 is a cylindrical particle made of a PHBV material , the outlet end of the denitrification device 2 is provided with a water intake 23;

The oxygen-reducing device 7 includes four grilles, and no filler is arranged therein.

Both the nitrification grid 11 and the denitrification grid 21 are composed of an upper opening grid a and a lower opening grid b arranged alternately, the bottom of the upper opening grid a is sealed, and the horizontal position of the upper end It is lower than the upper end of the lower opening grid b; the bottom of the lower opening grid b is open, and the horizontal position of the upper end is higher than the upper end of the upper opening grid a.

Embodiment 2: Referring to Fig. 1, Fig. 2 and Fig. 4, the difference from Embodiment 1 is that the nitrification filler 12 is an elastic filler 12-b suspended in the nitrification grid 11, and the elastic filler 12-b is surrounded by a number of extending branches.

Embodiment 3: with reference to Table 1, with reference to Fig. 5, Fig. 6, a kind of aquaculture wastewater treatment method, is used for processing soft-shelled turtle culture wastewater, comprises the steps:

①Microbial film formation: Inject aquaculture wastewater into the treatment system, and turn on the circulation pump to keep the treatment system in operation, adjust the circulation pump to circulate the aquaculture wastewater every 24 hours, keep the operating environment temperature at 25~30℃, and replace it every 3 days Half of the aquaculture wastewater, water samples were taken the next day to measure the concentration of NH ₄ -N, NO ₂ -N and TN. After the concentration of the above substances stabilized, the film formation was completed. This process lasted for 4 weeks, and finally the NH in the water was measured. The values of ₄ -N, NO ₂ -N and TN were stable at 1.0~1.4mg/L, 0.05~0.07mg/L, 12~15mg/L respectively, and the pH value was 7.2~7.5;

②Cyclic treatment: Inject the aquaculture wastewater to be treated, circulate it in the treatment system, control the circulation period of the aquaculture wastewater at 8 hours by setting the flow rate of the circulation pump, and discharge the treated aquaculture wastewater after 96 hours of treatment;

③Repeat: Repeat step ②.

The contents of NH ₄ -N, NO ₂ -N and TN in soft-shelled turtle breeding wastewater were reduced to 1.2mg/L, 0.05mg/L, 2.0mg/L respectively, and the removal rates of ammonia nitrogen, nitrite nitrogen and total nitrogen were 97.58% , 97.02% and 98.43%.

Table 1 The water quality of the waste water to be treated in Example 3 and Example 4

Embodiment 4: with reference to table 1, Fig. 7, a kind of aquaculture wastewater treatment method, is used to process South American prawn culture wastewater, comprises the steps:

1. Microbial film formation: the processing system used in Example 3 has been used to complete the film formation, and the present embodiment will not repeat the film formation;

②Cyclic treatment: Inject the untreated Penaeus vannamei culture wastewater, circulate it in the treatment system, control the circulation period of the culture wastewater at 8 hours by setting the flow rate of the circulation pump, and discharge the treated culture wastewater after 48 hours of treatment;

③Repeat: Repeat step ②.

The contents of NH4-N, NO2-N and TN in the South American shrimp culture wastewater were reduced to 0.36mg/L, 0.02mg/L and 1.2mg/L respectively, and the removal rates of ammonia nitrogen, nitrite nitrogen and total nitrogen were 90.24%, 98.60% and 90.4%.

When other types of aquaculture wastewater are treated in Example 3 and Example 4 thereafter, it is not limited to this type of aquaculture wastewater, and there is no need to repeat the step of microbial film formation.

Claims (9)

1. for the processing system of low ratio of carbon to ammonium aquiculture waste water, for handling aquiculture waste water, it is characterised in that：Including The nitrification installation linked together（1）And denitrification device（2）, storage of waste water device（3）, pipeline for connection（4）And Make the circulating pump that waste water is circulated in said apparatus（5）, waste water first flows through the nitrification installation（1）, pass through described anti- Nitrification installation（2）；The nitrification installation（1）By nitrification grid（11）Combine, the nitrification grid（11）It is interior to be filled with nitre Change filler（12）, the denitrification device（2）By denitrification grid（21）Combine, the denitrification grid（21）Interior filling There is solid-phase carbon source filler（22）.

2. the processing system according to claim 1 for low ratio of carbon to ammonium aquiculture waste water, it is characterised in that：The nitre Change filler（12）For several floating stuffings（12-a）, the floating stuffing（12-a）Circle and connection including some concentrics The connecting portion of the circle.

3. the processing system according to claim 1 for low ratio of carbon to ammonium aquiculture waste water, it is characterised in that：The nitre Change filler（12）To be suspended on the nitrification grid（11）Interior elastic filler（12-b）, the elastic filler（12-b）Surrounding It is provided with some branches extended out.

4. the processing system according to claim 1 for low ratio of carbon to ammonium aquiculture waste water, it is characterised in that：The nitre Change grid（11）With the denitrification grid（21）By the upper shed grid being staggered（a）With under shed grid（b）Combination Form, the upper shed grid（a）Bottom shut, the horizontal level under shed grid of upper end（b）Upper end it is low；Institute State under shed grid（b）Bottom opening, the horizontal level upper shed grid of upper end（a）Upper end it is high.

5. the processing system according to claim 1 for low ratio of carbon to ammonium aquiculture waste water, it is characterised in that：It is described solid Phase carbon source filler（22）The cylindrical pellet being made for PHBV materials.

6. the processing system according to claim 1 for low ratio of carbon to ammonium aquiculture waste water, it is characterised in that：It is described anti- Nitrification installation（2）The port of export be provided with intake（23）.

7. the processing system according to claim 1 for low ratio of carbon to ammonium aquiculture waste water, it is characterised in that：The nitre Makeup is put（1）With the denitrification device（2）Between be provided with drop oxygen device（7）, the drop oxygen device（7）Including several lattice No-arbitrary pricing in grid, the grid.

8. the processing system for low ratio of carbon to ammonium aquiculture waste water according to any bar in claim 1 ~ 7, its feature It is：The nitrification installation（1）Nitrification grid（11）Inside it is provided with aerator（6）.

9. one kind is using the method for wastewater treatment that processing system described in any bar is handled in claim 1 ~ 8, it is characterised in that：Bag Include following steps：

1. microorganism colonization：Breeding wastewater is injected in the processing system, and open the circulation pump causes processing system to be in operation shape State, it is 25 ~ 30 DEG C to remain on environment temperature, the breeding wastewater for changing half in every 3 days, and water sampling determines its NH every other day₄-N、 NO₂It is that biofilm is completed after-N and TN concentration, the measure value stabilization of above-mentioned substance content；

2. circular treatment：The pending breeding wastewater of injection, in the processing of processing system interior circulation, by the flow for setting circulating pump The cycle period of breeding wastewater was controlled at 8 hours, breeding wastewater is discharged after processing；

3. repeat：Repeat step is 2..