CN110915749A

CN110915749A - Method for efficiently collecting sewage by using water dynamics

Info

Publication number: CN110915749A
Application number: CN201911342877.8A
Authority: CN
Inventors: 舒锐; 尹立鹏; 黄江
Original assignee: Guangzhou Guanxing Agricultural Technology Co Ltd
Current assignee: Guangzhou Zhongmiao investment partnership (limited partnership)
Priority date: 2019-12-23
Filing date: 2019-12-23
Publication date: 2020-03-27
Anticipated expiration: 2039-12-23
Also published as: CN110915749B

Abstract

The invention discloses a method for efficiently collecting sewage by utilizing water dynamics, and aims to provide a sewage collecting method capable of effectively and obviously improving the sewage collecting capacity of a culture pond³/h。

Description

Method for efficiently collecting sewage by using water dynamics

Technical Field

The invention relates to a sewage collection method, in particular to a sewage collection method for a fish culture pond, and belongs to the technical field of aquatic animal culture.

Background

The prior aquatic animals such as fishes and the like usually adopt pond culture or cage culture technology, a large amount of feed is used for feeding in the culture process, feed scraps and fish excrement enter a water body, and residual feed is formed due to insufficient utilization of the feed in the feed feeding process. Excrement and urine and incomplete bait if not got rid of in time, can cause the rapid rising of ammonia nitrogen nitrite nitrogen, cause harm to the breed biology, and seriously influence the effect and the efficiency of water treatment, traditional handicraft is through water pump or waterwheel with the filth in the pond together with the pond water discharge away together, get rid of the filth completely, then pour into new water into again, this operation need consume a large amount of manpowers and human and materials, waste water resource, work efficiency is low.

Also some prior art adopt to breed the mode of aeration in the pond and carry out album dirty, at present, adopt among the prior art be unilateral aeration's mode, aeration pipe near waters region, the water velocity of flow is great relatively, leads to incomplete bait excrement and urine breakage easily, and other water velocity of flow are too little, lead to the granule free settlement easily and deposit the bottom, are unfavorable for keeping excrement and urine granule shape and collecting excrement and urine to collection dirty groove.

In addition, the dead water area in the culture pond has a large influence on the water quality of the culture system, the dissolved oxygen is low, germs are easy to breed, and if the adopted sewage collection method is improper, the area of the dead water area can be increased, so how to further improve the sewage collection capacity of the culture tank is the key point of research in the field.

Disclosure of Invention

The invention provides a sewage collecting method which can effectively and obviously improve the sewage collecting capacity of a culture pond.

Therefore, the technical scheme provided by the invention is as follows:

a method for efficiently collecting sewage by utilizing water dynamics comprises the steps of firstly assembling a circumferential aeration type sewage collecting box, and carrying out circumferential aeration in the circumferential aeration type sewage collecting box to collect sewage, so that the flow velocity of water in the circumferential aeration type sewage collecting box is 0.06-0.19m/s, and the flow rate of inlet air is 4.36-5.2m³/h。

Further, the method for efficiently collecting sewage by utilizing water dynamics is characterized in that a circumferential aeration type sewage collecting box is assembled firstly, and sewage is collected in the circumferential aeration type sewage collecting box in a circumferential aeration mode, so that the flow rate of water in the circumferential aeration type sewage collecting box is 0.13/h, and the air inlet flow rate is 4.84m³/h。

Further, the method for efficiently collecting sewage by utilizing water dynamics is characterized in that the circumferential aeration type sewage collecting tank comprises a tank body, a water inlet is formed in one side wall of the tank body, a water outlet is formed in the other opposite side wall of the tank body, a sewage collecting groove is formed in the tank body and is close to the side wall provided with the water outlet, a slope is further arranged at the inner bottom of the tank body, the lower end of the slope is fixed to the edge of the sewage collecting groove, and the upper end of the slope is fixed to the side wall provided with the water inlet; the side wall of the box body at the periphery of the slope is provided with a plurality of aeration pipes, the aeration pipes are distributed on the side wall of the box body in a ring shape, and a space is reserved between every two adjacent aeration pipes.

Further, the method for efficiently collecting sewage by utilizing water dynamics is characterized in that the center-to-center distance between the single-side-wall aeration pipes is 2.8 m.

Further, the method for efficiently collecting the sewage by utilizing the water dynamics is characterized in that the caliber of an inlet on the box body is 90mm, the caliber of an outlet is 75mm, and the total length of the aeration pipe is 2.2 m.

Compared with the prior art, the technical scheme provided by the invention effectively solves the problems that in the sewage collection process in the prior art, the broken residual bait and excrement is easy to cause, the particles are easy to settle freely to deposit at the bottom, the shape of the excrement particles is not favorably maintained, and the excrement is not favorably collected to the sewage collection box; and the probability of dead water zones and the area of the dead water zone is much smaller.

The technical scheme provided by the invention has high separation efficiency, and the peripheral aeration culture pond has high particle separation efficiency within 60s relative to the single-side aeration culture pond and is about 2 times of the single-side aeration culture pond.

Drawings

FIG. 1 is a schematic structural view of a circumferentially aerated dirt collection tank provided by the present application;

FIG. 2 is a schematic structural view of a single-side aeration type sewage collection tank in the prior art;

FIG. 3 is a graph showing the monitoring of the average flow rate in the aeration tank around the circumference;

FIG. 4 is a velocity profile (representative cross-sectional velocity cloud) in a single-sided aerated culture pond;

FIG. 5 is a velocity profile (representative cross-sectional velocity cloud) in a circumferential aeration aquaculture pond;

FIG. 6 is a cloud of velocity vector distributions for a single-side aeration culture pond;

FIG. 7 is a cloud of velocity vector distributions of the circumferential aeration culture pond;

FIG. 8 is a cloud view of the low flow velocity region distribution of a single-side aeration culture pond;

FIG. 9 is a cloud picture of the low flow rate region distribution of the circumferential aeration culture pond

FIG. 10 is a single-sided aerated culture pond fluid trace analysis;

FIG. 11 is a circumferential aeration culture pond fluid trace analysis.

Detailed Description

The following claims are presented to illustrate the invention in further detail in connection with the detailed description of the invention, but not to limit the invention in any way.

Example 1

The invention discloses a method for efficiently collecting sewage by utilizing water dynamics, which comprises the steps of firstly assembling a circumferential aeration type sewage collecting box, and carrying out circumferential aeration in the circumferential aeration type sewage collecting box to collect sewage, wherein the air inlet flow is 4.84m³H (0.022m/s) to ensure that the flow velocity of the water body in the circumferential aeration sewage collection tank is 15m³/h

(0.06-0.19 m/s).

Specifically, the circumferential aeration type sewage collection tank, referring to fig. 1, comprises a tank body 1, wherein one side wall of the tank body 1 is provided with a water inlet 2 with the caliber of 90mm, the other opposite side wall is provided with a water outlet 3 with the caliber of 75mm, and the water outlet is also provided with a filter screen. A sewage collecting groove 4 is formed in the box body 1, the sewage collecting groove 4 is close to the side wall provided with the water outlet 3, a slope 5 is further arranged at the inner bottom of the box body 1, the included angle between the slope and the horizontal plane is 10-20 degrees, the lower end of the slope 5 is fixed at the edge of the sewage collecting groove 4, and the upper end of the slope 5 is fixed on the side wall provided with the water inlet 2; five aeration pipes 6 are arranged on the side wall of the box body at the periphery of the slope 5, two aeration pipes 6 are respectively arranged at the front side and the rear side, and one aeration pipe 6 is arranged on the side wall provided with the water inlet 2. The aeration pipes 6 are preferably single-hole membrane aeration pipes, the total length of each single aeration pipe is 2.2m, the aeration pipes 6 are distributed on the side wall of the box body in a ring shape, and a space is reserved between every two adjacent aeration pipes 6. The center distance of the single-side wall aeration pipe is 2.8 m.

To better illustrate the advantages of the solution provided by the present application, a comparative solution using single-side aeration type sewage collection is given below:

the method is that a sheet is firstly assembledThe side aeration type sewage collecting tank collects sewage in a single side aeration mode in the single side sewage collecting tank, and the air inlet flow is 4.84m³H (0.022m/s) to ensure that the flow velocity of the water body in the single-side aeration sewage collection tank is between 0.06 and 0.19 m/s.

Specifically, the single-side aeration type dirt collection tank, referring to fig. 2, includes a tank body 1A, one side wall of the tank body 1A is provided with a water inlet 2A with a caliber of 90mm, the other opposite side wall is provided with a water outlet 3A with a caliber of 75mm, and the water outlet is also provided with a filter screen. A sewage collecting groove 4A is formed in the box body 1A, the sewage collecting groove 4A is close to the side wall provided with the water outlet 3A, a slope 5A is further arranged at the inner bottom of the box body 1A, the included angle between the slope and the horizontal plane is 10-20 degrees, the lower end of the slope 5A is fixed to the edge of the sewage collecting groove 4A, and the upper end of the slope 5A is fixed to the side wall provided with the water inlet 2A; five aeration pipes 6A which are arranged up and down are arranged on the side wall provided with the water inlet, the aeration pipe 6A is preferably a single-hole film aeration pipe, and the total length of the single aeration pipe is 2.2 m.

In order to better illustrate the advantages of the scheme provided by the application, the two schemes are given below to simulate the flow field condition of the container circulating water culture tank, and the excrement particles are simplified into spherical particles with the particle size of 1mm, and the density of the spherical particles is set to be 1.19g/cm³Eighteen typical position points are selected to release the particles, and the motion conditions of the particles at different positions are observed.

1. Calculation model

1.1. Geometric model

The material parameters and environmental condition settings for the simulation are shown in table 1:

TABLE 1 parameter settings

Parameter(s)	Numerical value
		Particle diameter mm	0.1
Density of the granules kg/m³	1190
		Density of culture water (liquid) kg/m³	1000
Acceleration of gravity N/kg	9.81
		Pressure Pa	101325

1.2. Mathematical model

For circulating water culture

For the colonial pool, the volume fraction of fecal particles is about 5%, and therefore, a discrete phase model was chosen for numerical simulation calculations. In addition, the flow field of the culture pond is turbulent flow, a Realisable k-e model is selected, and the condition of reinforcing the wall surface-wall surface is considered.

1.3. Simulation of operating conditions

Because the inflow flow can not be directly set in the CFD simulation process, relevant conversion is needed, and relevant working conditions are specifically shown in table 2 after conversion:

TABLE 2 analysis of the operating conditions

2. Analysis of simulation results

For the simulation of DPM, a continuous phase flow field is simulated without injecting particles, and particles are injected after the continuous phase calculation converges. Generally speaking, in the numerical simulation process, the simulation result is only representative based on the convergent flow field, and the convergence of the flow field can be judged through a residual error curve, but the convergence is also relative to different residual error standards, so that the average flow rate of the culture pond space is introduced and monitored in the report to assist in judging the convergence, and the analysis is performed by taking the circumferential aeration pond simulation as an example. As shown in fig. 3, which is a monitoring result of the change of the average velocity of the flow field with time after the single-side aeration tank simulated particles are injected, the simulation calculation of the circumferential aeration culture tank shown in the simulation shows that the average flow velocity of the flow field tends to be stable for about 70s, and the convergence of the flow field is determined by combining the corresponding residual curve result. Then, DPM simulation calculation is carried out, and the average flow velocity of the flow field after injection fluctuates and then tends to be stable.

2.1. Velocity profile analysis

FIGS. 4 and 5 show the velocity clouds (same scale) at representative cross-sections of the interior of the culture pond for two aeration modes under corresponding working conditions. As can be seen from the figure 4, in the water area of the aeration pipe accessory, the flow velocity of the water body is relatively large, so that the residual bait and the excrement are easily crushed, and the flow velocity of other water bodies is too small, so that the particles are easily deposited at the bottom by free sedimentation, and the shape of the excrement particles is not kept, and the excrement is collected to the excrement collecting box. As can be seen from FIG. 5, the distribution of the flow velocity of the water in the circumferential aeration culture pond is relatively uniform and smooth, the velocity is between 0.06 m/s and 0.19m/s, the shape of the excrement is relatively kept, and the bottom of the excrement can be prevented from being deposited by notification.

2.2. Velocity vector analysis

FIGS. 6 and 7 show the internal velocity vector cloud diagrams of the culture pond in two aeration modes under corresponding working conditions. As can be seen from FIG. 6, the water flow in the unilateral aeration culture pond mainly forms stronger vortex flow near the water inlet, and the other areas are plug flow, but the flow speed is lower. As can be seen from FIG. 7, for the circumferential aeration culture pond, more vortexes are formed in the culture pond, the flow field is relatively disordered, and the sedimentation of particles at the bottom is favorably avoided, so that the particles are discharged from the outlet of the culture pond and then are treated by the subsequent process.

2.3. Analysis of risk of dead water zone

Dead water in the culture pond has great influence on the water quality of a culture system, and dissolved oxygen is low at the dead water, so that germs are easy to breed. In general, areas with flow velocities less than 0.01m/s are considered as areas where high risk of dead water run-off occurs. FIGS. 8 and 9 show the distribution of the internal velocities of the culture ponds of the two aeration modes in the corresponding working conditions in the area less than 0.01m/s respectively. As can be seen from FIG. 8, as analyzed above, the distribution of the low flow rate in the single-side aeration culture pond is wide, and particularly, a large amount of low-speed flowing water is present in the bottom of the culture pond and the middle area of the culture pond below the aeration pipe. As can be seen from FIG. 9, in the case of the peripheral aeration culture pond, the low-speed flowing water area in the culture pond is small, particularly, the low-speed water area at the bottom corner of the culture pond is still small, and it can be judged that the probability of the dead water area of the culture pond relative to the single-side aeration culture pond and the area of the dead water area are much smaller.

2.4. Fluid trace analysis

The traces are the flow traces of the same particle over a continuous time course. The traces relate only to fluid particles and analyzing the trace shape allows a more detailed description of the flow state of the fluid, and is complementary to the velocity analysis. Fig. 10 and fig. 11 show the fluid traces (same density) in the culture pond of the two aeration modes respectively. The fluid trace cloud further verifies the analysis of the velocity vector cloud for water motion. As can be clearly seen from fig. 10, the unilateral aeration culture pond forms a large vortex at the air inlet, the water flow rate of the cutting accessory is high, and the traces are sparse in other areas due to low flow rate. As can be seen from FIG. 11, the circumferential aeration mode forms more rotational flows in the culture pond, so that the deposition of particles can be avoided, and the water flow speed is not high, so that the excrement particles are not broken. In general, the circumferential aeration type culture pond has a good sewage collecting effect compared with a single-side aeration type culture pond.

DPM model analysis

When the stokes number of the particles is small, the particle following performance is good, and the trace of the fluid represents the motion track of the particles, but in the model related to the simulation, the density of the solid particles is different from that of the fluid to a certain extent, and the density of the solid particles is influenced by the fluid turbulence effect, but the track of the solid particles is not similar to the motion track of the fluid, so that further analysis is needed to obtain the motion form of the whole flow field. The method is characterized in that a Discrete Phase Model (DPM) is adopted to carry out numerical simulation research on the method, and eighteen points in two culture ponds are adopted as particle source release points. The specific particle discharge conditions in the two culture ponds within 60s are shown in Table 3. As can be seen from Table 3, the start of the particle separation in the unilateral aerated culture pond relative to the circumferential aerated culture pond is earlier (5% already separated at 10 s), which may be caused by the deposition of particles near the water discharge port. However, in general, the efficiency of the separation of particles in the circumferential aeration culture pond is higher than that of the single-side aeration culture pond within 60s, and is about 2 times that of the single-side aeration culture pond.

TABLE 3 efficiency of particle exclusion

According to the analysis, the water body in the circumferential aeration culture pond is relatively disordered, the rotational flow is more, but the speed is not high, the water body in the unilateral aeration culture pond only forms strong rotational flow at the water inlet, the water body speed is higher, particles are easy to break, the subsequent solid-liquid separation treatment difficulty is increased, and the risk of a dead water area in other areas of the culture pond is higher. In addition, the peripheral aeration culture pond has strong sewage collecting capacity relative to a single-side aeration culture pond by combining the particle discharge efficiency. Aiming at the further improvement of the sewage collecting capacity of the circumferential aeration culture pond, the area of a dead water area with the central interval of 2800mm of the aeration pipe is smaller, and the improvement of the sewage collecting capacity is facilitated.

Claims

1. A method for efficiently collecting sewage by utilizing water dynamics is characterized in that a circumferential aeration type sewage collecting box is assembled firstly, and sewage is collected in the circumferential aeration type sewage collecting box in a circumferential aeration mode, so that the flow rate of water in the circumferential aeration type sewage collecting box is 0.06-0.19m/s, the air inlet flow is 4.36-5.2m³/h。

2. The method of claim 1, wherein the sewage collection tank is first assembled and sewage is collected by performing a circumferential aeration in the circumferential aeration sewage collection tank, so that the flow rate of water in the circumferential aeration sewage collection tank is 0.13m/s and the flow rate of intake air is 4.84m³/h。

3. The method for efficiently collecting sewage by utilizing water dynamics as claimed in claim 1, wherein the circumferentially aerated sewage collection tank comprises a tank body (1), one side wall of the tank body (1) is provided with a water inlet (2), the other opposite side wall is provided with a water outlet (3), a sewage collection tank (4) is arranged in the tank body (1), the sewage collection tank (4) is close to the side wall provided with the water outlet (3), the inner bottom of the tank body (1) is also provided with a slope (5), the lower end of the slope (5) is fixed at the edge of the sewage collection tank (4), and the upper end of the slope (5) is fixed on the side wall provided with the water inlet (2); the side wall of the box body at the periphery of the slope (5) is provided with a plurality of aeration pipes (6), the aeration pipes (6) are distributed on the side wall of the box body in a ring shape, and a gap is reserved between every two adjacent aeration pipes (6).

4. The method of claim 3, wherein the center-to-center distance between the aeration tubes is 2.8 m.

5. The method for efficiently collecting sewage by utilizing water dynamics as claimed in claim 3, wherein the caliber of the water inlet (2) on the box body (1) is 90mm, the caliber of the water outlet (3) is 75mm, and the total length of the aeration pipe is 2.2 m.