CN112537889B - Process for repairing aquaculture wastewater - Google Patents

Abstract

The invention belongs to the technical field of environmental protection, and discloses a process for repairing aquaculture wastewater, which comprises the following steps: step 1) preparing algae microspheres, step 2) pretreatment of cultivation wastewater, and step 3) wastewater restoration treatment. The algae microsphere preparation is adopted in the process, so that the treatment efficiency is high, the method is simple and feasible, and the environment friendliness is strong.

Description

Process for repairing aquaculture wastewater

Cross reference

The present application claims priority from chinese patent application No. 201711334763X, entitled "a process for remediation of aquaculture wastewater," filed on 12/14/2017, the disclosure of which is incorporated herein by reference in its entirety.

Technical Field

The invention belongs to the technical field of environmental protection, and particularly relates to a process for repairing aquaculture wastewater.

Background

The aquaculture wastewater is wastewater produced by the aquaculture industry. With the continuous expansion of the intensive cultivation scale, metabolites, residual bait organic matters, ammonia nitrogen and other inorganic matters generated by feeding become new pollution sources, and meanwhile, the increasingly aged and polluted water environment restricts the further development of the cultivation industry. The cultivation wastewater has typical three-high characteristic, COD is up to 3000-12000mg/l, ammonia nitrogen is up to 800-2200mg/l, and P exceeds the standard by tens of times. The method is limited to the cultivation industry, the current treatment process can only be used for greatly reducing COD, and great technical and economic difficulties exist for up-to-standard emission of ammonia nitrogen, phosphorus and the like. The large-scale livestock and poultry breeding wastewater treatment is paid great attention to the owners of farms and related departments, and a series of prevention measures and economic and efficient treatment technologies are adopted. Along with the increasingly updated national sewage discharge standard, the problem of standard discharge of high-concentration cultivation wastewater is more prominent.

The cultivation wastewater treatment technology adopted at present mainly comprises the following steps: a combined stabilizing pond process, a UASB+SBR process, a ZWD novel biogas digester+biological cycle treatment process, a reinforced pretreatment, a high-efficiency baffled anaerobic reactor, an oxidation pond, a multistage acidification-constructed wetland treatment process and the like. Although there are many researches on the treatment of farm wastewater at home and abroad, there are some treatment methods, from the comprehensive analysis of the existing reported data, the treatment effect of any method is not ideal, or the effluent quality can not meet the discharge requirement, or the cost is too high to be popularized and applied in China.

As the cultivation wastewater contains a large amount of nitrogen, phosphorus and other nutrient substances required by the growth of algae, the water treatment and the large-scale cultivation of the algae are combined, so that the wastewater can be discharged at low cost, the cost of microalgae cultivation can be saved, and meanwhile, the microalgae also contains a large amount of high-added-value products. At present, some reports about algae wastewater treatment exist, and the Chinese patent technology, namely a method for purifying pig farm fermentation wastewater by using chlorella, adopts domestication culture of the chlorella and then treats the wastewater. The prior art needs to develop a more efficient and simple processing method.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a process for repairing aquaculture wastewater. The process technology adopts the composite algae preparation, has high treatment efficiency, is simple and feasible, and has strong environmental friendliness.

The invention is realized by adopting the following technical scheme:

a process for remediation of aquaculture wastewater comprising the steps of: step 1) preparing algae microspheres, step 2) pretreatment of cultivation wastewater, and step 3) wastewater restoration treatment.

In particular, the method comprises the steps of,

the process comprises the following steps:

step 1) preparing algae microsphere: mixing the chlorella liquid, the clinopodium liquid and the Fusarium liquid according to the volume ratio of 2:1:1 to obtain mixed algae liquid, then adding sodium alginate aqueous solution with the concentration of 5wt% accounting for one half of the volume of the mixed algae liquid, urea accounting for 2wt% of the mixed algae liquid and sodium bicarbonate accounting for 4 wt% of the mixed algae liquid, uniformly stirring, then dropwise adding calcium chloride aqueous solution with the concentration of 2wt% accounting for 2 times of the volume of the mixed algae liquid, oscillating while dropwise adding, and standing for 9h after dropwise adding to obtain algae microspheres;

step 2) pretreatment of culture wastewater: the cultivation wastewater sequentially passes through a grid and a mud-water separator to collect solid matters which are used as fertilizer; aerating the liquid in an aeration tank for 48 hours, introducing the liquid into a precipitation flocculation tank for 6-9 hours, introducing the upper liquid into a disinfection tank, disinfecting the upper liquid with sodium hypochlorite for 9-12 hours, introducing the upper liquid into an acid-base regulating tank, and regulating the pH value to 7-7.5;

step 3) wastewater remediation treatment: the pretreated wastewater is discharged into an algae purifying tank according to 100-300g of algae microspheres: inoculating 1 ton of wastewater into the liquid in a proportion of 6-7 days, separating algae and water, and discharging the liquid.

Preferably, the method comprises the steps of,

the chlorella liquid is prepared by the following steps: taking the chlorella in logarithmic phase, separating at 7000rpmRemoving supernatant after 15min, adding sterile water, and adjusting the density of algae cells to 3×10 ⁷ And (5) cell/mL to obtain the chlorella liquid.

Preferably, the method comprises the steps of,

the scenedesmus obliquus liquid is prepared by the following method: taking Gracilaria obliqua in logarithmic growth phase, centrifuging at 5000rpm for 15min, removing supernatant, adding sterile water, and regulating algae cell density to 2×10 ⁷ And (5) cell/mL to obtain the scenedesmus obliquus liquid.

Preferably, the method comprises the steps of,

the sickle-shaped fiber algae liquid is prepared by the following method: collecting Fusarium in logarithmic growth phase, centrifuging at 5000rpm for 10min, removing supernatant, adding sterile water, and regulating algae cell density to 1×10 ⁷ And (5) cell/mL to obtain the Fusarium liquid.

Preferably, the method comprises the steps of,

the bottom layer of the sedimentation flocculation tank is provided with a filler, and the filler is a crushed stone layer, a river sand layer and a sponge iron layer from bottom to top.

Preferably, the method comprises the steps of,

the crushed stone layer consists of crushed stones with the particle size of 20mm, and the layer thickness is 30cm; the river sand layer consists of river sand with the particle size of 1-2mm and the layer thickness is 50cm; the sponge iron layer consists of sponge iron with the particle size of 0.5-1mm and the thickness of the layer is 20cm.

Preferably, the method comprises the steps of,

in the step 3), 200-500g of sodium hypochlorite is used per cubic meter of liquid,

preferably, the method comprises the steps of,

the parameters of the algae purifying pond are as follows: the temperature is 25-28 ℃, and the light-dark ratio is 12:12, the illumination intensity is 6000-8000LX.

The algae of the invention can obtain algae liquid with required concentration by a conventional culture method, which is not an innovation point of the invention, is limited in space and is not repeated.

Compared with the prior art, the invention can achieve the following main beneficial effects and improvements:

the process for treating the cultivation wastewater is simple and feasible in operation, can achieve the purpose of environment-friendly and environment-friendly restoration, is economical and efficient, is environment-friendly, and has low cost and wide application range; in the process of preparing the algae microsphere, three algae are used, the compatibility is reasonable, and the algae microsphere has better synergistic effect, so that the removal capacity of COD, BOD, SS, NH-N and TP in the wastewater is effectively improved; after the algae is fixed, the growth and physiological characteristics of the algae are changed, so that the absorption and enrichment efficiency of substances such as nitrogen, sulfur, phosphorus and the like is improved; the algae microsphere is used by combining two pore-forming agents, and the pore-forming mechanisms of different pore-forming agents are different, so that compared with the effect of a single pore-forming agent, the obtained pore structure is reasonable in size and uniform in distribution, and the number of pore structures can be ensured; the invention adopts the immobilization technology to position the algae cells in a limited space area, so that the immobilized algae can maintain the metabolic activity of the algae and can be recycled after continuous reaction; the sedimentation flocculation tank is designed into three filler layers in the treatment process, so that the dephosphorization and desulfurization efficiency can be improved on the basis of effectively carrying out sedimentation and denitrification of organic matters.

Drawings

Fig. 1: influence of the addition amount of the algae microsphere on the wastewater remediation effect.

Detailed Description

Those skilled in the art can, with the benefit of this disclosure, suitably modify the process parameters to achieve this. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and are deemed to be included in the present invention. While the products and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that the invention can be practiced with modification and alteration and combination of the products and methods described herein without departing from the spirit and scope of the invention. The present invention will be described in detail with reference to examples.

Example 1

A process for remediation of aquaculture wastewater comprising the steps of:

preparing algae microspheres: mixing the chlorella liquid, the clinopodium liquid and the Fusarium liquid according to the volume ratio of 2:1:1 to obtain mixed algae liquid, then adding sodium alginate aqueous solution with the concentration of 5wt% accounting for one half of the volume of the mixed algae liquid, urea with the concentration of 2wt% accounting for 2% of the mixed algae liquid and sodium bicarbonate with the concentration of 4% of the mixed algae liquid, uniformly stirring, then dropwise adding calcium chloride aqueous solution with the concentration of 2wt% accounting for 2 times of the volume of the mixed algae liquid, oscillating while dropwise adding, standing for 9h after dropwise adding, and obtaining the algae microsphere with the diameter of 3 mm;

pretreatment of cultivation wastewater: the cultivation wastewater sequentially passes through a grid and a mud-water separator to remove solid matters such as excrement and the like, and the solid matters are collected and can be used as fertilizer; the liquid enters an aeration tank for aeration for 48 hours, enters a sedimentation flocculation tank for 6 hours, the upper liquid enters a disinfection tank for disinfection by sodium hypochlorite, the sodium hypochlorite is 500g for each cubic meter of liquid, the disinfection time is 9 hours, and then enters an acid-base regulating tank for regulating the pH value to 7;

and (3) wastewater restoration treatment: the pretreated wastewater is discharged into an algae purifying tank, and 100g of algae microspheres are used for preparing the wastewater: inoculating 1 ton of wastewater into liquid, controlling the temperature to 25 ℃ and the light-dark ratio to be 12:12, the illumination intensity is 6000LX, the treatment time is 7 days, and finally, algae-water separation is carried out, and the liquid is discharged.

The bottom layer of the sedimentation flocculation tank is provided with a filler, and the filler is a crushed stone layer, a river sand layer and a sponge iron layer from bottom to top. The crushed stone layer consists of crushed stones with the particle size of 20mm, and the layer thickness is 30cm; the river sand layer consists of river sand with the particle size of 1-2mm and the layer thickness is 50cm; the sponge iron layer consists of sponge iron with the particle size of 0.5-1mm and the thickness of the layer is 20cm.

The chlorella liquid is prepared by the following steps: centrifuging Chlorella in logarithmic growth phase at 7000rpm for 15min, removing supernatant, adding sterile water, and adjusting the density of algae cells to 3×10 ⁷ And (5) cell/mL to obtain the chlorella liquid.

The scenedesmus obliquus liquid is prepared by the following method: taking Gracilaria obliqua in logarithmic growth phase, centrifuging at 5000rpm for 15min, removing supernatant, adding sterile water, and regulating algae cell density to 2×10 ⁷ And (5) cell/mL to obtain the scenedesmus obliquus liquid.

The Fusarium fiber algae liquid is prepared by the following method: collecting Fusarium in logarithmic growth phase, centrifuging at 5000rpm for 10min, removing supernatant, adding sterile water, and regulating algae cell density to 1×10 ⁷ And (5) cell/mL to obtain the Fusarium liquid.

Example 2

A process for remediation of aquaculture wastewater comprising the steps of:

preparing algae microspheres: mixing the chlorella liquid, the clinopodium liquid and the Fusarium liquid according to the volume ratio of 2:1:1 to obtain mixed algae liquid, then adding sodium alginate aqueous solution with the concentration of 5wt% accounting for one half of the volume of the mixed algae liquid, urea with the concentration of 2wt% accounting for 2% of the mixed algae liquid and sodium bicarbonate with the concentration of 4% of the mixed algae liquid, uniformly stirring, then dropwise adding calcium chloride aqueous solution with the concentration of 2wt% accounting for 2 times of the volume of the mixed algae liquid, oscillating while dropwise adding, standing for 9h after dropwise adding, and obtaining the algae microsphere with the diameter of 3 mm;

pretreatment of cultivation wastewater: the cultivation wastewater sequentially passes through a grid and a mud-water separator to remove solid matters such as excrement and the like, and the solid matters are collected and can be used as fertilizer; the liquid enters an aeration tank for aeration for 48 hours, enters a sedimentation flocculation tank for 9 hours, the upper liquid enters a disinfection tank for disinfection by sodium hypochlorite, the use of the sodium hypochlorite for each cubic meter of liquid is 300g, the disinfection time is 12 hours, and then enters an acid-base regulating tank for regulating the pH value to 7.5;

and (3) wastewater restoration treatment: the pretreated wastewater is discharged into an algae purifying tank, and the algae microspheres are prepared according to the following weight of 300g: inoculating 1 ton of wastewater into liquid, controlling the temperature to be 28 ℃ and the light-dark ratio to be 12:12, the illumination intensity is 8000LX, the treatment time is 6 days, and finally, algae-water separation is carried out, and the liquid is discharged.

The bottom layer of the sedimentation flocculation tank is provided with a filler, and the filler is a crushed stone layer, a river sand layer and a sponge iron layer from bottom to top. The crushed stone layer consists of crushed stones with the particle size of 20mm, and the layer thickness is 30cm; the river sand layer consists of river sand with the particle size of 1-2mm and the layer thickness is 50cm; the sponge iron layer consists of sponge iron with the particle size of 0.5-1mm and the thickness of the layer is 20cm.

The chlorella liquid is prepared by the following steps: taking logarithmic growth phaseCentrifugation at 7000rpm for 15min, removing supernatant, adding sterile water, and adjusting the density of algae cells to 3×10 ⁷ And (5) cell/mL to obtain the chlorella liquid.

The scenedesmus obliquus liquid is prepared by the following method: taking Gracilaria obliqua in logarithmic growth phase, centrifuging at 5000rpm for 15min, removing supernatant, adding sterile water, and regulating algae cell density to 2×10 ⁷ And (5) cell/mL to obtain the scenedesmus obliquus liquid.

The sickle-shaped fiber algae liquid is prepared by the following method: collecting Fusarium in logarithmic growth phase, centrifuging at 5000rpm for 10min, removing supernatant, adding sterile water, and regulating algae cell density to 1×10 ⁷ And (5) cell/mL to obtain the Fusarium liquid.

Example 3

The process of the invention repairs the test of the cultivation wastewater:

taking a certain cultivation wastewater as an example, the wastewater treatment effect of example 1 was detected: the detection indexes of the culture wastewater are shown in table 1:

TABLE 1

Project name	Water quality of inlet water	Pretreated water quality	Effluent quality
				CODcr（mg/L）	≥10000	960	22.1
BOD（mg/L）	≥10000	850	18.7
				SS（mg/L）	≥1000	171	11.7
NH3-N（mg/L）	≥1000	153	8.3
				TP（mg/L）	≥100	47	3.2
Chromaticity (dilution times)	≥200	78	16

Conclusion: after the treatment by the process provided by the invention, the content of various pollutants in the cultivation wastewater is greatly reduced, and the emission standard is met.

Example 4

Taking example 2 as an example, the influence of the addition amount of algae microspheres on the repairing effect is detected, and all main pollutant indexes of the pretreated wastewater are as follows: COD 1010mg/L, BOD 918 mg/L, SS 187mg/L, NH 3-N163 mg/L, TP mg/L;

setting a control group of algae microspheres, wherein the control group 1: no addition of chlorella was made and the remainder was the same as in example 2; control group 2: the other steps are the same as in example 2, except that no scenedesmus obliquus is added; control group 3: fusarium was not added, and the rest was the same as in example 2. As shown in FIG. 1, after treatment of the example 2 and the control groups 1-3, the levels of COD, BOD, NH-N, SS, TP and other pollutants in the wastewater are greatly reduced, and compared, the capacity of the example 2 for treating various pollutants is obviously better than that of the control groups 1-3, so that three algae used in the algae microsphere can mutually co-grow, the compatibility is reasonable, and the algae microsphere has better synergistic effect.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (1)

1. A process for remediation of aquaculture wastewater comprising the steps of:

1) Preparing algae microspheres: mixing the chlorella liquid, the clinopodium liquid and the Fusarium liquid according to the volume ratio of 2:1:1 to obtain mixed algae liquid, then adding sodium alginate aqueous solution with the concentration of 5wt% accounting for one half of the volume of the mixed algae liquid, urea with the concentration of 2wt% accounting for 2% of the mixed algae liquid and sodium bicarbonate with the concentration of 4% of the mixed algae liquid, uniformly stirring, then dropwise adding calcium chloride aqueous solution with the concentration of 2wt% accounting for 2 times of the volume of the mixed algae liquid, oscillating while dropwise adding, standing for 9h after dropwise adding, and preparing algae microspheres with the diameter of 3 mm;

2) Pretreatment of cultivation wastewater: the cultivation wastewater sequentially passes through a grid and a mud-water separator to remove solid matters such as excrement and urine, and the solid matters are collected and used as fertilizer; the liquid enters an aeration tank for aeration for 48 hours, enters a sedimentation flocculation tank for 6 hours, the upper liquid enters a disinfection tank for disinfection by sodium hypochlorite, the sodium hypochlorite is 500g for each cubic meter of liquid, the disinfection time is 9 hours, and then enters an acid-base regulating tank for regulating the pH value to 7;

3) And (3) wastewater restoration treatment: the pretreated wastewater is discharged into an algae purifying tank, and 100g of algae microspheres are used for preparing the wastewater: inoculating 1 ton of wastewater into liquid, controlling the temperature to 25 ℃ and the light-dark ratio to be 12:12, the illumination intensity is 6000LX, the treatment time is 7 days, and finally, algae-water separation is carried out, and liquid is discharged;

the bottom layer of the sedimentation flocculation tank is provided with a filler, and the filler is a crushed stone layer, a river sand layer and a sponge iron layer from bottom to top in sequence;

the crushed stone layer consists of crushed stones with the particle size of 20mm, and the layer thickness is 30cm; the river sand layer consists of river sand with the particle size of 1-2mm and the layer thickness is 50cm; the sponge iron layer consists of sponge iron with the particle size of 0.5-1mm and the thickness of the layer is 20cm;

the chlorella liquid is prepared by the following steps: centrifuging Chlorella in logarithmic growth phase at 7000rpm for 15min, removing supernatant, adding sterile water, and adjusting the density of algae cells to 3×10 ⁷ cell/mL to obtain a crescent algae liquid;

the scenedesmus obliquus liquid is prepared by the following method: taking Gracilaria obliqua in logarithmic growth phase, centrifuging at 5000rpm for 15min, removing supernatant, adding sterile water, and regulating algae cell density to 2×10 ⁷ Obtaining the cell/mL to obtain the scenedesmus obliquus liquid;

the sickle-shaped fiber algae liquid is prepared by the following method: collecting Fusarium in logarithmic growth phase, centrifuging at 5000rpm for 10min, removing supernatant, adding sterile water, and regulating algae cell density to 1×10 ⁷ And (5) cell/mL to obtain the Fusarium liquid.

Images