Method for purifying piggery wastewater by attaching and culturing Scenedesmus

Abstract

The present invention provides a method for purifying piggery wastewater by attaching and culturing Scenedesmus sp., and relates to the technical field of water quality treatment. The method of the present invention comprises the following steps: inoculating Scenedesmus sp. into piggery wastewater and culturing for 8 to 12 days; the Scenedesmus sp. is Scenedesmus sp. LX1; and Scenedesmus attachment material is added to the piggery wastewater. According to the method of the present invention, COD, TN, TP, NH4 in the piggery wastewater can be significantly removed. + ‑N, to purify pig farm wastewater.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a method for purifying piggery wastewater by attachment and cultivation of Scenedesmus. Background Art

[0002] The rapid development of the breeding industry has brought economic benefits while also generating a large amount of wastewater. Pig farm wastewater is a high-concentration wastewater with the characteristics of large instantaneous discharge volume, high nitrogen and phosphorus content, solid-liquid mixture and difficulty in degradation. If it is not properly treated, it will pollute the environment and affect human health if it is directly discharged into the environment. Algae can make use of a large amount of nutrients such as nitrogen and phosphorus in wastewater to maintain their own growth and proliferation, but if they are not cultivated properly, not only will the efficiency of purifying pig farm wastewater be low, but it will also consume a lot of material and financial resources. The cultivation methods of the prior art have extremely low purification efficiency when purifying pig farm wastewater, and usually consume a lot of material and financial resources when removing algae from wastewater, which is not conducive to large-scale production. Therefore, there is an urgent need for a method with high purification efficiency, large-scale production, cultivation and collection of microalgae to meet the deficiencies of the prior art. Summary of the invention

[0003] The purpose of the present invention is to provide a method for purifying piggery wastewater by attaching and culturing Scenedesmus.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for purifying piggery wastewater by attaching and culturing Scenedesmus, comprising the following steps:

[0006] Inoculate Scenedesmus into piggery wastewater and culture for 8 to 12 days;

[0007] The scenedesmus is Scenedesmus sp.LX1;

[0008] Scenedesmus attachment material is added to piggery wastewater.

[0009] Preferably, the inoculation density is 0.8×10 6 ~1.2×10 6 Pieces / mL.

[0010] Preferably, the attachment material is a geotextile;

[0011] The ratio of the area of ​​the geotextile to the bottom area of ​​the container for holding pig wastewater is 0.76-0.8:1.

[0012] Preferably, the pig farming wastewater is diluted pig farming wastewater;

[0013] The dilution multiple is 10 to 20 times; the dilution is performed using pure water.

[0014] Preferably, the COD value of the pig farming wastewater before dilution is 11000-13000 mg / L, the ammonia nitrogen content is 1100-1300 mg / L, the total nitrogen content is 1500-1900 mg / L, and the total phosphorus content is 70-90 mg / L.

[0015] Preferably, the culture temperature is 20-30°C.

[0016] Preferably, the illumination intensity of the culture is 1000-2000 lux.

[0017] Preferably, the light-dark ratio of the culture is 11-13h:11-13h.

[0018] Preferably, the method further comprises a step of collecting Scenedesmus;

[0019] The collection method is: taking out the attached material, and drying it at 100-110° C. for 1.5-2.5 hours.

[0020] The present invention provides a method for purifying piggery wastewater by attaching and culturing Scenedesmus, and the method of the present invention has the following advantages:

[0021] (1) Cultivating Scenedesmus in pig wastewater allows Scenedesmus to fully utilize nutrients such as nitrogen and phosphorus in the wastewater without adding additional nutrients to maintain its own growth and proliferation;

[0022] (2) Cultivating Scenedesmus in pig farm wastewater can also achieve the purification of pig farm wastewater and the accumulation of high-value substances;

[0023] (3) Inoculating Scenedesmus into pig farm wastewater carrying attachment materials can solve the problems of inconvenience in collecting and high costs caused by existing technologies such as sedimentation, flotation, flocculation, centrifugation, and fixation of Scenedesmus on seaweed salt polymers when harvesting Scenedesmus. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The dry weight content of Scenedesmus obtained in each treatment.

[0025] Figure 2 Each treatment has a significant effect on COD, TN, TP, NH4 + -N removal rate. DETAILED DESCRIPTION

[0026] The present invention provides a method for purifying piggery wastewater by attaching and culturing Scenedesmus, comprising the following steps:

[0027] Inoculate Scenedesmus into piggery wastewater and culture for 8 to 12 days;

[0028] The scenedesmus is Scenedesmus sp.LX1;

[0029] Scenedesmus attachment material is added to piggery wastewater.

[0030] The culture time is preferably 10 days.

[0031] In the present invention, the inoculation density is 0.8×10 6 ~1.2×10 6 / mL, preferably 1×10 6 Pieces / mL.

[0032] In the present invention, the attachment material is a geotextile;

[0033] The ratio of the area of ​​the geotextile to the bottom area of ​​the container for holding pig wastewater is 0.76-0.8:1, preferably 0.78:1.

[0034] In the present invention, the pig farming wastewater is diluted pig farming wastewater;

[0035] The dilution multiple is 10 to 20 times;

[0036] The dilution is carried out using pure water;

[0037] The diluted pig farming wastewater is sterilized to obtain sterile pig farming wastewater;

[0038] The diluted pig farming wastewater is not sterilized to obtain the sterilized pig farming wastewater;

[0039] The sterilization is high temperature and high pressure sterilization;

[0040] The sterilization temperature is 119-123°C, preferably 121°C;

[0041] The sterilization time is 25 to 35 minutes, preferably 30 minutes.

[0042] In the present invention, the COD value of the piggery wastewater before dilution is 11000-13000 mg / L, preferably 12000 mg / L;

[0043] Ammonia nitrogen content is 1100-1300 mg / L, preferably 1200 mg / L;

[0044] The total nitrogen content is 1500-1900 mg / L, preferably 1700 mg / L;

[0045] The total phosphorus content is 70-90 mg / L, preferably 80 mg / L.

[0046] In the present invention, the culture temperature is 20-30°C, preferably 25°C.

[0047] In the present invention, the illumination intensity of the culture is 1000-2000 lux, preferably 1500 lux.

[0048] In the present invention, the light-dark ratio of the culture is 11-13h:11-13h, preferably 12h:12h.

[0049] In the present invention, the method further comprises a Scenedesmus collection step;

[0050] The collection method is: taking out the attached material, and drying it at 100-110° C. for 1.5-2.5 hours.

[0051] The drying temperature is preferably 105° C., and the drying time is preferably 2 hours.

[0052] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0053] The Scenedesmus sp. LX1 used in the examples of the present invention was purchased from the General Microbiological Center of China Microbiological Culture Collection Committee, and the algae culture collection number is CGMCC No.3036.

[0054] The determination method of each index in the embodiment of the present invention is:

[0055] The COD content was determined by the closed-tube catalytic digestion colorimetric method HJ / T399-2007;

[0056] The TP content was determined using the ammonium molybdate spectrophotometric method GB11893-89;

[0057] The TN content was determined by alkaline persulfate digestion photometry EPA chromotropic acid method;

[0058] NH4 + The -N content was determined using Nessler's reagent method HJ535-2009.

[0059] The pig farming wastewater described in the embodiment of the present invention is taken from Leimu pig breeding farm in Pingyuan County, Dezhou City, Shandong Province.

[0060] In the embodiment of the present invention, biomass productivity = microalgae attachment amount / (material area×culture time).

[0061] In the embodiment of the present invention, the removal rate of COD=[(the content of COD in the treated piggery wastewater-the content of COD in the purified piggery wastewater) / the content of COD in the treated piggery wastewater]×100%;

[0062] TP removal rate = [(TP content in treated pig wastewater - TP content in purified pig wastewater) / TP content in treated pig wastewater] × 100%;

[0063] TN removal rate = [(TN content in treated pig wastewater - TN content in purified pig wastewater) / TN content in treated pig wastewater] × 100%;

[0064] NH4 + -N removal rate = [(NH4 + -N content - NH4 in pig wastewater after purification + -N content) / NH4 in treated pig wastewater + -N content] × 100%.

[0065] Example 1

[0066] Wastewater from a pig farm in Dezhou City, Shandong Province was filtered through two layers of gauze to obtain a filtrate, which was centrifuged at 8000rpm for 10 minutes to obtain a supernatant. The supernatant was diluted 10 times with pure water, and the sterile pig wastewater was sterilized at 121℃ for 30 minutes, and the sterile pig wastewater was not sterilized. The sterile pig wastewater and the sterile pig wastewater were used as culture media for Scenedesmus.

[0067] The COD content of the sterile piggery wastewater diluted 10 times is 1300 mg / L, NH4 + The -N content is 114.99 mg / L, the TN content is 168.2 mg / L, and the TP content is 8 mg / L.

[0068] The COD value of the 10-fold diluted bacterial piggery wastewater is 1300 mg / L, and NH4 + -N content is 115mg / L, TN content is 170mg / L, and TP content is 8mg / L.

[0069] Take logarithmically growing Scenedesmus and calculate the 6 The inoculation density was 1000 / mL, and it was inoculated into the wastewater carrying the geotextile. After 10 days of cultivation at 30°C, 1000 lux light intensity, and a light-dark ratio of 12:12, the geotextile carrying the Scenedesmus algae was taken out and the dry weight of the Scenedesmus algae was measured. The results are as follows Figure 1 The biomass productivity was calculated according to the formula. The results are shown in Table 1. The remaining wastewater, i.e. the piggery wastewater after purification by Scenedesmus, was taken to detect COD, TP, TN and NH4 +The contents of -N in sterile wastewater were 310, 2.89, 94.15 and 61.23 mg / L, and those in bacterial wastewater were 170, 2.05, 91.51 and 32.42 mg / L, and the corresponding removal rates were calculated. The results are shown in Table 1 and Figure 2 shown.

[0070] The volume of the Scenedesmus culture medium is 150 mL, and the container for holding wastewater is a beaker. The method for measuring the dry weight of the Scenedesmus is to dry the geotextile carrying the Scenedesmus algae at 105° C. for 2 hours, and then weigh the algae to obtain the value of the dry weight of the Scenedesmus, and the results are shown in Table 1. The ratio of the geotextile to the bottom area of ​​the beaker is 0.78.

[0071] Example 2

[0072] Wastewater from a pig farm in Dezhou City, Shandong Province was filtered through two layers of gauze to obtain a filtrate, which was centrifuged at 8000rpm for 10 minutes to obtain a supernatant. The supernatant was diluted 20 times with pure water, and sterilized at 121°C for 30 minutes to obtain sterile pig wastewater, while the non-sterilized pig wastewater was bacterial pig wastewater, which was used as a culture medium for Scenedesmus.

[0073] The COD content of the 20-fold diluted sterile piggery wastewater is 599.97 mg / L, and the NH4 + The -N content is 54.99 mg / L, the TN content is 85 mg / L, and the TP content is 3.88 mg / L.

[0074] The COD content of the 20-fold diluted bacterial piggery wastewater is 600 mg / L, and the NH4 + -N content is 55mg / L, TN content is 85mg / L, and TP content is 3.96mg / L.

[0075] Take logarithmically growing Scenedesmus and calculate the 6 The inoculation density was 1000 / mL, and it was inoculated into the culture medium of Scenedesmus carrying geotextile. After culturing for 10 days at 20℃, 1000lux light intensity, and a light-dark ratio of 12:12, the geotextile carrying Scenedesmus was taken out and the dry weight of Scenedesmus was measured. The results are as follows Figure 1 The biomass productivity was calculated according to the formula, and the results are shown in Table 1. The remaining wastewater, that is, the piggery wastewater after purification by Scenedesmus, was taken to detect COD, TP, TN and NH4 + The contents of -N in sterile pig wastewater were 136.67, 0.15, 33.36 and 16.04 mg / L, and those in bacterial pig wastewater were 86.67, 0.23, 35.75 and 16.11 mg / L, and the corresponding removal rates were calculated. The results are shown in Table 1 and Figure 2 shown.

[0076] The volume of the Scenedesmus culture medium is 150 mL, and the container for holding the Scenedesmus culture medium is a beaker. The dry weight is measured by drying the geotextile carrying the Scenedesmus algae at 105° C. for 2 hours and weighing the algae to obtain the value, and the results are shown in Table 1. The ratio of the geotextile to the bottom area of ​​the beaker is 0.8.

[0077] Table 1 Removal rate and adhesion amount obtained by each method in Example 1 and Example 2

[0078]

[0079]

[0080] Figure 1 The results showed that the dry weight of the attached Scenedesmus obtained by culturing with 10-fold diluted swine wastewater containing bacteria and the dry weight of the attached Scenedesmus obtained by culturing with 20-fold diluted swine wastewater without bacteria were the highest, which were 57.5 and 62.17 mg respectively, and the biomass productivity was 2.03 and 2.20 g / m 2 / d.

[0081] Figure 2 Display, COD, TN, TP, NH4 + The highest removal efficiencies of -N were 86.92%, 60.75%, 96.13% and 71.81%, respectively.

[0082] From the above examples, it can be seen that the present invention provides a method for purifying piggery wastewater by attaching and culturing Scenedesmus. The method of the present invention can significantly remove COD, TN, TP, and NH4 in piggery wastewater. + -N content, and increase the biomass of Scenedesmus. In addition, the present invention adds geotextile attachment materials to the piggery wastewater to allow Scenedesmus to attach and grow, and Scenedesmus can be removed from the piggery wastewater more conveniently.

[0083] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for purifying piggery wastewater by attaching and culturing Scenedesmus, characterized in that: The steps include: Inoculate Scenedesmus into piggery wastewater and culture for 8 to 12 days; The scenedesmus is Scenedesmus sp.LX1; Scenedesmus attachment material is added to piggery wastewater; The inoculation density is 0.8×10 6 ~1.2×10 6 Pieces / mL; The attachment material is a geotextile; The ratio of the area of ​​the geotextile to the bottom area of ​​the container for holding the pig wastewater is 0.76 to 0.8:1; The culture temperature is 20-30°C; The light intensity of the culture is 1000-2000 lux; The light-dark ratio of the culture is 11-13h:11-13h; The method further comprises a Scenedesmus collection step; The collecting method is: taking out the attached material, and drying it at 100-110° C. for 1.5-2.5 hours.

2. The method according to claim 1, characterized in that The pig farming wastewater is diluted pig farming wastewater; The dilution multiple is 10 to 20 times; the dilution is performed using pure water.

3. The method according to claim 2, characterized in that The COD value of the pig farming wastewater before dilution is 11000-13000 mg / L, the ammonia nitrogen content is 1100-1300 mg / L, the total nitrogen content is 1500-1900 mg / L, and the total phosphorus content is 70-90 mg / L.

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