Method for treating high-concentration ammonia nitrogen pig breeding biogas slurry

[0020] Example: According to the following process flow.

[0021] (1) Activation of artificial zeolite: immerse the artificial zeolite in a sodium chloride solution with a concentration of 0.5 mol/L, heat it in a water bath at 100 ℃ for 2 h, take it out, and dry to obtain activated artificial zeolite.

[0022] (2) Pretreatment of the biogas slurry: heat the pig biogas slurry at 100°C for 20 minutes, and then centrifuge at 4800 rpm after cooling. The supernatant is the high concentration ammonia nitrogen pig biogas slurry with total nitrogen of 308.97 mg/L and ammonia nitrogen of 174.07 mg/L, total phosphorus is 35.89 mg/L, COD is 361.33 mg/L. Take 3 L of this biogas slurry and put it into a 5 L triangular flask as the untreated group.

[0023] (3) Zeolite adsorption treatment of high-concentration ammonia-nitrogen pig biogas slurry: take the activated artificial zeolite from step (1) and put it into the high-concentration ammonia-nitrogen pig biogas slurry of step (2). The addition amount of artificial zeolite is 20 g/L. At room temperature, activated artificial zeolite adsorption treatment of high-concentration ammonia nitrogen pig biogas slurry for 24 hours, use 100 mesh filter cloth to filter out the zeolite, the zeolite adsorption treatment of biogas slurry, total nitrogen reduced to 196.64 mg/L, ammonia nitrogen reduced To 81.75 mg/L, total phosphorus dropped to 12.48 mg/L, and COD dropped to 290.23 mg/L. Take 3 L of the biogas slurry after adsorption treatment and put it into a 5 L Erlenmeyer flask as the zeolite treatment group.

[0024] (4) Preparation of BG11 medium: prepare 3 LBG11 liquid algae medium and put it into a 5 L Erlenmeyer flask as the artificial medium BG11 control group. Medium composition is NaNO 3 (1.5 g/L), K 2 HPO 4 ·3H 2 O (0.04 g/L), MgSO 4 ·7H 2 O (0.075 g/L), CaCl 2 ·2H 2 O (0.036 g/L), citric acid (0.006 g/L), ferric ammonium citrate (0.006 g/L), EDTANa 2 (0.001 g/L), Na 2 CO 3 (0.02 g/L) and trace element A5 (1.0 mL). The composition of trace element A5 is H 3 BO 3 (2.86 g/L), MnCl 2 ·4H 2 O (1.86 g/L), ZnSO 4 ·7H 2 O (0.22 g/L), Na 2 MoO 4 ·2H 2 O (0.39 g/L), CuSO 4 ·5H 2 O (0.08 g/L), Co(NO 3 ) 2 ·6H 2 O (0.05 g/L).

[0025] (5) Microalgae inoculation: Scenedesmus obliquus ( Scenedesmus obliquus FACHB-276) Centrifuge at 4800 rpm for 20 min, wash and centrifuge with distilled water, and repeat twice. The centrifuged algae mud was eluted with distilled water, and the same amount of algae mud was inoculated into the untreated group of step (2), the zeolite treatment group of step (3), and the BG11 control group of step (4) to make the initial OD 680 Place the Erlenmeyer flask inoculated with microalgae at 24-26°C, 3000 lx environment, and incubate for 11 days in light of 1.5 L/min ventilation.

[0026] (6) Detection of microalgae growth and water quality change: OD was measured with UV-Vis spectrophotometer every day during the experiment 680 , Indicating the growth of microalgae, OD on day 1 680 The values ​​are 0.235, the OD of the untreated group on day 3 680 Value begins to decrease and continues to the end of the experiment, OD 680 Value decreased to about 0.100; while the medium BG11 control group and zeolite treatment group OD 680 Value continued to rise, and increased rapidly after the 4th day. On the 11th day of the experiment, the OD of the BG11 group 680 Value reached 1.143, OD of zeolite treatment group 680 Reach 0.997 (see attached figure 1 ). During the experiment, the water quality changes were measured every two days. Attached Figure 2-5 It can be seen that the N and P in the wastewater are used during the growth of microalgae to purify the water quality of the wastewater. In the untreated group, when the microalgae is connected, although the microalgae cells are dead, they still have a surface adsorption effect, which can make the water quality get a certain level. Degree of purification; the zeolite treatment group has a better water purification effect. On the first day of microalgae inoculation, the total nitrogen of the untreated group was 308.97 mg/L, the ammonia nitrogen was 174.07 mg/L, the total phosphorus was 35.89 mg/L, the COD was 361.33 mg/L, and the total nitrogen of the zeolite treatment group was 196.64 mg/L , Ammonia nitrogen is 81.75 mg/L, total phosphorus is 12.48 mg/L, COD is 290.23 mg/L, on the 11th day of the experiment, total nitrogen in the untreated group is 180.75 mg/L, ammonia nitrogen is 105.17 mg/L, and total phosphorus is 18.08 mg/L, COD is 230.70 mg/L, total nitrogen in zeolite treatment group is 99.13 mg/L, ammonia nitrogen is 43.61 mg/L, total phosphorus is 2.05 mg/L, COD is 200.52 mg/L. The total nitrogen removal rate of the untreated group was 41.50%, the ammonia nitrogen removal rate was 39.58%, the total phosphorus removal rate was 49.62%, and the COD removal rate was 36.15%. The total nitrogen removal rate of the zeolite treatment group was 67.92%, the ammonia nitrogen removal rate was 74.95%, the total phosphorus removal rate was 94.29%, and the COD removal rate was 44.51%. Compared with the untreated group, the total nitrogen removal rate of the zeolite treatment group increased by 26.42 %, the ammonia nitrogen removal rate increased by 35.37%, the total phosphorus removal rate increased by 44.67%, and the COD removal rate increased by 8.36%. The harvested microalgae oil content can reach 30%, which can be used to develop microalgae biomass energy.