Rapid construction method of half-amount shortcut nitrification granular sludge system

Abstract

The invention discloses a rapid construction method of a half partial nitrification granular sludge system, which comprises the following steps: starting a reactor by adopting a sequencing batch reactor (SBR) and inoculated and stored heterotrophic granular sludge, measuring the ammoxidation rate of the granular sludge at the early stage of operation of each stage, measuring nitrite nitrogen and ammonia nitrogen in effluent in a first period, and determining the ammonia nitrogen in the effluent in a second period; when the ratio of the two is greater than 1.32, the aeration time is recalculated along with the correction of the ammoxidation rate so as to reduce the aeration time in the next period; if the ratio of nitrite nitrogen to ammonia nitrogen in the effluent in the first period is less than 1.32, correcting the ammoxidation rate, and recalculating the aeration time to increase the aeration time in the next period; and repeatedly correcting the aeration time and the standing time in each period through the ammoxidation rate until the ratio of nitrite nitrogen to ammonia nitrogen in effluent is stabilized between 1.28 and 1.35. The half-amount short-cut nitrification granular sludge system rapidly constructed by the method is low in operation cost and high in reliability, and an effective new method is provided for rapid construction of the half-amount short-cut nitrification granular sludge system in the SBR.

Description

Technical Field

[0001] The invention relates to the technical field of biological treatment of ionic rare earth mine tailings, and in particular to a method for quickly constructing a semi-quantitative short-range nitrification granular sludge system. Background Art

[0002] Ionic rare earth mines in southern Jiangxi use a large amount of ammonium leaching agents during the mining process. The uncollected leaching agents will flow into the streams and rivers around the mining area with groundwater, undercurrent, rainwater, etc., thus generating a large amount of nitrogen-containing tailwater. The tailwater from ionic rare earth mines is characterized by acidic, inorganic, high-ammonia nitrogen wastewater, and has become an important source of pollution in the region. Since it is difficult to collect accurately, the existing control measures are to set up tailwater treatment stations in the downstream rivers of the mining area to prevent the transport of pollutants to the main stream section. At present, a number of tailwater stations for ionic rare earth mines have been built in southern Jiangxi. The primary treatment usually uses the addition of quicklime to adjust the pH, and the secondary treatment is mainly the activated sludge method or the biofilm method. There are generally problems such as high denitrification costs.

[0003] Anaerobic ammonium oxidation has the advantages of high denitrification efficiency and low operating energy consumption. Compared with traditional nitrification and denitrification processes, anaerobic ammonium oxidation reactions can save more than 60% of aeration energy consumption, reduce sludge production by 80%~90%, and do not require an organic carbon source. It is considered to be a sustainable sewage denitrification process. However, the anaerobic ammonium oxidation reaction requires a stable supply of nitrite nitrogen, which makes semi-quantitative short-range nitrification a focus of attention. The key to semi-quantitative short-range nitrification is to increase the activity of ammonia-oxidizing bacteria and inhibit the growth of nitrite-oxidizing bacteria. According to the growth differences of the two types of bacteria, semi-quantitative short-range nitrification of activated sludge or biofilm systems can be achieved through oxygen-limited aeration, temperature control, pH adjustment, and the addition of inhibitors. However, the sedimentation performance of the free activated sludge system is poor, and the biofilm system requires the addition of fillers. In contrast, autotrophic nitrification granular sludge is favored due to its high biological density, fast sedimentation, and strong toxicity resistance, and has the potential to be used as a semi-quantitative short-range nitrification before anaerobic ammonium oxidation. Through the regulation of operating parameters, there are some methods for constructing short-term nitrification granular sludge, such as the patent with publication number CN112250167A, entitled: A device and method for quickly realizing short-term nitrification aerobic granular sludge, the patent with publication number CN107089721A, entitled: A method for cultivating short-term nitrification granular sludge and a continuous flow reactor, and the patent with publication number CN113697951A, entitled: A device and method for realizing short-term nitrification of granular sludge-anaerobic ammonia oxidation coupled with endogenous denitrification and denitrification at low temperature. The control factors of these methods are different, and they are basically regulated by empirical parameters. Whether changing the operating conditions or the operator can achieve precise half-quantity short-term nitrification control still needs to be tested. Summary of the invention

[0004] The purpose of the present invention is to solve the above-mentioned deficiencies of the prior art and provide a method for quickly constructing a semi-quantitative short-range nitrification granular sludge system with low cost and high reliability, which can accurately control the aeration time through oxygen-limited aeration and ammonia oxidation rate correction.

[0005] The purpose of the present invention is achieved through the following technical solutions: A method for rapidly constructing a semi-quantity short-range nitrification granular sludge system, which rapidly constructs a semi-quantity short-range nitrification granular sludge system before anaerobic ammonia oxidation denitrification of ionic rare earth mine tail water, and the method for rapidly constructing a semi-quantity short-range nitrification granular sludge system comprises the following steps: (1) A sequencing batch reactor (SBR) was used with a 6-hour operation cycle, including: 30 min of water inlet, 5 min of aeration and mixing, 218-128 min of standing, 80-180 min of aeration, 10 min of sedimentation, and 5 min of drainage; (2) The reactor was started by inoculating the stored heterotrophic granular sludge. Due to long-term storage, the granules were dark brown, but the granular structure was still maintained. The granulation rate was 99%, the average particle size was 0.98 mm, the MLVSS / MLSS was 0.82, and the SOUR was 7.53 mgO2 / gVSS•h. (3) To treat ionic rare earth mine tailings, the ammonia oxidation rate of granular sludge is measured at the beginning of each stage of operation. The theoretical aeration time is obtained by dividing the influent ammonia nitrogen by the ammonia oxidation rate, which is the aeration time in the first cycle. (4) Determine the nitrite nitrogen and ammonia nitrogen in the effluent of the first cycle. When the ratio of the two is greater than 1.32, it means that the ammonia nitrogen removal rate is too high. With the correction of the ammonia oxidation rate, recalculate the aeration time to reduce the aeration time of the next cycle; (5) If the ratio of nitrite nitrogen to ammonia nitrogen in the effluent of the first cycle is less than 1.32, it means that the nitrogen removal rate is insufficient. With the correction of the ammonia oxidation rate, the aeration time is recalculated to increase the aeration time of the next cycle; (6) The aeration time and standing time in each cycle are repeatedly corrected by the ammonia oxidation rate until the ratio of nitrite nitrogen to ammonia nitrogen in the effluent is stabilized between 1.28 and 1.35. The remaining time in the cycle is the standing time. The aeration time is re-determined according to this method each time the influent ammonia nitrogen changes.

[0006] Furthermore, the limiting aeration intensity of the sequencing batch reactor SBR of the present invention is 1.6 L / min, which oxidizes 56%-58% of the ammonia nitrogen in the influent into nitrite nitrogen.

[0007] Furthermore, the ratio of the ammonia oxidation rate to the nitrite oxidation rate of the present invention is between 1.4 and 2.4.

[0008] Furthermore, the nitrogen load of the ionic rare earth mine tailings water of the present invention is 0.24-0.48 kg / m3•d, and the main water quality indicators are: pH 3-4, ammonia nitrogen 100-200 mg / L, TP 2.4 mg / L, and the pH is adjusted to 8-8.5 before entering the reactor.

[0009] The present invention inhibits further oxidation of nitrite nitrogen through oxygen-limited aeration; corrects the theoretical aeration time and standing time in each cycle through the ammonia oxidation rate, and then increases or decreases the aeration time according to the accumulation of nitrite nitrogen in the reactor, thereby achieving precise control of the mass ratio of nitrite nitrogen to ammonia nitrogen and precise control of the actual aeration time. The semi-quantity short-range nitrification granular sludge system that is rapidly constructed has low operating cost and high reliability, and provides an effective new method for the rapid construction of a semi-quantity short-range nitrification granular sludge system in an SBR. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a graph showing the particle morphology change (scale = 10 mm) of an embodiment of the present invention; Figure 2 This is a graph showing changes in the water quality of the reactor effluent according to an embodiment of the present invention. DETAILED DESCRIPTION

[0011] The stored granular sludge was inoculated in the sequencing batch reactor (SBR) to make the initial sludge concentration (MLSS) 6500 mg / L. The treatment object was simulated ionic rare earth mine tailings. The specific influent water quality at different stages is shown in Table 1: Table 1 Influent water quality at each stage

[0012] The cycle time is 6 hours, and the distribution of cycle time in different stages is shown in Table 2: Table 2 Cycle time composition of different stages

[0013] At the beginning of each stage, the sludge ammonia oxidation rate is measured. The theoretical aeration time is obtained by dividing the influent ammonia nitrogen by the ammonia oxidation rate. The aeration time is then increased or decreased based on the ratio of nitrite nitrogen to ammonia nitrogen in the effluent until the ratio stabilizes at around 1.32. The ammonia oxidation rate and aeration time control at each stage are shown in Table 3: Table 3 Ammonia oxidation rate and aeration time at each stage

[0014] The inoculated granular sludge is dark brown, with different sizes and shapes. On the 7th day, the granules are obviously yellow, and on the 15th day, the granules are denser and smoother. After increasing the nitrogen load, the shape and color of the nitrified granular sludge do not change much. Figure 1As shown. The dominant bacterial genus in the nitrifying granular sludge on the 90th day was Nitrosomonas , 20.32% relative to Fengdu, achieving the enrichment of ammonia oxidizing bacteria.

[0015] like Figure 2 As shown, NO3 in the SBR effluent in the first 7 days - -N showed an overall increasing trend, and then gradually stabilized. At the end of stage I, the effluent NH4 + -N and NO2 - -N were stable between 25.51-40.84 mg / L and 39.86-50.65 mg / L, NH4 + -N removal rate was maintained above 60%. When the influent ammonia nitrogen in stage II was increased to 125 mg / L, the effluent NO3 - -N is still low (mostly maintained below 5 mg / L), and the effluent NH4 + -N and NO2 - -N increases accordingly (between 40.95-58.86 mg / L and 68.40-80.67 mg / L, respectively), and the NH4 + -N removal rate slightly decreased (down to about 56% after the system stabilized). When the influent ammonia nitrogen in stage III increased to 150 mg / L, the effluent NH4 + -N and NO2 - -N were maintained between 70.75-86.86 mg / L and 93.79-102.00 mg / L, respectively, while 150 mg / L influent had no significant effect on NH4 + -N removal rate was slightly affected, down to 51%. In stage IV, when the influent ammonia nitrogen increased to 175 mg / L, the effluent still contained NH4 + -N and NO2 - -N, which are mainly stable between 85.35-94.03 mg / L and 116.95-123.25 mg / L, NH4 + -N removal rate dropped to 48%. By stage V, the effluent NH4 + -N and NO2 - -N is between 93.68-111.68 mg / L and 123.94-138.64 mg / L, respectively, NH4 + The -N removal rate is between 44% and 53%.

[0016] In the first 7 days, NAR gradually increased to more than 90%, and then slowly decreased with the increase of nitrogen load. - -N / NH4 + -N ratio fluctuates greatly, but the effluent NO2 can be controlled by aeration time- -N / NH4 + -N gradually stabilized and remained at around 1.32.

[0017] It can be seen that nitrifying granular sludge can be cultivated within 10 days using stored granular sludge as a carrier. By precisely controlling the aeration time through oxygen-limited aeration and ammonia oxidation rate, stable semi-short-term nitrification can be achieved in the SBR, providing a new method for the construction of semi-short-term nitrification before anaerobic ammonia oxidation denitrification of ionic rare earth mine tailings.

Claims

1. A method for rapidly constructing a semi-quantitative short-range nitrification granular sludge system, characterized in that: A semi-quantity short-range nitrification granular sludge system is quickly constructed before anaerobic ammonia oxidation denitrification of ionic rare earth mine tail water. The method for quickly constructing the semi-quantity short-range nitrification granular sludge system comprises the following steps: (1) A sequencing batch reactor (SBR) was used with a 6-hour operation cycle, including: 30 min of water inlet, 5 min of aeration and mixing, 218-128 min of standing, 80-180 min of aeration, 10 min of sedimentation, and 5 min of drainage; (2) The reactor was started by inoculating the stored heterotrophic granular sludge. Due to long-term storage, the granules were dark brown, but the granular structure was still maintained. The granulation rate was 99%, the average particle size was 0.98 mm, the MLVSS / MLSS was 0.82, and the SOUR was 7.53 mgO2 / gVSS•h. (3) To treat ionic rare earth mine tailings, the ammonia oxidation rate of granular sludge is measured at the beginning of each stage of operation. The theoretical aeration time is obtained by dividing the influent ammonia nitrogen by the ammonia oxidation rate, which is the aeration time in the first cycle. (4) Determine the nitrite nitrogen and ammonia nitrogen in the effluent of the first cycle. When the ratio of the two is greater than 1.32, correct the ammonia oxidation rate and recalculate the aeration time to reduce the aeration time of the next cycle; (5) If the ratio of nitrite nitrogen to ammonia nitrogen in the effluent of the first cycle is less than 1.32, the aeration time is recalculated according to the corrected ammonia oxidation rate to increase the aeration time of the next cycle; (6) The aeration time and standing time in each cycle are repeatedly corrected by the ammonia oxidation rate until the ratio of nitrite nitrogen to ammonia nitrogen in the effluent is stabilized between 1.28 and 1.

35. The remaining time in the cycle is the standing time. The aeration time is re-determined according to this method each time the influent ammonia nitrogen changes.

2. The method for rapidly constructing a semi-quantitative short-range nitrification granular sludge system according to claim 1, characterized in that: The limiting aeration intensity of the sequencing batch reactor SBR is 1.6 L / min, which oxidizes 56%-58% of the ammonia nitrogen in the influent into nitrite nitrogen.

3. The method for rapidly constructing a semi-quantitative short-range nitrification granular sludge system according to claim 1, characterized in that: The ratio of the ammonia oxidation rate to the nitrite oxidation rate is between 1.4 and 2.

4.

4. A method for rapidly constructing a semi-quantitative short-range nitrification granular sludge system according to any one of claims 1 to 3, characterized in that: The nitrogen load of the ionic rare earth mine tailings is 0.24-0.48 kg / m 3 •d, main water quality indicators: pH 3-4, ammonia nitrogen 100-200 mg / L, TP 2.4 mg / L, adjust the pH to 8-8.5 before entering the reactor.

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