Embedding Immobilized Microorganism Technology to Treat High Ammoniatric Wastewater

[Corresponding author] Zhang Zhenjia, contact telephone number; ammonia nitrogen is the main oxygen contaminant in water, and it is also an important pollutant of eutrophication and environmental pollution. Entering water body can cause aquatic grass, blue-green algae and other organisms to multiply, resulting in lack of water body. Oxygen seriously affects water quality. For high ammonia nitrogen wastewater, the commonly used treatment methods include biological method, blow-off method, distillation of ammonia distillation tower, MAP method, and chlorination at break point. Due to the low biological investment and operating costs and mature technology, large-scale high ammonia nitrogen wastewater is used. Treatment is still based on biological methods.

Embedding immobilized microorganisms is a method of using chemical or physical means to position free microorganisms in a limited area of ​​carrier space and keep them active for repeated use. The method of immobilizing bacteria can purify and maintain high-efficiency strains, and therefore has the advantages of high processing efficiency, easy control of reaction, high purity and high efficiency of bacteria species, high biological concentration, no sludge generation, and good solid-liquid separation effect, etc., and is waste water. Dealing with a particular type of wastewater, such as ammonia-nitrogen wastewater, provides new ideas. Yu Dongdong studied the embedding of microorganisms in the treatment of ammonia nitrogen in surface water sources in urban water plants. Xia Yu studied the use of microbes to treat ammonia nitrogen in micro-polluted raw water. For the low ammonia nitrogen municipal water supply and micro-polluted raw water, the embedding of microbial technology has achieved a very good effect of ammonia removal. For the application of high ammonia nitrogen wastewater in industrial wastewater, no research has been done in this area.

This experiment mainly studies the feasibility of combining embedded immobilized microbial particles abbreviation embedded particles technology and A/O process to treat high ammonia nitrogen industrial wastewater, and provides the basis for the engineering application and promotion of this technology.

Test materials and methods 1.1 Embedded particles The embedded particles used in the test have been preliminarily domesticated and stored for about 2 weeks. They are 3 mm × 3 mm × 3 mm cubes of colloidal particles embedded in polymer materials with a smooth surface. Mechanical Good strength, black particles, embedding sludge for biological denitrification in Suzhou Sewage Plant Immobilized microbiological process technology for treatment of high ammonia nitrogen wastewater Lee Jung 1, Zhang Zhenjia 1, Fang Haijun 1. Environmental Science and Engineering, Shanghai Jiaotong University College, Shanghai 200240, China; 2. Sembcorp Utilities Investment Management Co., Ltd., Shanghai 200120, The filling rate of entrapped bacteria was 10, the influent ammonia nitrogen concentration was 623643 mg/L, the COD removal rate was more than 95, and the effluent reached “Sewage Synthesis Emission Standard "GB 8978-1996 Level 1 emission standard requirements.

High ammonia nitrogen wastewater embedding technology domesticated alkalinity carbon source water purification technology in the system of activated sludge.

1.2 Raw water quality The influent water adopts the integrated wastewater discharged from a chemical plant. The pollutants in the wastewater are mainly composed of easily biodegradable organic matter and ammonia nitrogen. Since the wastewater is taken from the regulating tank of the plant, the water quality changes little, and the influent water quality condition is as follows: Table 1 shows.

1.3 Test device The test device consists of an anoxic zone, an aerobic zone, and a sedimentation zone. The organic glass material is used. The effective volume of the anoxic zone is 8 L, and the effective volume of the aerobic zone is 20 L. The denitrification reaction is mainly performed in the anoxic zone. In the aerobic zone, nitrification reaction and biodegradation of organic materials are performed. An anoxic zone is equipped with a stirring device, an aeration device is installed at the bottom of the aerobic zone, and a wire screen is installed at the inlet and outlet of the aerobic zone to allow the sludge to pass through and block the embedded particles. In the precipitation zone, the mixture is returned to the anoxic zone by a pump, and the reflux ratio is 300%. The schematic diagram of the test flow is shown in Figure 1.

1.4 Determination method pH value using glass electrode method; COD potassium dichromate method; ammonia nitrogen using Nessler spectrophotometry; MLSS using 105 °C dry weight loss method; TN alkaline potassium persulfate digestion UV spectrophotometry.

Test contents and results discussion 2.1 Activated sludge and embedded particles During the acclimatization stage, the aerobic zone was added to the activated sludge in the biochemical pool of the sewage plant, maintaining aerobic 6.8 to 8.2 by adding enough sodium bicarbonate to maintain the system pH.

The temperature is 22 to 26°C. The anoxic zone is added to the sludge in the anoxic tank of the wastewater treatment plant, and the mixed liquid return pump is turned on. HRT was controlled at 24 h, and after the water was stable, 10% of the embedded particles were added to the aerobic zone to continue the operation. The ammonia in and out of the water was shown in Figure 2.

The activated sludge added is the sludge that has been domesticated in the wastewater treatment plant. Therefore, the removal efficiency of ammonia nitrogen is stable, HRT is 24 hours, and the removal rate of ammonia nitrogen is about 9-15 days. It is the data that the HRT in aerobic area gradually increases from 24 hours to 36 hours. The figure shows that when the HRT in the aerobic zone is increased to 36 h, the effluent ammonia nitrogen is about 810 mg/L.

After the activated sludge treatment stage is stable, 10% of the embedded particles are added to the aerobic zone, and the HRT in the aerobic zone is reduced to 24 h. The other conditions of the DO remain unchanged, because the embedded particles need to be adapted to the new wastewater. In the stage, it is necessary to increase the activity of embedded particles by acclimation. In Fig. 2, in 1622d, the removal efficiency of ammonia nitrogen is very slow because the embedded particles have not yet adapted to the new environment. 23 ~ 37 d embedded particles slowly adapt to the environment, ammonia nitrogen removal effect improved rapidly, after 22 days of acclimation, the ammonia nitrogen of the reactor's effluent dropped from an average of 200 mg/L to less than 10 mg/L, ammonia nitrogen removal efficiency From 70% to more than 98%. Some studies have shown that under the condition of sufficient alkalinity, the activity of the four-month-old embedding carrier is not long enough to preserve the embedded carrier of 10 mgNH. It has a certain activity in itself, so after 22 days, the domestication system has been Achieve high ammonia nitrogen removal efficiency.

2.2 Control of Nitrification Alkalinity Studies have shown that simultaneous nitrification consumes alkalinity in the water resulting in a drop in the pH of the system, in order to ensure the pH of the system is suitable for the nitrification reaction pH indicator values ​​1 - storage tank 2 - lift pump 3 - agitator 4 - Anoxic Zone 5 - Aerobic Zone 6 - Embedding Carrier 7 - Aeration Tube 8 - Sedimentation Zone 9 - Mixed Liquid Return Pump 10 - Wire Screen 11 - Effluent Mixture Backflow Water Running Days / d Inlet Ammonia nitrogen is added into the granules to embed granules. Effluent ammonia nitrogen HRT=24 h Activated sludge effluent Ammonia nitrogen only HRT=24 h Activated sludge effluent Ammonia nitrogen HRT=24～36 h, need to be added alkalinity to increase the pH change Buffering effect, the commonly used agents for adding alkalinity include sodium carbonate and sodium bicarbonate. The test uses direct addition of raw water. It is not appropriate to use sodium carbonate to raise the pH too fast. Therefore, sodium bicarbonate is used to increase the alkalinity of the incoming water. In theory, the oxidation of 1 g of ammonia to nitrate requires consumption of 7.14 g of alkalinity, and removal of 1 g of BOD can produce 0.3 g of alkalinity. During denitrification, reduction of 1 g of nitrate nitrogen to nitrogen can theoretically recover 3.57 g of alkalinity, so the theoretical alkalinity to be added = 7.14 x nitrification nitrogen - influent total alkalinity - 0.3 x BOD removal - anti Nitrification consumption of BOD 3.14 × denitrification denitrification amount, calculated by the need to add additional sodium bicarbonate should be 1 ~ 2 g / L. Different influent sodium bicarbonate dosing amount of ammonia on the water as shown in Table 2 .

As can be seen from Table 2, the nitration reaction consumes a large amount of alkalinity in water. If the amount of sodium bicarbonate is 1 g/L, the alkalinity will be insufficient, the effluent pH will be as low as 5.5, and the ammonia removal efficiency will also be reduced to 75%; The increase amount was increased to 2 g/L, the pH of the effluent was normal, and the ammonia nitrogen removal rate also reached 98%. The control of alkalinity has a great influence on the nitrification reaction. The optimal pH value for the growth of nitrifying bacteria is in the neutral or weak alkaline range. When the pH value deviates from the optimum value, the reaction rate gradually decreases. To ensure efficient nitration, raw water should be added with 2 g/L sodium bicarbonate.

2.3 Control of denitrification carbon source Under deoxygenation conditions, denitrifying bacteria use nitrate nitrogen as electron acceptor and organic carbon as electron donor to reduce nitrate nitrogen to gaseous nitrogen N to achieve nitrogen removal. . Therefore, the sufficient carbon source in the influent water is an important condition for the denitrification reaction to proceed smoothly. This experiment originally had the problem of insufficient carbon source, and often metoxic carbon source requirements were met by adding methanol and glucose. Studies have shown that glucose is The optimum carbon source dosage was 3.2 g methanol: 1 g nitrate nitrogen, 6 g glucose: 1 g nitrate nitrogen. This experiment increased the carbon source by adding glucose to the feed water. The amount of different glucose added to the TN The effect of the removal is shown in Table 3.

As can be seen from Table 3, although 2 g/L of glucose was added to the influent, the effluent COD was still lower than 50 mgL. The main reason was that the HRT in the aerobic zone was long and the excess glucose was activated sludge in the aerobic zone. degradation. When the influent glucose is 1 g/L, the TN removal rate is only 53 to 63%. When the influent glucose dosage reaches 2 g/L, the TN removal rate can reach 88 to 90%. In order to ensure the removal rate of TN, at least 2 g/L of glucose is added to the influent to increase the carbon source.

2.4 The removal rate of ammonia nitrogen, TN, and COD in the system The influent water is added with 2 g/L glucose and 2 g/L sodium bicarbonate. The anoxic zone starts the agitator, the mixture reflux ratio is 300%, and the HRT is good by 24 h. After reducing to 20 h, the system continued to run to examine the removal efficiency of ammonia nitrogen, TN, and COD. The inflow and outflow water quality in the stable operation stage is shown in Figure 3.

From Fig. 3, we can see that during the stable operation phase, influent ammonia nitrogen 623-643 dosing amount test result input amount effluent ammonia nitrogen effluent ammonia nitrogen removal rate dosing effluent TN effluent COD NT removal rate operation days/d influent ammonia nitrogen effluent ammonia nitrogen influent TN Effluent TN days of operation /d influent COD effluent COD Li Wei, Zhang Zhenjia, Fang Haijun. Implantation of immobilized microbiological process technology to treat high ammonia nitrogen effluent water purification technology is followed Page 31 [6] Chen Ying, Liu Mingqing, Hui Zugang, et al. Fenton Oxidation Cracking of Excess Sludge Experimental Study [8] CJ/T 221–2005, Sludge Detection Methods for Municipal Wastewater Treatment Plants [S]. Beijing: China Standard Press, 2005.

[9] Lu Wen, Zhang Dengfeng, Hu Kailin, et al. Effect of Cationic Surfactant on Dewatering Performance of Sludge and Mechanism of Action[J].Environmental Chemistry,2008,27(4):444448.

[10] Xie Min, Shi Zhou, Li Shuzhan. Sludge Dewatering Performance Parameters-Some Problems of Specific Resistance Test [11] GB 14-2002, Water and Wastewater Monitoring and Analysis Methods [S]. Beijing: China Environmental Science Press, 2002.

[12] Xia Chen Jiao. Research on Advanced Treatment of Dewatering of Residual Activated Sludge [D]. Nanjing: Nanjing [13] Li Juan. Fenton Oxidation Cracked Municipal Sludge and Bioleaching Treatment of River Sediments [D].

Changsha: Hunan University, 2008: 2829.

[14] Chen Chuanhao, Xie Bo, Ren Yuan, et al. Fenton reagent treatment of various impact factors in wastewater [15] Lu Wen. The effect of extracellular polymer EPS on the physical and chemical properties of sludge [J]. Environmental Science [17] Chen Yinguang, Yang Haizheng, Wu Guibiao, et al. Surfactant Improves Dewatering Performance and Mechanism of Activated Sludge[J].Chinese Journal of Environmental Science,2000,21(5):97100.

Conclusion 1 Using embedded immobilized microbial technology and A/O process to treat high ammonia nitrogen industry wastewater, the influent ammonia nitrogen is 623643 mg/L and the average effluent ammonia nitrogen is 10 mg/L under the influent alkalinity and denitrification components. Ammonia nitrogen removal rate of more than 98%; influent TN is more than 88%; influent COD are out of water COD effluent COD, ammonia nitrogen up to "Integrated Wastewater Discharge Standard" GB 8978-1996 Level 1 emission standards.

2 After adding the embedded particles to the aerobic section of A/O process, after 22 days of acclimation, the removal efficiency of ammonia nitrogen increased from 70% to 98%; the same effluent concentration of ammonia nitrogen was reached, and HRT decreased from 36 h to 20 h.

After adding the embedding particles, the ammonia nitrogen removal efficiency of the system can be effectively improved, and the carrier dosing is simple and easy, which is very suitable for the upgrading of the existing wastewater treatment plant. The ammonia nitrogen of the effluent can be achieved without expanding the reaction tank.

3 For high ammonia wastewater, the alkalinity required for nitrification and the carbon source required for denitrification are important factors affecting the denitrification efficiency. Sufficient nitrogen and nitrogen removal effects can be achieved by adding sodium bicarbonate and glucose through the feed water to ensure sufficient alkalinity and carbon source.

[1] Fang Aihong, Huang Yinzhi, Qian Yu. On the cause, harm and prevention of blue algae outbreak in Taihu Lake [2] Pan Xinsheng, Jia Zhiyu, Yang Haizhen. Ammonia nitrogen treatment technology in wastewater [J]. Water purification technology, [3] Li Yu. Biological immobilization technology in the treatment of nitrogenous wastewater [J]. Industrial safety and [4] Yu Dongdong, Jin Yongwei, Zhang Zhen, etc. Experimental study on embedding immobilized microbes to treat micro-polluted water source[J].China Water & Wastewater,2008,24(13):8588.

[5] Xia Yu, Zhang Zhenjia, Wang Xi. Research on the treatment of effluent from wastewater treatment plant with embedded immobilized bacteria [6] Chen Yajie, Yao Tao, Li Zhirong. Nitrification of Immobilized Nitrifiers under Different DO Conditions[J].Environmental Science and Technology,2006,29(5):1719.

[7] Deng Yanyan, Chi Lina, Zhou Weili, et al. Embedded in the characteristics of the acclimation stage of immobilized nitrifying bacteria [8] Alchemist. The influence of pH value on the rate of nitrosation/denitritation reaction of ammonia wastewater with high concentration [9] Chen Xuliang. The nitrification system alkalinity characteristics and control strategy research [J]. Zhejiang University [10] Suining. Comparison of methanol and glucose as carbon source in denitrification process[J].Shanghai Normal University