Does anyone have any good methods for drying acrylic wastewater?

Acrylic wastewater treatment is difficult and has not been done very well at present. Here is an article for your reference. Dry process acrylic wastewater treatment technology Wang Hongwei, Sun Zaibai, Sun Guohua 1. School of Environmental Engineering and Chemical Engineering, Shanghai University, Shanghai 200072 ； 2． Shanghai Shangda Science and Technology Park Environmental Engineering Co., Ltd., Shanghai 200072 ； 3． Shanghai Petrochemical Co., Ltd. Ministry of Environmental Protection, Shanghai 200540 my country's acrylic fiber production began in the 1970s and reached its peak in the 1990s, and is expected to increase in the next few years. However, acrylic wastewater is a high-concentration organic wastewater that contains a variety of pollutants. It seriously pollutes the environment and is difficult to treat, which seriously hinders the development of acrylic production. The production process of acrylic fiber is divided into two categories: dry process and wet process. There are many reports on the treatment methods of wet acrylic wastewater, but there are fewer research reports on the treatment technology of dry acrylic wastewater, mainly Yang Xiaoyi from Tongji University and Lu Bin from Tsinghua University. Although the experimental results are good, they have not been promoted and applied in industry. The wastewater produced by 5 dry-process acrylic fiber production units of the same type across the country is mainly treated by the anaerobic-aerobic-biological activated carbon process. However, because the wastewater contains a certain concentration of sulfates and a large number of difficult-to-biodegrade oligomers, it is difficult to directly treat it with biochemical methods. As a result, external drainage cannot reach the * * Emission standards. . We use pretreatment and subsequent biochemical treatment processes to treat dry acrylic wastewater and have achieved good results. 1 Experimental part 1.1 Wastewater quality The wastewater used in the experiment was taken from a large domestic dry-process acrylic fiber production plant. Its water quality is shown in Table 1. http://www.wateradd.com/img/2006215114717.gif The pollutants in dry-process acrylic wastewater are mainly acrylonitrile, succinonitrile, acetonitrile, dimethylformamide, organic oligomers, etc. 1.2 Experimental instruments, materials and pharmaceutical equipment: ACO-380 Haili electromagnetic air compressor ； HL-2 constant flow pump ； LZB-3 glass rotor flowmeter ； LZB～8 gas flow meter ； Model 6511 electric mixer ； PHS-3CT pH meter ； TG328B electro-optical analytical balance ； 7321-Type I spectrophotometer. filler: The filler for iron-carbon internal electrolysis is an iron-palladium porous internal electrolysis sintered filler independently developed by Shanghai Shangda Science and Technology Park Environmental Engineering Co., Ltd. The filler is made of scrap cast iron filings and 10-20 mesh activated carbon according to 1: 1 volume ratio. It is then sintered at high temperature with a certain proportion of non-metallic particles and metal particles. ； The fillers used in the hydrolysis acidification tank and nitrification tank are combination fillers produced by Shanghai Petrochemical Environmental Protection Equipment Factory ； The filler used in the fluidized bed is Jw type three-dimensional porous biological suspension filler. Potion: Polyferric sulfate (PFS), purchased from outside ； Anionic polyacrylamide, cationic polyacrylamide, nonionic polyacrylamide, their relative molecular weight is about 4.5 million, purchased from outside ； Other analytical reagents are of analytical grade. 1.3 Wastewater treatment process flow The dry process acrylic fiber wastewater treatment process flow is shown in Figure 1. Since the dry acrylic wastewater treatment process is long and requires a lot of power and equipment, the pretreatment in the front stage is a discontinuous experiment, and the biochemical treatment in the back stage is a continuous experiment. The experimental time is from August to January of the following year. The temperature in winter is low, which is not conducive to the growth and reproduction of microorganisms. A submersible explosion-proof constant temperature heating rod is used to control the temperature of the biochemical reactor (28-35°C). 1.4 Sludge culture, acclimation and film inoculation The sludge was obtained from Ningbo Jinyong Acrylic Fiber Factory. First, the sludge is exposed for 24 hours to restore the activity of the sludge. ； The hydrolysis acidification, fluidization and nitrification were separately membrane-coated. In the early stage of start-up, the water distribution was mainly glucose. As the experiment progressed, glucose was gradually replaced by acrylic wastewater. After each film is successfully hung, the three reactors are connected in series and run stably for a period of time. The entire film hanging time is about 2.5 months. During the start-up and stable operation stages of film hanging, the performance of the sludge, the removal rates of BOD and COD, and their respective volumetric loads were examined to determine whether the film hanging was successful. In addition, a certain amount of phosphorus needs to be added during the film hanging period. 1.5 Determination of process parameters The hydraulic retention time of the subsequent biochemical treatment unit is shown in Table 2. During the experiment, different hydraulic retention times (HRT) can be controlled by adjusting different water outlet heights and inlet flow rates (Q). The dissolved oxygen mass concentration in the hydrolysis acidification tank is controlled at less than 0.5 mg/L, the dissolved oxygen mass concentration in the biological fluidized bed is controlled at 2-4 mg/L, and Q is 2 L/h. Potassium dihydrogen phosphate is based on a BOD to P mass ratio of 100: Add in a ratio of 1. 1.6 Experimental method 1.6.1 Pretreatment Use waste acid to adjust the pH of the wastewater to about 4, use polymeric ferric sulfate as the flocculant of the internal electrolyzed water, use polyacrylamide as the coagulant, and use 10% mass fraction of lime emulsion to adjust the pH of the internal electrolytic cell effluent to 8.0-8.5, stir for 3-5 minutes, settle for 1.5 hours, and then take the supernatant for measurement. Polymeric ferric sulfate is prepared into a solution with a mass fraction of 10%, and the dosage is 0.05% ； Polyacrylamide is prepared into a solution with a mass fraction of 0.3%, and the dosage is 450 g/m. 1.6.2 Subsequent biochemical treatment The hydrolysis acidification tank, biological fluidized bed and nitrification tank all adopt the method of water inlet from the bottom and water outlet from the top. Add potassium dihydrogen phosphate to the hydrolysis acidification tank to supplement phosphorus ； Add sodium carbonate to the nitrification tank to supplement alkalinity. The sludge and mixed liquid discharged from the bottom of the nitrification tank are returned with a volume fraction of 30%-50%. The main function of reflux is: (1) Supplement the sludge loss caused by the impact of wastewater quality and quantity in the hydrolysis acidification tank ； (2) Improve the denitrification function of the nitrification tank. Take the effluent from each reaction unit and let it stand for 30 minutes before measuring COD, BOD, ammonia nitrogen concentration and SS concentration. 1.7 Analysis method COD is determined by potassium dichromate method (GB11914-89) ； BOD was measured using the dilution and inoculation method (GB7488-87), and the ammonia nitrogen concentration was measured using the Sodium reagent photometric method (GB7479-87). ； DO concentration was measured using the modified iodometric method (GB7489-89) ； pH was measured using the glass electrode method (GB6920-86). 2 Results and Discussion 2.1 Pretreatment 2.1.1 Effect of HRT on COD removal efficiency When the coagulant is anionic polyacrylamide, the effect of internal electrolysis HRT on COD removal rate is shown in Figure 2. It can be seen from Figure 2 that the longer the internal electrolysis reaction time, the higher the COD removal rate. ； However, when the HRT exceeds 120 min, the COD removal rate increases slowly with time. Too long HRT will increase iron consumption and increase wastewater treatment costs. ； In addition, the longer the HRT, the more unfavorable it is for practical engineering applications. Therefore, the internal electrolysis HRT should be controlled at 2 h. 2.1.2 The influence of polyacrylamide type on coagulation effect. The influence of polyacrylamide type on COD removal rate is shown in Figure 3. Experiments show that using anionic polyacrylamide + polymeric ferric sulfate has a better effect on wastewater coagulation treatment. 2.1.3 Effect of pretreatment After pretreatment of acrylic wastewater by internal electrolysis and coagulation precipitation, its COD dropped from 1.650 mg/L to 1.310 mg/L, the COD removal rate was 20.6%, and the BOD/COD increased from the original 0.27 to 0.38. During the internal electrolysis reaction, some refractory organic macromolecules and soluble oligomers in the acrylic wastewater are converted into biodegradable substances. Therefore, the biodegradability of the wastewater is improved. The concentration of ammonia nitrogen in the water produced by internal electrolysis did not change, indicating that internal electrolysis had no effect on the removal of ammonia nitrogen. 2.2 Biochemical treatment The effluent quality of each biochemical treatment unit is shown in Table 3. The average COD and BOD removal rates and volume loads of each biochemical treatment unit are shown in Table 4. It can be seen from Table 3 and Table 4 that after the anoxic reaction, the COD of the effluent decreased. Although the removal rate was 15.4%, the BOD/COD increased from 0.38 to 0.48, and the BOD increased, making the subsequent aerobic treatment easier. At the same time, hydrolysis and acidification degrade some organic amines in the wastewater into low-molecular inorganic ammonia. COD and BOD in wastewater are mainly removed in the biological fluidized bed, and the COD removal rate reaches 71.6%. The ammonia nitrogen content continues to increase. This is due to the continued ammoniation of nitriles (such as acrylonitrile, acetonitrile, etc.) in the wastewater to generate ammonia. The effluent BOD is reduced to 57 mg/L, which is conducive to the growth of nitrifying bacteria in the nitrification tank. The original ammonia nitrogen in the wastewater, the ammonia nitrogen generated in the hydrolysis acidification tank and the ammonia nitrogen generated in the biological fluidization tank are removed in the nitrification tank, while COD is further reduced. The COD of the effluent after sedimentation in the secondary sedimentation tank is less than 160 mg/L, the BOD is less than 30 mg/L, and the ammonia nitrogen mass concentration is less than 160 mg/L, reaching the first-level discharge standard for wastewater in the acrylic industry. The volume load in Table 4 shows that this treatment process is suitable for application and promotion in actual projects. The anoxic-aerobic (biological fluidized bed)-nitrification process is used to further treat the dry acrylic wastewater pretreated by internal electrolysis and coagulation sedimentation process. The effect is good, and the effluent can meet the discharge standards. 3 Conclusions and Suggestions a) Using the iron-carbon internal electrolysis and coagulation precipitation pretreatment process to pretreat acrylic wastewater can reduce COD from 1 650 mg/L to 1 310 mg/L, the COD removal rate is 20.6%, and the BOD5/COD is increased from the original 0.27 to 0.38 ； The pretreated effluent was subjected to hydrolysis, acidification, aerobic biochemistry (biological fluidized bed), and nitrification biochemical treatment. The final effluent COD was 148 mg/L, BOD5 was 16 mg/L, ammonia nitrogen mass concentration was 13 mg/L, and SS mass concentration was less than 100 mg/L. The effluent water quality reached the first-level emission standard of the acrylic fiber industry. b) Use iron-palladium porous internal electrolytic sintering filler as the filler of the internal electrolytic cell, and the wastewater treatment effect is better. The filler has a porous structure with a large specific surface area, which allows acrylic wastewater to pass through with low water head resistance, thus avoiding common phenomena such as iron filings easily agglomerating and channeling when internal electrolysis is used to treat wastewater. But wastewater treatment costs increase. c) Since acrylic wastewater has poor biodegradability, if conditions permit, it can be combined with domestic sewage or chemical wastewater with higher biochemical properties to improve the treatment efficiency of acrylic wastewater and reduce its treatment cost. References 1 Jin Lichen. World acrylic fiber and acrylonitrile development forecast. Synthetic fiber industry, 1997, 20(1): 46～48 2 Cui Ruifang． An analysis of the current situation and development prospects of my country's acrylic fiber industry. Shandong Textile Technology, 2001, (4): 54～56 3 Gao Minhui． The development prospects of my country's acrylic fiber industry. Synthetic fiber industry, 2001, 24(1): 6～8,42 4 Huang Minsheng, Huang Sheng. Experimental study on the treatment of nitrile-containing wastewater from wet acrylic fiber production. Industrial Water Treatment, 2002, 22(5): 15～18 5 Xu Yatong． Treatment of nitrogen and phosphorus in wastewater. Shanghai: East China Normal University Press, 1994.43～63 6 Ouyang Li, Wang Xiaoming, Zhao Jianfu, etc. Progress in biochemical treatment of acrylic wastewater in my country. Industrial Water Treatment, 2001, 21(9): 11～14 7 Yang Xiaoyi, Shi Shaoqi, Jiang Zhanpeng, etc. Research on the treatment of acrylic wastewater by coagulation-two-phase anaerobic-anoxic-aerobic process. Water supply and drainage, 2001, 27(6): 40～45 Wang Hongwei, Sun Zaibai, Sun Guohua1. School of Environmental Engineering and Chemical Engineering, Shanghai University, Shanghai 200...

Thank you, this project was not completed in the end.