Engineering Design And Commissioning Of Aniline Chemical Wastewater

Aniline is an important organic chemical material in human daily life.It is widely used in many fields,such as pharmaceutical,printing and dyeing,paint and so on.The wastewater produced during the industrial production of aniline is highly toxic.It usually contains a large amount of aniline,inorganic salts and other types of organic matters,which seriously pollute the water and should be strictly controlled.The purpose of this project is to design a sewage treatment station to treat aniline wastewater produced in the production of acetanilide and N,N-methylaniline according to the requirements of EIA and conducts operational commissioning of the project.The project focus on the removal efficiency and standard of COD,NH₃-N,pH,SS,aniline and other pollution factors.This project uses a combination process of triple effect evaporation+Fenton oxidation+UBF+A/O-MBR+O₃ catalytic oxidation,according to the discharge rules and characteristics of the wastewater in the process of production the domestic and combined with the advanced water treatment technology at homeandabroad.Thedesignscaleis 48m³/d,the influent water quality of COD?11000mg/L,NH₃-N?30mg/L,aniline?150mg/L,p H=9¹1,SS?350mg/L,effluent discharge standard of COD?40mg/L,NH₃-N?2mg/L,aniline?2mg/L,pH=6-9,SS?150mg/L.The design feature of this project is the combination of advanced oxidation technology and biochemical treatment technology,which provides a new design idea for the treatment of Aniline Wastewater with refractory biochemical degradation.The design scale of the triple effect evaporator is 2t/h,the Fenton oxidation reactor adopts three lattice structures.The total residence time of Fenton oxidation reactor is 2.6h.The wastewater treated by a triple-effect evaporator and Fenton oxidize reactor was mixed with the domestic wastewater?24m³/d?.Then wastewater inflows into the UBF reactor.The design parameters of UBF anaerobic tower are depicted as follows:water quantity=48m³/d,D=4m,the effective volume=125m³,hydraulic residence time=62.5h.The design parameters of A/O reactor are depicted as follows:effective volume=42.5 m³,total residence time=21.25h.The design parameters of MBR reactor are depicted as follows:effective volume=12.15m³,residence time=6h.O₃ catalytic oxidation tower design size is?×H=800×5000mm.That set up two layers of modified activated carbon catalyst bed and each bed is 0.5 meters high.The effective volume and hydraulic retention time of is 2.6m³ and 1.3h.During the commissioning period,actual the influent water quality of COD?10231mg/L,NH₃-N?34mg/L,aniline?110mg/L,pH=9¹1,SS?328mg/L.The removal of inorganic salt by triple effect evaporator is less than 110mg/L.The experimental results show that the best operating conditions for this project are depicted as follows:pH=4,H₂O₂ dosage=25ml/L,FeSO₄·7H₂O dosage=1.25g/L.COD and aniline removal rate by Fenton oxidation is more than 33.7% and 84.6% in the above conditions.The B/C value increased from 0.12 to 0.37 and the biochemical properties of the wastewater were significantly improved by Fenton oxidation.The start-up period of the UBF reactor is three months.The excess sludge from a domestic sewage treatment plant in Xinxiang was used as the inoculation sludge.COD volume load increased gradually from 0.3kg COD/?kgMLVSS·d? to 1.5kg COD/?kgMLVSS·d?.The temperature of UBF is controlled at 35?.The results showed that the removal rate of COD and aniline by UBF anaerobic tower is more than 71.7%and 38.4%.The commissioning of A/O-MBR system is synchronous with the start of UBF reaction tower.The remaining sludge of a domestic sewage treatment plant in Xinxiang is still used as mud.In the aerobic reactor,sludge was cultivated with clean water and then domesticate sludge gradually with the wastewater which UBF reactor effluent.The debugging results showed that COD and ammonia nitrogen removal effect is the best in the condition of aerobic reactor DO=2⁴mg/L,internal recycle ratio=200%.The COD and ammonia nitrogen removal rate is more than 90.3%and 89.7%in the above condition.SS of the wastewater is reduced to less than 21mg/L by MBR.The removal rate of COD and aniline is more than 38.3%and 24.5%by ozonation.The discharged wastewater is COD?38mg/L,NH3-N?2mg/L,aniline?1.8mg/L,pH?6-9,SS?21mg/L by this project,it is satisfy the standard of drainage.