Study Of Enhanced Coagulation Combined With Ultrafiltration Membrane System

In the study,enhanced coagulation ultrafiltration membrane system for the treatment of simulated surface water is investigated.Effect of increase the dosage of coagulant and the use of complex coagulant AlCl₃-CPAM on the efficiency and stability of the system is studied.Three-dimensional fluorescence and differential UV is used to characterize the changes of the organic matter.Effect of ultrasound on enhanced coagulation and ultrafiltration are analyzed.The findings are as follows:The system plays a significant role in the control of membrane fouling.Enhanced coagulation-ultrafiltration system significantly reduces the fine particles,organic matter accumulated in the ultrafiltration membrane.The removal of organic matter increased significantly during the enhanced coagulation.The coagulation-ultrafiltration system has a significant impact on the fluorescence intensity of water,which can effectively reduce the peak Ex/Em at 220-230 nm/350 nm?II?,215 nm/400 nm,275nm/350 nm?IV?fluorescence.The fluorescence of the regions of tyrosine,tryptophan,similar protein and others were weakened.The effects of coagulation on UV absorption are mainly concentrated at wavelengths 216 nm,254 nm and 280nm.The removal of UV absorption by ultrafiltration membrane mainly concentrates at two wavelengths 216 nm and 272 nm,indicating that it has selective retention of organic matter in water and may have an important influence on the control of the formation of disinfection by-products.NOM as a major pollutant in water treatment has many effects on the operation of water treatment.Ultrasound has complex effect on water quality,which has an impact on the process of enhanced coagulation and treatment of ultrafiltration.The effect of ultrasound on the behavior of organic matter is reflected in pH,turbidity and TOC.The study shows that ultrasound can reduce the pH and the concentration of TOC in the AHA solution.The structure and properties of organics are changed by ultrasound.Ultrasound decreases the pH and TOC of the solution.At the same time,the total amount of carboxyl and phenolic groups in the natural organic matter is reduced by ultrasound,leading to the amount of DOM-Me(Ca²⁺and Al³⁺)decrease,during which mitigates the membrane fouling.The quantity of carboxyl and phenolic groups in natural organic matter was quantitatively analyzed by spectral parameters DSlope_350-400 combined with NICA model.It demonstrates that the decrease of total amount of carboxyl and phenolic groups in the natural organic matter caused by ultrasound,which leading to the amount of DOM-Me(Ca²⁺and Al³⁺)decrease.It shows that the concentration of carboxylic groups decreased with the increase of ultrasound power,while the concentration of the operationally defined phenolic groups increased with the increase of ultrasound power.It illustrates that the complexation between metal and DOM by ultrasound is related to the metal species,the power of ultrasound and the intrinsic properties of DOM.Ultrasound,as a pretreatment,reduces the complexation of DOM with metal ions and affects the process of coagulation and the presence of metal,which changes the behavior of subsequent process.Ultrasound plays an important role in improving the effect of coagulation and controlling of membrane fouling...