Study On Ultrafiltration Combined Process Optimization And Performance Evaluation

The pollution of water resource in our country is more and more serious andthe drinking water quality safety standards are getting more and more strictly.Under such grim circumstances, ultrafiltration technology brings hope to ourdrinking water treatment field. However, the membrane fouling severely restrictsapplication of ultrafiltration technology in our country. As a consequence,membrane fouling control is the most fatal issue to be resolved in ultrafiltrationtechnology. Simultaneously, because of its late-starting in our country, the stableoperation and management experience of the ultrafiltration system are lacking. Thewater purification safety guarantee system of the ultrafiltration technolgy as thecore which has universal adaptability has not been formed. To solve these proble ms,this paper launched the researches: the flux of ultrafiltration is optimized to controlmembrane fouling control, premembrane chlorination and powder active carbonadsorption improve ultrafiltration combination process water purification effic iencyand membrane fouling control and evaluate ultrafiltration water plant performance.During the research ultrafiltration membrane of critical flux, the result ofcritical flux measurement test show that the critical flux of UF locate between23L/（m²·h） and25L/（m²·h）. Then ultrafiltration system was operated undersubcritical flux23L/（m²·h）, to study water purification performance and membranefouling of the ultrafiltration combined process, which result shows that thecombined process of UV₂₅₄, COD_Mn and TOC average removal rate were25.4%,24.8%and28.4%respectively; transmembrane pressure rose average0.37kPa aday; TMP appeared to stabilize or fall for several times during the polit test.During the study of premembrane chlorination and powder activated carboncontrolling membrane fouling, the experiments such as powder activated carbonabsorption effectiveness beaker test、 coagulation-sedimentation beaker test、coagulation-powder activated carbon absorption-sedimentation beaker test andpremembrane chlorination-ultrafiltration treating effluent of sedimentation tanklab-scale test were carried out. According to the above test results the best runningparameters of the integrated ultrafiltration pilot tests were determined: powderactivated carbon dosage10mg/L, powder activated carbon additive in position ofcoagulant3min later, PACl dosage4.5mg/L, available chlorine dosage0.5mg/L.Soon afterwards coagulation-sedimentation-ultrafiltration process pilot test,coagulation-sedimentation-premembrane chlorination-ultrafiltration process pilot test and coagulation-powder active carbon adsorption-sedimentation-premembrane chlorination-ultrafiltration process pilot test were conducted oneafter another. The test results show that: powder activated carbon absorptionstrengthen the coagulation sedimentation on organic matter removal efficiency, canalleviate ultrafiltration membrane fouling. After the pretreatment of coagulationsedimentation, premembrane chlorination slightly reduced ultrafiltration on organicpurification effic iency, but it alleviate ultrafiltration membrane fouling.In evaluation of ultrafiltration water plant performance, some traditionalindicators of water from the various stages process were detected, and the resultsshow that the water plant based on ultrafiltration technology as the core performgood water purification efficiency. To interpret what substance can cause themembrane fouling of the Dongying waterwork, UV254organics molecular weightdistribution, hydrophobicity/hydrophilicity and fluorescence characteristics of waterfrom the various stages process were studied, which suggest that hydrophilicaromatic protein-like organic matter could cause ultrafiltration membrane fouling.Finally the vector regression model was employed to analysis the transmembranepressure of unit flux, and the result show that the transmembrane pressure isalmost determine by the value of the previous day, which prove the ultrafiltrationsystem has the high stability.This thesis propose sustainable flux operation solution of ultrafiltrationcombination process, after studying the critical flux of ultrafiltration. Pre-treatmentcombined process before ultrafiltration was optimized and put forward the methodto strengthen ultrafiltration combination process water purification efficiency andmembrane fouling control by powder activated carbon adsorption and premembranechlorination. Besides, the performance of Dongying ultrafiltration waterworks wasevaluated.The research results provides technical support to ultrafiltration waterplant for the safe and stable operation.