Study On Membrane Pretreatment Process To Alleviate Ultrafiltration Membrane Fouling

In the environment of drinking water health and safety facing severe challenges,the third generation water treatment technology with ultrafiltration technology as the core has been paid more and more attention.However,in the process of water treatment,ultrafiltration membrane will inevitably be polluted.Therefore,on the premise of ensuring the effluent quality to meet the standard,reducing the falling speed of membrane flux,reducing the degree of membrane pollution and prolonging the service life of membrane are the key and difficult points in the field of membrane technology.However,the membrane pretreatment technology has been concerned and studied because of its potential to reduce membrane pollution.In this study,PACL was used as coagulant and PAC as adsorbent.PVDF100k Da,PVDF50k Da,PES100k Da and PES50k Da were selected Four different specifications of k Da ultrafiltration membrane were used to treat the raw water of Ganjiang River and Poyang Lake.Combined with two membrane pretreatment processes,coagulation pretreatment and adsorption pretreatment,the causes of membrane pollution were analyzed from the removal of organic matter in water,the change of membrane flux and three-dimensional fluorescence characteristics,and the effective methods to alleviate membrane pollution were discussed.The main conclusions are as follows:1.The three-dimensional fluorescence technology was used to measure the organic matter in the raw water of Ganjiang River and Poyang Lake,and the fluorescence response in the fluorescence spectrogram was analyzed.It was found that the organic matter in the raw water of Ganjiang River and Poyang Lake was mainly tryptophan protein and soluble microbial product.In addition,there were more tyrosine protein in the raw water of Ganjiang River and Poyang Lake,and more tyrosine protein in the raw water of Poyang Lake Humic acid organic matter.2.In the ultrafiltration treatment of Ganjiang and Poyang Lake raw water,the removal rate of UV₂₅₄ and TOC in Ganjiang and Poyang Lake Raw Water by ultrafiltration membrane is between 10.00%and 20.00%,respectively.The main organic component of membrane pollution is protein-like.At the same time,the fluorescence response of Ganjiang raw water in this area is stronger than that of Poyang Lake raw water,which shows that the protein-like content of Ganjiang raw water intercepted by ultrafiltration membrane is more than that intercepted by Poyang Lake raw water,which can explain the two kinds of sources After the water was treated by membrane,the membrane flux of Ganjiang raw water decreased more seriously than that of Poyang Lake raw water.3.Compared with the direct ultrafiltration of raw water,when the coagulation pretreatment is increased,the decrease of membrane flux decreases,and the difference of membrane flux between the direct ultrafiltration of raw water and the direct ultrafiltration of raw water becomes larger,which can increase the membrane flux of raw water of Ganjiang River and Poyang Lake by at least 16%and 20%;when the adsorption pretreatment is increased,the decrease of membrane flux also decreases,and the difference of membrane flux between the direct ultrafiltration of raw water and the direct ultrafiltration of raw water becomes larger The membrane flux of seed water can be increased by more than 20%.It shows that coagulation pretreatment and adsorption pretreatment can improve the membrane flux of ultrafiltration membrane and slow down membrane pollution.4.By analyzing the change of fluorescence difference map before and after ultrafiltration,coagulation ultrafiltration and adsorption ultrafiltration,the ultrafiltration membrane intercepts more organic matters in the raw water after increasing pretreatment,and the protein like substances in the raw water are the main substances that cause the decrease of ultrafiltration membrane flux,which indicates that the organic matters that contribute more to membrane pollution in the raw water of Ganjiang River and Poyang Lake are protein like substances.