本文選題：反洗水組分　切入點：反洗效率　出處：《天津工業(yè)大學》2017年碩士論文　論文類型：學位論文

【摘要】：反洗水組分對超濾膜污染進程有重要影響,以腐殖酸(Humic acid,HA)、Na+和Ca2+模擬反洗水中的小分子有機物、一價和二價金屬陽離子,以腐殖酸、海藻酸鈉(Sodium alginate,SA)和牛血清蛋白(bovine serum albumin,BSA)模擬真實微污染地表水中的天然有機物(natural organicmatter,NOM)主要組分,通過死端過濾的方式研究了反洗水中的不同組分對PVDF超濾膜通量和反洗后膜通量恢復(fù)情況的影響。同時借助質(zhì)量守恒準確地對膜可逆污染物和不可逆污染物進行定量的分析。通過實驗對比分析可得,NOM各污染物之間存在協(xié)同作用,小分子污染與大分子污染物共同生成更為致密的濾餅層,使得膜通量急劇下降。金屬陽離子之間的與NOM污染物質(zhì)之間的作用是影響膜通量變化的主導因素;NOM各組分對膜面的累積的不可逆污染存在一定規(guī)律,蛋白質(zhì)類物質(zhì)BSA對膜面不可逆污染貢獻最大,多糖類物質(zhì)SA次之,腐殖質(zhì)類小分子有機物HA最小;通過質(zhì)量守恒定律分析發(fā)現(xiàn),經(jīng)過反向水力清洗后,濾餅層變得膨松,膜通量得到一定恢復(fù),污染物并未完全有效去除,隨著過濾進程又重新被壓實至膜面;超濾進水和反洗水中的二價金屬陽離子Ca2+均能夠與污染物或膜之間產(chǎn)生架橋作用、靜電屏蔽作用,加固膜面和污染物之間的作用,產(chǎn)生較多的不可逆污染;Na+的放電能力較Ca2+強,能夠獲得較Ca2+多與NOM污染物結(jié)合的機會,減少了由于Ca2+"架橋作用"產(chǎn)生的污染物,減少了不可逆污染。反洗水中的Na+也能夠和濾餅層中的Ca2+發(fā)生離子交換,破壞部分架橋,增加污染物的可逆性。反洗溶液中單獨存在的小分子有機物HA對膜面污染存在一定的影響,但當存在Ca2+時,HA對膜面污染的作用明顯增強,一方面Ca2+架橋作用強化了小分子有機物在膜面的吸附,另一方面HA分子和Ca2+共同形成較大的有機物聚集體,堵塞反洗通道,形成反洗無效孔,反洗通道的堵塞,使得產(chǎn)生較為明顯的不可逆污染。
[Abstract]:The backwash water component has an important effect on the process of ultrafiltration membrane fouling. Humic acid humic acid (humic acid) and Ca2 are used to simulate the small molecule organic compounds, monovalent and divalent metal cations in the backwash water, which are used as humic acids. Sodium alginate (sodium alginate) and bovine serum albumin (BSAs) were used to simulate the main components of natural organic matter (NOM) in real micro-polluted surface water. The effects of different components in backwash water on the flux of PVDF ultrafiltration membrane and the recovery of membrane flux after backwash were studied by dead-end filtration. The reversible and irreversible pollutants of membrane were accurately and accurately treated with the help of mass conservation. Quantitative analysis. Through the comparative analysis of experiments, we can find that there is a synergistic effect among the pollutants of NOM. Small molecule pollution and macromolecular pollutants together form a denser filter cake layer. The interaction between metal cations and NOM pollutants is the main factor affecting membrane flux change. The protein substance BSA contributed the most to the irreversible fouling of the membrane surface, followed by the polysaccharide SA, and the humus small molecule organic matter HA was the smallest. Through the analysis of the law of conservation of mass, it was found that the filter cake layer became dilated after reverse hydraulic cleaning. The membrane flux was recovered, the pollutants were not completely removed, and the membrane surface was compacted again with the filtration process, and the bivalent metal cation Ca2 in the ultrafiltration and backwash water could bridge with the pollutants or the membrane. Because of the effect of electrostatic shielding, strengthening the film surface and the effect of pollutants, the discharge ability of Na produced more irreversible pollution is stronger than that of Ca2, and it can obtain more chances of combining with NOM pollutants than Ca2. The pollution caused by "bridging action" of Ca2 is reduced, and irreversible pollution is reduced. Na in backwash water can also exchange ions with Ca2 in filter cake layer and destroy some bridges. To increase the reversibility of pollutants, HA, which exists alone in backwash solution, has a certain effect on membrane surface fouling, but when Ca2 exists, the effect of HA on membrane surface fouling is obviously enhanced. On the one hand, the bridging effect of Ca2 enhances the adsorption of small molecular organic compounds on the membrane surface, on the other hand, HA molecules and Ca2 together form a larger organic aggregates, blocking backwash channels, forming ineffective pores for backwashing and blocking backwash channels. The result is more obvious irreversible pollution.
【學位授予單位】：天津工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X703;TQ028.8

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