印染废水对超滤膜污染的机理及防控工艺研究

发布时间：2018-01-03 21:14

  本文关键词：印染废水对超滤膜污染的机理及防控工艺研究　出处：《浙江理工大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： 印染废水 超滤 膜污染 混凝 臭氧氧化 清洗

【摘要】：纺织印染废水作为最主要的水体污染源,具有有机物含量高、成分复杂、色度高、水质变化大等特点,且回用率低。随着水资源的日益短缺,印染废水回用技术势必逐渐推广,而超滤/反渗透双膜技术是目前对印染废水进行深度处理和回用的有效技术之一,但是超滤作为反渗透的预处理很容易被污染,导致超滤的分离效率和使用寿命降低。如何在保证出水水质的前提下降低膜污染,是膜技术领域研究的重点和难点。本文利用阻力串联模型研究超滤膜过滤印染废水过程中膜污染的阻力分布,分析印染废水对超滤膜的污染机理,确定印染废水中造成超滤膜污染的主要污染物。在此基础上,系统研究了混凝预处理和臭氧氧化预处理对降低超滤膜污染的效果、以及不同清洗工艺对超滤膜通量的恢复效果,确定最佳的预处理及清洗工艺,减轻和控制超滤膜过滤印染废水过程中的膜污染。得出以下结论:(1)利用阻力串联模型,通过分析超滤处理印染废水过程中的污染阻力的分布,发现印染废水对超滤膜的污染主要集中于超滤膜表面,其污染机理主要为膜表面滤饼层的形成,膜表面污染阻力占总污染阻力的75.3%,而超滤膜孔内污染阻力仅占24.7%。通过单因素实验,发现印染废水对超滤膜的污染主要源自于废水中所含的浆料和助剂中的大分子有机物如PAM、PVA、CMC等。(2)混凝预处理实验表明:氯化铁混凝剂与聚丙烯酰胺助凝剂结合使用,混凝效果明显优于其他混凝剂。氯化铁的混凝效果随其用量的增大而增大,当氯化铁和聚丙烯酰胺用量分别为300 mg/L和2 mg/L时,其对印染废水COD和UV254的去除率分别可达26.8%和13.1%。确定混凝的最佳工艺参数为:废水pH为碱性、温度为20~30℃、沉降时间为100 min。印染废水经300 mg/L三氯化铁混凝处理后,在75 L/(m2h)的恒膜通量模式下进行超滤,可使超滤跨膜压差的上升速率由55 kPa/h降至6 kPa/h左右。(3)臭氧氧化对有机物的去除率随pH的增大而增大,当pH达到11时其上升速率减慢,因此控制原水pH为11进行氧化。温度对氧化效果的影响并不明显,因此控制臭氧氧化温度为常温。臭氧投加量为80 mg/L时,废水COD和UV254的去除率分别达到26.8%和44.8%左右,但是印染废水经臭氧氧化后,在75 L/(m2h)恒定膜通量下进行超滤,超滤跨膜压差的上升速率仅由55 kPa/h降至32 kPa/h左右,表明臭氧氧化对降低超滤膜污染不如混凝。(4)用经过混凝处理后的印染废水的上清液,在0.03 MPa恒定操作压力下进行超滤,研究不同清洗工艺的清洗效率。确定最佳清洗工艺为:每运行1小时用超滤产水在0.1 MPa下反洗2 min,选用pH值为12的2000 mg/L的次氯酸钠+氢氧化钠溶液作为清洗剂对超滤系统进行化学清洗,化学清洗周期为10小时。在此清洗工艺条件下,超滤系统可以长期稳定运行。
[Abstract]:Textile printing and dyeing wastewater, as the main water pollution source, has the characteristics of high organic content, complex composition, high chroma, great water quality change, and low reuse rate. With the increasing shortage of water resources, textile printing and dyeing wastewater is characterized by high organic content, complex composition, high chroma, and low reuse rate. The reuse technology of printing and dyeing wastewater will be popularized gradually, and ultrafiltration / reverse osmosis dual-membrane technology is one of the effective technologies for advanced treatment and reuse of printing and dyeing wastewater. However, as the pretreatment of reverse osmosis, ultrafiltration is easy to be contaminated, resulting in the separation efficiency and service life of ultrafiltration reduced. How to ensure the quality of effluent under the premise of reducing membrane fouling. In this paper, resistance series model is used to study the resistance distribution of membrane fouling in the process of UF membrane filtration of dyeing wastewater, and the mechanism of UF membrane fouling by printing and dyeing wastewater is analyzed. On the basis of this, the effects of coagulation pretreatment and ozone oxidation pretreatment on the reduction of ultrafiltration membrane fouling were studied systematically. As well as the recovery effect of different cleaning processes on the flux of ultrafiltration membrane, determine the best pretreatment and cleaning process. To reduce and control the membrane fouling in the process of ultrafiltration membrane filtration printing and dyeing wastewater. The following conclusion is drawn: 1) by using the resistance series model, the distribution of pollution resistance in ultrafiltration treatment of printing and dyeing wastewater is analyzed. It was found that the fouling of UF membrane by printing and dyeing wastewater was mainly concentrated on the surface of UF membrane, and the fouling mechanism was mainly the formation of filter cake layer on the membrane surface, and the fouling resistance of membrane surface accounted for 75.3% of the total fouling resistance. The fouling resistance of UF membrane is only 24.7. through the single factor experiment, it is found that the pollution of UF membrane from printing and dyeing wastewater is mainly caused by the macromolecular organic matter such as PAM in the slurry and auxiliaries contained in the wastewater. The experiment of coagulation pretreatment showed that ferric chloride coagulant combined with polyacrylamide coagulant. The coagulation effect of ferric chloride increased with the increase of its dosage, when the dosage of ferric chloride and polyacrylamide were 300 mg/L and 2 mg/L, respectively. The removal rates of COD and UV254 in printing and dyeing wastewater were 26.8% and 13.1.The optimum parameters of coagulation were determined as follows: the pH of wastewater was alkaline and the temperature was 2030 鈩，

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