铝系混凝剂减缓DOM引发膜污染的红外光谱-多变量曲线分辨分析

论文总字数：36265字

摘 要

膜过滤是一种高效的水处理技术，尤其是超滤技术凭借其分离效率高、分离过程无相变、绿色节能等优势，近年来被广泛应用于工业废水处理、生活污水回用、海水淡化预处理等领域。然而，由于原水中的杂质被截留或吸附在膜表面，以及膜与原水中存在的各种组分之间发生物理、化学、生物等作用导致膜孔堵塞，产生膜污染。膜污染过程导致膜通量下降，因此需要定期清洗或更换超滤膜，增加了超滤膜的应用成本。当超滤技术应用于生活污水处理厂二级出水深度处理时，出水中的胶体物质和溶解性有机质（Dissolved Organic Matter，DOM）是形成超滤膜污染的主要污染物。

本课题使用不同形态的Al（氯化铝、聚合氯化铝、硫酸铝），通过在线混凝结合超滤的方式处理含有不同DOM组分（腐殖酸(HA)、高岭土溶液、牛血清白蛋白(BSA)）的模拟原水研究不同Al形态、不同组分及其相互作用对超滤膜污染过程的影响。本实验建立流量衰减模型模拟膜污染过程，结合衰减全反射红外光谱(IR-ATR)和多变量曲线分辨-交替最小二乘法(MCR-ALS)的数据处理方法解析膜污染相对浓度丰度，揭示硫酸铝缓解DOM膜污染过程的机理。本实验的创新点在于用MCR-ALS对膜上的多种污染物进行定性和定量分析，确定混凝剂的去除机理和对膜污染的影响。

最终实验结果表明，硫酸铝和氯化铝混凝剂均可明显提高膜比通量，减缓膜污染。铝离子浓度为0.4 mg/L时，氯化铝混凝效果较好。铝离子浓度为2.4 mg/L时，硫酸铝混凝效果较好。但低浓度PAC（Al³ 浓度0.2 mg/L、0.4 mg/L）对缓解膜污染效果不明显，反而加重膜污染。超滤膜污染主要由原水中BSA引起，因为BSA的存在大大降低了混凝的效果，阻碍疏松滤饼层的形成。向DOM原水中投加硫酸铝混凝剂，膜污染主要发生在过滤前期，即膜孔窄化、堵塞。过滤后期，膜表面形成疏松滤饼层，对膜通量影响不大，膜污染减缓。

关键词：超滤膜，膜污染，铝系混凝剂，衰减全反射红外光谱，多变量曲线分辨-交替最小二乘法

ABSTRACT

Membrane filtration is an efficient water treatment technology. Especially, in recent years ultrafiltration technology has been widely used in industrial wastewater treatment, domestic wastewater reuse and seawater desalination pretreatment fields due to its high separation efficiency, non-phase change in separation process, and green energy conservation. However, since impurities in the raw water are trapped or adsorbed on the surface of the membrane, and physical, chemical, biological, etc. are occurred between the membrane and various components present in the raw water. Because of this the membrane pores are clogged, resulting in membrane fouling. The membrane fouling process leads to a decrease in membrane flux, so it is necessary to periodically clean or replace the ultrafiltration membrane, increasing the application cost of the ultrafiltration membrane. When ultrafiltration technology is applied to the secondary effluent treatment of domestic sewage treatment plants, the colloidal substances and dissolved organic matter (DOM) in the effluent are the main pollutants that form ultrafiltration membrane pollution.

This study uses different forms of Al (aluminum chloride, polyaluminum chloride, aluminum sulfate) to treat simulated raw water containing different DOM components (humic acid(HA), kaolin solution, bovine serum albumin(BSA)) by on-line coagulation combined with ultrafiltration. The effects of different Al forms, different components and their interactions on the ultrafiltration membrane fouling process are studied. This experiment establishes a flow attenuation model to simulate the membrane fouling process, and combines the infrared attenuated total reflection (IR-ATR) and multivariate curve resolution-alternating least squares (MCR-ALS) data processing methods to analyze the relative concentration abundance of membrane fouling, revealing The mechanism of aluminum sulfate to alleviate the DOM membrane fouling process. The innovation of this experiment is to use MCR-ALS to qualitatively and quantitatively analyze various pollutants on the membrane to determine the removal mechanism of the coagulant and the the effect on the membrane fouling.

The final experimental results showed that both aluminum sulfate and aluminum chloride coagulant could significantly increase the membrane specific flux and slow down the membrane fouling. When the aluminum ion concentration was 0.4 mg/L, the aluminum chloride coagulation effect was better. When the concentration of aluminum ion was 2.4 mg/L, the effect of aluminum sulfate coagulation was better. However, the low concentration of PAC (Al³ concentration 0.2 mg/L, 0.4 mg/L) had no obvious effect on the membrane fouling, but rather increasesed the membrane fouling. Ultrafiltration membrane fouling was mainly caused by BSA in raw water, because the presence of BSA greatly reduced the effect of coagulation and hindered the formation of loose filter cake layer. After the aluminum sulfate coagulant added to the DOM raw water, the membrane fouling mainly occured in the pre-filtration stage, that was, the pores of the membrane were narrowed and blocked. At the end of filtration, a loose filter cake layer was formed on the surface of the membrane, which had little effect on membrane flux and membrane fouling was slowed down.

KEY WORDS: ultrafiltration membrane, membrane fouling, aluminum coagulant, IR-ATR, MCR-ALS

目 录

摘要 ……………………………………………………………………………………………………………Ⅰ

Abstract …………………………………………………………………………………………………… Ⅱ

第一章 绪论 1

1.1引言 1

1.2溶解性有机质 1

1.3膜技术 1

1.3.1简介 1

1.3.2超滤膜 2

1.4膜污染 2

1.4.1简介 2

1.4.2膜污染的控制方法 3

1.4.3膜污染过程的表征 4

1.5 衰减全反射红外光谱技术 5

1.5.1简介 5

1.5.2 IR-ATR技术用于表征膜污染过程及其数据处理方法 6

1.6本文的研究目的和主要研究内容 7

1.6.1研究目的 7

1.6.2主要研究内容及创新点 7

第二章 材料与方法 9

2.1实验材料与装置 9

2.2在线混凝-超滤实验方法 9

2.3检测方法 10

2.3.1膜比通量归一化方法 10

2.3.2 AFM检测方法 11

2.3.3 IR-ATR检测方法 11

2.3.4 MCR-ALS计算方法 11

第三章 超滤膜污染过程 13

3.1引言 13

3.2流量衰减曲线 13

3.3 AFM检测膜污染 15

3.4 本章小结 18

第四章 红外光谱及MCR-ALS处理分析 19

4.1引言 19

4.2衰减全反射红外光谱 19

4.3多变量曲线分辨-交替最小二乘法 20

4.4 本章小结 28

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