Department of Biological Science and Technology, China University of Science and Technology, Taipei, ROC.
Environ Technol. 2013 Jan-Feb;34(1-4):283-8. doi: 10.1080/09593330.2012.692718.
Chitosan is a potential substitute for traditional aluminium salts in water treatment systems. This research compared the coagulant performance of acid-soluble chitosan with water-soluble chitosan and with coagulant mixtures of chitosan and aluminium sulfate (alum). We also assessed the coagulant performance of chitosan and poly-aluminium chloride (PAC) to remove kaolinite from turbid water. In addition, we evaluated their respective coagulation efficiencies under different coagulant concentrations, degrees of turbidity (NTU) and pH levels. Furthermore, we determined the size and settling velocity of flocs formed by these coagulants in order to illustrate major factors affecting kaolinite coagulation. The optimal concentrations of acid- versus water- soluble chitosan required to remove kaolinite from a 300 NTU suspension were 4.0 and 10.0 mg/l, respectively-with individual efficiencies of 79.3 and 92.4%, in that order. Optimum concentrations ofwater-soluble chitosan demonstrated a broader range than that of acid-soluble chitosan. In addition, it is of note that chitosan/alum and chitosan/PAC water-soluble coagulant mixtures demonstrated much wider ranges of optimal concentrations for turbidity reduction than either alum or PAC alone. Moreover, our water-soluble chitosan coagulant mixtures produced denser floc with elevated settling velocities that favour cost savings relevant to both installation and operational expenses. Based on our observations of these noteworthy performances, we confidently propose that a coagulant mixture with a 1:1 mass ratio of chitosan and alum presents a remarkably more cost-effective alternative to the use of chitosan alone in water treatment systems.
壳聚糖是水处理系统中传统铝盐的潜在替代品。本研究比较了酸溶性壳聚糖、水溶性壳聚糖以及壳聚糖与硫酸铝（明矾）的混凝剂混合物的混凝性能。我们还评估了壳聚糖和聚合氯化铝（PAC）去除浊水中高岭土的混凝性能。此外，我们评估了它们在不同混凝剂浓度、浊度（NTU）和 pH 值水平下的混凝效率。此外，我们还确定了这些混凝剂形成的絮体的大小和沉降速度，以说明影响高岭土混凝的主要因素。从 300 NTU 悬浮液中去除高岭土所需的酸溶性壳聚糖与水溶性壳聚糖的最佳浓度分别为 4.0 和 10.0 mg/L，去除效率分别为 79.3%和 92.4%。最佳水溶性壳聚糖浓度范围大于酸溶性壳聚糖。此外，值得注意的是，壳聚糖/明矾和壳聚糖/PAC 水溶性混凝剂混合物的最佳浓度范围比单独的明矾或 PAC 更宽，有利于降低浊度。此外，我们的水溶性壳聚糖混凝剂混合物产生的絮体密度更高，沉降速度更快，有利于节省与安装和运营成本相关的成本。基于我们对这些显著性能的观察，我们有信心提出，在水处理系统中，壳聚糖和明矾的质量比为 1:1 的混凝剂混合物是一种比单独使用壳聚糖更具成本效益的替代方案。
