Environmental Engineering Reference
In-Depth Information
38
Al
13
Cluster Nanolocculants for Remediation
of Dissolved Organic Compounds and
Colloidal
Particles in Water
Dongsheng Wang, Hongxiao Tang, and Jiuhui Qu
Research Center for Eco-Environmental Sciences (RCEES),
Chinese Academy of Sciences (CAS), Beijing, China
CONTENTS
38.1 Introduction ........................................................................................................................ 777
38.2 Loss of Al
13
in High-Concentration PACl ....................................................................... 778
38.3 Preparation and Stability of Pure Al
13
............................................................................ 779
38.4 Particle Size Effect of Coagulation with Nano-IPF ....................................................... 780
38.5 Industrialization of Nano-IPF .......................................................................................... 781
38.6 Summary ............................................................................................................................. 784
Acknowledgments ...................................................................................................................... 784
References ..................................................................................................................................... 784
38.1 Introduction
Poly-aluminum chlorides (PACls) of the form Al
n
Cl
(3
n
−
m
)
OH
m
are typically used as coagu-
lants in water and wastewater treatment to remove dissolved organic compounds and
suspended colloidal particles. The eficiency of the coagulation process depends largely on
the highly eficient locculant, matching reactor (locculator), and auto-dosing control tech-
nique (as in the FRD system suggested in the early 1990s; Tang, 1998) besides the source
water quality. Among the inluencing factors, the deciding one is the physicochemical
properties and the speciation distribution of the coagulant. Traditionally, the most widely
applied coagulants are alum and ferric chloride. However, inorganic polymer locculants
(IPFs) developed based on the salts in the 1960s are typically applied instead because of
their high eficiency with relatively low cost, as well as other merits such as tight loc for-
mation, eficient sediment quality and suitability at low temperature, high natural organic
matter, wider alkalinity region, etc. (Bottero et al., 1987; Hu et al., 2006; Tang and Luan,
1996; Tang, 1998; Van Benschoten and Edzwald, 1990; Wang et al., 2002; Zhao et al., 2013).
Therefore, IPFs could be regarded as second-generation coagulants.
777
