Removal of natural organic matter by titanium tetrachloride: The effect of total hardness and ionic strength

This study is the first attempt to investigate the effect of total hardness and ionic strength on coagulation performance and the floc characteristics of titanium tetrachloride (TiCl4). Membrane fouling under different total hardness and ionic strength conditions was also evaluated during a coagulat...

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Bibliographic Details
Published in:Journal of environmental management 2014-02, Vol.134, p.20-29
Main Authors: Zhao, Y.X., Shon, H.K., Phuntsho, S., Gao, B.Y.
Format: Article
Language:English
Subjects:
Animal, plant and microbial ecology
Applied ecology
Benzopyrans - chemistry
Biological and medical sciences
Coagulation
Coagulation–flocculation
Conservation, protection and management of environment and wildlife
Flocculation
Fundamental and applied biological sciences. Psychology
General aspects
Hardness
Humic Substances
Ionic strength
Membrane fouling
Membranes
Membranes, Artificial
Molecular weight
Osmolar Concentration
Simulation
Titanium - chemistry
Titanium tetrachloride
Total hardness
Ultrafiltration - methods
Water Pollutants - chemistry
Water Purification - methods
Water treatment
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Summary:This study is the first attempt to investigate the effect of total hardness and ionic strength on coagulation performance and the floc characteristics of titanium tetrachloride (TiCl4). Membrane fouling under different total hardness and ionic strength conditions was also evaluated during a coagulation–ultrafiltration (C–UF) hybrid process. Coagulation experiments were performed with two simulated waters, using humic acid (HA, high molecular weight) and fulvic acid (FA, relatively low molecular weight), respectively, as model natural organic matter (NOM). Results show that both particle and organic matter removal can be enhanced by increasing total hardness and ionic strength. Floc characteristics were significantly influenced by total hardness and ionic strength and were improved in terms of floc size, growth rate, strength, recoverability and compactness. The results of the UF tests show that the pre-coagulation with TiCl4 significantly improves the membrane permeate fluxes. Under different total hardness and ionic strength conditions, the membrane permeate flux varied according to both NOM and floc characteristics. The increase in total hardness and ionic strength improved the membrane permeate flux in the case of HA simulated water treatment. [Display omitted] •Increase in total hardness and ionic strength enhanced organic matter removal.•Increase in total hardness and ionic strength could improve floc characteristics.•Pre-coagulation with TiCl4 could significantly improve the permeate fluxes.•Increase in total hardness and ionic strength could improve membrane permeability.
ISSN:0301-4797
1095-8630
DOI:10.1016/j.jenvman.2014.01.002