Title page for ETD etd-06292001-090818


Type of Document Master's Thesis
Author Kvech, Steven Joseph
URN etd-06292001-090818
Title Formation of Aluminum Containing Solids in Drinking Water: Influence on Pb/Cu Corrosion, Al Solubility and Enhanced Softening
Degree Master of Science
Department Environmental Engineering
Advisory Committee
Advisor Name Title
Edwards, Marc A. Committee Chair
Dietrich, Andrea M. Committee Member
Knocke, William R. Committee Member
Keywords
  • coagulation
  • magnesium
  • lead corrosion
  • softening
  • silica
  • copper corrosion
  • aluminum
Date of Defense 2001-05-10
Availability unrestricted
Abstract
Aluminum salts are used as the primary coagulants in the majority of United States drinking

water treatment plants. Despite decades of practical experience, there are important knowledge

gaps regarding the effects of residual Al on distribution system materials as well as specific types

of solids formed. The first phase of this work examined the formation of aluminosilicate

deposits in copper and lead pipes using water from Denver, Colorado. It was anticipated was

that these deposits could form barrier films on the pipe, protecting it from corrosion. However,

the deposits had slightly detrimental effects on leaching of metal to water, and higher levels of

aluminosilicates could further worsen corrosion by-product release.

The second phase of work attempted to extend understanding of aluminum solubility controls by

accounting for effects of sulfate and formation of solids other than Al(OH)3 during water

treatment. Sulfate was found to destabilize small Al(OH)3 colloids resulting in agglomeration

into larger flocs from pH 5.0-6.2 . At pH 9.0 and above, Al-Mg, Al-Mg-Si and Al-Si solids were

discovered to control Al solubility, while also having significant impacts on the precipitation of

calcite in the presence of silica and overall softening effectiveness. This could be of

considerable importance to water treatment practice. These solids also had some potential for

removal of arsenic, TOC and boron.

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