Chlorine Decay and Disinfection By-product Formation of Dissolved Organic Carbon Fractions with Goethite
Water from the raw water intake at Barberton, Ohio water treatment plant was collected on two separate dates and fractionated into operationally defined dissolved organic carbon (DOC) fractions following Pu's (2005) procedure which stemmed from Leenheer (1981). Six solutions were prepared at a DOC of approximately 3.0 mg/L for subsequent testing: (1) Hydrophobic neutral (2) Hydrophobic acid (3) Hydrophilic neutral (4) Hydrophilic acid (5) Raw water and (6) a mixture of the four fractions (comprised of 25% each fraction by DOC mass). Chlorination of the six solutions in the presence of increasing concentrations of goethite, an iron oxide, quantified the reactivity compared to a control test (without goethite).
The four operationally defined DOC fractions represented more than 92% of the dissolved organic carbon (DOC) present in the raw water for both sample days. The four fractions were studied for their adsorptive nature with goethite, chlorine consumption, and HAA5 and THM4 formation with goethite. As expected, unaltered raw water exhibited the greatest DOC adsorption, increase in chlorine consumption and DBP increases with goethite. The raw water tested demonstrated that the only DBPs that potentially change with the addition of goethite were chloroform, TCAA and DCAA. While chloroform increased for all fractions except HPIN, change in TCAA and DCAA production caused by goethite was insignificant for all four fractions. The HPOA fraction was the most susceptible to the effect of goethite as HPOA had the greatest increase due to the presence of goethite. Though HPIA was similar to HPOA in TTHM production with goethite, HPIN had the least amount of change in TTHM with goethite. The TTHM increases brought about by goethite were not dependent on the amount of DOC mass that adsorbed to goethite or the increase in chlorine consumption caused by adsorption. Instead, it was the type of DOC fraction, suggesting that the different DOC fractions contain different conglomerations of NOM moieties which change in reactivity to chlorine in as little time as a couple months.
School:The University of Akron
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:goethtie nom fractions fractionation disinfection byproducts dbp
Date of Publication:01/01/2008