Changes in the quality of river water before, during and after a major flood event associated with a La Ni?a cycle and treatment for drinking purposes.
,
Zeeshan Aslam
,
Rosmala Lewis
,
Christopher Chow
,
Dongsheng Wang
,
Mary Drikas
,
John van Leeuwen
DOI:
Received December 18, 2013,Revised February 08, 2014, Accepted February 12, 2014, Available online 2014-07-03
Volume ,,Pages -
- Summary
- References
- Related Articles
The treatment of organics present in waters of the lower reaches of a major river system (of the Murray-Darling Basin, Australia) before (March-July 2010), during (December 2010 - May 2011) and after (April – December 2012) a major flood period was investigated. The flood period (over 6 months) occurred during an intense La Ni?a cycle, leading to rapid and high increases in river flows and organic loads in the river water. DOC increased (~2-3 times) to high concentrations (up to ~16 mg/L) and was found to correlate with river flow rates. The treatability of organics were studied using conventional jar tests with alum and an enhanced coagulation model (mEnCo ?). Predicted mean alum dose rates (per mg DOC) were higher before (9.1 mg alum/mg DOC) and after (8.5 mg alum/mg DOC) than during the flood event (8.0 mg alum/mg DOC), indicating differences in the character of the organics in raw waters. To assess the character of NOM present in raw and treated waters, HPSEC with UV and fluorescence detectors were used. During the flood period, high molecular weight (HMW) UV absorbing compounds (> 2kDa) were mostly detected in waters collected, but were not evident in waters collected before and afterwards. The relative abundances of humic-like and protein-like compounds during and following the flood period were also investigated and found to be of a higher molecular weight during the flood period. The treatability of the organics was found to vary over the three climate conditions investigated.
