SOLUBLE Fe AND Mn FLUX AT THE SEDIMENT-WATER INTERFACE DURING HYPOLIMNETIC OXYGENATION OF A STRATIFIED WATER SUPPLY RESERVOIR

摘要

The depletion of dissolved oxygen in the bottom waters of seasonally stratified reservoirs can lead to the release of dissolved Fe(II), Mn(II) and other reduced compounds from the sediments to the water column. Excessive amounts of these compounds degrade the quality of the raw water, ultimately leading to increased costs for water treatment and reduced overall quality of the product water after treatment. For example, the use of raw water derived from an anoxic system requires increased additional disinfectant dose to meet the elevated chlorine demand, thus leading to greater susceptibility of disinfection by-products. One strategy for improving raw water quality is to install hypolimnetic aeration and oxygenation systems in stratified reservoirs. These systems increase dissolved oxygen levels in the reservoir while maintaining stratification of the water column. These systems are known to increase oxygen demand in the sediments; however, the impact of these systems on sediment Fe(II) and Mn(II) flux has not been closely investigated.