Abstract
Trihalomethanes (THMs) are toxic disinfection by-products, formed in the reaction of chlorine with organic matter. This work aimed to study THM formation during a unique case study of managed aquifer recharge (MAR) with chlorinated desalinated seawater. THM formation was tested in the field, along a 3.0 m deep vadose zone gallery. Two small-scale experiments were conducted in the site, with untreated and with bromide spiked desalinated seawater. These were accompanied by a large-scale, ~1-month long operational MAR event. In the small-scale experiments, THM concentrations were shown to increase with bromide concentrations, with increasing dominance of the brominated species. Nevertheless, concentrations remained within the single µg/L range, which is an order of magnitude lower than drinking water regulations. Such low THM concentrations were also determined in the large-scale event. In both cases, THM formation occurred in the ponding water, without significant formation or degradation in the upper 3.0 m of the vadose zone. This study shows that MAR with chlorinated (<0.5 mg/L) desalinated seawater through sandy infiltration basins does not pose a threat to drinking water quality at this site.
Highlights
Desalinated seawater (DSW) is an increasing source for domestic water, especially in Mediterranean and Middle East countries
Two field experiments were conducted for determining the influence of bromide on THM formation during aquifer recharge
This work studied THM formation during managed aquifer recharge with chlorinated desalinated seawater
Summary
Desalinated seawater (DSW) is an increasing source for domestic water, especially in Mediterranean and Middle East countries. With the relatively high costs of this water source [2], motivation to reduce expenses is clear. This may be achieved by technological development, as well as by management flexibility, which enables the economical optimization of water production regardless of its consumption. This latter option demands considerable storage capacity. MAR may be a preferred solution for the storage of temporal DSW surpluses, and was practiced mainly in countries of the Persian Gulf. It was shown to facilitate stable water distribution, overcoming operational disturbances and enabling the construction of desalination plants
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