Study shows saline groundwater beats seawater

Researchers at Israel’s Ben-Gurion University of the Negev (BGU) have found that water from saline groundwater coastal aquifers is a better raw source than seawater for reverse osmosis (RO) desalination owing to the groundwater’s lower membrane fouling and pre- treatment costs.

One of the lead researchers, Dr. Roni Kasher, said: “Decision-makers in both California and Israel can use this research to seriously consider saline groundwater as a realistic alternative when planning future large-scale seawater desalination facilities.”

The study was by researchers at the BGU Zuckerberg Institute for Water Research, the BGU Department of Geological and Environmental Sciences and the Israel Geological Survey and was published in Environmental Science & Technology.

A senior lecturer in the BGU Zuckerberg Institute’s Department of Desalination and Water Treatment, Kasher, said: “In Israel, seawater desalination accounts for 60 percent of the total freshwater supply, so these findings are significant.”

Other saline groundwater benefits included consistent annual water temperatures, and lower levels of dissolved oxygen, silt density and phytoplankton. It also decreases the cost of desalination according to the researchers. RO desalination of seawater required significant energy and large plant on valuable shorefront real estate, they said.

“The study showed that aquifer filtration increases the feed water quality and reduces the need for extensive pre-treatment processes,” said BGU researcher Shaked Stein. “RO desalination with saline groundwater as feed water is also more efficient, with higher freshwater recoveries, less chemical use and maintenance, and therefore less overall operational costs.”

Stein recommended using saline groundwater rather than seawater in the summertime because the research identified higher seawater RO membrane fouling in summer. “Salt rejection decreases in elevated temperatures due to changes in membrane permeability and mass transfer,” he added.

According to Kasher, “In our study, we used normal (vertical) wells to take samples from the saline groundwater. All the wells were a maximum of 100 metres from the shoreline. However, the water intake can be accomplished using several different types of wells.”