|dc.description.abstract||The objective of this study was to evaluate the effects of fluctuating energy and pH on retention
of dissolved contaminants from real Australian groundwaters using a solar (photovoltaic)
powered ultrafiltration – nanofiltration/reverse osmosis (UF-NF/RO) system. Four NF/RO
membranes (BW30, ESPA4, NF90, and TFC-S) were used. Energy fluctuations affected pressure
and flow. Solar irradiance levels impacted retention of fluoride, magnesium, nitrate, potassium,
and sodium where convection/diffusion dominated retention. Retention of calcium, strontium,
and uranium was very high and independent of solar irradiance, which was attributed to a
combination of size and charge exclusion and for some solutes sorption and precipitation.
Groundwater characteristics affected retention and the solutes were categorized into two groups
according to retention as a function of pH: (1) pH independent retention (arsenic, calcium,
chloride, nitrate, potassium, selenium, sodium, strontium, and sulfate); and (2) pH dependent
retention (copper, magnesium, manganese, molybdenum, nickel, uranium, vanadium, and zinc).
The retention of Group 1 solutes was typically high and attributed to steric effects. Group 2
solutes had dominant, insoluble species under certain conditions which led to deposition on the
membrane surface (and thus varying apparent retention). The renewable energy membrane
system removed a large number of groundwater solutes reliably over a range of real energy and