Renewable energy powered membrane technology: Salt and inorganic contaminant removal by nanofiltration/reverse osmosis

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 pH conditions.

Arsenic and fluoride contaminated groundwaters: A review of current technologies for contaminants removal

“…It has been suggested that variations in retention based on membrane type were likely due to membrane characteristics. Further, the same membranes were used in another study for photovoltaic powered UFeNF/RO system in real water treatment to confirm the results (Richards et al, 2011). A recent study on forward osmosis (FO) has demonstrated promising results (~95%) for As(V) removal in presence of F (Mondal et al, 2014).…”

“…This resulted in low power requirements and the plant was operated at 80% recovery without using a scaling inhibitor. Richards et al (2011) used four commercial NF/RO membranes in Australian groundwaters. Their investigations showed the influence of solar irradiance levels on retention of F, Mg, NO 3 , K and Na where convection/diffusion predominated the retention.…”

Experimental and Modeling Assessment of Sulfate and Arsenic Removal from Mining Wastewater by Nanofiltration

“…The rejection of sulfate by using various nanofiltration membranes including NF90 and NF270 has been reported in the literature (Kosutic et al 2004;Krieg et al 2004;Richards, Richards, and Schafer 2011;Schaep et al 2001). Individually, arsenic rejection has also been reported on the same respective membranes (Do et al 2012;Figoli et al 2010;Richards et al 2009;Saitua et al 2005;Yu et al 2013).…”

Manganese Removal from Drinking Water Sources

“…However, the increased concentration of ions in the reject or concentrate stream as well as feed stream pH conditions and the possible presence of oxidants results in concerns that rejected Mn(II) may be oxidized and precipitated on the membrane surface resulting in membrane fouling (e.g., [50]). Thus, selection of NF or RO membranes on the basis of Mn removal is very unlikely.…”