Fertiliser drawn forward osmosis process: Pilot-scale desalination of mine impaired water for fertigation

Abstract

The pilot-scale fertiliser driven forward osmosis (FDFO) and nanofiltration (NF) system was operated in the field for about six months for the desalination of saline groundwater from the coal mining activities. Long-term operation of the FDFO-NF system indicates that simple hydraulic cleaning could effectively restore the water flux with minimal chemical cleaning frequency. No fouling/scaling issues were encountered with the NF post-treatment process. The study indicates that, FDFO-NF desalination system can produce water quality that meets fertigation standard. This study also however shows that, the diffusion of solutes (both feed and draw) through the cellulose triacetate (CTA) FO membrane could be one of the major issues. The FO feed brine failed to meet the effluent discharge standard for NH 4 + and SO 4 2+ (reverse diffusion) and their concentrations are expected to further increase at higher feed recovery rates. Low rejection of feed salts (Na + , Cl-) by FO membrane may result in their gradual build-up in the fertiliser draw solution (DS) in a closed FDFO-NF system eventually affecting the final water quality unless it is balanced by adequate bleeding from the system through NF and re-reverse diffusion towards the FO feed brine. Therefore, FO membrane 2 with higher reverse flux selectivity than the CTA-FO membrane used in this study is necessary for the application of the FDFO desalination process.

Evaluation of fertilizer-drawn forward osmosis for sustainable agriculture and water reuse in arid regions

“…To date, all FDFO studies have either used brackish water (Phuntsho, Hong et al, 2013;Phuntsho, Lotfi et al, 2014;Raval and Koradiya, 2016), treated coalmine water with a TDS of about 2.5 g/L (Phuntsho, Kim et al, 2016) or seawater (Phuntsho, Shon et al, 2011;Phuntsho, Shon et al, 2012a;Phuntsho, Shon et al, 2012b;Phuntsho, Sahebi et al, 2013) as the FS. However, the relatively low salinity of most impaired waters makes them potentially suitable candidate for such dilution (Lew, Hu et al, 2005).…”

Exploration of polyepoxysuccinic acid as a novel draw solution in the forward osmosis process

“…However, the nal diluted solutes are usually higher than the acceptable level for fertilization, and thus require a large amount of water to reduce their concentrations. 4,28 In a previous paper, a novel bulky hydroacid complex Na 4 [Co(C 6 H 4 O 7 ) 2 ]$2H 2 O(Na-Co-CA) was synthesized as the draw solute in FO, which showed high water ux and high rejection to remove heavy metal ions from wastewater. 29 However, it is still necessary to explore more suitable draw solutes.…”

Separation Technologies for Salty Wastewater Reduction in the Dairy Industry

“…For instance, a waste brine stream might be used as a draw solution and then disposed directly to the open ocean as a more dilute brine, if this option is available. In fertigation, water is extracted from a brine or other wastewater stream through an FO membrane to dilute concentrated fertilisers on farm (126), allowing the delivery of the fertiliser and fresh water to the land for minimal cost .…”