Use of Concentrate from Reverse Osmosis for Agricultural Use.

The Brackish Groundwater National Desalination Research Facility (BGNDRF) in Alamogordo, New Mexico uses reverse osmosis to treat water prior to domestic use. The process of desalination results in a highly concentrated solution that must be disposed of in an environmentally sound way. Land application of desalination concentrate is one approach to its disposal. Objectives in this study are: 1) to evaluate the transport behavior of concentrates for two soil types with contrasting texture, and 2) to measure the effects of BGNDRF concentrate on growth of six plant species Hordeum vulgare, Triticum aestivum x Secale cereale, Atriplex canescens, Distichlis stricta, Lepidium alyssoides, and Panicum virgatum. Plant growth was monitored for 90 days in a greenhouse experiment that used two soils (a clay soil from BGNDRF and commercially available silica sand) and three water treatments: tap water from greenhouses (EC = 1.0 dS/m), well water from BGNDRF (EC =4 dS/cm), and concentrate from BGNDRF (EC =10 dS/cm). Plants were grown in cells (1 plant per cell) that were uniformly watered as needed.  Both non-destructive measurements (height, number of leaves, length of leaves, photosynthetic rates) and destructive measurements (stem water potential, osmotic potential, ion uptake) are guiding the selection of candidate plant species for BGNDRF land application sites.  Results from experiments related to transport behavior of concentrates have indicated precipitate deposition on the particle surface and in the pores, have shown reductions in hydraulic conductivity caused by pore clogging. Sustainable safe and local management of the highly saline concentrate resulting from reverse osmosis could provide widespread implementation of inland groundwater desalination in New Mexico and the southwestern U.S.