Maximizing water recovery from reverse osmosis for agricultural brine reuse in Kenya

Water-stressed regions like Kenya rely on saline water sources, which can pose serious health hazards if not treated. While desalination is a burgeoning solution, safe disposal of desalination brine is often infeasible or too expensive. To circumvent this disposal challenge, we examine the maximum desalination recovery ratio (RR_max) for which desalination brine can safely be reused for many agricultural applications. Water samples from the Mara Triangle and data from past studies were collected and analyzed to measure contaminant concentrations against established safety limits of salinity and potentially hazardous elements for multiple agricultural use cases. The results suggest that high water recoveries were possible in the Mara Triangle, with the maximum recovery ratio reaching greater than 94% and 98% for crop irrigation and livestock watering, respectively. Brine reuse in this region was mostly limited by salinity, with Boron content ranking second. The most salt-tolerant crops (i.e., barley, sorghum, and wheat) were shown to be cultivable in all locations. According to calculations of the Heavy Metal Evaluation Index, groundwater in the Mara Triangle was generally safer for direct use by all users than the surface waters sampled in the past Lake Victoria and Nairobi studies.