Evaluation of environmental geochemical signatures due to RO rejects on arid agricultural farms and tangible solutions  

作　　者：Harish Bhandary Chidambaram Sabarathinam Adnan Akber Tariq Rashid Dhanu Radha Samayamanthula Yogeesha Jayaramu Bedour Alsabti 

机构地区：[1]Water Research Centre,Kuwait Institute for Scientific Research,P.O.Box:24885,Safat 13109,Kuwait

出　　处：《Geoscience Frontiers》2024年第6期494-515,共22页地学前缘（英文版）

基　　金：the Kuwait Foundation for the Advancement of Sciences(KFAS)for funding the study(Grant No.PN20-25EV-01).

摘　　要：The impact of reverse osmosis(RO)rejects in the groundwater presents a significant challenge in arid regions.This study collected groundwater samples,product water,and reverse osmosis brine(ROB)from evaporation ponds and analyzed them for major ions and trace elements.Test boreholes were drilled near the ROB site along the flow direction,and borehole sediment samples were collected.The samples were predominantly gravelly sand,and the depth to water level fluctuated around 30 m below ground level(bgl),with minerals mainly consisting of calcite,gypsum,and quartz.Data loggers reflected a rise in water level(<22 m bgl)corresponding to higher electrical conductivity(>16 mS/cm)during the cropping period in many locations,confirming the impact of ROB in groundwater.The results were further supported by enriched signatures ofδ^(18)O(∼+1.5‰)andδ^(2)H(∼+15‰).The saturation index of the minerals reflected that carbonate minerals(Calcite>Dolomite)were saturated in the ROB relative to the groundwater.The vertical variation of mineral assemblages in the boreholes indicated gypsum precipitation in the capillary zone along with calcite and dolomite.The assemblage varies as the groundwater moves from the disposal site.The speciation of different compounds along the groundwater path indicated higher carbonate and sulfate species(CaCO_(3)>CaHCO_(3)>CaSO_(4)>NaSO_(4)>MgSO_(4))near the disposal site,with variations along the flow direction.Considering the significant variation in temperature in the region(5 to 50℃),the water sample composition was modeled using PHREEQC,suggesting that the increase in temperature led to supersaturation of epsomite and gypsum compositions.The ROB was theoretically mixed with groundwater and product water in different proportions,and an optimum composition(10:90)for safe disposal was derived and tested fit for reuse in agriculture.

关 键 词：Brine disposal Groundwater GEOCHEMISTRY Monitoring Modeling RECOMMENDATION 

分 类 号：P597.3[天文地球—地球化学]