Cailiao Baohu (Apr 2023)
Application of IA-AMPS-HEMA in the Treatment of Geothermal Tail Water Scaling by Reverse Osmosis
Abstract
During the process of geothermal water recharge，the high salt tail water would affect the chemical composition of geothermal fluids and block the migration channels of geothermal water.Firstly，the water quality characteristics of geothermal tail water were analyzed.Based on the mechanism of blockage during geothermal tail water reinjection and the scale inhibition mechanism of scale inhibitors，a carboxylic acid type copolymer scale inhibitor IA-AMPS-HEMA suitable for reverse osmosis membrane technology was synthesized.It could be found from the infrared spectrogram that the copolymer had a rich variety of structural functional groups and contained multiple carboxylic acid groups.SEM analysis showed that the copolymer could effectively avoid the formation of calcium carbonate scale.Through experiments，it was found that the scale inhibition effect of low dose IA-AMPS-HEMA reached 97.6%，which was much better than that of commercially available scale inhibitors.A set of reverse osmosis system equipped with descaling agent pretreatment device was used to remove insoluble inorganic salt deposits in the geothermal tail water，making the geothermal return water meet the requirements of recharge and replenishment.After the continuous operation of the equipment，it was proved that the addition of IA-AMPS-HEMA was effective and feasible for the treatment of geothermal tail water in reverse osmosis units.The removal rates of Ca2+，Ba2+，Mg2+ and other hardness ions and corrosive salts was more than 95%.It reduced the coagulation of insoluble sediments in the geothermal tail water，which met the water quality requirements of geothermal wells.And meanwhile，it effectively avoided the hard scale to damage the surface of the reverse osmosis membrane，prolonged the service time of the reverse osmosis membrane and reduced the operating cost of the equipment.
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