POSSIBILITIES FOR REDUCING THE HARDNESS OF REVERSE OSMOSIS WASTEWATER AND ITS APPLICATION AS A LIQUID FERTILIZER FOR AGRICULTURAL CROPS

This study investigates the possibilities of reducing the hardness of highly mineralized wastewater generated as a result of reverse osmosis (RO) technology and reprocessing it for use as a liquid fertilizer.As the object of the research, wastewater obtained from the RO unit of Soda Workshop No. 3 at JSC "Ferganaazot" was selected.The high concentrations of calcium and magnesium ions in RO wastewater make its direct discharge into the environment environmentally hazardous; however, the presence of potassium and nitrogen-containing compounds turns this water into a promising resource for use as a liquid fertilizer in agriculture.Since the high hardness of the wastewater limits this possibility, KU-2/8 cation-exchange and AB-17/8 anion-exchange resins were used to reduce hardness.Experiments were conducted under laboratory conditions using individual cation-exchange, anion-exchange, and mixedbed (FSD) systems.The chemical composition of the water samples was analyzed in terms of pH, total hardness, Ca² + , Mg² + , SO₄² -, NO ₃-, NH ₄+ , K + , Na + , and other ions.The obtained results showed that the KU-2/8 cation-exchange resin reduced total hardness from 42 mg eq/dm³ to 1.25 mg eq/dm³ in the first cycle and effectively removed Ca² + and Mg² + ions.Although the AB-17/8 anion-exchange resin significantly reduced SO₄² -and NO ₃-ions, it was found to undergo rapid degradation under conditions of strong alkaline regeneration.Using the mixed-bed (FSD) system, total water hardness was reduced to 0.45 mg eq/dm³; however, excessive demineralization of the water led to a decrease in the content of beneficial macroelements.

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