POSSIBILITIES FOR REDUCING THE HARDNESS OF REVERSE OSMOSIS WASTEWATER AND ITS APPLICATION AS A LIQUID FERTILIZER FOR AGRICULTURAL CROPS
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Sherkuziev Doniyor, Zebuniso Khamdamova
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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 mixed-bed (FSD) systems. The chemical composition of the water samples was analyzed in terms of pH, total hardness, Ca²⁺, Mg²⁺, SO₄²⁻, NO₃⁻, NH₄⁺, 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 NO₃⁻ 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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Authors
Sherkuziev Doniyor, Zebuniso Khamdamova
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