| Summary: | The coal mining sector is being particularly affected by the saline waste waters problem. One of the possible solutions is to use the effluents as the source of raw materials: demineralized water, salt, magnesium hydroxide. This paper presents the results obtained in a pilot plant of capacity of 400 L/h, which was in operation for 9 months in the “Bolesław Śmiały” coal mine in Łaziska Górne, Poland. The coal mine water was being pre-treated with ultrafiltration and decarbonization and subjected to a two-pass nanofiltration, which splits the feed into two streams: salt-rich permeate, and calcium- and magnesium-rich retentate, which can be used for recovery of magnesium hydroxide by either conventional precipitation or by CrIEM technology. The nanofiltration permeate was concentrated in a hybrid reverse osmosis-electrodialysis system, producing demineralized water and highly saline concentrate, which could be used as a feedstock for salt production by either thermal crystallization or eutectic freeze crystallization.
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