Physicochemical and Ecotoxicological Assessment of the Fraction of Impurities Present in Washings Obtained in Ultrafiltration and Nanofiltration

The washings remaining after rinsing the pressure filters in swimming pool facilities constitute a stream representing the full array of impurities found in these waters. To separate individual fractions of these impurities, pressure membrane processes, ultra-, and nanofiltration have been used. The washings from water circuits in pools of different intended use and with various impurities were analyzed. Six fractions were obtained, with an apparent molar mass of: >200; <200; 200-30; <30 kDa; 30 kDa-300 Da; <300 Da. The quality of each fraction was evaluated in terms of physicochemical characteristics - concentration of total organic carbon (TOC), absorbable organic halogens (AOX) - and ecotoxicological characteristics (Microtox (R), Artemia sauna). The distribution of the impurities in individual fractions varied. The highest concentrations of impurities were observed in the washings from the swimming pool, in the >200 kDa fraction, 7.87, and 2.85 mg Cl/L. However, in the fraction below 300 Da, TOC and AOX concentrations reached 0.93 and 0.47 mg Cl/L, respectively. It should be noted that all analyzed samples of impurity fractions were characterized by low/nontoxicity. There was no correlation between selected physicochemical parameters, or the concentration of TOC and AOX, and the toxicity level.