Assessment of the possibility of using flocculation to improve properties of ultrafiltration membranes used in the purification of swimming pool water system washings

The paper presents the possibility of using an in-line mode flocculation-ultrafiltration system for the purification of backwash water from flushing the beds of pressure filters used in the indoor swimming pool water treatment circulation. The effect of flocculation operational conditions (the flocculant dose in the range from 16 to 240 mg/dm³ and the process temperature of 8-30°C) on the transport-separation properties of ultrafiltration membranes has been examined. To establish the effectiveness of the conducted processes, the contaminant retention coefficients, among others, were determined (based on the measurements of turbidity and UV254 ultraviolet absorbance). A significant influence of the flocculation process operational parameters on the performance of ultrafiltration was noted. With increasing flocculant dose, the efficiency of contaminant removal in the ultrafiltration process increased simultaneously. Moreover, the change in the temperature conditions of the flocculation process had a fundamental effect on the transport properties of the ultrafiltration membranes. The most advantageous temperature for conducting the processes was considered to be 21°C. Under those conditions, all flocculant doses contributed to a significant improvement in the transport properties of the ultrafiltration membranes. High values of the contamination retention coefficients and the permeate volumetric flux were obtained already at a flocculant dose of 80,160 and 240 mg/dm³.