Effects of High Salinity on Alginate Fouling during Ultrafiltration of High-Salinity Organic Synthetic Wastewater

Abstract

Ultrafiltration is widely employed in treating high-salinity organic wastewater for the purpose of retaining particulates, microbes and macromolecules etc. In general, high-salinity wastewater contains diverse types of saline ions at fairly high concentration, which may significantly change foulant properties and subsequent fouling propensity during ultrafiltration. This study filled a knowledge gap by investigating polysaccharide fouling formation affected by various high saline environments, where 2 mol/L Na+ and 0.5-1.0 mol/L Ca2+/Al3+ were employed and the synergistic influences of Na+-Ca2+ and Na+-Al3+ were further unveiled. The results demonstrated that the synergistic influence of Na+-Ca2+ strikingly enlarged the alginate size due to the bridging effects of Ca2+ via binding with carboxyl groups in alginate chains. As compared with pure alginate, the involvement of Na+ aggravated alginate fouling formation, while the subsequent addition of Ca2+ or Al3+ on the basis of Na+ mitigated fouling development. The coexistence of Na+-Ca2+ led to alginate fouling formed mostly in a loose and reversible pattern, accompanied by significant cracks appearing on the cake layer. In contrast, the fouling layer formed by alginate-Na+-Al3+ seemed to be much denser, leading to severer irreversible fouling formation. Notably, the membrane rejection under various high salinity conditions was seriously weakened. Consequently, the current study offered in-depth insights into the development of polysaccharide-associated fouling during ultrafiltration of high-salinity organic wastewater.

Magneto-Priming of Seeds Decreases the Saline Effect of Wastewater Irrigation on Broccoli Germination and Seedling Growth

“…Wastewater's high salinity usually consists of several concentrated ions such as Na + , Ca 2+ , and Al 3+ that are generated through industrial processes including reverse osmosis or food processing, which account for as much as 5% of the wastewater requiring treatment worldwide [35,36]. Salinity exerts an impact on the seedling growth of plants, manifesting in the deceleration of reserve food mobilization, suspension of cell division and enlargement, and injury to hypocotyls [37].…”