Effect of extremely high specific flow rates on the removal of NOM and arsenic from groundwater with an ion-exchange resin: A pilot-scale study in Northern Serbia

Abstract

A pilot-scale study was performed to explore the possibility of the removal of natural organic matter (NOM) and arsenic from groundwater in the village of Melenci (Northern Serbia) using strongly basic, macroporous ion-exchange resin, commercially available as Amberlite IRA 958-Cl. The influences of the specific flow rate (SFR) and a broad range of contact times were studied using native groundwater and the same water pretreated with sodium hypochlorite (NaClO) for the oxidation of As(III) to As(V) and the degradation of NOM. The investigated SFR exceeded the manufacturer's recommended maximum value by up to ten times. In the range of SFR from 50 to 300 bed volumes per hour (BV/h), a higher efficiency of NOM removal was achieved in the absence of the oxidant, whereas at lower SFR and shorter contact times, the efficiency was higher when the water was pretreated. The arsenic removal from the oxidant-pretreated water was equally efficient at all SFR, whereas in the absence of the oxidant the efficiency was significantly lower and did not depend on SFR. The effectiveness of the resin illustrates the fact that the experimentally determined optimum SFR value of 30 BV/h is stated as the maximum in the manufacturer's specifications.

Keywords:

• Arsenic
• NOM
• groundwater
• specific flow rate
• strongly basic macroporous resin

Acknowledgments

This paper was jointly supported by funds from Envirotech, d.o.o. Kikinda, Serbia and the Institute of Work Safety, Novi Sad, Serbia.