Natural organic matter removal by ion exchange at different positions in the drinking water treatment lane

Abstract

Abstract. To guarantee a good water quality at the customers tap, natural organic matter (NOM) should be (partly) removed during drinking water treatment. The objective of this research was to improve the biological stability of the produced water by incorporating anion exchange (IEX) for NOM removal. Different placement positions of IEX in the treatment lane (IEX positioned before coagulation, before ozonation or after slow sand filtration) and two IEX configurations (MIEX ® and fluidized IEX (FIX)) were compared on water quality as well as costs. For this purpose the pre-treatment plant at Loenderveen and production plant Weesperkarspel of Waternet were used as a case study. Both, MIEX ® and FIX were able to remove NOM (mainly the HS fraction) to a high extent. NOM removal can be done efficiently before ozonation and after slow sand filtration. The biological stability, in terms of assimilable organic carbon, biofilm formation rate and dissolved organic carbon, was improved by incorporating IEX for NOM removal. The operational costs were assumed to be directly dependent of the NOM removal rate and determined the difference between the IEX positions. The total costs for IEX for the three positions were approximately equal (0.0631 € m −3 ), however the savings on following treatment processes caused a cost reduction for the IEX positions before coagulation and before ozonation compared to IEX positioned after slow sand filtration. IEX positioned before ozonation was most cost effective and improved the biological stability of the treated water.

Removal of disinfection by-product precursors by coagulation and an innovative suspended ion exchange process

“…The SIX process provided only 10-20% removal of the highest MW (>20,000 Daltons) biopolymer fraction, comprising organic colloids, polysaccharides and protein like substances. This outcome is consistent with that from other studies which have reported low removal of the highest MW organics (biopolymers) by IEX (Mergen et al 2009;Huber et al 2011;Grefte et al 2013). This is a phenomenon related to decreasing charge density with increasing MW and/or size exclusion, where the organics are prevented from entering the IEX resin pores (Croué et al 1999;Humbert et al 2007).…”

The Influence of the Removal of Specific NOM Compounds by Anion Exchange on Ozone Demand, Disinfection Capacity, and Bromate Formation

“…Thus IEX and coagulation are supplementary to each other (Bolto et al 2002). Nanofiltration is able to remove all NOM fractions (Matilainen et al 2004), but this process is more expensive and has a higher environmental impact (Liikanena et al 2006) than IEX (Grefte et al 2013). …”

Isolation and Fractionation of Humic Substances Present in Water With the Use of Anion-Exchange Resins and Ultrafiltration

“…The main group of natural organic matter (NOM) present in raw water sources are dissolved humic substances (HS) (Baalousha et al, 2008). Their presence in the water is quite troublesome for many reasons, e.g., they are responsible for water taste, smell and, most importantly, they act as precursors of disinfection by-products (Grefte et al, 2013;Krupińska et al, 2013;Rajca, 2015). Disinfection by-products are a product of the oxidation of organic compounds with the use of chlorine or ozone, leading to the formation of carcinogenic chlorine-derived organic compounds and non-fully oxidized organic compounds, respectively (Bond et al, 2014;Tubić et al, 2013).…”