Modeling Nonequilibrium Adsorption of MIB and Sulfamethoxazole by Powdered Activated Carbon and the Role of Dissolved Organic Matter Competition

Abstract

This study demonstrates that the ideal adsorbed solution theory−equivalent background compound (IAST−EBC) as a stand-alone model can simulate and predict the powdered activated carbon (PAC) adsorption of organic micropollutants found in drinking water sources in the presence of background dissolved organic matter (DOM) under nonequilibrium conditions. The IAST−EBC represents the DOM competitive effect as an equivalent background compound (EBC). When adsorbing 2-methylisoborneol (MIB) with PAC, the EBC initial concentration was a similar percentage, on average 0.51%, of the dissolved organic carbon in eight nonwastewater impacted surface waters. Using this average percentage in the IAST−EBC model yielded good predictions for MIB removal in two nonwastewater impacted waters. The percentage of competitive DOM was significantly greater in wastewater impacted surface waters, and varied markedly in DOM size fractions. Fluorescence parameters exhibited a strong correlation with the percentage of competitive DOM in these waters. Utilizing such correlations in the IAST−EBC successfully modeled MIB and sulfamethoxazole adsorption by three different PACs in the presence of DOM that varied in competitive effect. The influence of simultaneous coagulant addition on PAC adsorption of micropollutants was also investigated. Coagulation caused the DOM competitive effect to increase and decrease with MIB and sulfamethoxazole, respectively.

Super-fine powdered activated carbon (SPAC) for efficient removal of micropollutants from wastewater treatment plant effluent

“…The validity of this simplified approach has been confirmed for various micropollutants at concentrations ranging from 50 to 200 mg/L in complex wastewater matrices (Kovalova et al, 2013a;Shimabuku et al, 2014;Zoschke et al, 2011). The derivation of eqn.…”

“…LC-OCD analysis of the wastewater used in this work revealed that, compared to typical surface water, the wastewater matrix contained a relatively large fraction of biopolymers (19%, very high MW (>20 kDa) hydrophilic compounds), but also a significant fraction of low MW neutral compounds (MW < 350 Da, 17.3%) that could compete for adsorption sites with the targeted micropollutants. Correspondingly, recent work showed that the fraction of organic matter competing with MIB and sulfamethoxazole for adsorption sites on PAC was significantly higher in wastewater impacted waters than in non-wastewater impacted surface waters (Shimabuku et al, 2014). A larger fraction of competing EfOM should impact both PAC and SPAC, assuming both the micropollutants and the competing EfOM adsorb to internal pores.…”

Impacts of ozonation on the competition between organic micro-pollutants and effluent organic matter in powdered activated carbon adsorption

“…The procedure combines the mass balance equations for the adsorbate in the liquid/solid phase system of the solution/adsorbent with equations from the Ideal Adsorbed Solution Theory (IAST) for two solutes of which one is the respective OMP under consideration and the other is a fictive component (the EBC) that accounts for the observed adsorption competition with the considered OMP (Shimabuku et al, 2014;Worch, 2012). For more information on the mathematical modeling procedure we refer to a previous publication (Zietzschmann et al, 2014c).…”

Comparing and modeling organic micro-pollutant adsorption onto powdered activated carbon in different drinking waters and WWTP effluents

“…However, also non-equilibrium adsorption data (i.e. liquid and solid phase concentrations are still changing) can be modeled with the EBCM because of the fictive character of the EBC whose Freundlich parameters are usually fitted to experimental data during backmodeling (Shimabuku et al, 2014;Zietzschmann et al, 2015a;Zoschke et al, 2011).…”

“…Another approach was to relate the fitted initial EBC concentration c 0,EBC (non-equilibrium conditions), divided by the DOC of several surface waters to the fluorescence index (FI, ratio of emission intensities at 520 nme470 nm at an excitation at 370 nm) of these waters as higher FI indicated higher BOM competitiveness against OMP adsorption (Shimabuku et al, 2014). Other studies used the EBCM on waters whose BOM was artificially altered (membrane filtration, ozonation), and related increased BOM competitiveness to smaller molecular sizes (Zietzschmann et al, 2014b) or aromaticity and polarity (Zietzschmann et al, 2015b).…”