Guar gum coupled microscale ZVI for in situ treatment of CAHs: Continuous-flow column study

Pressure-controlled injection of guar gum stabilized microscale zerovalent iron for groundwater remediation

“…The polymer concentration measured in the injection well P704 one day after injection was 1.1 g/l, while 0.35 g/l was measured after 12 days. After 29 days, guar gum concentrations were below detection limits (50 mg/l) indicating fast guar gum biodegradation and/or removal by groundwater flow (Velimirovic et al, 2014b).…”

“…A detailed description of the method is provided in the Supporting Information. The concentration of zerovalent iron was determined via hydrogen (H 2 ) gas evolution after acid digestion (Velimirovic et al, 2014b) of a limited number of samples taken from the cores at depths and directions of particular interest (zero-, mean-, maximum-iron concentration) and used for the calibration of susceptibility to concentration values (Supporting Information).…”

“…Since the adsorption of biopolymer chains can hinder the reactivity, it is important to use easily biodegradable biopolymers (e.g. guar gum) which can be removed by enzymatic breakdown (Di Molfetta and Sethi, 2006;Gastone et al, 2014a;Kirschling et al, 2011;Reddy et al, 2011;Velimirovic et al, 2012) or by soil microbial population (Velimirovic et al, 2014b). If the polymer is dosed in significantly higher concentrations (in the order of grams per liter), part of the polymer chains adsorb onto the ZVI surface, until saturation, and part stay in suspension, increasing the viscosity of the dispersing fluid (kinetic stabilization) and consequently significantly reducing aggregation and sedimentation rate (Dalla Vecchia et al, 2009b;Tiraferri et al, 2008;Velimirovic et al, 2012;Xue and Sethi, 2012).…”

Wheat straw biochar-supported nanoscale zerovalent iron for removal of trichloroethylene from groundwater

“…The main approaches for reducing nZVI aggregation include coating with organic polymer materials, including guar gum[10], carboxyl methyl cellulose (CMC)[11] and polyacrylic acid (PAA)[12], and inorganic adsorbent material, including sepiolite[13], smectite[14], alginate bead[15] and activated carbon[9,16]. Activated carbon materials can not only effectively decrease nZVI aggregation, but also rapidly increase the concentrations of contaminants in the micro environments surrounding nZVI because of its adsorption capacity[17].…”

Stabilization of Iron (Micro)Particles with Polyhydroxybutyrate for In Situ Remediation Applications

“…), with the major drawback being the need for their continuous delivery in the groundwater for a lengthy period (long periods are usually required to achieve the remediation goals by using this approach). To overcome these limitations, in recent years, several researchers have shown a growing interest in developing composite materials obtained by the combination of consolidated chemically reactive media with a slow-releasing carbon source (i.e., guar gum, cellulose, starch) to extend treatment to recalcitrant compounds and/or to enhance microbial activity in a synergistic reaction [24][25][26][27]. In this context, polyhydroxybutyrate (PHB) could be a valuable carbon source.…”