Aluminium migration through a geosynthetic clay liner

Abstract

Water treatment plants (WTPs) can produce significant amounts of residual solids (i.e. sludge) as a result of coagulation, flocculation, clarification, and filtration processes to treat raw source water. In North America, alum is a common coagulant used in this process, resulting in the requirement for disposal of significant amounts of alum residual solids. Anticipated improved water quality treatment guidelines for trace metals such as arsenic in North America will result in more alum waste being generated in the future and hence increased pressure on water utilities to examine monofilling of alum-based residual solids to reduce waste management costs. GCLs are a potential cost-effective liner system for this type of application. However, there is currently a paucity of literature related to aluminium migration through GCLs.This paper presents results of GCL hydraulic conductivity, diffusion, and batch testing performed with a simulated WTP monofill leachate. Results of both short term and long term hydraulic conductivity tests show only modest increases in hydraulic conductivity, k, are observed for the tests conditions employed (k< 5x10 /s and a linear distribution coefficient, K d , of 30 mL/g. Batch testing is used to provide additional insight into the sorption behavior of aluminium with the bentonite from the GCL. Based on the limited results presented herein, it appears as if GCLs are suitable at maintaining low hydraulic conductivity values for at least 12 pore volumes of permeation with the high concentration alum residual monofill leachate simulated in this study. The information presented herein also provides WTP monofill designers with estimates of contaminant migration parameters necessary for establishing "alternative" GCL based liner designs.

Sorption and diffusion of bisphenol-A (BPA) through a geosynthetic clay liner (GCL)

“…The diffusion of BPA through a GCL at room temperature was measured using two-compartment (source and receptor) cells Rowe, 2000, 2004;Rowe et al, 2005;Lake et al, 2007;Lange et al, 2009). The stainless steel cells were 71 mm in diameter and 47 and 119 mm in depth for the receptor and the source chambers, respectively.…”

Strategic pathways for the sustainable management of water treatment plant residuals

“…For example, in Nova Scotia, if one was to propose a WTP residual monofill with a cost-effective geosynthetic clay liner system, the proponent would have to demonstrate to provincial regulatory authorities that the proposed liner system for the landfill would ensure minimal impact on the surrounding environment through contaminant migration modeling of the proposed engineered landfill using techniques described by Lake et al (2004). Preliminary results of recent research indicate that cost-effective liner systems such as geosynthetic clay liners (GCLs) may be adequate for the containment of such wastes in monofill designs (Lake et al 2005).…”

Effect of the durability of GCLs on Contaminants transfer through a composite liner exhibiting a hole in the geomembrane: A numerical approach

“…Studies of inorganic compounds such as sodium and chloride, and some metals (Al, As, Cd, Cu, Fe, K, Mg, Mn, Ni, Sr, Zn) have been well documented with successful experimental and numerical analyses using GCLs and composite liners [2,15], [16][17][18]. Also, several cases have been interested on studying the diffusion of organic compounds through virgin and aged GCLs.…”