Long-term Performance of a Permeable Reactive Barrier in Acid Sulphate Soil Terrain

Regmi, Gyanendra; Indraratna, Buddhima; Nghiem, Long D.

doi:10.1007/s11267-009-9230-1

Cited by 19 publications

(14 citation statements)

References 23 publications

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“…The experimental data contributes to knowledge, providing insight to PRB rejuvenation and enhancement of longevity using alkaline wastewaters and the study gains a valuable insight into the suitability of waste alkaline rejuvenation for future PRB installations, and additionally what this means for future PRB design and PRB technology. (Regmi et al, 2009) and alkaline wastewater chemistry (courtesy of Manildra Group) …”

Section: Discussionmentioning

confidence: 99%

“…This was the same batch of recycled concrete used in the pilot-scale PRB. The major cations in the recycled concrete are predominantly calcium (Ca, 57.3%), Fe (21.4%), Al (9.85%), magnesium (Mg, 5.27%), silica (Si, 3.06%) and others (3.04%) (Regmi et al, 2009).…”

Section: Reactive Materialsmentioning

confidence: 99%

“…The influent for the column experiment (Table 1) was a synthetic acidic solution prepared with the concentration of all major constituents matching average values in groundwater from ASS terrain on the Shoalhaven Floodplain measured continuously for 1.5 years (Regmi et al, 2009). …”

Section: Synthetic Acidic Groundwater and Alkaline Wastewatermentioning

confidence: 99%

“…The alkaline injection column apparatus was constructed similar to previous column design (Regmi et al, 2009). The design was initially modified to replicate the alkaline injection strategies that can be adopted at the pilot-scale PRB field site for rejuvenation by means of downwards infiltration i.e.…”

Section: Experimental Protocolmentioning

confidence: 99%

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Permeable reactive barrier rejuvenation by alkaline wastewater

Banasiak

Indraratna

Lugg

et al. 2015

Environmental Geotechnics

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Chemical armouring of recycled concrete in a permeable reactive barrier (PRB) used for the neutralisation of acidic groundwater in acid sulfate soil terrain significantly decreases its acid neutralising capacity (ANC) by approximately 50% compared with its theoretical ANC. A long-term column test was conducted under simulated field groundwater conditions to assess the re-conditioning of armoured recycled concrete aggregates with alkaline wastewater, with the aim to restore and enhance the ANC and longevity of the PRB. The benefits of alkaline wastewater injection included sharp but short enhancement of the recycled concretes' ANC, as indicated by an increase in effluent pH (pH 3 to 7·7) and alkalinity (0 to 21·6 mM CaCO3) and a reduction in oxidation reduction potential (ORP,. While the results showed that the alkaline wastewater did not significantly reduce chemical armouring, it aided in the liberation of lodged mineral precipitates between concrete aggregates, reducing the severity of chemical and physical clogging. Batch tests demonstrated that, when exposed to acidic water, the ANC of recycled concrete pre-conditioned with alkaline wastewater was enhanced as indicated by higher pH, lower ORP and greater release of calcium (Ca2+) and alkalinity, compared to non-pre-conditioned concrete.

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Section: Discussionmentioning

confidence: 99%

Section: Reactive Materialsmentioning

confidence: 99%

Section: Synthetic Acidic Groundwater and Alkaline Wastewatermentioning

confidence: 99%

Section: Experimental Protocolmentioning

confidence: 99%

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Permeable reactive barrier rejuvenation by alkaline wastewater

Banasiak

Indraratna

Lugg

et al. 2015

Environmental Geotechnics

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“…There are thirteen primary mineral dissolution-precipitation reactions as shown in [3]. To confirm the adoption of only these thirteen reaction equations in the geochemical algorithm, inverse geochemical modelling has been carried out by [22] which consider all the possible mineral phases in the upstream of the PRB and inside the PRB. The results from inverse geochemical modelling confirmed that these thirteen reactions are the dominant reactions in terms of acid neutralisation.…”

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confidence: 99%

Coupled hydro-geochemical modelling of a permeable reactive barrier for treating acidic groundwater

Indraratna

Pathirage

Rowe

et al. 2014

Computers and Geotechnics

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This study focuses on coupling geochemistry with geo-hydraulics to enable time-dependent modelling of the remediation of acidic groundwater using an alkaline permeable reactive barrier (PRB). Chemical clogging due to secondary mineral precipitates reduces the porosity and hydraulic conductivity of the reactive medium. The governing equations are incorporated into commercial numerical codes, MODFLOW and RT3D. An original algorithm was developed for RT3D to simulate geochemical reactions occurring in the PRB. The results and the model predictions are in agreement, confirming that the hydraulic conductivity reduction due to mineral precipitation occurs at the start of permeation and continues until halfway through the testing phase. This study focuses on coupling geochemistry with geo-hydraulics to enable time-dependent modelling of the remediation of acidic groundwater using an alkaline permeable reactive barrier (PRB). Chemical clogging due to secondary mineral precipitates reduces the porosity and hydraulic conductivity of the reactive medium. The governing equations are incorporated into commercial numerical codes, MODFLOW and RT3D. An original algorithm was developed for RT3D to simulate geochemical reactions occurring in the PRB. The results and the model predictions are in agreement, confirming that the hydraulic conductivity reduction due to mineral precipitation occurs at the start of permeation and continues until halfway through the testing phase.Keywords: acidic groundwater, chemical clogging, permeable reactive barrier, mineral precipitation, transport modelling 2 IntroductionAcidic groundwater generated from acid sulfate soil (ASS), which occupies over 200,000 This head will be the input into MODFLOW which in return will be used to couple the groundwater flow with reaction kinetics in RT3D. User-defined module facilitated in RT3D was used to feed the geochemical algorithm into the numerical codes. This model is beneficial for practising engineers and scientists who have to deal with ASS especially in coastal areas of Australia. Laboratory column experiments were carried out under constant flow of 1.2 mL/min (millilitres per minute) using a Masterflex peristaltic pump (Fig. 2). Two simultaneous column experiments were run as suggested by [29] one for sampling and one to take pressure readings. The purpose of running two simultaneous columns instead of one column was to eliminate the impact of sampling activities on the pressure in the column [29]. The pressures at the onset were measured for both columns using pressure transducers at both ends which were almost the same. The input and environmental conditions were maintained the same for both columns, so the pressure readings calculated at each port was assumed similar to the respective sampling port at the same height in the other column. Methodology Laboratory column experimentsThe crushed recycled concrete used in this study was a waste material discarded after the demolition of old concrete structures. The particle size of crushed concre...

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