Particle Size and Clogging of Granular Media Permeated with Leachate

Rowe, R. Kerry; Armstrong, M.; Cullimore, D. R.

doi:10.1061/(asce)1090-0241(2000)126:9(775)

Cited by 71 publications

(40 citation statements)

References 12 publications

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“…5, further confirming the accuracy of the developed model. Several studies carried out for zero-valent iron columns [26], [45], organic sediment columns [46], glass bead columns [19] and recycled concrete columns [27] have reported that excessive clogging is greatest near the inlet to the column (reactive materials) and is not uniform throughout the column. For the current case, the porosity and hydraulic conductivity reductions due to mineral precipitation and dissolution were calculated from Eq.…”

Section: Resultsmentioning

confidence: 99%

“…The performance of PRBs has been hindered by mineral fouling wherein the pore space is reduced by mineral precipitation in the reactive media. Fouling of the pore spaces reduces the porosity and hydraulic conductivity of the reactive medium [16], [17], [18], [19], [20], [21], [22], [23], [24], which then directly affects the reorientation of flow paths and changes reactive times. Porosity reductions due to secondary mineral precipitation usually are calculated by the volumes of secondary minerals observed in cores or from stoichiometric calculations using measured changes in aqueous concentrations [5].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

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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“…Many field studies had shown that leakage of leachate from the landfills have resulted in the contamination of surface and groundwater (Kaushik and Sethi 2007;Rowe 2009;Rowe andYu 2010, 2013). Rowe et al (2000) reported findings of laboratory research, using columns represented saturated zone of 0.5 m over leachate collection pipes. Leachate was allowed to pass upward through columns filled with uniformly graded glass beads of different sizes.…”

Section: Lcrsmentioning

confidence: 99%

“…Gravel size was selected based upon the experimental studies conducted by Rowe et al (2000), Rowe and Mclsaac (2005), Mclsaac andRowe (2005, 2007) in which gravel size used as drainage layer material was optimized using the leachate collected from Keele Vally landfill, Canada. Results showed that 38-40 mm gravel performed much better than all other sizes and maintained high hydraulic conductivity for relatively longer duration.…”

Section: Apparatus and Experimental Approachmentioning

confidence: 99%

“…Humphrey and Sandford (1993), Bouchez et al (2003), Adyilek et al (2006), Junqueria et al (2006), Mondal and Warith (2008), Rowe andYu (2010, 2013) showed that a biofilm grows on the materials in the collection layers of LCRS's followed by biological induced deposition of inorganic constituents, on the material (from the leachate flow). Rowe et al (2000), Fleming and Rowe (2004) indicated that the microbial consortia of methanogens, denitrifies, sulfate reducing and other facultative anaerobes were present inside the columned drainage media. The clog that developed decreased the pore space available to transmit leachate, reduced hydraulic conductivity of drainage materials and the service life of LCRS's.…”

Section: Gravel-tire Chips Combinations Arranged In Layers and As Ranmentioning

confidence: 99%

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Performance Assessment of Gravel–Tire Chips Mixes as Drainage Layer Materials Using Real Active MSW Landfill Leachate

2015

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Potential of clogging for rubber tire chips, gravel and their relative performance for transmitting high strength leachate when arranged in proportionate layers of relative thickness and in random state mixes of various percentage compared to the case of used alone were studied through column experiments. Comparative hydraulic performance of gravel and tire chips in their different combinations with percentage change (reduction) in COD, TSS, Ca-hardness and TDS concentration levels for the real active high strength MSW landfill leachate with time were investigated. Experiments were performed to simulate conditions occurring at the base of all active MSW landfills, in an attempt to replicate reasonably worst case conditions. Results clearly showed that the combinations ds (scrap tire chips layer thickness)/dg (gravel layer thickness) = 0.25, 0.50 (arranged by relative thickness) and Ws:Wg = 1:3 (25 % tire chips:75 % gravel; mixed by weight friction of each component) were good in term of obtaining initially relatively free drainage. Minor reduction in hydraulic conductivity for fairly longer duration, due to lesser clogging and small reduction in COD, TSS and Cahardness concentration levels were observed for these combinations. These experimental findings may prove to be very useful for the proper design, long term performance and service life of all tire chips-gravel made drainage layers of all the active MSW landfill leachate collection and removal systems.

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