A Comparison of In Situ Constant and Falling Head Permeameter Tests to Assess the Distribution of Clogging Within Horizontal Subsurface Flow Constructed Wetlands

Pedescoll, Anna; Knowles, Paul; Davies, Philip A.; García, Joan; Puigagut, Jaume

doi:10.1007/s11270-011-1021-4

Cited by 20 publications

(11 citation statements)

References 26 publications

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“…The form, density and water retention characteristics of the solids effects the free volume available for water movement and therefore the local water content, hence the hydraulic conductivity [25,55]. To determine the hydraulic conductivity two in situ methods can be used, namely the falling head and the constant head method [56].…”

Section: Methods To Evaluate Clogging Behaviormentioning

confidence: 99%

The State of the Art of Clogging in Vertical Flow Wetlands

Pucher

Langergraber

2019

Water

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Clogging in vertical flow (VF) wetlands is an important process influencing water purification processes. The main contributing factors are the growth of microorganisms within the filter media, the accumulation of suspended solids on top of the wetland, as well as within the filter media. Both processes lead to a decrease of the available pore space, hence changing the soil’s hydraulic properties. This will alter the water flow and cause malfunctioning of the system. This paper summarizes the state of the art of the prevailing physical, biological and chemical processes influencing clogging in VF wetlands. Different design and operational parameters are discussed to give a better understanding on their influence to prevent malfunctioning. Based on a literature review, a detailed overview on experimental as well as modelling studies carried out is presented. The main conclusions are that on the one hand, important insights on clogging processes in VF wetlands have been gained but, on the other hand, design parameters such as intermittent loading operation and the grain size of the filter media are not well represented in those studies. Clogging models use different conceptual approaches ranging from black box models to process based models.

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Section: Methods To Evaluate Clogging Behaviormentioning

confidence: 99%

The State of the Art of Clogging in Vertical Flow Wetlands

Pucher

Langergraber

2019

Water

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“…The Professional Standards Compilation Group of People's Republic of China 1999;Pedescoll et al 2011bPedescoll et al , 2012.…”

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confidence: 99%

Effects of plant roots on the hydraulic performance during the clogging process in mesocosm vertical flow constructed wetlands

Zhao

Kong

et al. 2014

Environ Sci Pollut Res

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The aim of this study was to evaluate the effects of plant roots (Typha angustifolia roots) on the hydraulic performance during the clogging process from the perspective of time and space distributions in mesocosm vertical flow-constructed wetlands with coarse sand matrix. For this purpose, a pair of lab-scale experiments was conducted to compare planted and unplanted systems by measuring the effective porosity and hydraulic conductivity of the substrate within different operation periods. Furthermore, the flow pattern of the clogging process in the planted and unplanted wetland systems were evaluated by their hydraulic performance (e.g., mean residence time, short circuiting, volumetric efficiency, number of continuously stirred tank reactors, and hydraulic efficiency factor) in salt tracer experiments. The results showed that the flow conditions would change in different clogging stages, which indicated that plants played different roles related to time and space. In the early clogging stages, plant roots restricted the flow of water, while in the middle and later clogging stages, especially the later stage, growing roots opened new pore spaces in the substrate. The roots played an important role in affecting the hydraulic performance in the upper layer (0-30 cm) where the sand matrix had a larger root volume fraction. Finally, the causes of the controversy over plant roots' effects on clogging were discussed. The results helped further understand the effects of plant roots on hydraulic performance during the clogging process.

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“…These results can be associated with a longer operating time of assessed systems (about two years), which allows a greater porous space occupation with solids from the applied wastewater, detached from the substrate, precipitated, and from the biofilm developed in the system. In other studies, Ks heterogeneity has also been reported, as in PEDESCOLL et al (2012) and RANIERI & YOUNG (2012).…”

Section: Resultsmentioning

confidence: 62%

Hydraulic Conductivity Variability in Horizontal Subsurface Flow Constructed Wetlands

et al. 2017

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Many modifications in hydrodynamic conditions occur inside the bed of a horizontal subsurface flow constructed wetland (HSSF-CW) in operation. Studies on hydraulic conductivity measurement techniques in HSSF-CW are imperative since the monitoring of flow conditions is essential for understanding and controlling its clogging. This study aimed to assess the hydrodynamic behavior in HSSF-CW by means of saturated hydraulic conductivity (Ks) analysis. For this, six HSSF-CW were used: two non-cultivated (control), two cultivated with Tifton 85 (Cynodon spp.), and two cultivated with alligator weed (Alternanthera philoxeroides). Application of swine wastewater (SW) in HSSF-CW started on June 15, 2011, with Ks measurement period between September 9 and November 11, 2011, in which five measurements were performed in different positions along the system length and over experimental period in order to assess the effects of vegetation, position, and time factors on this variable. Ks values ranged from 1,392 to 2,834 m d −1 . Plant presence led to Ks decreasing in the systems, but cultivated species had no influence on this variable. Monitoring time of HSSF-CW was no longer enough to provide a reduction in Ks, at 10% probability level.

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A Comparison of In Situ Constant and Falling Head Permeameter Tests to Assess the Distribution of Clogging Within Horizontal Subsurface Flow Constructed Wetlands

Cited by 20 publications

References 26 publications

The State of the Art of Clogging in Vertical Flow Wetlands

The State of the Art of Clogging in Vertical Flow Wetlands

Effects of plant roots on the hydraulic performance during the clogging process in mesocosm vertical flow constructed wetlands

Hydraulic Conductivity Variability in Horizontal Subsurface Flow Constructed Wetlands

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