MRI measurements of dynamic clogging in porous systems using sterilised sludge

Shamim, M.F.; Bencsik, Martin; Morris, Robert H.; Newton, Michael I.

doi:10.1016/j.micromeso.2013.04.025

Cited by 6 publications

(3 citation statements)

References 8 publications

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“…However, this method has the disadvantages of being time-consuming, having low accuracy, and causing secondary pollution. Some exotic techniques for in situ detection of clogging matter, such as ground-penetrating radar, nuclear magnetic resonance, and microbial fuel cell, have been presented to quantify the accumulated solid [10][11][12]. However, as they are susceptible to environmental factors, their accuracy and practicability should be further discussed.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Detection of Clogging in Horizontal Subsurface Flow Constructed Wetland Using the Resistivity Method

Liu

Song

et al. 2018

Water

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Substrate clogging seriously affects the lifetime and treatment performance of subsurface flow constructed wetlands (SSF CWs), and the quantitative detection of clogging is the key challenge in the management of substrate clogging. This paper explores the feasibility of the resistivity method to detect the clogging degree of an SSF CW. The clogged substrate was found to have a high water-holding capacity, which led to low apparent resistivity in the draining phase. On the basis of the resistivity characteristics, clogging quantification was performed with a standard laboratory procedure, i.e., the Wenner method used in a Miller Soil Box. The apparent resistivity to sediment fraction (v/v) (ARSF) model was established to evaluate the degree of clogging from the apparent resistivity. The results showed that the ARSF model fit well with the actual values (linear slope = 0.986; R-squared = 0.98). The methods for in situ resistivity detection were applied in a lab-scale horizontal subsurface flow constructed wetland (HSSF CW). Combined with the ARSF model, the two-probe method demonstrated high accuracy for clogging quantification (relative error less than 9%). These results suggest that the resistivity method is a reliable and feasible technique for in situ detection of clogging in SSF CWs.

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Section: Introductionmentioning

confidence: 99%

Quantitative Detection of Clogging in Horizontal Subsurface Flow Constructed Wetland Using the Resistivity Method

Liu

Song

et al. 2018

Water

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“…Determining the clog state of both model systems and wetland samples have been extensively investigated in the laboratory setting using relaxation measurements [10], [11], [12], [13], [14]. The parameter T2 eff has been previously used to successfully characterize clogging in a model system where a highly homogeneous magnetic field has been used for MR measurements [11], [12], however this was not possible with the inhomogeneous magnetic field of a low-cost permanent magnet system such as the type used in this work [14].…”

Section: Introductionmentioning

confidence: 99%

“…The parameter T2 eff has been previously used to successfully characterize clogging in a model system where a highly homogeneous magnetic field has been used for MR measurements [11], [12], however this was not possible with the inhomogeneous magnetic field of a low-cost permanent magnet system such as the type used in this work [14]. Therefore this work focusses on T1 relaxation measurements which have also been used to determine the clog state with a similar sensor in the past [10], [13], [14].…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of magnetic resonance probes for use as embedded sensors in constructed wetlands

Hughes‐Riley

Dye

Anderez

et al. 2016

Sensors and Actuators A: Physical

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Constructed wetlands are now accepted as an environmentally friendly means of wastewater treatment however, their effectiveness can be limited by excessive clogging of the pores within the gravel matrix, making this an important parameter to monitor. It has previously been shown that the clog state can be characterised using magnetic resonance (MR) relaxation parameters with permanent magnet based sensors. One challenge with taking MR measurements over a time scale on the order of years is that seasonal temperature fluctuations will alter both the way that the sensor operates as well as the relaxation times recorded. Without an understanding of how the sensor will behave under different temperature conditions, meaningful information about the clog state cannot be successfully extracted from a wetland. This work reports the effect of temperature on a permanent magnet based MR sensor to determine if the received signal intensity is significantly compromised as a result of large temperature changes, and whether meaningful relaxation data can be extracted over the temperature range of interest. To do this, the central magnetic field of the sensor was monitored as a function of temperature, showing an expected linear relationship. Signal intensity was measured over a range of temperatures (5 °C to 44 °C) for which deterioration at high and low temperatures compared to room temperature was observed. The sensor was still operable at the extremes of this range and the reason for the signal loss has been studied and explained. Spin-lattice relaxation time measurements using the sensor at different temperatures have also been taken on a water sample and seem to agree with literature values. Further to this, measurements have been taken in an operational wetland over the course of 203 days and have shown a linear dependence with temperature as would be expected. This work concluded that the sensor can perform the task of measuring the spin-lattice relaxation time over the required temperature range making it suitable for long-term application in constructed wetlands.

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