Time-domain induced polarization as a tool to image clogging in treatment wetlands

Garcia-Artigas, R.; Himi, Mahjoub; Revil, A.; Urruela, A.; Lovera, R.; Sendròs, A.; Casas, A.; Rivero, L.

doi:10.1016/j.scitotenv.2020.138189

Cited by 16 publications

(11 citation statements)

References 39 publications

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“…While there have been numerous studies on the rate and development of clogging and, consequently, on the changes to the hydraulic characteristics of HSTWs, research has not acquired a clear understanding of the processes [5]. In addition to techniques that measure the properties of clog matter (elucidating the nature and the degree of clogging) [6,7] and tomography (allowing for the production of a 3D image of the distribution of the clogging and its concentration in the filter) [8], all the other approaches are based on the evaluation of HSTW hydraulic behavior. In particular, one of the main effects of clogging is a reduction of the hydraulic conductivity (K s ) at saturation of the porous media [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Different Methods to Assess the Hydraulic Behavior in Horizontal Treatment Wetlands

Licciardello

Sacco

Barbagallo

et al. 2020

Water

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While there have been numerous studies on the rate and development of clogging in horizontal subsurface treatment wetlands (HSTWs) and, consequently, the effects on its hydraulic characteristics, research has not shown a clear understanding of the processes. The existing methods for measuring the impact of clogging provide limited information on the extension and degree of the phenomenon. This study aimed to evaluate the capacity of various measurement techniques to assess the degree and variation in space and time of clogging in HSTWs. Hydraulic conductivity at saturation (Ks) measurements were conducted using a newly implemented scheme, the drainage equation method, and traditional tracer tests, which were carried out in a full-scale HSTW system, located in Sicily, Italy, during 2019. After five years of operation, the results highlighted a severe decrease in Ks (<1000 m day−1) in the inlet zone (despite the fact that the filter gravel was replaced in 2017), a very high reduction of Ks along the central path inside the bed, a nonuniform flow through the HSTW, the presence of stagnant zones, and a reduction of the porosity of the bed gravel. Nonetheless, the mean values of the physical–chemical and bacteriological parameters at the hybrid treatment wetland (hybrid TW) outlet indicated that the partial clogging had no significant effect on the quality of the discharged water. Moreover, the results obtained using the different measurement techniques (in terms of both the Ks values and the flow distribution inside the bed) were consistent with each other and with results obtained previously for the same system. Finally, the most efficient combination of methods to assess clogging in HSTWs was identified.

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Section: Introductionmentioning

confidence: 99%

Evaluation of Different Methods to Assess the Hydraulic Behavior in Horizontal Treatment Wetlands

Licciardello

Sacco

Barbagallo

et al. 2020

Water

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“…The reduced outlet velocity (implying hydraulic conductivity) of the substrate resulted from the progressive attachment of accumulated solids restricting the passage of treated wastewater and favoring more contact between particles. It is possible to schedule a partial substitution of the media with high clogging, thus reducing both the economic cost of the operation and the time to stop the system 10 . However, replacement of the inflow zone substrates when partial clogging takes place may not significantly improve the removal performance of BOD 5 , COD and TSS 4 …”

Section: Resultsmentioning

confidence: 99%

“…It is possible to schedule a partial substitution of the media with high clogging, thus reducing both the economic cost of the operation and the time to stop the system. 10 However, replacement of the inflow zone substrates when partial clogging takes place may not significantly improve the removal performance of BOD 5 , COD and TSS. 4…”

Section: Clogging Developmentmentioning

confidence: 99%

“…5 Many studies have reported restorative strategies (such as backwash, excavation and replacement) and preventative strategies (such as optimizing operational conditions, size selection and filling of substrate) to alleviate and avoid clogging in biofiltration systems. [6][7][8][9] A number of studies have also simulated the development of clogging and its associated processes, such as clogging time, clogging area and flow patterns, using mathematical models, [10][11][12][13][14] which are hoped to eventually provide practitioners with predictive tools that can guide necessary intervention, and indicate how various operational and maintenance routines may affect clogging development. De Matos et al reviewed various factors causing clogging like influent SS loading, biofilm growth, precipitates (mainly calcium carbonates) and gases (mainly hydrogen sulfide), and their rough contributions to the clog components of CWs.…”

Section: Introductionmentioning

confidence: 99%

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Can phosphorus adsorption clog an alum sludge‐based biofiltration system? Evidence and insight

Yang

Wang

Zhao

et al. 2020

J of Chemical Tech & Biotech

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BACKGROUND: Aluminium-based drinking water treatment residual (Al-DWTR) has been used as an emergent substrate in laboratory-scale and pilot-scale biofiltration systems (biofilters and constructed wetlands) for its good affinity for phosphorus (P) adsorption. However, there is a concern about whether the P adsorption process will contribute to substrate clogging. Two laboratory-scale up-flow biofiltration systems were set up to identify the contribution of the P adsorption process to clogging under various operation conditions. RESULTS: Contributions of individual processes to clogging from biosolids production (S BS), inert matter generated from the conversion of residual biomass (S IS), P adsorption (S P) and inert matter production from influent total suspended solids (S SS) during operation of the two systems were assessed. After 262 days of operation, results indicated that S BS contributed most (53.16 ± 7.73%) to the clogging, followed by S SS (41.48 ± 8.02%), S P (3.14 ± 0.06%) and S IS (2.20 ± 0.27%) when treating the influent with concentrations of 284-558 mg L −1 for COD, 54-197 mg L −1 for SS and 5-13 mg L −1 for P. CONCLUSIONS: The minor contribution of the P adsorption process to substrate clogging further suggests that dewatered Al-DWTR with a high P removal capacity is a promising substrate for use in biofiltration systems.

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“…In field data acquisition, a negative IP response, i.e., a negative apparent chargeability or a positive apparent phase, is sometimes observed in the measurements. Such negative IP measurements are often treated as errors and deleted during the data inversion or interpretation (e.g., Mary et al 2016;Ntarlagiannis et al 2016;Kelter et al 2018;Garcia-Artigas et al 2020).…”

Section: Introductionmentioning

confidence: 99%

On negative induced polarization in frequency domain measurements

Wang

Binley

Slater

2020

Geophysical Journal International

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Summary Induced polarization (IP) has been widely used to non-invasively characterize electrical conduction and polarization in the subsurface resulting from an applied electric field. Earth materials exhibit a lossy capacitance defined by an intrinsic negative phase in frequency-domain IP (FDIP) or positive intrinsic chargeability in time-domain IP (TDIP). However, error-free positive apparent phase or negative apparent chargeability (i.e. negative IP effects) can occur in IP measurements over heterogeneous media. While negative IP effects in TDIP datasets have been discussed, no studies have addressed this topic in detail for FDIP measurements. We describe theory and numerical modeling to explain the origin of negative IP effects in FDIP measurements. A positive apparent phase may occur when a relatively high polarizability feature falls into negative sensitivity zones of complex resistivity measurements. The polarity of the apparent phase is determined by the distribution of subsurface intrinsic phase and resistivity, with the resistivity impacting the apparent phase polarity via its control on the sensitivity distribution. A physical explanation for the occurrence of positive apparent phase data is provided by an electric circuit model representing a four-electrode measurement. We also show that the apparent phase polarity will be frequency dependent when resistivity changes significantly with frequency (i.e. in the presence of significant IP effects). Consequently, negative IP effects manifest themselves in the shape of apparent phase spectra recorded with multi-frequency (spectral IP) datasets. Our results imply that positive apparent phase measurements should be anticipated and should be retained during inversion and interpretation of single frequency and spectral IP datasets.

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Time-domain induced polarization as a tool to image clogging in treatment wetlands

Cited by 16 publications

References 39 publications

Evaluation of Different Methods to Assess the Hydraulic Behavior in Horizontal Treatment Wetlands

Evaluation of Different Methods to Assess the Hydraulic Behavior in Horizontal Treatment Wetlands

Can phosphorus adsorption clog an alum sludge‐based biofiltration system? Evidence and insight

On negative induced polarization in frequency domain measurements

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