Media filter fouling assessment using optical coherence tomography: New methodology

Miquel Duran-Ros,Carles Solé-Torres,Nassim Ait-Mouheb,Bruno Molle,Gerard Arbat,Jaume Puig-Bargués

doi:10.1016/j.biosystemseng.2021.01.008

Abstract

Drip irrigation is an efficient and safe system for reusing wastewater in agriculture. Since emitter clogging is its main limitation, filtration is needed for preventing it. Media filters are commonly used when irrigation water has a high particle load. However, particle removal through a media bed in media filters used in drip irrigation systems has not been widely studied mainly due to experimental difficulties. To overcome this issue a new methodology using optical coherence tomography (OCT) is presented here. Experiments were carried out on a media filter at laboratory scale using wastewater. Once the filter was clogged, several 20 mm slices were taken and the retained total suspended solids were analysed by gravimetry. Following this, particles retained at six different locations of each slice were also determined using OCT. Results show a good agreement between total suspended solids experimentally determined and particles determined with OCT, especially when pixels attributed to particles were 30–45% of the total. Therefore, OCT could be a useful technique for assessing particle retention at different media depths. • Particle retention at different depths on media filters was studied in the laboratory. • Optical coherence tomography (OCT) was used. • OCT is a promising technique for analysing particle removal in media filters.

Highlights

Good agricultural practices, consistent irrigation management and efficient treatments that limit the impact of wastewater reuse on the environment (Lazarova & Bahri, 2004; AitMouheb et al, 2018) make it possible to reserve good quality water for more sensitive uses such as drinking water
Emitter clogging is a major issue (Nakayama et al, 2007, Lequette, Ait-Mouheb, Wery, 2020) since it disturbs operation, reduces distribution uniformity and longevity and this can affect the economic competitiveness of drip irrigation systems (Lamm & Rogers, 2017)
Media filters used in drip irrigation are usually pressurised vertical cylindrical tanks, where packed sand is used as filtering media (Burt & Styles, 2016)

Summary

Introduction

Consistent irrigation management and efficient treatments that limit the impact of wastewater reuse on the environment (Lazarova & Bahri, 2004; AitMouheb et al, 2018) make it possible to reserve good quality water for more sensitive uses such as drinking water. Drip irrigation improves water use efficiency (Ayars et al, 2007) and allows a safe use of reclaimed wastewater (RWW) (WHO, 2006). Emitter clogging is a major issue (Nakayama et al, 2007, Lequette, Ait-Mouheb, Wery, 2020) since it disturbs operation, reduces distribution uniformity and longevity and this can affect the economic competitiveness of drip irrigation systems (Lamm & Rogers, 2017). Irrigation water filtration is a key maintenance practice for preventing emitter clogging (Nakayama et al, 2007). Media filters used in drip irrigation are usually pressurised vertical cylindrical tanks, where packed sand is used as filtering media (Burt & Styles, 2016). Sole-Torres et al (2019) pointed out that a Nomenclature

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