Application of modified qualitative index for surveillance of water-filtration process in turbidity removal by different media

Abstract

Several media have been used in treatment plants, however, their efficiency for turbidity removal, which is determined by qualitative indices, has been considered. Current qualitative indices such as turbidity and escaping particle number could not completely measure the efficiency of the filtration system; therefore defining new qualitative indices is essential. In this study, the efficiency of two different dual media filters in turbidity removal was compared in different operating condition using qualitative indices. The pilot consisted of a filter column (1-m depth) in which the filter-1 was consisted of a layer of anthracite (450-mm depth) and a layer of silica sand (350-mm depth); and filter-2 had the same media characteristics except for the first layer that was light expanded clay aggregates (LECA). Turbidities of 10, 20, and 30 NTU, coagulant concentrations of 4, 8, and 12 ppm and filtration rates of 10, 15, and 20 m/h were considered as variables. Results showed that the media of filter-2 is a suitable substitute for the media of filter-1 (P value \ 0.05). Turbidity removal efficiencies in different condition were 79.97 ± 1.79 to 91.37 ± 1.23% for the filter-2 and 75.12 ± 2.75 to 86.82 ± 1.3% for the filter-1. The LECA layer efficiency in turbidity removal was independent of filtration rates and due to its low head loss; LECA can be used as a proper medium. Results also showed that the particle index was a suitable index as a substitute for turbidity and escaping particle number as indices.

Effectiveness of two lightweight aggregates for the removal of heavy metals from contaminated urban stormwater

“…Lightweight aggregates (LWAs) are low-density construction aggregates. They have been employed in a wide range of water treatments, such as turbidity removal (Badalians Gholikandi et al, 2012), decontamination of drinking water (Haque et al, 2008), improvement in runoff quality (Vijayaraghavan and Badavane, 2017) and wastewater treatments (Camaño Silvestrini et al, 2019). LWAs are granular materials with mineral origin characterised by particle and loose bulk densities <2000 kg/m 3 and < 1200 kg/m 3 , respectively.…”

“…Besides, the sorbent capacities demonstrated by LWAs (Nkansah et al, 2012;Petrella et al, 2017) complement their features in promoting both the infiltration of urban runoff stormwater and the recharging of groundwater, meeting the established quality requirements. Novel applications of LWAs are hence continuously proposed for a wide variety of water treatments, such as turbidity removal (Badalians Gholikandi et al, 2012), the decontamination of drinking water (Haque et al, 2008), the improvement of runoff quality (Vijayaraghavan and Badavane, 2017) and wastewater treatment (Camaño Silvestrini et al, 2019).…”