Organic carbon: An overlooked factor that determines the antibiotic resistome in drinking water sand filter biofilm

Assessing Pretreatment Effectiveness for Particulate, Organic and Biological Fouling in a Full-Scale SWRO Desalination Plant

“…Therefore, free chlorine reaches the media filtration and destroys the biofilm layers on the filter media, as discussed earlier. It should be noted that biofilms need a long time to be formed/developed on the filter media (2-7 days) [44]. Thus, to further An insignificant change in the BGP was found before and after backwashing of the first stage of the DMF (Figure 6d), which could indicate either the absence of a biofilm layer on the media filter or that the biofilm layer attached to the media was not influenced by backwashing (strong biofilm layer), which is unlikely as low removal of BGP was detected in the first stage of the DMF (Figure 5).…”

“…Therefore, free chlorine reaches the media filtration and destroys the biofilm layers on the filter media, as discussed earlier. It should be noted that biofilms need a long time to be formed/developed on the filter media (2-7 days) [44]. Thus, to further reduce the BGP of SWRO feed water, priority should be given to (i) reducing the frequency of chlorination in intakes and/or (ii) performing the neutralization step before media filtration, and not after, as is the current practice in many full-scale SWRO plants.…”

Chlorination contributes to multi-antibiotic resistance in a pilot-scale water distribution system

“…The pH, temperature, dissolved oxygen (DO), and turbidity (NTU) were measured on site with a portable multi-parameter water quality meter (Muti 3420, WTW, Germany). The physicochemical properties of the influent water included the following: total nitrogen content (TN), total organic carbon content (TOC), chemical oxygen demand (COD Mn ), total phosphorus (TP), the residual chlorine, UVA 254 , and ammonia nitrogen (NH 4 þ -N), nitrate (NO 3 À -N) and nitrite (NO 2 À -N) concentrations were measured according to China's national standards (Chen et al 2017;Wan et al 2019). The detailed data are listed in Table 1.…”

“…A total of 299 validated primer sets were applied, and the primers contained a 16S rRNA gene, 286 ARG primer sets, nine transposase gene primer sets and three integrase gene primer sets (Zhu et al 2013;Liu et al 2014b;Wan et al 2019). Thus, this experiment used primers that contained almost all the resistant gene classes that have been studied so far.…”

“…All the HT-qPCR manipulations were performed in triplicate, and a threshold cycle of 28 was used as the detection limit (Lin et al 2016). The number of the ARGs discovered was used to evaluate the richness of ARGs, and the relative abundance of ARG was regarded as normalized ARG copies to the 16S rRNA copies (Lin et al 2016;Wan et al 2019).…”