Integrated Metagenomic and Physiochemical Analyses to Evaluate the Potential Role of Microbes in the Sand Filter of a Drinking Water Treatment System

Abstract

While sand filters are widely used to treat drinking water, the role of sand filter associated microorganisms in water purification has not been extensively studied. In the current investigation, we integrated molecular (based on metagenomic) and physicochemical analyses to elucidate microbial community composition and function in a common sand filter used to treat groundwater for potable consumption. The results revealed that the biofilm developed rapidly within 2 days (reaching ∼1011 prokaryotes per gram) in the sand filter along with abiotic and biotic particulates accumulated in the interstitial spaces. Bacteria (up to 90%) dominated the biofilm microbial community, with Alphaproteobacteria being the most common class. Thaumarchaeota was the sole phylum of Archaea, which might be involved in ammonia oxidation. Function annotation of metagenomic datasets revealed a number of aromatic degradation pathway genes, such as aromatic oxygenase and dehydrogenase genes, in the biofilm, suggesting a significant role for microbes in the breakdown of aromatic compounds in groundwater. Simultaneous nitrification and denitrification pathways were confirmed as the primary routes of nitrogen removal. Dissolved heavy metals in groundwater, e.g. Mn2+ and As3+, might be biologically oxidized to insoluble or easily adsorbed compounds and deposited in the sand filter. Our study demonstrated that the role of the microbial community in the sand filter treatment system are critical to effective water purification in drinking water.

Metagenomic analysis of rapid gravity sand filter microbial communities suggests novel physiology of Nitrospira spp.

“…Archaea represented less than 1% of the filter community in both top and bulk samples (ISLBulk, 0.74 ± 0.10; ISLTop, 0.43 ± 0.02), consistent with previous studies examining the microbial communities in rapid gravity filtrations filters (Bai et al, 2013;Wang et al, 2014) and with a previous pyrosequencing analysis of the same community (Gülay et al, 2016). At the phylum level, Proteobacteria and Nitrospirae dominate bulk sample communities with a relative abundance of 18.93% ± 1.31% and 9.22% ± 4.72%, respectively; in the top of the filter these phyla were also dominant, with Nitrospirae most abundant (26.08% ± 0.94%), followed by Proteobacteria (14.47% ± 1.07%; Figure 1).…”

Metagenomic analysis reveals microbial diversity and function in the rhizosphere soil of a constructed wetland

“…Cluster generation was performed on an Illumina cBot (Illumina Inc., San Diego, CA, USA) automated cluster generation system and the Illumina Hiseq 2000 sequencing system was used for sequencing (90 bp pair-end reads). Similar to our previous study, [18] the raw sequence reads were initially filtered to remove adapters and ambiguous reads. The filtered reads (∼2 Gbps for each data set) were assembled using velvet software.…”

Treatment of groundwater containing Mn(II), Fe(II), As(III) and Sb(III) by bioaugmented quartz-sand filters

“…However its biological roles in pollutant removal still remain largely unknown. We previously demonstrated that abundant microbes exist on the surface of sand filters to form stable biofilms (Bai et al, 2013). As microbial community diversity and function in engineering settings are strongly related to treatment effects, optimizing the microbial community within a sand filter would be of benefit for the improvement of effluent quality.…”