Effect of multiwalled carbon nanotubes on UASB microbial consortium

Abstract

The continuous rise in production and applications of carbon nanotubes (CNTs) has grown a concern about their fate and toxicity in the environment. After use, these nanomaterials pass through sewage and accumulate in wastewater treatment plants. Since, such plants rely on biological degradation of wastes; their activity may decrease due to the presence of CNTs. This study investigated the effect of multiwalled carbon nanotubes (MWCNTs) on upflow anaerobic sludge blanket (UASB) microbial activity. The toxic effect on microbial viability, extracellular polymeric substances (EPS), volatile fatty acids (VFA), and biogas generation was determined. The reduction in a colony-forming unit (CFU) was 29 and 58 % in 1 and 100 mg/L test samples, respectively, as compared to control. The volatile fatty acids and biogas production was also found reduced. The scanning electron microscopy (SEM) and fluorescent microscopy images confirmed that the MWCNT mediated microbial cell damage. This damage caused the increase in EPS carbohydrate, protein, and DNA concentration. Fourier transform infrared (FTIR) spectroscopy results supported the alterations in sludge EPS due to MWCNT. Our observations offer a new insight to understand the nanotoxic effect of MWCNTs on UASB microflora in a complex environment system.

Carbon nanotubes accelerate methane production in pure cultures of methanogens and in a syntrophic coculture

“…In addition, Yadav et al . () correlated the cell damage (on UASB microbial flocs) caused by CNT with the increase of extracellular polymeric substances production. However, in the present study, the amount of extracellular substances seems to decrease with increasing concentrations of CNT (Figs and 3).…”

“…Toxic effects of CNT have also been reported. These materials may affect microbial community diversity and reduce the number of actively growing bacteria (Kang et al ., ; Pasquini et al ., ; Mohanty et al ., ; Yadav et al ., ). In addition, Yadav et al .…”

“…These materials may affect microbial community diversity and reduce the number of actively growing bacteria (Kang et al, 2008b;Pasquini et al, 2012;Mohanty et al, 2014;Yadav et al, 2016). In addition, Yadav et al (2016) correlated the cell damage (on UASB microbial flocs) caused by CNT with the increase of extracellular polymeric substances production. However, in the present study, the amount of extracellular substances seems to decrease with increasing concentrations of CNT (Figs 2 and 3).…”

Response of anaerobic granular sludge to iron oxide nanoparticles and multi-wall carbon nanotubes during beet sugar industrial wastewater treatment

“…However, its integration into various sectors, including pharmaceutical, energy, agriculture, construction, and wastewater treatment (Yadav et al 2016, Casals et al 2014, has raised concerns with respect to the environmental safety; most investigations focus on the potential effects on human health and the environment (Helland et al 2008, Petersen et al 2011. Some studies have reported the toxic effects of carbon nanotubes (Yadav et al 2016, Mwangi et al 2012, Simon-Deckers et al 2009) and zinc oxide nanoparticles (Mu et al 2012) on microorganisms, cells, and bacteria.…”

Graphene-family nanomaterials in wastewater treatment plants

“…Li et al [111] followed up on the degradation of sucrose with 0 or 1000 mg/L of SWNT for 174 h, and indicated that faster substrate consumption and higher amount of methane took place when the nanotubes were added. Yadav et al [112] incubated the sludge with 0, 1 and 100 mg/L of MWNT for 15 days, and noticed that the higher the nanomaterial concentration, the lower the microbial growth, the cell membrane integrity, the amount of volatile fatty acids generated and the biogas volume.…”