Abstract: A local wastewater treatment plant (WWTP)
experiencing poor nitrification tracked down high level of
surfactants in the plant-s influent and effluent. The aims of this project were to assess the potential inhibitory effect of surfactants on activated sludge processes. The effect of the
presence of TergitolNP-9, TrigetolNP-7, Trigetol15-S-9,
dodecylbenzene sulphonate (SDBS) and sodium dodecyl
sulfate (SDS) on activated sludge oxygen uptake rate (OUR) and nitrification were assessed. The average concentration of non-ionic and anionic
surfactants in the influent to the local WWTP were 7 and 8.7 mg/L, respectively. Removal of 67% to 90% of the non-ionic and 93-99% of the anionic surfactants tested were measured. All surfactants tested showed inhibitory effects both on OUR
and nitrification. SDS incurred the lowest inhibition whereas
SDBS and NP-9 caused severe inhibition to OUR and
Nitrification. Activated sludge flocs sizes slightly decreased
after 3 hours contact with the surfactant present in the test.
The results obtained indicated that high concentrations of
surfactants are likely to have an adverse effect on the
performance of WWTPs utilizing activated sludge processes.
Abstract: Carbon nanotubes (CNTs) are attractive because of
their excellent chemical durability mechanical strength and electrical
properties. Therefore there is interest in CNTs for not only electrical
and mechanical application, but also biological and medical
application.
In this study, the dispersion power of surfactant-treated multiwalled
carbon nanotubes (MWCNTs) and their effect on the antibacterial
activity were examined. Surfactant was used sodium
dodecyl-benzenesulfonate (SDBS). UV-vis absorbance and
transmission electron microscopy(TEM) were used to characterize the
dispersion of MWCNTs in the aqueous phase, showing that the
surfactant molecules had been adsorbed onto the MWCNTs surface.
The surfactant-treated MWCNTs exhibited antimicrobial activities
to streptococcus mutans. The optical density growth curves and viable
cell number determined by the plating method suggested that the
antimicrobial activity of surfactant-treated MWCNTs was both
concentration and treatment time-dependent.