Evaluation of the impact of single-walled carbon nanotubes in an activated sludge wastewater reactor

Abstract

This paper evaluated the impact of single-walled carbon nanotubes (SWCNTs) on the performance and activated sludge properties in an activated sludge wastewater reactor. The reactor was shock loaded with 270 mg/L of 90% purified SWCNTs after the reactor reached quasi-steady state and the reactor was monitored for 18 days after the shock loading. Various experimental parameters were measured and compared. Overall the addition of SWCNTs did not negatively impact the performance of the activated sludge reactor; on the other hand, SWCNTs improved sludge settleability and sludge dewaterability. The cake solids of the sludge were increased and the activated sludge flocs became less negatively charged. The positive impacts were more significant in Phase II (after running the reactor for one solids retention time, SRT) than that in Phase III (after running for additional 1.5 SRT).