Sandile Simelane
University of Johannesburg, South Africa
Title: The fate, behavior and effect of WO3 nanoparticles on the functionality of an aerobic treatment unit
Biography
Biography: Sandile Simelane
Abstract
As a promising organic photocatalyst in wastewater treatment, understanding the fate and behavior of the WO3 nanoparticles and its impact on the functionality on the treatment plant is of paramount importance for accurate toxicological risk assessment. This was achieved through acclimatization of activated sludge to the simulated wastewater treatment plant operated according to the Organization for Economic Co-operation and Development 303A guidelines. During acclimatization, chemical oxygen demand (COD), and a five-day biological oxygen demand (BOD5) were monitored. Humic acid impact on the functionality of the domestic waste water treatment plant was investigated as it is a major constituent of wastewaters. The COD removal was above 80% suggesting that humic acid had no impact on the activated sludge activity. The fate of m-WO3 was monitored using X-ray diffraction and scanning electron microscope coupled with electron dispersive x-ray. X-ray diffraction analysis showed presence of m-WO3 in the sludge which was further confirmed with electron dispersive x-ray -mapping which showed presence of tungsten signifying adsorption of the nanoparticles on the sludge. Up-to the addition of 15 ppm WO3 showed to have an effect on functionality of the treatment plant as the COD removal dropped to 70 % which is below the 80% stipulated guideline signifying adequate removal of the COD. This implies that WO3 nanoparticles possess toxicity effects on the activated sludge. An increase in conductivity was observed in the test effluent suggesting the possibility of dissolution of the nanoparticle. The ICP-OES analyses showed that 80% of W was retained in the sludge while 20-21% m/m actually run out with the effluent.
