Wastewater emptying from our nation's homes and industries is approximately 99% water and 1% contaminants. This 1% however, places a billion-dollar burden on the US taxpayer and poses a formidable environmental threat. Improper treatment of wastewater has already polluted many of our natural waterways and caused outbreaks of public illness. Left alone, this hazardous 1% would decompose to its non-toxic components. The challenge of sewage treatment lies in accelerating this natural decomposition to below the seven hours within which wastewater becomes septic.

Current treatment relies on two stages, primary and secondary. Wastes are allowed to settle out by gravity and then any remaining suspended solids are degraded by bacteria. We propose an alternate, single-step utilization of titanium dioxide (Ti02), which has been shown to catalyze the naturally-occurring, solar-mediated breakdown of organic compounds in aqueous solution. Previously tested only on the clean-up of oil spills, here we show through a series of experiments that TiO2 can also be applied to the purification of wastewater within a time-frame realistic for treatment.

Titanium dioxide could be applied to local sewage plants with minimal difficulty and financial outlay, taking advantage of equipment already in place. In addition to removing trace levels of carcinogens, TiO2 would also eliminate the secondary (bacterial) stage of treatment at a savings of millions of dollars, presenting both an ecological and economical solution. s



Students: Supinda Bunyavanich f

Minsu Longiaru

Teacher-Advisor:

Judy Ferris