Amir Saffar Perez, Wadson Phanord and Pedro J. Tarafa
The objective of this project is to develop and evaluate a hybrid multimedia filter system for pathogens control and for the degradation of organic compounds in water. The hybrid aspect of the system is based on combining a lab-scale biosand filter (LSBF) and a glass-TiO2 porous composite. The sand filter works under the influence of gravity in order to pass the raw water through the sand bed to remove suspended solids (i.e. turbidity) while a biolayer is established at the sand bed surface (standing zone) allowing the removal of viruses and bacteria simultaneously. Two LSBF sets with different heights were designed and run to evaluate the effect of the filtration media depth upon the removal of the pathogens. E.coli and Enterococcus were the indicators being used. Both are easily detected with selective agars, and their presence can indicate the presence of other, more dangerous bacteria. Afterwards, the treated water is exposed to a glass-TiO2 composite and ultraviolet (UV) light to assess the capability of the TiO2 to get photo-activated and promote a photo-chemical reaction to degrade organic matter in the water. According to preliminary results, the biosand filter was able to eliminate over 95% E. coli, as well as lowering the organic matter, quantified as total organic carbon (TOC). When combined with the glass-TiO2 composite under UV light, the organic carbon levels are lowered to a 60-75% range, which is substantial. Ultimately, the hybrid system is an affordable and efficient water purification system, and deserves further improvement and refinement.