Determining and Comparing the Effect of Nanoparticle CuO, TiO2 and ZnO in Removing Gram Positive and Negative Bacteria from Wastewater

Due to the unique absorption and anti-microbial properties of nanoparticles,making use of them for removal of bacteria in water and wastewater is growing. Application of these substances in removal of bacteria in municipal wastewater is an important matter which we will investigate in this research. In this cross-sectional study, the sampling period was completed from summeruntill fall of the year 2010at incoming sewage treatment plant in Kerman City. Sampleswere grown on nutrient agar culture media and then 180 Mueller Hinton agar medium wasprepared. Different concentrations of nanoparticles at ratio of 1:10 were injected on media containing the bacteria. After incubation, the level of CFU per milliliter was calculated by counting the number of colony. Tests were done based on 'water and wastewater standards" book. No observed effect concentration (NOEC) for zinc oxide nanoparticles forstaphylococcus aureus bacteria, bacillus subtilis and pseudomonas aeruginosa, andescherichia coli was 5, 5, 8, and 80 mg/l respectively, and 100% mortality for all thebacteria was in 6000 mg/l. NOEC of nano copper oxide for mentioned bacteria was in, 5, 7, 90, and 98 mg/l respectively and in the concentration of 6000mg/l the mortality percent of all three bacteria excluding escherichia coli (staphylococcus aureus, bacillus subtilis, pseudomonas aeruginosa) was 100% and for escherichia coli was 92%. NOEC of nano titanium dioxide for mentioned bacteria was 5, 90, 95, and 200 mg/l respectively, and in the concentration of 6000mg/l mortality of staphylococcus aureus, bacillus subtilis, pseudomonas aeruginosa, and escherichia coli was 96%, 81%, 89%, and 43% respectively. The results showed that with increasing concentration of nanoparticles,removal of bacteria increased as well. (P<0.05). The effect of zinc oxide nanoparticles onthe removal of gram negative and positive bacteria was higher than Titanium dioxide andcopper oxide nanoparticles. So application of this method after investigating economicbalances and other factors for removing of bacteria from sewage via this method isrecommended.