Removal of methyl tertiary butyl ether from wastewaters using photolytic, photocatalytic and microbiological degradation processes

Contamination of groundwater by methyl tertiary butyl ether (MTBE), that is detected in wastewater of petrochemical industry, is an increasing problem to water supply companies. The subjects of this research were the methods of photolytic, photocatalytic and microbiological degradation of methyl tertiary butyl ether (MTBE) dissolved in wastewaters. The effects of concentrated solar radiation simulated with sodium lamp (SONT UV 400) have been investigated in laboratory experiments. Our result indicated that bacteria Pseudomonas strain CY, isolated from the kerosene, and added alone, was able to gradually degrade MTBE and to decrease its concentration for 93.6% in 12 h. However, the percentage of photolytic degradation decrease in only 4 h was 99.2%. By adding Pseudomonas strain CY after 4 h of light treatment, the degradation was enhanced to 99.55% in additional 5 h. The photocatalytic process was performed in slurry-catalyst reactor with different concentrations

Our result showed that bacteria Pseudomonas strain CY, isolated from the kerosene, and added alone, was able to degrade 93.6% of MTBE in water solution during 12 h. The growth rate of microorganisms was found to be dependent on the MTBE concentration in water solution. Photolytic degradation proceeded at much higher rate than the microbiological one, and 99.2% of MTBE present in water solution was removed during 4 h. The comparison of MTBE degradation rates for photolytic and photocatalytic process indicated higher rates of degradation when TiO2 catalyst was applied. Photocatalytic experiments were conducted in the slurry-catalyst batch photoreactor and the application of 5 g/L TiO2 resulted in MTBE conversion of 91.14% in 150 min. The effect of catalyst efficiency decrease at higher catalyst loadings was observed during experiments and determined values of the pseudo-first order kinetic constant were in good agreement with previously published data. On the basis of these results, it was concluded that photolytic and photocatalytic degradation of MTBE should be applied to decrease MTBE concentration in water to relatively low values below 100 ppm, after which, the microbiological process could be applied.