Improving the Microorganism Function at Different Concentrations of Folic Acid, Nitrogen and Phosphor in Biological Wastewater Treatment of Tabriz Petrochemical

Biological treatment of wastewater depends on different factors including the nutrient and vitamin contents. In this study, the effects of different concentrations of folic acid (0.1 ppm, 0.2 ppm, and 0.4 ppm) together with different amounts of nitrogen (20 ppm, 30 ppm, and 40 ppm) and phosphorus (4 ppm, 6 ppm, and 10 ppm) were studied on the biological treatment of the industrial effluent from Tabriz Petrochemical Plant. The Taguchi method with an L9 orthogonal array was used to determine the optimum conditions for the growth of microorganisms. Turbidity, BOD5, TSS, and MLSS were measured as the main parameters of the treated effluent. The results showed that only N has a significant effect (78.4%) on BOD5 removal. Folic acid had the greatest effect (42.7%) on TSS reduction. This is while folic acid had a significant effect (90.1%) only on increasing MLSS. The optimum conditions for microorganism activity consisted of a folic acid concentration of 0.2 ppm, an N concentration of 30 ppm, and a P concentration of 4 ppm. Interactions between first level of folic acid×second level of P on turbidity reduction, second level of folic acid×second level of P on BOD5 reduction, second level of N×second level of P on TSS reduction, and first level of N×first level of P on increasing MLSS were highly significant. These results show that adding folic acid, N, and P to the effluent from Tabriz Petrochemical Plant not only enhances the growth of microorganisms but also leads to the improvement of the treated effluent for discharge into the environment.