Authors: Ali BERKTAY, Mehmet Emin AYDIN
Abstract: The use of pressure is a relatively new technique in the field of biological wastewater treatment. The main objective of the use of pressure on a biological treatment process is to increase the amount of dissolved oxygen available for biological activity. This is achieved by increasing the rate of oxygen transfer from the gas phase to the liquid phase as a result of increasing the pressure. The aim of the work reported here was to investigate the effects of increasing pressure on the operating of a suitable biological wastewater treatment system in comparison with an equivalent unit held at atmospheric pressure, but otherwise operating under identical conditions. An investigation is reported into the effect of pressures of up to 6 bar on the operation of a laboratory-scale reactor. All results are compared with those of an identical reactor operating at atmospheric pressure. Although improved BOD5 and COD removal, compared to that of the reference unit, was evident as the pressure was increased, the principal benefits of increasing pressure were recorded as being, significantly improved nitrification and a decrease in the sludge yield coefficient. Both these factors improved regularly with increasing pressure.
Keywords: Biological wastewater treatment, BOD5 and COD removal, nitrification, pressure.