Effects of salinity on the respirometric activities of mixed culture bacteria from activated sludge process

Abstract

Salinity or saltiness is dissolved in water by the relative proportion of salt in a solution. All organisms have to keep their cells alive a water balance in their bodies. The activated sludge process (ASP) containing aerobic microorganisms located nearby the coastal area may be faced the problems of salinity from sea water. In this research, the effects of salinity on the respirometric activities of mixed culture bacteria from activated sludge process were evaluated at different levels of NaCl concentrations ranging between 0-25 g/L in the OxiTop system at the temperature of 20 °C. The oxygen uptake rate (OUR) was used to reveal the effects of salinity. The experiments results indicated that the OURs decreased as the NaCl concentrations increased, resulting in the failures of bacterial osmotic pressure systems and causing the lysis of bacteria. The COD and nitrification were failed because the nitrogen and COD loadings to the systems were increased by the lysis of bacteria.