Acetate utilization by sulfate reducing bacteria in an uaff reactor

ABSTRACT

Industrial development in Egypt, like in many other developing countries in the world, is causing serious environmental problems due to the increasing influence of the disposal of heavy metals and organic wastes in the natural water bodies and on the land. Such pollutants in water, soil and air environments are causing damaging impact on the health of all the living beings. This study was carried out to develop new processes for the treatment of heavy metals and organic wastes, which can be considered as environment friendly, and will cause minimum damage to the environment and human health. The proposed method for the removal of heavy metals and organic matter from the waste stream is based on the use of sulfate reducing bacteria which convert sulfate to sulfide which in turn remove metals as metal sulfide. The sulfate reducing bacteria, SRB, have been used widely for the removal of heavy metals from industrial wastewaters. In this research, it was decided to determine the optimum controlling factors affecting the growth of the SRB utilizing acetate as an organic carbon source in an up flow anaerobic fixed film reactor, UAFFR. A series of continuous flow experiments were carried out to measure the optimum values for these parameters. Substrate, containing acetate as the organic carbon source along with other nutrients such as sulfate, ammonia and phosphates was fed to the experimental units. It was found experimentally that the optimum SRB growth activity occurred with an organic loading rate, OLR, of 6 kg/d/m[3], and the theoretical oxygen demand to sulfate ratio, Th.O.D./SO[4], ranged from 1.5 to 2.0. The optimum hydraulic retention time HRT was found to be equal to or higher than 11 hours. The effect of the reactor's packing material on SRB growth was also studied. Different packing materials with different surface areas were used. It was shown that the SRB growth does not depend on the nature of the packing material of the reactor