Combining submerged membrane technology with anaerobic and ...

(mg·L -1 )Chapter 4and ammonium) need to be considered in irrigation water (Lazarova and Bahri, 2004). Asan example in the case of treated wastewater reuse for cooling systems, the beneficial ofammonia for the control of biological as makeup water with monochloramine has beenrecently reported by Chien et al. (2012). The biocide monochloramine would be formed insitu through the reaction of free chlorine and ammonia in the incoming water to the coolingsystem. Thus, it could be important to avoid nitrification. It should be taken intoconsideration the great amounts of water required in thermoelectric power plants. Forinstance, the freshwater withdrawal for thermoelectric power plant cooling exceedswithdrawals for agricultural irrigation in the United States (Chien et al., 2012).Nitrogen removal was not observed during period IV (figure 4.3), when anoxic cycleswere implemented in order to stimulate denitrification process. Nevertheless, nitrogenremoval feasibility in the system was analyzed in further experiments. The reason of suchbehaviour will be explained there (Chapter 6) and is related with the imput of oxygenassociated with aeration in the aerobic/anoxic biofilm chamber.4540N-NH 4+ and N-NOx35302520151050Period I Period II Period III Period IVFigure 4.3. N-NH4+ concentration in the UASB effluent (•); DTN concentration in thepermeate (•); N-NOx- concentration in the first chamber of the MBR (•) and thepermeate () during periods I, II, III and IV.4.4.2. BiomassThe retention of anaerobic biomass was almost complete during the fourexperimental periods. During periods I, III and IV anaerobic granules washed-out were120