High Strength Ammonium Wastewater Treatment With Aerobic Granules By Simultaneous Nitrification Denitrification

Aerobic granular sludge has great applicable values in wastewater treatment due to it advantages, such as excellent settling ability, high biomass retention and shock loading resistence ability. With aerobic granules, nitrogen removal by simultaneous nitrification denitrification (SND) can be achieved, whereas, up to now most research focused on low-concentration ammonium wastewater or artificial domestic wastewater treatment by this process. Therefore, this research attempts to cultivate aerobic granules, which are capable to treat high strength ammonium wastewater and achieve SND. In addition, by using theories of nitrification/denitrification and microbiology, the key factors affecting nitrogen removal with aerobic granules were investigated in order to enhance the treatment efficiency.Sequencing batch reactors (SBRs) were employed to cultivated aerobic granules with ethonal, sodium acetate and glucose as the organic carbon source, respectively. The results indicated that the nitrogen removal rate by aerobic granules was no more than 30% when ethanol was the organic carbon source. When soudium acetate was the carbon source, the pH value of the reactor increased with actate degradation, and the consequencial much free ammonia (FA) produced with 200mg/L of NH4+-N in the solution led to granulation failure. However, with 20mg/L of NH4+-N, aerobic granulation and nitrogen removal by SND realized. When glucose was the organic carbon source, aerobic granules formed much faster and the MLSS reached 8g/L. The removal rate of NH4+-N and TN reached 94.4% and 66.4%, respectively. At the same time, SND was achieved under high DO level.The sludge samples taken at different phases of aerobic granulation were analyzed by Denaturing Gradient Gel Electrophoresis (DGGE). It revealed that the populations in the reactor varied obviously during the whole aerobic granulation. Certain bacteria enriched and others disappeared. Filamentous bacteria were found enriched, which might be a convincing evidence to believe that filaments founctioned as the primary matrix during aerobic granulation. Some bacteria in the reactor were able to synthesize poly-β-hydroxybutyrate...