Study On N-removal Of Livestock Wastewater Treatment In Sequencing Batch Biofilm Reactor

Large-scale livestock and poultry breeding has met social needs and accelerated economic development, however, it has also caused increasing environmental pollution. It is an urgent need to treat the livestock wastewater pollution. Sequencing batch biofilm reactor (SBBR) has a prominent effect on nitrogen-removal in all kinds of wastewater treatment technologies. It is necessary to examine the mechanism of nitrogen-removal (N-removal) under SBBR treatment, which is of great significance in practice.In this study, a new-style SBBR was started up with artificial wastewater, and processed with the actual livestock wastewater as test wastewater. The new-style SBBR reactor was operated alternately under aerobic and anaerobic modes, in fluent and smooth water currents. By adjusting the pH and CODcr/TN values of influent, the nitrogen-removals in SBBR reactor under different flow conditions were investigated. The optimal treatment condition and the nitrogen removal mechanism under different conditions were also discussed. The results showed that:(1) It's feasible to start-up the new-style SBBR with sequential influent/effluent water and sequential aeration, in this way, active biomembrane and luxuriant microbe can be achieved, the N-removal processes involve simultaneous nitrification- denitrification and shortcut nitrification-denitrification in the new-style SBBR reactor.(2) The pH value has an impact on N-removal. N-removals under pH= 7 and pH= 8 were found to be better than those under pH= 6 and pH= 9. When the pH value of wastewater in SBBR reactor was more acidic and alkaline, the system has an ability to regulate pH value to a more neutral value. Suitable CODcr/TN are benefit to N-removal, when the TN kept about 140mg/L, The mode was 2.5 hours aeration+1.5 hours anaerobic +2.5 hours aeration+1.5 hour anaerobic, if the CODcr/TN is lower than 7, it will suppress the denitrification; if the CODcr/TN is too high, it will suppress the nitrification.(3) At room temperature when the CODcr, the TN and the dissolved oxygen concentrations of the influent were kept about 2000mg/L,140mg/L and 2.0-2.5mg/L, respectively, the treatment effect under an alternative aerobic and anaerobic mode was superior to those under aerobic or anaerobic mode with one sole. The mode of 3.0 hours aeration+1.5 hours anaerobic+1.5 hours aeration+1.0 hour anaerobic has the highest removal rate of TN (about 90%) among the all investigated SBBR runs. It was explained that the alternative aerobic and anaerobic mode was more suitable to TN and NH3-N removing in the new-style SBBR.