Enhanced biodegradation of organic nitrogenous compounds in resin manufacturing wastewater by anoxic denitrification and oxic nitrification process

In this study, a stream of resin manufacturing wastewater with high contents of organic nitrogenous compounds was treated by a conventional activated sludge process with extended aeration and a modified anoxic denitrification unit followed with two oxic activated sludge units respectively. Performance comparison of these two processes showed that the enhanced biodegradation of organic nitrogen in the modified process was attained with 69.0% of organic nitrogen removal that related to 39.0% removal in the conventional process. The anoxic/oxic process also promoted the removal efficiencies of COD, TKN and TN (total nitrogen) from 91%, 49.6% and 7.4% to 95.3%, 83.8% and 74.4% respectively, in comparison with the conventional extended activated sludge process. These cheerful results also corresponded to the acceptable averaged effluent quality: 82 mg/l of CODs, 48 mg/l of Org.-N, 11 mg/l of NH4+-N, and 42 mg N/l of NO3−-N, that could meet the national effluent standard of ROC-EPA in 1998. The successful investigation also demonstrated that about 50% of the total organic nitrogen removal was achieved in the anoxic unit associated with denitrification, while the residual organic nitrogen was removed in the oxic unit. The pilot-study results suggested that the resin manufacturing wastewater containing high concentration of organic nitrogen should be treated by the anoxic denitrification and oxic nitrification process instead of the conventional activated sludge process with extended aeration.