SWINE WASTEWATER NITROGEN REMOVAL AT DIFFERENT C/N RATIOS USING THE MODIFIED LUDZACK-ETTINGER PROCESS

摘要

The swine industry has been presented strong growth and thus is producing large volumes of effluents that must be correctly management. Nitritation/denitritation process can be used to improve system performance, saving the energy cost with aeration and with the external source of carbon due to the lower C/N requirement. The aim of this study was to evaluate swine wastewater Nitrification/Denitrification (NDF) and Nitritation/denitritation (NDT) processes at different C/N ratios, using the Modified Ludzack-Ettinger (MLE) process, in order to obtain a system with efficient nitrogen removal and low oxygen and carbon consumption. Four phases were conducted during the experiment: Phase I) DO between 2.0-3.0 mg L-1 of O-2 and C/N 1.5 (NDF); Phase II) DO between 0.6-0.7 mg L-1 of O-2 and C/N 1.5 (NDT); Phase III) DO between 0.6-0.7 mg L-1 of O-2, C / N ratios of1.5, 0.9, 0.75 and 0.6 (NDT); Phase IV) DO between 2.0-3.0 mg L-1 of O-2, C / N ratios of 1.5, 0.9, 0.75, and 0.6 (NDF). The best operational condition was found in the C / N ratio of 0.9 (Phase III) obtaining an optimum N removal of 86.3. In this condition, the system saved around 26.8 in total organic carbon consumption and operated at conditions of 74 lower dissolved oxygen when compared to conventional process for N-removal. This strategy can be very useful for nitrogen removal for low carbon swine wastewater as digestate from anaerobic processes.