Swine Wastewater Nitrogen Removal at Deferents C/N Ratios Using The MLE Process

Adelcio Giongo, Marcelo Bortoli, Marina Celant De Prá, Marcos Veruck, Airton Kunz

Resumo


The swine industry has been presented strong growth and thus is producing large volumes of effluents that must be correctly management. Therefore, when land application is not possible, treatment must be applied. Nitrification/denitrification (NDF) process is a frequently applied technology, however when the effluent presents low C/N ratio, such as digestate from anaerobic processes, denitrification efficiency is reduced and the overall nitrogen removal affected. Nitritation/denitritation (NDT) 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 NDF and NDT processes at different C/N ratios 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 mgO2L-1and C/N 1.5; Phase II) DO between 0.6-0.7 mgO2L-1and C/N 1.5; Phase III) DO between 0.6-0.7 mgO2L-1, C / N ratios of1.5, 0.9, 0.75 and 0.6; Phase IV) DO between 2.0-3.0 mgO2L-1, C/N ratios of 1.5, 0.9, 0.75, and 0.6. Under carbon limitation conditions, the best operational condition was at C/N ratio of 0.9, 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.

Palavras-chave


Nitritation/Denitritation; Nitrification/Denitrification; Biological Nitrogen Removal; Total Organic Carbon consumption; animal production wastewater



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