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Lignin degradation through a combined process of ionizing irradiation and a biological treatment

Abstract:

In this work, the degradation of lignin was studied through a combined process of ionizing irradiation and a biological treatment. For the irradiation stage, two options were tested at the beginning: a gamma irradiation from a Cobalt source at a dose rate of 0.4 kGy/h and a beta irradiation from a linear electron accelerator at a dose rate of 827 kGy/h, in both cases for a dose of 10 kGy. Through UV-visible spectrophotometric scanning, we found better results for the lignin degradation by the beta irradiation; therefore, five higher doses: 20, 30, 40, 50 and 60 kGy were tested. Spectrophotometry, infrared spectrometry and waste water analysis allowed to determine 60 kGy as the best dose. Finally, an anaerobic biological treatment was used for the subsequent degradation of lignin. It was carried out as a batch process that lasted approximately 11 days. The combined process enhanced the BOD5/COD ratio from 0.26 to 0.51, and reduced TOC by 37% and COD by 45%.