A novel technique for waste sludge solubilization using a combined magnetic field and CO_2 injection as a pretreatment prior anaerobic digestion

摘要

In this study, the effect of combined magnetic field and CO2 microbubble technology on the solubilization rate and performance of municipal waste activated sludge (WAS) was investigated. Four numerical variables (CO2 injection, initial pH, magnetic field, and retention time) were selected to analyze and optimize the process. The region of exploration for the process was taken as the area enclosed by CO2 flow rate (0-1 L/min), initial pH (3-11), magnetic field (0-40 mT) and retention time (20-180 min) boundaries. In order to analyze the process, three dependent parameters as the process responses were studied. The results showed that the disintegration performance of WAS was effectively improved in the presence of magnetic field and CO2 microbubble. The sCOD, sTKN and PO43- concentrations in sludge supernatant increased to 48%, 40% and 47% respectively, with increasing CO2 flow rate from 0 to 1 L/min and magnetic field from 0 to 40 mT. This study showed that the initial pH was a key factor affecting the process performance, cell lysis and disintegration. The result showed that acid and base range of pH caused an increase in the WAS degradation. It was also observed that the sludge settleability was improved about 43% and oxygen uptake rate decreased by 30%. In conclusion, the combined magnetic field and CO2 microbubble pretreatment is an effective method to disintegrate the waste activated sludge. (C) 2017 Elsevier Ltd. All rights reserved.