Temperature effect of 2450MHz electromagnetic wave during sludge dewatering
LI Dan-yi1, SANG Wen-jiao1, ZHANG Qian1, ZHANG Wan-jun2, FENG Yang-yang3, LI Zhi-xuan1
1. School of Civil Engineering & Architecture, Wuhan University of Technology, Wuhan 430070, China;
2. Central and Southern China Municipal Engineering Design & Research Institute Co. Ltd., Wuhan 430010, China;
3. Anhui Urban Construction Design Institute Co. Ltd., Hefei 230051, China
In this paper, the influence of temperature on residual sludge properties and solubility was studied during the process of sludge dewatering with 2450MHz electromagnetic wave. Results showed that sludge volume index (SVI) decreased from 130.73mL/g to 95.25mL/g at 80℃, which improved the sludge settlement performance. At the same time, the centrifugal water content of the sludge achieved the lowest of 93.52% at 80℃ and the capillary suction time (CST) of the sludge decreased to 23.2s at 60℃. The value of the specific resistance to filtration (SRF), however, was always higher than the initial value of the raw sludge. Therefore, electromagnetic wave treatment of sludge could improve the dewaterability of centrifugal and plate frame filter press of residual sludge, while deteriorated the dewaterability of vacuum filtration. According to the analysis of the extracellular polymeric substances (EPS) and the soluble chemical oxygen demand (SCOD) in the supernatant, higher temperature was beneficial for the solubilization of sludge. The SCOD raised from the initial value of 124.1mg/L to 883.4mg/L at 80℃. The disruption of microbial cell in sludge was more obvious, when the sludge temperature was higher than 60℃. The EPS in the sludge was closely related to the change of dewaterability of the sludge.
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