The characteristics of stepwise ultrasonic hydrolysates of sludge for enhancing denitrification

Bo Cheng You, Cheng Chung Huang, Shun Hsing Chuang

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The disposal of waste activated sludge (WAS) accounts for approximately 60 % of wastewater treatment plant operating costs. In this study, according to the reaction time and water quality parameters, ultrasonic hydrolysis of WAS is divided into three stages, including floc-disintegration (0–25.2 kJ/g TS), cell-disruption (25.2–36 kJ/g TS), and cell-degradation (over 36 kJ/g TS). The results show that more than 70 % carbon distributes inside the cell, which also contains 63.8 % protein enhancing denitrification capacity. Moreover, cell-degradation hydrolysate has a higher proportion of readily biodegradable COD, indicating that intracellular organic matter is more capable of denitrification than extracellular. Therefore, the optimal ultrasonic operating range is Es = 36–72 kJ/g TS as carbon source, and obtain the hydrolysate with high ratio of soluble chemical oxygen demand to total nitrogen for denitrification. Furthermore, this study supports the comprehensive interpretation of ultrasonic hydrolyzed WAS and the characteristics of hydrolysate as carbon source for enhancing denitrification.

Original languageEnglish
Article number128566
JournalBioresource Technology
StatePublished - Feb 2023


  • Carbon source
  • Circular economy
  • Denitrification
  • Hydrolysis stage
  • Waste activated sludge


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