Correlation between oxidation-reduction potential values and sludge dewaterability during pre-oxidation

Yang Lv, Keke Xiao, Jiakuan Yang*, Yuwei Zhu, Kangyue Pei, Wenbo Yu, Shuangyi Tao, Hui Wang, Sha Liang, Huijie Hou, Bingchuan Liu, Jingping Hu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


Pre-oxidation is effective in enhancing sludge dewaterability. Different types and doses of oxidants are used to improve sludge dewaterability in pre-oxidation. Rapid evaluation of the sludge dewaterability is vital for optimizing the type and dose of oxidants in pre-oxidation. It normally takes more time to evaluate sludge dewaterability by measuring typical indicators such as specific resistance to filtration (SRF), content of bound water, and composition of EPS. This study presented a rapid parameter, oxidation-reduction potential (ORP), to correlate it with the dewaterability of pre-oxidized sludge samples. An index of ΔORP (ΔORP = ORPt=0.5 min–ORPt=0 min) showed positive correlations with SRF (r = 0.89, p < 0.05), content of total organic carbon in soluble and loosely-bound EPS (r = 0.86 and 0.84, p < 0.05), zeta potential (r = 0.86, p < 0.05), and content of Fe(III) in the sludge cake (r = 0.92, p < 0.01). However, the ΔORP index showed negative correlations with tryptophan-like proteins, tyrosine-like proteins, microbial byproduct-like materials in tightly-bound EPS (r = −0.85, −0.90 and −0.90, p < 0.05), and sludge particle sizes (p < 0.01). A multiple linear regression model was developed to further reflect the linear correlation between the ΔORP values and the key factors reflecting sludge dewaterability. An optimal dose of oxone (0.4 mmol/g VS) for sludge pre-oxidation with the ΔORP value of 387 mV combined with Fe(III) coagulation conditioning system were verified by the results of dewatering experiments using a laboratory-scale diaphragm filter press. This study demonstrated the feasibility of using ΔORP as a potential rapid evaluation tool for sludge dewaterability.

Original languageEnglish
Pages (from-to)96-105
Number of pages10
JournalWater Research
StatePublished - 15 May 2019
Externally publishedYes


  • Correlation
  • Oxidation-reduction potential
  • Pre-oxidation
  • Sludge dewaterability
  • Waste activated sludge


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