4. Conclusions
The Fenton-like sludge dewatering process is proven to be
effective for the release of water in sludge. The moisture content
of dewatered sludge cake could decrease from 80% to 66.1% by
simultaneously reducing the dry solid. The optimal conditions
obtained from the response of moisture content are as follows:
H2O2 of 373 mg/g DS, Fe3+ of 288 mg/g DS and pH 2.0–2.5. The
Fenton-like peroxidation leads to the dissolution of plentiful EPS
and lysis of sludge cells, and the transformation of more bound
water into free water. Moreover, the degradation of plentiful EPS
led to an increase in the hydrophobicity and a decrease in the
energy barrier to reflocculation. All of these results are responsible
for the lowest moisture content in the sludge conditioned by the
Fenton-like reaction. Besides, the Fenton-like sludge dewatering
process could promote the release of metals from sludge, especially
Zn, Cu, Cd and Ni. The release of both water and toxic metals is
beneficial to the further agricultural application of sludge. In addition,
Fenton-like treatment introduces plentiful Fe3+ ion to sludge
and the Fe-loading sludge could be used as iron fertilizer to accelerate
the growth of plants. Therefore, the Fenton-like peroxidation
has a potential to be a pretreatment in sludge disposal.
Acknowledgements
The authors wish to thank the Key Special Program on the S&T
for the Pollution Control (2012ZX07103-001 and 2011ZX07303-
002-04), the National 863 Program (2012AA063608-01), and the
Program for Changjiang Scholars and Innovative Research Team
in University and the Collaborative Innovation Center of Suzhou
Nano Science and Technology of the Ministry of Education of
China for the partial support of this study.