posted on 2024-01-26, 17:04authored byYu Wang, Shengyu Xie, Chunxing Li
Hydrothermal combined pyrolytic treatment is a promising
technology
for improving the dewaterability of sewage sludge (SS) and food waste
digestate (FD) with additional heavy metal (HM) risk reduction. The
effect of cohydrothermal coupled pyrolysis with different temperatures
(300, 500, and 700 °C) at different mixture proportions (1:0,
3:1, 1:1, 1:3, and 0:1) on the migration and transformation of HMs
was investigated. In addition, the effects on the properties of biochar
and the assessment of the risk of HMs in biochar were studied. The
results showed that the addition of FD increased the residual fractions
of Cr, Zn, and Cd during the hydrothermal process of SS. Followingly,
Cu and As were better immobilized in biochar from cohydrothermal combined
pyrolytic treatment than SS treatment alone, with the low potential
ecological risk (indices: 9.13–11.62) of biochar at 700 °C.
In addition, cohydrothermal combined pyrolytic treatment (1:1, w/w)
at 700 °C can significantly improve the aromaticity and specific
surface area of SS biochar. This work reveals that the codisposal
of SS and FD has superior application potential in HM immobilization
and biochar property improvement.