Comparison of Heavy Metal Speciation of Sludge During Mesophilic and Thermophilic Anaerobic Digestion
- 15 Downloads
Mobility of representative heavy metals during the anaerobic digestion of sludge under mesophilic and thermophilic conditions was compared.
The exchangeable, carbonates (F1), Fe and Mn oxides (F2), organic matter, sulfides (F3) and residual (F4) fractions of heavy metals in sludge were fractionated by the modified BCR procedure. Inductively coupled plasma-optical emission spectrometry (ICP-OES) was used to determine the Cu, Ni and Zn concentrations of the different fractions.
The mobile fraction (F1, F2 and F3) of Cu, Ni and Zn increased with the progression of the anaerobic digestion process. The mobile fraction of Cu, Ni and Zn under thermophilic conditions was greater than under mesophilic conditions. The mobile fraction of Cu, Ni and Zn also increased with the increase of the ammonia concentration, especially under mesophilic conditions. The acid-soluble fraction levels of the studied metals were ranked as follows Ni > Zn > Cu.
The mobility of the representative heavy metals (Cu, Ni and Zn) during the anaerobic digested of sludge under thermophilic conditions was greater than under mesophilic conditions. These results show that more attention to the negative impacts of heavy metals present in anaerobically digested sludge under thermophilic conditions before land applying.
KeywordsSludge Anaerobic digestion Cu Ni Zn Speciation
This work was supported by the National Natural Science Foundation of China (51741805, 21767013 and 21567011), State Key Laboratory of Pollution Control and Resource Reuse Foundation (PCRRF16025) and the China Scholarship Council (201708360130).
- 15.Rauret, G., Lopez-Sanchez, J.F., Sahuquillo, A., Barahona, E., Lachica, M., Ure, A.M., Davidson, C.M., Gomez, A., Luck, D., Bacon, J., Yli-Halla, M., Muntau, H., Quevauviller, P.: Application of a modified BCR sequential extraction (three-step) procedure for the determination of extractable trace metal contents in a sewage sludge amended soil reference material (CRM 483), complemented by a three-year stability study of acetic acid and EDTA extractable metal content. J. Environ. Monit. 2, 228–233 (2000)CrossRefGoogle Scholar
- 17.APHA: Standard Methods for the Examination of Water and Wastewater. United Book Press, Baltimore (1998)Google Scholar
- 21.Farno, E., Baudez, J.C., Parthasarathy, R., Eshtiaghi, N.: Impact of temperature and duration of thermal treatment on different concentrations of anaerobic digested sludge: kinetic similarity of organic matter solubilisation and sludge rheology. Chem. Eng. J. 273, 534–542 (2015)CrossRefGoogle Scholar