Two-stage anaerobic digestion enables heavy metal removal.
Author
Summary, in English
To fully exploit the environmental benefits of the biogas process, the digestate should be recycled as biofertiliser to agriculture. This practice can however be jeopardized by the presence of unwanted compounds such as heavy metals in the digestate. By using two-stage digestion, where the first stage includes hydrolysis/acidification and liquefaction of the substrate, heavy metals can be transferred to the leachate. From the leachate, metals can then be removed by adsorption. In this study, up to 70% of the Ni, 40% of the Zn and 25% of the Cd present in maize was removed when the leachate from hydrolysis was circulated over a macroporous polyacrylamide column for 6 days. For Cu and Pb, the mobilization in the hydrolytic stage was lower which resulted in a low removal. A more efficient two-stage process with improved substrate hydrolysis would give lower pH and/or longer periods with low pH in the hydrolytic stage. This is likely to increase metal mobilisation, and would open up for an excellent opportunity of heavy metal removal.
Publishing year
2008
Language
English
Pages
553-558
Publication/Series
Water Science and Technology
Volume
57
Issue
4
Document type
Journal article
Publisher
IWA Publishing
Topic
- Industrial Biotechnology
Keywords
- iminodiacetate
- cryogel
- anaerobic digestion
- metal chelate
Status
Published
ISBN/ISSN/Other
- ISSN: 0273-1223