Energy and phosphorous recovery through hydrothermal carbonization of digested sewage sludge.
Waste Manag
; 105: 566-574, 2020 Mar 15.
Article
in En
| MEDLINE
| ID: mdl-32169812
ABSTRACT
This work evaluates the potential of hydrothermal carbonization (HTC) to valorize the digestate derived from the anaerobic digestion of sewage sludge into useful materials for P and energy recovery. The hydrothermal treatment of digestate at 180-240 °C did not lead to high-rank hydrochars. On the other hand, inorganic P concentration did not change with the temperature, while as the carbonization temperature increased, the organic P retention yield in hydrochar became lower, increasing the total P in the process water obtained at the highest temperature, up to 25.3%. P recovery from acid leaching of the hydrochar obtained at 180 °C, via precipitation with CaO at pH up to 9, led to a brown solid precipitate with total P content close to 42 mg g-1, in the range of low grade phosphorus ores. Moreover, acid leaching reduced by 50% the ash content, yielding lignite-like upgraded hydrochars with higher heating values in the range of 20.5-23.1 MJ kg-1, fairly interesting as solid fuels. Anaerobic digestion of the process water enabled additional energy recovery in form of biogas (325 and 279 mL CH4 g-1 VS -at standard temperature and pressure; STP- from the process water resulting at 180 and 210 °C, respectively).
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Sewage
/
Carbon
Language:
En
Journal:
Waste Manag
Journal subject:
SAUDE AMBIENTAL
/
TOXICOLOGIA
Year:
2020
Type:
Article
Affiliation country:
Spain