TY - JOUR
T1 - Carbon dioxide as a carrier gas and mixed feedstock pyrolysis decreased toxicity of sewage sludge biochar
AU - Kończak, Magdalena
AU - Pan, Bo
AU - Ok, Yong Sik
AU - Oleszczuk, Patryk
N1 - Funding Information:
The project was funded by the National Science Centre granted on the basis of the decision number DEC-2012/07/E/ST10/00572 . M. Kończak is financially supported by the Foundation for Polish Science (FNP).
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/6/25
Y1 - 2020/6/25
N2 - The common use of sewage sludge (SSL)-derived biochar can be limited due to contaminants present in SSL, which may affect SSL-derived biochar toxicity. We propose the reduction of SSL-derived biochar toxicity by it co-pyrolysis with biomass and in CO2 atmosphere. Ecotoxicity of biochars produced at 500, 600, and 700 °C from SSL and SSL with the addition of willow (at a ratio of SSL:willow - 8:2 and 6:4, w/w) in an atmosphere of N2 or CO2 were investigated. The toxicity of aqueous extracts derived from the biochars (Lepidium sativum - Elongation test, Vibrio fischeri - Microtox) or solid-phase toxicity (Lepidium sativum - Phytotoxkit F, Folsomia candida - Collembolan test) was also studied. SSL-derived biochar produced at N2 atmosphere usually was toxic for all tested organisms. Co-pyrolysis of mixed feedstock reduced the toxicity of the produced biochar. In the case of biochars produced from SSL and willow under N2 atmosphere decrease in inhibition of F. candida reproduction (from 27 to 58%) or its stimulation (from 7 to 30%) in comparison to SSL alone derived biochar, was observed. Co-pyrolysis of SSL with willow significantly reduced the toxicity of extracts the SSL-derived biochar towards L. sativum. The aqueous extracts obtained from the biochars produced at temperatures of 500 and 600 °C with willow addition were also less toxic to V. fischeri than the biochars produced from SSL alone. The change of carrier gas from N2 to CO2, regardless of the feedstock used, in most cases reduced toxicity or positively affected the test organisms. This was probably caused by changes in the physicochemical properties and content of contaminants in the biochars produced in an atmosphere of CO2, compared to N2. An exception was root growth inhibition in the solid phase tests where no significant differences were found between biochars produced in N2 and CO2.
AB - The common use of sewage sludge (SSL)-derived biochar can be limited due to contaminants present in SSL, which may affect SSL-derived biochar toxicity. We propose the reduction of SSL-derived biochar toxicity by it co-pyrolysis with biomass and in CO2 atmosphere. Ecotoxicity of biochars produced at 500, 600, and 700 °C from SSL and SSL with the addition of willow (at a ratio of SSL:willow - 8:2 and 6:4, w/w) in an atmosphere of N2 or CO2 were investigated. The toxicity of aqueous extracts derived from the biochars (Lepidium sativum - Elongation test, Vibrio fischeri - Microtox) or solid-phase toxicity (Lepidium sativum - Phytotoxkit F, Folsomia candida - Collembolan test) was also studied. SSL-derived biochar produced at N2 atmosphere usually was toxic for all tested organisms. Co-pyrolysis of mixed feedstock reduced the toxicity of the produced biochar. In the case of biochars produced from SSL and willow under N2 atmosphere decrease in inhibition of F. candida reproduction (from 27 to 58%) or its stimulation (from 7 to 30%) in comparison to SSL alone derived biochar, was observed. Co-pyrolysis of SSL with willow significantly reduced the toxicity of extracts the SSL-derived biochar towards L. sativum. The aqueous extracts obtained from the biochars produced at temperatures of 500 and 600 °C with willow addition were also less toxic to V. fischeri than the biochars produced from SSL alone. The change of carrier gas from N2 to CO2, regardless of the feedstock used, in most cases reduced toxicity or positively affected the test organisms. This was probably caused by changes in the physicochemical properties and content of contaminants in the biochars produced in an atmosphere of CO2, compared to N2. An exception was root growth inhibition in the solid phase tests where no significant differences were found between biochars produced in N2 and CO2.
KW - Biochar
KW - Biomass
KW - Carrier gas
KW - Sewage sludge
KW - Toxicity
UR - http://www.scopus.com/inward/record.url?scp=85082170345&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2020.137796
DO - 10.1016/j.scitotenv.2020.137796
M3 - Article
C2 - 32222497
AN - SCOPUS:85082170345
VL - 723
JO - Science of the Total Environment
JF - Science of the Total Environment
SN - 0048-9697
M1 - 137796
ER -