TY - JOUR
T1 - Assessing the potential of waste activated sludge and food waste co-fermentation for carboxylic acids production
AU - Vidal-Antich, C.
AU - Perez-Esteban, N.
AU - Astals, S.
AU - Peces, M.
AU - Mata-Alvarez, J.
AU - Dosta, J.
N1 - Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2021/2/25
Y1 - 2021/2/25
N2 - This study investigated waste activated sludge (WAS) and food waste (FW) co-fermentation in batch assays to produce carboxylic acids. Three mixtures (50%, 70% and 90% WAS in VS basis) were studied under different conditions: with and without extra alkalinity, and with and without WAS auto-hydrolysis pre-treatment. All tests were carried out at 35 °C, without pH adjustment and without external inoculum. Experimental results showed that co-fermentation yields, including volatile fatty acids and lactic acid, were always higher than WAS and FW mono-fermentation yields (ca. 100 and 80 mgCOD/gVS, respectively). Co-fermentation yields increased as the proportion of FW in the mixture increased, indicating that the improvement was primarily due to a higher FW degradation under co-fermentation conditions. The maximum co-fermentation yield was on average 480 mgCOD/gVS for the WAS/FW_50/50 mixture. The importance of pH on co-fermentation performance was evident in the experiments carried out with extra alkalinity, which showed that the proportion of WAS in the mixture should be high enough to keep the pH above 5.0. However, fermenters operational conditions should also prevent the enrichment of acetic acid consuming microorganisms. WAS auto-hydrolysis pre-treatment did not enhance co-fermentation yields but showed minor kinetic improvements. Regarding the product profile, butyric acid was enriched as the proportion of FW in the mixture increased and the concomitant pH decreased to the detriment of propionic acid. Propionic acid prevailed under neutral pH in the WAS mono-fermentation and the WAS/FW_90/10 mixture.
AB - This study investigated waste activated sludge (WAS) and food waste (FW) co-fermentation in batch assays to produce carboxylic acids. Three mixtures (50%, 70% and 90% WAS in VS basis) were studied under different conditions: with and without extra alkalinity, and with and without WAS auto-hydrolysis pre-treatment. All tests were carried out at 35 °C, without pH adjustment and without external inoculum. Experimental results showed that co-fermentation yields, including volatile fatty acids and lactic acid, were always higher than WAS and FW mono-fermentation yields (ca. 100 and 80 mgCOD/gVS, respectively). Co-fermentation yields increased as the proportion of FW in the mixture increased, indicating that the improvement was primarily due to a higher FW degradation under co-fermentation conditions. The maximum co-fermentation yield was on average 480 mgCOD/gVS for the WAS/FW_50/50 mixture. The importance of pH on co-fermentation performance was evident in the experiments carried out with extra alkalinity, which showed that the proportion of WAS in the mixture should be high enough to keep the pH above 5.0. However, fermenters operational conditions should also prevent the enrichment of acetic acid consuming microorganisms. WAS auto-hydrolysis pre-treatment did not enhance co-fermentation yields but showed minor kinetic improvements. Regarding the product profile, butyric acid was enriched as the proportion of FW in the mixture increased and the concomitant pH decreased to the detriment of propionic acid. Propionic acid prevailed under neutral pH in the WAS mono-fermentation and the WAS/FW_90/10 mixture.
KW - Acidogenic fermentation
KW - Biowaste
KW - Co-fermentation
KW - Sewage sludge
KW - Short-chain fatty acids (SCFA)
KW - Volatile fatty acids (VFA)
UR - http://www.scopus.com/inward/record.url?scp=85097468081&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2020.143763
DO - 10.1016/j.scitotenv.2020.143763
M3 - Journal article
C2 - 33288258
AN - SCOPUS:85097468081
SN - 0048-9697
VL - 757
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 143763
ER -