Title：Fermentation Liquor of CaO2 Treated Chemically Enhanced Primary Sedimentation (CEPS) Sludge for Bioplastic Biosynthesis
Journal/Publisher：ELSEVIER
Year：2018
Authors：Juan Xu, Xiuyan Li, Lihong Gan, Xiaoyan Li
Abstract
Chemically enhanced primary sedimentation (CEPS) technology has been widely applied in Hong Kong, exhibiting excellent performance in contaminants removal fromsewage. The generated CEPS sludge contains abundance of organics which could be recovered as volatile fatty acids (VFAs) by fermentation for further utilization. In this work, the effect of calcium peroxide (CaO2) on the fermentation of FeCl3 based CEPS sludgewas investigated. The feasibility of utilizing the fermentation liquor as substrate for polyhydroxyalkanoates (PHAs) biosynthesis was also evaluated. Results demonstrated that CaO2 addition facilitated the disintegration of CEPS sludge and enhanced VFAs production. The maximumVFAs yield of 455.8mg COD/g VSS was obtained with the dosage of 0.1 g CaO2/g SS, improving by 44.7% compared with the control sludge. Acetic and propionic acid were the predominant components of the VFAs. Microbial analysis indicated that CaO2 inducedmicrobial reduction of Fe(III), accelerating the initial disintegration of FeCl3 based CEPS sludge. Microbial communities with hydrolysis and acidogenesis functions were enriched effectively. CaO2 treatment had no significant influence on the release of ammonia nitrogen (NH4 +-N),while reduced the concentration of orthophosphate (PO4 3−-P) and ferrous (Fe2+) in fermentation liquor, thatwas beneficial to the further utilization as substrate for PHAs biosynthesis. The VFA-rich fermentation liquor was proved to be a suitable substrate for PHAs biosynthesis. After cultivation, the PHAs content in activated sludge reached 22.3%,which was comparable to those obtained using waste materials as carbon source. This integrated technology could be a superior alternative of realizing sludge disposal and bioplastic production simultaneously.
Keywords: calcium peroxide (CaO2), chemically enhanced primary sedimentation (CEPS), fermentation, polyhydroxyalkanoates (PHAs), volatile fatty acids (VFAs)
