Insight into the improvement of dewatering performance of waste activated sludge and the corresponding mechanism by biochar-activated persulfate oxidation
SCIENCE OF THE TOTAL ENVIRONMENT
Authors: Guo, Junyuan; Jia, Xiaojuan; Gao, Qifan
Abstract
A novel activator, corn biochar, was produced to activate persulfate to dewater waste activated sludge (WAS). Results demonstrated that the biochar-activated persulfate oxidation can effectively improve the dewatering performance of WAS. After treating WAS by biochar-activated persulfate oxidation (biochar dosage: 2.1 g/L, persulfate concentration: 7.5 mM) at the original WAS pH, standardized-capillary suction time (SCST) increased to 4.21 times and moisture content (MC) decreased to 43.4%, indicating an excellent performance of WAS dewatering. The decrease of residual persulfate with the increasing biochar dosage during WAS dewatering process illustrated that the role of persulfate in improving WAS dewatering was because of the biochar activation. The behaviors of extracellular polymers (EPS) proved that the protein in tightly bound EPS (TB-EPS) linked to WAS dewatering, and its content significantly reduced to 10.5 mg/g-volatile solids (VS) after WAS treatment. Three-dimensional fluorescence spectroscopy for EPS once again proved that the disintegration of tryptophan protein and humic acid (hydrophobic organic substances in EPS) was responsible for the improvement of WAS dewatering. To sum up, the biochar-activated persulfate oxidation was a feasible application in improving WAS dewatering. (C) 2020 Elsevier B.V. All rights reserved.
Trehalose against UVB-induced skin photoaging by suppressing MMP expression and enhancing procollagen I synthesis in HaCaT cells
JOURNAL OF FUNCTIONAL FOODS
Authors: Xiao, Zhenbang; Yang, Shengtao; Chen, Jiali; Li, Chengyong; Zhou, Chunxia; Hong, Pengzhi; Sun, Shengli; Qian, Zhong-Ji
Abstract
Ultraviolet radiation B cause photoaging of the skin by enhancing the high expression of matrix metalloproteinases (MMPs) to degrade collagen and inhibit the synthesis of procollagen. Trehalose (TRE), a widely occurring natural disaccharide, has been shown to play a cytoprotective role in many pathological processes. However, few studies have evaluated whether it has anti-photoaging potential. In this study, we investigated the anti-photoaging and mechanism of action of TRE using Human immortalized keratinocytes (HaCaT) cells. The results indicated that TRE pretreatment effectively scavenges reactive oxygen species (ROS) accumulation induced by UVB and increases the content of certain endogenous antioxidant factors in HaCaT cells. TRE suppressed UVB-induced MMP expression by blocking mitogen-activated protein kinases (MAPKs), activator protein 1 (AP-1) and NF-kappa B signaling. TRE treatment increased procollagen I synthesis via activating transforming growth factor-beta (TGF-beta)/Smad pathway and demonstrated that TRE may be a potential natural disaccharide for photoaging therapy in the future.