Role of extracellular polymeric substances in sludge dewatering under modified corn-core powder and sludge-based biochar pretreatments.

Extracellular polymeric substances (EPS) which wrapped on sludge particles were deemed to hinder the outflowing of combined water in sludge system. The complex composition of EPS was the bottleneck for revealing its relationship with sludge dewaterability. In this study, a combined modified corn-core powder (MCCP) and sludge-based biochar (SBB) condition was executed to treat sludge for enhancing dehydration performance, and the concentration and the form distribution of organics in EPS, the variances of protein secondary structures were investigated. Correlation between the sludge dewaterability and EPS components were performed, found strong correlations among the net sludge solids yield (YN) and the specific resistance of filtration (SRF) (R = -0.923), Zeta potential (R = -0.971). Furthermore, the relationship between the secondary structures of protein and dehydration performance were strong related. With the optimal dosage of SBB and MCCP, aggregated strands and α -helix were released, indicated that the unfolding and despiralization in soluble EPS (S-EPS) were improved, disordered the sludge network, reduced the flowing resistance of bound water, finally enhancing sludge dewaterability.

NO oxidation performance and kinetics analysis of BaMO3 (M=Mn, Co) perovskite catalysts.

Perovskite is an efficient and emerging catalyst for NO oxidation. In this study, BaMnO3 and BaCoO3 perovskite catalysts were synthesized by the sol-gel method, and their catalytic oxidation performances of NO were studied. The catalytic performances indicated that BaMnO3 and BaCoO3 perovskites had the highest NO oxidation activities with the NO conversions of 78.2% at 350 °C and 84.3% at 310 °C, respectively. The high activities of BaMnO3 and BaCoO3 perovskite catalysts were related to the abundant surface adsorption oxygen (OA = 76.21% and 78.57%, respectively) and the high concentration of Mn4+ (Mn4+/Mn = 66.95%) and Co3+ (Co3+/Co = 63.8%). Moreover, the results of FT-IR and kinetics revealed that NO and O2 adsorbed on the surface of samples and combined with the B-O band to form bidentate nitrate and bridging nitrate, which eventually was converted into NO2. The kinetics analysis revealed that the NO oxidation reaction followed the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms. In addition, the activation energies were 36.453 kJ/mol for BaMnO3 and 30.081 kJ/mol for BaCoO3, implying that BaMnO3 and BaCoO3 provide low-cost and efficient catalysts, which can be comparable to Pt noble metal catalysts.