Relationship between physicochemical properties and dewaterability of hydrothermal sludge derived from different source

Sewage sludge（SS） and deinking sludge（DS） were used to comparatively study the hydrothermal dewatering of sludge with different components. For a better overview, an insight into the relationship between physicochemical properties and dewaterability of hydrothermal sludge was provided. Results found that not all kinds of sludge were suitably conditioned by hydrothermal treatment（HT） in term of the elevation of dewaterability.Higher hydrothermal temperature tended to enhance the dewaterability of SS rather than DS, which was supported by the variation of their physicochemical properties（including water distribution, bonding energy, extracellular polymeric substance（EPS）, particles size,acid functional groups and zeta potential in this study）. In addition, the changes in surface morphology suggested that the reverse effect of HT on sludge dewaterability was mainly due to their dewatering behavior. For SS, the destruction of EPS structure leaded to the release of bound water, thereby strengthening sludge dewatering. Conversely, ＂Bridging effect＂ generated by lignocellulose in DS was beneficial for sludge dewatering; however, the increasing hydrothermal temperature degraded part of lignocellulose and weakened＂bridging effect＂, finally resulting in worse dewaterability of DS.

Diverse molecular compositions of dissolved organic matter derived from different composts using ESI FT-ICR MS

Dissolved organic matter(DOM)derived from various composts can promote significant changes of soil properties.However,little is known about the DOM compositions and their similarities and differences at the molecular level.In this study,the molecular compositions of DOM derived from kitchen waste compost(KWC),green waste compost(GWC),manure waste compost(MWC),and sewage sludge compost(SSC)were characterized by electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry(ESI FT-ICR MS).The molecular formulas were classified into four subcategories:CHO,CHON,CHOS,and CHONS.The KWC,MWC,and SSC DOM represented the highest fraction(35.8%-47.4%)of CHON subcategory,while the GWC DOM represented the highest fraction(68.4%)of CHO subcategory.The GWC DOM was recognized as the nitrogen-and sulfurdeficient compounds that were less saturated,more aromatic,and more oxidized compared with other samples.Further analysis of the oxygen,nitrogen-containing(N-containing),and sulfur-containing(S-containing)functional groups in the four subcategories revealed higher organic molecular complexity.Comparison of the similarities and differences of the four samples revealed 22.8%ubiquitous formulas and 17.4%,11.1%,10.7%,and 6.3%unique formulas of GWC,KWC,SSC,and MWC DOM,respectively,suggesting a large proportion of ubiquitous DOM as well as unique,source-specific molecular signatures.The findings presented herein provide new insight into the molecular characterization of DOM derived from various composts and demonstrated the potential role of these different compounds for agricultural utilization.