Emission characteristics of nitrogen and sulfur containing pollutants during the pyrolysis of oily sludge with and without catalysis.

The oily sludge is a category of hazardous solid waste generated in petrochemical industries. Pyrolysis is an efficient approach for sustainable treating the oily sludge with limited environmental impacts, but the pollutant emission during the pyrolysis process is still a big challenge. Herein, the emission characteristics of nitrogen (N) and sulfur (S) containing pollutants during the oily sludge pyrolysis with and without catalysis was illuminated via a TG-FTIR-MS system (ThermoGravimetric-Fourier Transform InfaRed-Mass Spectroscopy). The FeMg layer double hydroxide (FeMg LDH) was employed as a catalyst for pyrolysis. The emission characteristics of six inorganic N-/S-containing pollutants, as well as ten organic N- and nine S-containing pollutants were analyzed. The results indicate that the FeMg LDH could efficiently suppress the emission of N-/S-containing pollutants. The amide and heterocyclic-N species were identified as primary resources of N-containing pollutants emission. The aliphatic- and disulfides-S were the main contributions to the S-pollutants emission. Comprehensive analysis of pollutants emission characteristics for oily sludge pyrolysis could provide a better understanding for sustainable managements of the hazardous solid wastes.

[Temporal and spatial variation rule of mercury in sediments in middle and lower reaches of the Second Songhua River].

Temporal variation rule of mercury during 1973, 1976, 1983, 1991 and 2004 in surface sediments from the Second Songhua River was get. Mercury levels increased before 1976 and decreased on a certain extent in 1976-1982; mercury pollution source was halted in 1982, so mercury levels fell greatly; in the following years, mercury levels was in the slow purification time. Sediment samples taken this time were divided into three granularity scales. Based on sediments of 63 microm granularity, the horizontal variation rule was analyzed. Mercury levels reached the maximum at the pollution source site, increased from Shaokou Segment to Chaoyangqiao Segment, and fell largely from Chaoyangqiao Segment to Wujiazhan Segment, where mercury levels attained the minimum. And mercury levels slightly increased from Wujiazhan Segment to Ganshuigang Segment. In addition, the vertical variation rule of mercury levels in sediments of typical segments was shown.