Search

Regional PM

Vertical profiles of PM

The settleability performance of activated sludge (AS) is a very important indicator in the biological treatment of wastewater. In this paper, we investigated the influence of hydrocyclone treatment on sludge settleability and explored the influence mechanism by sorting the excess sludge (ES) with a hydrocyclone. A lateral-line test of the treatment process of the campus wastewater treatment plant (WWTP) at East China University of Science and Technology (ECUST) was carried out by using a sequencing batch reactor (SBR) AS process equipped with a hydrocyclone. The results showed that the sludge flocs rotate and revolve in the hydrocyclone; the resulting shear and centrifugal stress cause the flocs to crack into smaller pieces and can break the extracellular polymeric substances (EPS) on the floc surface, thus changing the floc structure and density. After density sorting by the hydrocyclone, the particle size of the sludge floc returned to the bioreactor decreased, the compactness increased, the settleability performance improved, the sludge volume index (SVI) decreased by 6.1%, and the effluent suspended solid (SS) concentration decreased by 6.1%. Meanwhile, the broken EPS caused organic carbon sources, such as polysaccharides and proteins, in the floc channels to be released into the water phase, supplementing the carbon source for denitrification and improving the effluent water quality: the removal rates of soluble chemical oxygen demand (SCOD), total nitrogen (TN), and NH4-N increased by 6.9%, 8.9%, and 8.4%, respectively.

A dense radiation fog event occurred at the Shouxian site, Anhui Province, China, from the evening of January 2 to noon on January 3, 2017. During this event, vertical profiles of particulate matter (PM) and meteorological parameters within the lower troposphere (0-1000 m) were collected using a tethered balloon. This study assessed the evolution of the PM

Electrically generated negative air ions (ENIs) have been widely used to improve indoor air quality. However, the effects of ENIs reported so far were inconsistent due to the variance in test systems, end points detected and the exposure methods. In this study, a simple model organism, the nematode Caenorhabditis elegans, was used as an in vivo system to assess the biological effects of continuous ENIs exposure. The worms were exposed to ENIs in a 10(5) 10(5) ions/cm(3) chamber and their development period, lifespan, brood size and germline cell apoptotisis were examined. The results showed that ENIs decreased the development period, shortened the lifespan, increased the germline cell apoptosis and reduced the brood size, suggesting that persistent ENIs exposure might induce damage in C. elegans. To further scrutinize the mechanisms underlying these damage effects, a reactive oxygen species (ROS) sensitive C. elegans, mev-1(kn1) mutant, and sod-3::gfp transgenic strains were used. The results showed that the persistent ENIs exposure significantly shortened the lifespan of mev-1(kn1) mutant compared to the wild type. Moreover, levels of SOD-3 were increased in an exposure time-dependent manner. Treatment with either DMSO or l-ascorbic acid, effective ROS scavengers, could rescue the upregulation of germline cell apoptosis and SOD-3 level induced by ENIs exposure, indicating that ROS may be involved in ENIs exposure-induced damaging effects.