Triclosan is an antimicrobial agent which is widely used in many personal care products. This toxic chemical is frequently found in the aquatic environment. The municipal wastewater treatment plant (WWTP) effluent has been reported to be one of the major sources for triclosan in the aquatic system. The aim of the present study was to investigate the accumulation of triclosan in the surface sediments near the outfalls of the five major municipal WWTPs of Nanjing, China, as well as to evaluate its potential ecological risk. The concentration of triclosan in the sediment samples ranged from 48.3 to 226 ng/g dry weight, which was well correlated with the acute and genetic toxicity by bioassay. The results suggested that triclosan released from municipal WWTPs could accumulate in the surface sediments nearby and may pose undetermined risk to aquatic organisms.

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To develop a method of recycling solid wastes, blast furnace slag (BFS) and sewage sludge (SS) were added as components for making ceramsite. This study examined the sintering characteristics of ceramsite at different sintering temperatures and duration and different mass ratios of materials (BFS:SS:clay). The results show that as the sintering temperature and duration increased, the pore-size diameter gradually increased, reaching a maximum of 120 nm at 1100°C for 20 min. The turning point for the pore-size diameter was at 1050°C for 20 min. In keeping with the variation in pore-size diameter, the highest and lowest porosity of the ceramsite reached 88 and 62%, respectively. The different mass ratios of three raw materials (BFS, SS and clay) had no significant effect on the thermal behaviors of the ceramsite, with the DT-TG analysis curves showing essentially the same trends in terms of variation. As the sintering temperature increased, the complex crystalline phases appeared at 900°C, while no variation occurred within the main crystalline phases except for the transformation from akermanite (Ca 2 MgSi 2 O 7) to gehlenite [Ca 2 Al(AlSiO 7)] at 1050°C.

In order to solve disposal problem of solid waste, blast furnace slag (BFS) and sewage sludge (SS) were tested as components for producing ceramsite. This study investigated the feasibility of that at different preheating and sintering temperature and duration and different mass ratios (BFS: SS: clay). The results show that the optimal preheating temperature and duration were 400°C and 20 min and that of sintering were 1000°C and 20 min. When the content of BFS increased and that of SS declined, the bulk and apparent density gradually increased while the 1 h water adsorption rate relatively decreased. The ceramsite produced had very good characteristics of solidifying heavy metal and the values of Cd, Cr and Sn met China national standard (GB5085.3-2007); the leaching dose of heavy metals reached minimum at 1100°C. With the increasing of sintering temperature and duration, the gas was gradually released from the ceramsite to form many pores and the glass phase and smooth surface appeared in the ceramsite. The turning point of sintering temperature and duration were 1000°C and 20 min. The conclusions reveal that it is feasible to produce ceramsite by using blast furnace slag and sewage sludge.