Based on field detected water quality data, the distribution characteristics of different forms of nitrogen in a reservoir as drinking water source in Dongguan, which locates at the Pearl River Delta of China, have be...Based on field detected water quality data, the distribution characteristics of different forms of nitrogen in a reservoir as drinking water source in Dongguan, which locates at the Pearl River Delta of China, have been analyzed in order to provide theoretical bases for prevention and reduction of eutrophication. The analyzed results show that nitrogen forms in the influent area of the reservoir are given priority to ammonia nitrogen and nitrate nitrogen, whose proportion is more than 45% respectively, and this is probably caused by the pollution of inflow water quality;but in the effluent area, the forms are given priority to nitrate nitrogen, whose proportion is as high as 96% and above;also the proportion of ammonia nitrogen drops by more than 80% during the process from the influent area to the effluent area, and this shows that the natural process of nitrification and denitrification can be well accomplished in the reservoir. We recommend here that to reduce the input amount of ammonia nitrogen and organic nitrogen into the reservoir is the most efficient way to prevent or mitigate eutrophication of water body.展开更多
In order to improve the purification properties of polysulfone (PSF) ultrafiltration membranes (UFM), nano-graphene oxide (nano-GO) was taken as modifier, and the physical blending process was adopted in our experimen...In order to improve the purification properties of polysulfone (PSF) ultrafiltration membranes (UFM), nano-graphene oxide (nano-GO) was taken as modifier, and the physical blending process was adopted in our experiment. The microstructure, surface morphology and functional groups of modified UFM have been characterized respectively by scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy, and the static contact angle between the membrane surface and the water droplet has also been detected to show the change of its hydrophilicity. Through experiments, it has been found that modified UFM has larger and more developed finger micro-pores, and there exist a large number of -OH groups on its surface, and also its hydrophilicity has been enhanced. The result of the experiments show that the modified UFM may keep rejection above 97% and its water flux can be reached at about 219.1 L/(m2·h) under pressure of 1 bar if 0.4 wt% of nano-GO was added. Additionally, the nano-GO can increase the flux recovery radio (FRR) of the membranes, and the maximum FRR was observed as 74.4% if 0.3 wt% of nano-GO was appended.展开更多
Interactions of chloramine with organic nitrogen compounds during purification of water for drinking may generate carcinogenic N-nitrosodime-thylamine (NDMA) as byproduct, and it has been found that cationic amine-bas...Interactions of chloramine with organic nitrogen compounds during purification of water for drinking may generate carcinogenic N-nitrosodime-thylamine (NDMA) as byproduct, and it has been found that cationic amine-based water treatment polymers may be one of the important precursors of NDMA. We have analyzed experimentally the influence rule of NDMA formation during chlorination and disinfection, in order to provide technical support for reducing or even avoiding the formation of NDMA. The formation characteristics of nitrosamines during the chlorination of poly-diallyldimethylammonium chloride (polyDADMAC) have been studied during our experiments. The results show that the type of chlorinating agent is crucial for the generation of NDMA;if pH = 7, NDMA has the great potential formation;the NDMA potential formation increases with temperature. The yield of NDMA will be higher as the concentration of monochloramine is 1.5 to 2.5 times of the precursor;the variation of polymer with reaction time can explain the concentration of NDMA in terminal water of pipe network is higher than that in drinking water.展开更多
文摘Based on field detected water quality data, the distribution characteristics of different forms of nitrogen in a reservoir as drinking water source in Dongguan, which locates at the Pearl River Delta of China, have been analyzed in order to provide theoretical bases for prevention and reduction of eutrophication. The analyzed results show that nitrogen forms in the influent area of the reservoir are given priority to ammonia nitrogen and nitrate nitrogen, whose proportion is more than 45% respectively, and this is probably caused by the pollution of inflow water quality;but in the effluent area, the forms are given priority to nitrate nitrogen, whose proportion is as high as 96% and above;also the proportion of ammonia nitrogen drops by more than 80% during the process from the influent area to the effluent area, and this shows that the natural process of nitrification and denitrification can be well accomplished in the reservoir. We recommend here that to reduce the input amount of ammonia nitrogen and organic nitrogen into the reservoir is the most efficient way to prevent or mitigate eutrophication of water body.
文摘In order to improve the purification properties of polysulfone (PSF) ultrafiltration membranes (UFM), nano-graphene oxide (nano-GO) was taken as modifier, and the physical blending process was adopted in our experiment. The microstructure, surface morphology and functional groups of modified UFM have been characterized respectively by scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy, and the static contact angle between the membrane surface and the water droplet has also been detected to show the change of its hydrophilicity. Through experiments, it has been found that modified UFM has larger and more developed finger micro-pores, and there exist a large number of -OH groups on its surface, and also its hydrophilicity has been enhanced. The result of the experiments show that the modified UFM may keep rejection above 97% and its water flux can be reached at about 219.1 L/(m2·h) under pressure of 1 bar if 0.4 wt% of nano-GO was added. Additionally, the nano-GO can increase the flux recovery radio (FRR) of the membranes, and the maximum FRR was observed as 74.4% if 0.3 wt% of nano-GO was appended.
文摘Interactions of chloramine with organic nitrogen compounds during purification of water for drinking may generate carcinogenic N-nitrosodime-thylamine (NDMA) as byproduct, and it has been found that cationic amine-based water treatment polymers may be one of the important precursors of NDMA. We have analyzed experimentally the influence rule of NDMA formation during chlorination and disinfection, in order to provide technical support for reducing or even avoiding the formation of NDMA. The formation characteristics of nitrosamines during the chlorination of poly-diallyldimethylammonium chloride (polyDADMAC) have been studied during our experiments. The results show that the type of chlorinating agent is crucial for the generation of NDMA;if pH = 7, NDMA has the great potential formation;the NDMA potential formation increases with temperature. The yield of NDMA will be higher as the concentration of monochloramine is 1.5 to 2.5 times of the precursor;the variation of polymer with reaction time can explain the concentration of NDMA in terminal water of pipe network is higher than that in drinking water.
