Factor Analysis on Quantity of Discharged Pollutants in Wastewater in Major Cities

The research performed statistical analysis on 186 data concerning the amount of discharged industrial wastewater, the amount of oxygen demand of industrial wastewater, the amount of ammonia and nitrogen discharged from industries, the amount of urban discharged domestic sewage, the amount of daily life chemical oxygen demand, and the amount of domestic ammonia and nitrogen to explore source of pollutants from wastewater and guarantee urban water quality.Factor analysis was then performed with SPSS according to discharge quantity of pollutants. The results should that the major pollutants are from domestic sewage it is expected scientific suggestions be proposed on water quality in our country.

Effects of Gamma-Ray Irradiation on Dielectric Surface Breakdown of Polybutylene Naphthalate and Polybutylene Terephthalate Under Reduced Pressure

With the increasing application of electric and electronic devices in space and nuclear power stations, the polymeric insulation materials are inevitably exposed to various kinds of environments. Accordingly, it becomes necessary to investigate the effects of the radiation and air pressure on insulation materials. This paper describes the effects of gamma-ray irradiation and reduced pressure on dielectric breakdown of polybutylene naphthalate (PBN) and polybutylene terephthalate (PBT) by applying a DC pulse voltage. Both PBN and PBT were irradiated in air up to 100 kGy and then up to 1 000 kGy with a dose rate of 10 kGy/h by using a60Co gamma-source. The effects of total dose and reduced pressure on the time to dielectric breakdown and discharge quantity were discussed. Obtained results show that, while increasing the total dose, the discharge quantity decreased with PBN, but increased with PBT. With decreasing the air pressure, the discharge quantity increased with PBN, but decreased with PBT. With increasing the total dose, the time to dielectric breakdown increased with PBN, but decreased with PBT. With decreasing the air pressure, the time to dielectric breakdown increased with both PBN and PBT. The experimental results suggest that the chemical structure of polybutylene polymers plays a main role in the result of radiation reaction, which is related to cross-linking and degradation reaction.

An evaluation of mercury emissions from the chlor-alkali industry in China

The present status and the history of chlor alkali industry using mercury as cathode in China has been studied. Quantitative mercury emission has been estimated. At present, 17.5%—20% of the consumed mercury is released into water, 49.1%—53.3% of the Hg is discharged to the brine system outside the plants. 10%—14% of the Hg is emitted directly to the atmosphere, 5 3%—6 7% enters waste materials. The chlor alkali industry in China discharged about 17 tons every year. The total amount of mercury released by the chlor alkali industry in China is estimated to be 1400—2700 tons since 50's. With the result of improved technology and more strict environmental regulations started in late 1970's, chlorine plants reduced their mercury loss factor from 0 5? ? 4 kg/t NaOH before 1977 to 0.16—0.18 kg/t NaOH in 1997. The number of mercury cells in alkali plants was also reduced. In 1998, China is planning to finish the history of producing chlorine and caustic soda using the mercury cell process in the near future. How to deal with the emitted mercury will remain a main problem.