A Research on the Recycling of PVC Waste by “Three-Rail Green Cycle”

Based on the hazardous effect of PVC incineration, the perception of public and the condition of waste management, PVC should be considered as recessive deleterious substance in our life. An investigation about the perception and ways of disposal of PVC has got 1096 efficative questionnaires to analyze.The investigated group includes residents which mainly consist of students in 25 high schools and dozens of communities in 9 districts or counties in Tianjin. At the same time, the production, sale, management, recycling, and treatment link of PVC plastics has been investigated. Base on the results and the current circumstances in China, the"three-rail green cycle"system to recycle PVC waste is recommended,and high school students may help promote the system.

Indigofera species with agronomic potential in the tropics. Rat toxicity studies

Lack of information on the feeding value and on the presence of deleterious substances in many species belonging to the genus Indigofera has limited the potential use of these species as feed and fodder legumes. To obtain such information, leaves and seeds of 46 accessions representing 19 species of Indigofera that had shown some agronomic value were incorporated into a semi-synthetic diet at 5% w/w (seed) or 20% w/w (forage). The diets were fed to groups of young rats for 4 weeks, and dry matter intakes and growth rates relative to control diets were measured. Selected organs were examined for any histological changes. Seed and forage samples were analysed for indospicine, a hepatotoxin, and for the presence of another potentially deleterious substance, 3-nitropropanoic acid. Thirteen of the accessions representing 8 species were readily eaten and did not depress growth rates relative to control feeds, and another 13 representing 10 species gave acceptable growth rates. Liveweight gains were less affected by forage diets than by those containing seeds. With the exception of those in rats fed on diets containing I. spicata and I. nigritana, the organs of all other rats were histologically normal. It is unlikely that the concentration of 3-nitropropanoic acid (0.5-3.4 mg g-1 dry matter) in any feed was high enough to cause any of the observed toxic signs. Indospicine was present in only 4 of the 23 species tested, including all accessions of I. spicata, and the concentration of indospicine was a good indicator of the toxicity of these feeds. It is concluded that accessions that had produced growth rates comparable to those of controls may be recommended as non-toxic feeds suitable for further testing.