tailieunhanh - Synthetic Organic Chemicals in Biosolids

It was noted before that several synthetic copper chemicals are used in organic agriculture as fungicides. Although small amounts of copper are essential for life, it is a toxic element at higher levels. There have been reports of people committing suicide by ingesting it. Vineyard sprayers have experienced liver disease from exposure to it. It is corrosive to the skin and eyes and is absorbed through the skin. It causes reproductive problems in birds, hamsters and rats. It has been shown to induce heart disease in the offspring of pregnant hamsters that were exposed to it. It has caused endocrine tumors in chickens. Copper sulfate and. | C. Henry UWB Understanding Biosolids 1 05 Chapter 7 Synthetic Organic Chemicals in Biosolids Society produces and consumes immense quantities of organic chemicals. Synthetic organic chemicals are made in the laboratory and as by-products of manufacturing burning or other human activities. Organic once described anything that was originally living matter in the scientific world however any substance containing carbon molecules is organic. Here synthetic organic chemicals are referred to simply as organics to distinguish them from organic matter derived from plants and animals. Natural processes do not create organics of general environmental concern. The differences between organics and trace metals are important. In particular concentrations of organics are extremely low in biosolids - industrial pretreatment and household hazardous waste programs are working well. Metals can be measured at 10 to 1000s of parts per million ppm 10-1000s of mg kg but organics seldom reach concentrations of 1 ppm and often are either below detection levels or measured in the parts per trillion ppt range. Their toxic potential in biosolids is thus remote even though they are far more toxic than metals at similar concentrations. A few of the more common organics are listed in Table and some are present in biosolids because households and industries continue to discharge minute amounts as sewage. The levels of organics are very low in biosolids for two reasons. First increased awareness of their dangers has led to regulations eliminating persistent ones in favor of others that are more easily degraded. Second many organics are volatile. Compounds such as benzene trichloroethylene and chloroform are lost to the atmosphere in sewers and aeration basins of wastewater treatment facilities. Also unlike metals organics degrade with time. Some degrade very slowly but many of the most persistent are no longer produced . polychlorinated biphenyls -- PCBs -- once commonly used in .