The presence of water or air in the waste feed for an incinerator's smokestack could have a greater influence on the creation of dioxin in waste gases than chlorine, according to a newAmerican Society of Mechanical Engineers study. H. Gregory Rigo, of the Berea, Ohio, environmental engineering firm of Rigo & Rigo, conducted the ASME study, which concluded separating out PVC is not environmentally beneficial from the perspective of dioxin control.
Significant about the study is its breadth. Some 1,900 test results from waste-to-energy plants, hazardous waste incinerators and cement kilns nationwide were included in the study. Critics of the chlorine and plastics industries previously have connected the presence of PVC with the presence of dioxin,but they have used selected data and different scientific methods to arrive at their conclusions, Rigo said.
Opponents such as Greenpeace have argued that chlorine present in PVC is a major contributor to the presence of dioxins, which are highly toxic even in small amounts in the atmosphere. The ASME study contends that ambient sources of chlorine in a waste feed stream may be more indicative of the presence of dioxin.
According to Rick Hind, a Greenpeace spokesman, the Rigo & Rigo study ``is absolutely useless.''
``Comparing other incinerators is like comparing apples and oranges. Studies of specific facilities conclusively show that dioxin comes from sources of chlorine in the waste stream. It can't come out of thin air,'' he said.
``This is an internally consistent evaluation of all the available data, and it reaches a different conclusion than selectively looking at parts of the data using different methodologies,'' Rigo said.
The first study of its kind for ASME, it reanalyzed the data of a 1986 study by the New York State Energy Research and Development Authority at the Pittsfield, Mass., incinerator and confirmed that adding or deleting PVC from the waste feed stream did not change the amount of dioxin in the emissions, Rigo said.
``The Relationship between Chlorine in Waste Streams and Dioxin Emissions From Waste Combustor Stacks'' is available from ASME at (800) 843-2763.