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' 'Ibe Relatiouhip Between Chlorine in Wute $Irr~ms and Dioxin Emissions from Wute Combustor Sucks Similar techniques were employed to analyze the results of the major pazametric MWC studies conducted under the auspices of Environment Canada, Environmental Protection Agency, New York State Energy Research and Development Authority and the Great Lakes Regional Coun- cil of Governors. No statistically significant relationship betwcen PCDD/F concentrations in the products of combustion and chlorine input was found in the data from these studies. The same mixed picture is found for MWI's with 15 percent showing an increase and 7 per- cent showing a decrease in PCDD/F concentrations in the stack gases with increasing chlorine feed. IiWi's taken as a whole show no observable relationship between PCDD/F and chlorine con- centrations in the waste being burned. Examination of individual facilities reveals that some have been tested over a 10:1 range of chlorine contents, up to almost 80 percent chlorine, and display no discernible relationship. Eightcen percent of the HWI facilities, however, showed ' an increase, while 78 percent showed a decrease with increasing chlorine feed. Cement Kilns displayed no apparent stack gas PCDD/F concentration increase with increasing chlorine ftxd rate. This is not surprising, since chlorine is frequently added to remove natural alkalis and produce Portland cement meeting federal and state construction standazds. The waste fired boilers showed decreasing PCDD/F rnncentrations with increasing chlorine, ' but boiler design and cofiring fuel differences confound this finding. Biomass combustors produce PCDD/F, but there is too little simultaneous PCDD/F and chlo- tine data to determine if there is a general trend. One test replacing salt laden wood with higher chlorine sludge displayed reduced PCDD/F concentrations rn the stack gases. While some laboratory experiments show that there is a functional relationship between chlo- rine input and PCDD/F concentrations in the products of combustion under certain conditions, the effect is much smaller than the effect of confounders like combustor design, operating practices and the normal variability found in emission measurements made at commercial scale systems. Whatever effect chlorine has on stack gas PCDD/F concentrations from waste combustors is masked by these other variables. Discernible changes and consistent improvements in PCDD/F waste combustor stack concentrations are unlikely to be realized by reducing waste chlorine content. Y i