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The Relationship 13etwaa Chlorine io Wute Strains and Dioxin Emission from Wute Combustor Stacks ABSTRACT This study investigated the impact that waste feed chlorine content and waste stream tempo- rents, including PVC plaztics and salts, have on PCDD/F concentrations in the flue gases at waste combustion facilities. The effort was not intended to develop emission factors, evaluate ' control system performance or azsess PCDD/F relationships in liquid effluents or solid residues. The data were mostly obtained from full-scale tests. Seminal laboratory studies were used to suggest the form relationships might take and help identify significant confound- ing factors which must be taken into aooount. Over 1,900 Municipal Wazte Combustor [MWC], Hazardous Wazte Incinerator [HWIJ, Medi- cal Waste Incinerator [MWIJ, Hazardous Wazte Fired Boiler [HWB], Cement Kiln [CK], ' Biomazs Combustor [BMC], and Laboratory- Bench- and Pilot-Scale Combustor [[,BP] test re- sults from 169 facilities, many with multipPle units, were analyzed to determine whether there is a relationship between stack gas PCDD/F concentrations and chlorine input or uncontrolled gas phase chlorine concentration az a surrogate. Chlorine feed concentration ranked from less than 0.1 percent for many BMC up to 80 percent for some HWI. The chlorine feed con- centration was between these two extremes for most of the other sources and generally spanned an 8:1 range in each category. The data were carefully checked to identify errors and statistical outliers, standardized to common reference condtuons and analyzed to determine if there were any changes in either the signature (composition) or quantity of PCDD/F concentrations. Changes that were greater than meazurement method imprecision were studied to determine whether they were related to differences in waste stream or flue gaz chlorine content. Detailed analysis of the signatures was done using Cluster Analysis. Signatures for data col- lected at the same sampling point within a combustor family (i.e., MWC, HWI, etc.) were all the same unless the run produced a significant number of below detection limit values. Some facilities displayed signature differences exceeding PCDD/F measurement method imprecision betwcen sampling locations. No observable changes in PCDD/F profile were associated with differences in chlorine content. A general review, using a combination of Canonical CotTelation Analysis and simple Linear Regression, found no staUStically significant relationship between chlonne input and PCDD/F stack gaz concentrations for the majority (80 percent) of the 90 facilities which had sufficient simultaneous data to detect a statistically significant trend. Eleven percent displayed an in- crease; 9 percent of the facilities displayed decreasing PCDD/F concentrations with increasing chlorine. i i 1 i Analysis of Variance [ANOVA] and combustion engineering models were combined using Muluvariant Linear and Autoregressive Regression to analyze three major controlled expen- menu at Municipal Wazte Combustors during which PVC, mixed plastics or salt was spiked into the feed. No statistically significant relationship was found betwcen PCDD/F wncentra- tions and chlorine in two of the experiments. In the third, a relationship waz found when the PVC was sufficient to raise the chlorine content to about 10 times that normally found in MWC's. This data set displays severe autocorrclation (run-to-run memory effects), so the ob- served effect may be due to something other than the spiking. iv