Unintended organic compounds formed when combustion of a target contaminant is incomplete, including dioxins, furans, polycyclic aromatic hydrocarbons, and lower-molecular-weight chlorinated organics. PIC formation is the primary off-gas concern for any thermal treatment system.
Products of Incomplete Combustion form when combustion temperatures, residence time, oxygen, and mixing (the Three T's plus mixing) are insufficient to fully oxidize the organic feed. Dioxins and furans are the most regulated PICs because trace formation is thermodynamically favoured in chlorine-bearing waste streams between 250 and 450 degrees Celsius, the temperature window through which flue gas passes during cooling.
PIC control is the central engineering challenge for thermal remediation of chlorinated waste. The standard design defense is a secondary combustion chamber above 1,000 degrees Celsius with at least two seconds of residence time, followed by rapid quench through the 250 to 450 degree window to prevent post-combustion reformation, and activated-carbon polishing of the cooled flue gas. Continuous monitoring of surrogate indicators (carbon monoxide, total hydrocarbons) is required by most permits, with periodic stack testing for the PIC compounds themselves.
Also known as: PIC, PICs, products of incomplete combustion.
Dioxins and Furans (PCDD/PCDF): treatment approach
A family of 210 chlorinated tricyclic aromatic congeners — including 2,3,7,8-TCDD — formed as unintended byproducts of combustion, chlorine chemistry, and legacy herbicide manufacture; persistent, bioaccumulative, and destroyed only by high-temperature thermal treatment.
The regulatory metric for thermal destruction performance, expressed as the percentage of a target contaminant destroyed across the system. Common permit thresholds range from 99.99 percent for general hazardous organics to 99.9999 percent (six nines) for PCBs, dioxins, and PFAS.
The duration that gas, vapor, or solids remain inside the heated zone of a thermal treatment unit; together with temperature and turbulence, one of the three governing parameters of complete contaminant destruction.
Liquid that has percolated through contaminated soil, waste, or stockpiles, dissolving and carrying contaminants downward to groundwater or to a collection system. The principal migration pathway for PFAS, dissolved metals, salts, and hydrocarbons from impacted sites.
Laboratory method that oxidizes PFAS precursors in a sample into measurable perfluoroalkyl acids, then quantifies the difference against a pre-oxidation baseline. Reveals the hidden precursor mass that targeted PFAS analysis alone misses.