Investigation on organic pollutants from a domestic heating system using various solid biofuels

Various herbaceous biofuels (straw, whole plant cereals and set aside hay) and spruce wood were tested for their potential to form PCDD/F, PCPh, PCBz and PAH during combustion. The trials were conducted in an automatically ch arged multi-fuel furnace for domestic applications (50 kW(th)). Both, flue gas and the different ash fractions were analysed. GO-emission results show , that combustion conditions were relatively uniform (mean GO-level: 200 mg /m(3) at 13% O-2 in flue gas). Likewise, the TOC- and PAM-emissions in the fuel gas remained constantly on a relatively low level. However, for the PC DD/F, PCPh and PCBz increased emissions were detected when herbacious fuels were applied. This may be attributed to their higher chlorine concentratio n and the high ash content, which is responsible for increased dust emissio ns during combustion. Similar observations were also found for the PCDD/F-c oncentrations in the ashes. Combustion chamber ashes usually showed a drast ically reduced contamination with highly toxical compounds, compared to the ash fraction from the heat exchanger ash or to chimney soot. (C) 2000 Else vier Science Ltd. All rights reserved.